Introduction

Microalgae, a diverse group of photosynthetic microorganisms encompassing both prokaryotic and eukaryotic characteristics, have captured significant scientific interest in recent years. Their remarkable ability to thrive in challenging environments, coupled with their rich composition of bioactive compounds, makes them a promising resource for a multitude of applications.

These microscopic powerhouses are wellsprings of essential nutrients, including proteins, lipids, polyunsaturated fatty acids, antioxidants, and other bioactive molecules. Recent advancements in physicochemical and bioactive studies of microalgae have shed light on the intricate interplay between these components, revealing their potential health benefits1. Understanding microalgae’s bioactivities has paved the way for their exploration as novel and sustainable ingredients in food fortification.

The quest for enhancing the nutritional value and health attributes of dairy products has led to the exploration of novel and sustainable ingredients2. Microalgae, with their unique composition and functional properties, have emerged as a frontrunner in this endeavor. Their incorporation into various food products, such as biscuits, bread, noodles, pasta, burgers, and dairy products, offers a promising approach to fortification3,4. This nutritional enrichment not only enhances the quality of food products but also offers the potential for significant health benefits, making it a promising avenue for both the food industry and consumer well-being1,5,6.

Among the diverse microalgae, Spirulina spp. and Chlorella spp. have garnered widespread recognition due to their readily available forms, well-documented health benefits, and particularly their favorable protein and lipid profiles. These features make them suitable candidates for incorporation into reduced-fat labneh. Notably, Spirulina and Chlorella boast a wealth of bioactive compounds, including antioxidants, anticancer agents, antidiabetic properties, and anti-inflammatory effects. Studies have also revealed their potential in managing blood pressure and cholesterol levels, accelerating wound healing, strengthening the immune system, and alleviating conditions like gastric ulcers, constipation, and anemia6. Therefore, this study delves into the potential of incorporating Spirulina and Chlorella into reduced-fat labneh, aiming to enhance its nutritional profile while preserving its sensory characteristics.

Labneh is a dairy product made by straining yogurt to remove its whey, resulting in a thicker, more concentrated yogurt with a creamy white color, a soft and spreadable texture, and a slightly acidic flavor. It is popular in Middle Eastern and Mediterranean cuisines and is often used as a dip, spread, or component in various dishes. Reducing its fat content helps to avoid health problems associated with high dietary fat intake7.

Our novel approach focuses on incorporating Spirulina platensis and Chlorella vulgaris microalgae to enhance the characteristics of reduced-fat Labneh. This is an interesting and unique approach, as it appears that no previous work has been reported on this specific area of microalgae for improving the properties of Labneh with reduced fat content. Further, this approach could be the base for supporting other dairy products, especially soft cheese.

Hence, the primary aim of the present study was to scrutinize the impact of individually incorporating Spirulina platensis or Chlorella vulgaris into reduced-fat labneh, employing three distinct concentrations (0.25, 0.50, and 1.0%). This investigation sought to evaluate the alterations in sensory attributes, physicochemical properties, rheological characteristics, and antioxidant properties induced by these microalgae additions. Additionally, a key aspect under examination was the influence of these incorporations on the viability of the bacterial starter culture throughout refrigerated storage. Finally, the ultrastructural features of the product were explored.

Materials and methods

Milk and microorganisms

Standardized raw buffalo milk (1.5% fat) was obtained from the Dairy Processing Unit, Dairy Department, Faculty of Agriculture, Mansoura University, Egypt.

Two different microalgae species Spirulina platensis and Chlorella vulgaris in the dried powder form were obtained from Microalgae Biotechnology Unite, National Research Center, Cairo, Egypt. According to the provider, microalgae were grown in photobioreactors, containing water and supported with required growth conditions based on the modified Kuhl’s medium8,9. The algae were then collected over periods ranging from two to ten days. The algae were then dried to become suitable for use.

Mixed lyophilized commercial starter (YO-Mixtm 495 LYO 100 DCU), containing Streptococcus thermophiles, and Lactobacillus delbrueckii subsp. bulgaricus was obtained from the Danisco Culture Unit, Danisco, France. To activate the probiotic starter, 2% (w/v) was inoculated in sterilized skim milk (10% total solids), followed by mixing well to dissolve the starter. The inoculated milk was incubated at 42°C to obtain satisfactory coagulation. The resultant coagulation milk was used to inoculate labneh milk at a concentration of 2%, w/v10.

Manufacturing of labneh

Reduced fat labneh was prepared from standardized buffalo’s milk. Milk was pasteurized through heating at 95°C for 10 min, then rapidly cooled to 42°C. It was then divided into seven equal portions. The first portion was used as a control labneh sample. The other six portions were fortified with either Spirulina platensis or Chlorella vulgaris powder at concentrations of 0.25, 0.50, and 1.00% (w/v), followed by mixing very well to dissolve the microalgae powder. Prepared milk with or without microalgae was inoculated with a mixed commercial starter culture containing Streptococcus thermophiles, and Lactobacillus delbrueckii subsp. bulgaricus at 2% (w/v). All seven resulting treatments were incubated at 42°C till obtaining satisfactory coagulum. The resultant curds were scooped into a cloth bag, to drain the excess of whey overnight. Resultant labneh samples were removed from the bag, salted with 2% NaCl, packed into sterile plastic containers, and kept in the refrigerator at 6°C until further analyses. The production process illustrated in the flowchart (Fig. 1) effectively clarifies the overall study design and the integration of microalgae into the labneh production in addition to the process evaluation.

Fig. 1
figure 1

Flowchart of labneh production with microalgae incorporation, and process evaluation.

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Physicochemical properties

The content of total solids, fat, total protein, carbohydrates, and ash in the samples was determined following the methodologies outlined by the Association of Official Analytical Chemists11.

Total solids represent the non-water portion of milk and milk products, encompassing proteins, fat, lactose, minerals, and other components. Measuring total solids is a crucial quality control step in dairy production12,13. In our analysis, a two-gram sample of each product underwent oven drying at 105°C in an air-drying oven until a constant weight was reached. The total solids content was then calculated as a percentage.

Fat content varies within milk, impacting its quality, value, and purchasing decisions14. Typically, milk fat falls between 3.5 and 4.7%, although it can range from 3 to 6%. This fat content influences milk’s nutritional profile, physical characteristics, and even its chemical make-up. Traditionally, the Soxhlet method extracts fat from food samples. This method involves drying and grinding the sample before placing it in a thimble within a three-part apparatus: a flask, an extraction chamber, and a condenser15. In our analysis, a two-gram sample underwent a 24-h fat extraction using n-hexane solvent in a Soxhlet apparatus. After solvent removal, the fat content was expressed as a percentage.

The Kjeldahl method remains the most common technique for determining milk protein concentration16. This method involves digesting protein with concentrated sulfuric acid. Following digestion, sodium hydroxide liberates ammonia gas, which is then steam-distilled into a boric acid solution. Titration with sulfuric acid quantifies the captured ammonia, allowing calculation of the total nitrogen content in the sample using a conversion factor. The standard conversion factor of 6.25 assumes all proteins contain 16% nitrogen and that all nitrogen originates solely from protein17,18.

Ash content, a key component of nutritional evaluation, represents the inorganic minerals remaining after burning a food sample. To determine the ash content in milk, we incinerated 2-g samples in silica crucibles at 600°C within a muffle furnace until a constant weight was achieved19. The final ash residue was then expressed as a percentage of the initial sample weight.

The pH value decides whether the labneh will be soft or hard. pH is also checked during cheese preparation, the souring of milk, and cream maturation. The growth of pathogens in fresh and soft varieties can be slowed down drastically by ensuring that the pH stays within the 4.1 and 5.3 range, pH is measured for a plethora of reasons, such as a measure of milk quality (microbial spoilage), acidification of casein, cheese production, maintaining optimum conditions during protein hydrolysis20. pH values were determined electrometrically with a pH meter (Hanna Instruments Microprocessor pH Meter 211).

The phenol–sulfuric acid method is a widely used technique for total carbohydrate analysis due to its simplicity and sensitivity21. This method effectively detects a broad range of carbohydrates, including mono-, di-, oligo-, and polysaccharides22. Total carbohydrates were also determined by using the phenol–sulfuric acid method as described by23.

Determination of amino acids content by HPLC

To determine specific amino acid profiles in 50 mg labneh samples after 7 days’ refrigeration, hydrolysis was performed with 4 M HCl at 100°C for 12 h, followed by filtration, drying, and resuspension in 0.1 M HCl. An Agilent 1260 series HPLC system equipped with a suitable column analyzed 1 mL injections using a gradient mobile phase (A: sodium phosphate dibasic and sodium borate, pH 8.2; B: ACN: methanol: water 50:40:10) at 1 ml/min and 40°C. The gradient started at 98% A and held for 0.84 min, then decreased linearly to 43% A in 32.6 min, dropped to 0% A for 6 min, held at 0% A for 0.2 min, then returned to 98% A within 0.6 min and held for the final 0.4 min. This method optimizes hydrolysis and gradient for better separation and sensitivity, particularly for glutamine, tryptophan, and hydrophobic amino acids like phenylalanine and leucine.

Fatty acid detection by gas chromatography

Following a modified Zahran and Tawfeuk24 method, the fatty acid composition was determined after 7 days. Sample fatty chains were transmethylated to FAMEs and separated using an HP 6890 GC equipped with a Supelco SP-2380 column and FID detector. Both injector and detector temperatures were set at 250°C. The column temperature started at 140°C (held for 5 min) and then ramped to 240°C at 4°C/min (held for 10 min). Helium served as the carrier gas at 1.2 mL/min. 1 µL samples (in n-hexane) were injected with a 100:20 split ratio. Identification occurred by comparing retention times to known FAME standards (Supelco 37 component mix). Results were reported as the relative percentage of each fatty acid based on the total peak area.

Determination of pigment content

Labneh pigments were measured after adding algae to assess its impact on sensory aspects for consumer acceptance. Labneh samples contents from pigments including chlorophyll a, b, and carotenoid were determined at zero and 21 days of refrigerated storage as described by Barkallah, et al.25. Determination of chlorophylls and carotenoids was performed on a fresh representative homogeneous sample of labneh. 500 mg of each sample was mixed well with 10 ml acetone (80%), followed by centrifugation at 3000 rpm for 15 min and the supernatant was stored. The pellet was re-extracted by repeat washing with 5 ml acetone (80%) till it became colorless. All extracts were pooled, and the pigment content was estimated by measuring the supernatant absorbance at A480, A510, A645, and A663 nm. The optical density of those samples was used to calculate the concentration of pigments by applying the internationally recognized equations25,26,27. The concentration of pigments was calculated (mg/g) using the following Eqs. (1–4):

$${\text{Chlorophyll a}} = \left( {\left( {12.7 \times {\text{A}}_{663} - 2.69 \times {\text{A}}_{645} } \right) \times {\text{V}} \times {\text{W}}} \right)/1000$$
(1)
$${\text{Chlorophyll b}} = \left( {\left( {22.9 \times {\text{A}}_{645} - 4.68 \times {\text{A}}_{663} } \right) \times {\text{V}} \times {\text{W}}} \right)/1000$$
(2)
$${\text{Total chlorophylls }}\left( {\left( {20.2 \times {\text{A}}_{645} + 8.02 \times {\text{A}}_{663} } \right) \times {\text{V}} \times {\text{W}}} \right)/1000$$
(3)
$${\text{Carotenoids}} = \left( {\left( {7.6 \times {\text{A}}_{480} - 1.49 \times {\text{A}}_{510} } \right) \times {\text{V}} \times {\text{W}}} \right)/1000$$
(4)

where; V is the total volume, and W is the total weight.

Total phenolic compounds

Total phenolic content was also determined in the labneh samples as described by28. A weight of 0.5 g sample was mixed with 5 ml ethanol (80%) by vortex, and then left to stand for 20 min, then mixed by inversion. 2 ml were transferred to into clear Eppendorf and followed by centrifugation at 12,000 rpm for 5 min at 4°C. 150 µl supernatant was mixed with 150 µl MeOH (80%), 150 µl Folin-Ciocalteu reagent, and 1050 µl Na2CO3 (20%) by vortex, followed by centrifugation at 13,000 rpm for 3 min at 4°C. The absorbance was measured at A725 nm relative to a blank containing 80% aqueous methanol instead of extract. The concentration was determined from a calibration curve using gallic acid as standard. The results were expressed as gallic acid equivalents (mg GAE/g).

Antioxidant activity

Free radical scavenging activity of labneh samples was evaluated at zero and 21 days of refrigerated storage according to the method described by Siger, et al.29 as follows, 0.5 g sample was mixed with 5 ml ethanol (80%) by vortex, and then left to stand for 20 min, then mixed by inversion. 2ml were transferred into clear Eppendorf and followed by centrifugation at 12,000 rpm for 5 min at 4°C. 1 ml supernatant was mixed with 3 ml methanol, followed by the addition of 1 ml 2,2-diphenyl-1-picrylhydrazyl (DPPH) (0.1mM) and incubated in the dark for 30 min. The absorbance was measured at A517 nm. The antioxidant scavenging activity was calculated using the following Eq. (5):

$${\text{DPPH antioxidant scavenging activity }}\left( {\text{\% }} \right) = \left( {\frac{{{\text{A}}_{{{\text{control}}}} - {\text{A}}_{{{\text{sample}}}} }}{{{\text{A}}_{{{\text{control}}}} }}} \right)/100$$
(5)

Texture analysis

After coagulation, both curd tension and syneresis were assessed for each labneh treatment. Curd tension followed the method of Chandrasekhara, et al.30, expressed as the weight (grams) required to remove a knife from the curd. Conversely, curd syneresis followed the method of31. This phrasing condenses the original while maintaining clarity and referencing the methodologies.

Texture analysis of resulting labneh from various treatments was conducted on both day 0 and day 21 of refrigerated storage. A texture analyzer (Multi-test 1dMemesin, Food Technology Corporation, UK) equipped with a 25 mm diameter perplex conical probe facilitated this evaluation. Following the methodology outlined by Soliman, et al.32, texture profile analysis was performed on all samples. Textural parameters were subsequently calculated from the generated force–time curves33.

Rheological features

Rheological properties were measured with a texture analyzer (Multi-test 1dMemesin, Food Technology Corporation, UK) that allows for the automated computation of various sample characteristics such as hardness, springiness, cohesiveness, gumminess, and chewiness. These parameters, which form the texture profile, were successfully determined, and computed34,35.

Microbiological evaluation

To assess the impact of different treatments on the microbial ecology of labneh, a comprehensive microbiological evaluation was performed. This analysis provided a detailed profile of the bacterial and fungal communities within the labneh samples. The standard plate count technique was employed to quantify starter culture (lactic acid bacteria) on M17 agar (Oxoid) after anaerobic incubation at 37°C for 24 h36. Total aerobic bacteria were enumerated on tryptone soy agar plates under aerobic conditions at 37°C for 24 h37. Coliform bacteria presence was assessed using MacConkey agar with similar incubation parameters38. Finally, mold and yeast counts were determined on potato dextrose agar, following aerobic incubation at 30°C for 24 h39.

Sensory evaluation

A sensory evaluation was conducted on labneh samples, with a total score of 100 points assigned to flavor and taste (40 points), body and texture (30 points), and color and appearance (30 points)40,41. The sensory evaluation adhered to the ethical guidelines for sensory evaluation outlined by the Institute of Food Science and Technology42. A panel of twelve highly trained panelists (selected based on their sensory analysis expertise) evaluated the sensory properties. A standardized protocol was followed to prevent bias and ensure the health and safety of the panelists. This included blind testing with samples coded with random three-digit numbers and maintaining a controlled environment to minimize external influences. The recruitment of trained panelists and adherence to ethical guidelines underscored our commitment to conducting sensory evaluation with scientific rigor and ethical responsibility. All panelists were volunteers who had provided informed consent, were informed of their right to withdraw at any time.

Chemical analysis of whey

The resultant whey samples were chemically analyzed to determine their content from moisture, total solids, fat, protein, carbohydrates, and ash by using the previously mentioned chemical analysis methods used for labneh samples11.

Determination of labneh yield

Labneh yield refers to the percentage of labneh obtained from a specific initial amount of milk43. The yield of labneh was expressed as a percentage, calculated as the weight of the final labneh product, after separation of the whey from the curd by filtration, divided by the initial weight of the milk used, multiplied by 100% (Eq. 6).

$${\text{Labneh yield}},{\text{\% }} = \left( {{\text{Labneh weight}}/{\text{Milk weight}}} \right) \times 100$$
(6)

Scanning electron microscopy (SEM)

Labneh samples were fixed overnight at 4°C in a 1–2.5% buffered solution of glutaraldehyde + 2% paraformaldehyde in 0.1 M sodium cacodylate buffer (pH 7.4). Following three 15-min rinses in 0.1 M cacodylate buffer with 0.1 M sucrose, samples underwent post-fixation in 2% sodium phosphate buffered osmium tetroxide (pH 7.4) for 90 min, with subsequent rinsing in 0.1 M cacodylate buffer. Dehydration involved graded ethanol washes (50, 80, 90, and 96%) for 15 min each, followed by three 20-min immersions in 100% ethanol. Dehydrated samples were mounted on gold–palladium membranes, sputter-coated with a gold–palladium alloy, and examined using a Jeol JSM-6510 L.V SEM operated at 30 kV.

Statistical procedures

All trials were performed in at least three replicates. The data were introduced as the mean ± standard deviation. The completely randomized design was used, and a one-way analysis of variance was performed, followed by Tukey’s honestly significant difference (HSD) test to compare among mean at a significant level of alpha (α) at 0.05, using CoStat software (version 6.450, CoHort Software, Birmingham, UK) was applied.

For the experiments obtained from single injection, i.e. amino acid (HPLC) and fatty (gas chromatography) acids analysis, bootstrapping was employed to test the variability, and validity of the data, using Minitab software (version 22, Minitab LLC, State College, PA, USA). Bootstrapping is a resampling technique that involves repeatedly drawing samples from the original data with replacement to create numerous simulated samples for estimation of confidence intervals (CI). Two separate bootstrap analyses were conducted: one for the entire treatments considering all amino acids collectively and one for each amino acid considering all treatments. For each analysis, 10,000 bootstrap iterations were performed to estimate the distribution of the mean concentrations. The 95% confidence intervals for the mean concentrations were derived from the bootstrapped distributions, providing an estimate of the variability and reliability of the data despite the lack of experimental replicates.

Results and discussion

Physicochemical characteristics of the fortified labneh

To evaluate the effect of adding S. platensis or C. vulgaris at different concentrations of 0.25, 0.50, and 1.00% on the various characteristics of labneh. Based on recent studies44,45,46, low concentrations (under 1%) of microalgae were used for the fortification process to avoid the negative impact on the organoleptic properties of labneh. Labneh samples were chemically analyzed after zero, 7, 14, and 21 days of refrigerated storage.

Chemical composition

Data (Table 1) show that the addition of S. platensis or C. vulgaris at the concentrations of 0.25%, and 0.50% increased the total solids, fat, carbohydrates, and ash contents compared to the control sample. However, using the concentration of 0.5% from S. platensis increased protein content in labneh samples compared with the concentration of 0.50% from C. vulgaris. S. platensis is a good source of protein as it represents 60–70% of its dry weight47,48.

Table 1 Physicochemical characteristics of control and different treatments of microalga-fortified labneh during the refrigerated storage period.
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Table 1 shows that using 1.0% from S. platensis or C. vulgaris had a very negative effect on the chemical composition, as it caused a high decrease in the total solids, fat, protein, and carbohydrate, contents due to the weakness of the resultant curd and increasing its content from moisture. However, these labneh samples containing 1.0% microalgae had a similar ash content to the control.

The pH values of different labneh treatments during the refrigerated storage period (Table 1) increased by increasing the concentration of added microalgae in comparison with the control sample. However, labneh samples enriched with C. vulgaris had a higher pH value than those enriched with S. platensis. The increasing pH values of labneh samples by the addition of microalgae at different concentrations resulted from the buffering effect of microalgae components such as protein, phosphate, citrate, and lactate49. However, the current study shows that C. vulgaris has a higher buffering effect than S. platensis.

This might be attributed to the capacity of thermotolerant lactic acid bacteria, which is the main factor responsible for lactic acid production50. Lactic acid bacteria are fastidious and require complex growth factors51. Therefore, the total aerobic counts do not include lactic acid bacteria. The stability of the acidity of the milk containing 0.6% of different extracts is probably related to the antimicrobial activity of these extracts52.

Amino acids content

Data from Table 2, and Supplementary files (1–7) show the concentration of amino acids (mg/g) in different labneh treatments compared with the control sample. As shown in this table, the fortification of labneh samples with 0.25% S. platensis increased the concentration of all amino acids compared with the control sample. While the fortification with 0.25% C. vulgaris increased the concentration of some amino acids such as (arginine, tyrosine, valine, isoleucine, and leucine) and had similar concentrations from (aspartic, histidine, glycine, and alanine) to the control sample. However, fortification with 0.5% from S. platensis or C. vulgaris had a similar effect in increasing the amino acid concentrations compared with the control sample.

Table 2 The concentration of amino acids in different treatments of microalgal-fortified labneh detected by HPLC analysis after 7 days of refrigerated storage, including bootstrap analysis for entire treatments and individual amino acids.
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Results also show that the fortification with 1% from S. platensis increased the concentration of amino acids compared with the control sample but to a lesser extent than other concentrations of 0.25, and 0.50%. While the fortification with 0.1% from C. vulgaris increased the concentration of some amino acids such as (histidine, arginine, alanine, tyrosine, methionine, and proline), it also decreased the concentration of other amino acids compared with the control sample.

From these results, it is concluded that the concentration of 0.5% from S. platensis or C. vulgaris had a high effect in increasing the content of labneh samples from non-essential and essential amino acids, which cannot be manufactured by the body and need to be consumed externally from food, and they also have many health benefits. According to WHO/FAO/UNU recommendations, microalgae such as Chlorella sp. and Spirulina sp. contain well-balanced essential amino acids content required for human consumption53. The resulting fortified product contains several amino acids that are regarded as essential for humans and are required during the growth of infants and children54,55.

Fatty acids content

The concentration of fatty acid in different labneh treatments was detected by using gas chromatography analysis. As shown in Table 3 the most abundant fatty acids in the control sample were palmitic acid (31.32%), followed by oleic acid (21.98%), stearic acid (10.98%), and myristic acid (10.58%). Data represented in Table 3, and Supplementary files (8–14) show that the addition of S. platensis or C. vulgaris at different concentrations had a similar effect in increasing the content of fatty acids compared with the control sample. However, the addition of S. platensis and C. vulgaris at 0.5% increased the concentration of α-Linolenic acid to 0.92%, and 0.67 respectively while it was not detected in the control sample, and the addition of C. vulgaris at 0.5% increased the concentration of stearic acid to 44.16%. It is also noted that the concentration of saturated fatty acids is higher than the concentration of unsaturated fatty acids in all treatments and control samples. The high content of unsaturated fatty acids increases the health benefits of the product56. These results agree with the results of the study conducted on yogurt enriched with Spirulina25.

Table 3 The concentration of individual fatty acids (%) in control and different treatments of Spirulina or Chlorella fortified labneh detected by gas chromatography analysis after 7 days of refrigerated storage, including bootstrap confidence intervals.
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Bootstrapping analysis of amino acids and fatty acids

In our study, where single injections were used for amino acid and fatty acid detection, bootstrapping, a non-parametric statistical technique, proved valuable for estimating the variability and reliability of the data. Bootstrapping’s strength lies in its ability to assess variability even with limited data. It achieves this by resampling the original data with replacement, creating numerous simulated datasets that reflect the inherent variability within the population. By analyzing the distribution of statistics (e.g., mean, standard deviation) across these simulations, bootstrapping allows us to estimate how much these statistics might vary if a different sample were drawn from the same treatment group. This approach is particularly advantageous because it requires fewer assumptions about the underlying data distribution compared to traditional methods57,58,59.

We conducted separate statistical bootstrap analyses (Tables 2 and 3) for both amino acids (HPLC analysis) and fatty acids (gas chromatography analysis). One analysis considered all treatments collectively for each class of biomolecules (amino acids or fatty acids), while the other analysis focused on each amino/fatty acid across all treatments.

Bootstrapping revealed significant variability in the concentrations of both amino acids and fatty acids across the different microalgae fortification treatments. This information, despite the limitations of using single injections, provided crucial insights into how fortification impacted the overall nutrient profile of the labneh. The variability observed in the CI from the bootstrap analyses reflects the abundance of specific amino or fatty acids in the samples and suggests differential responses to the treatments57,58,59. These comprehensive analyses provided robust statistical validation of our findings and ensured the reliability of the data regarding the impact of microalgae fortification on the nutrient profile.

Pigments content

In our study, chlorophyll content in labneh was quantified following the addition of algae. This determination was necessary to assess the potential impact of algal pigments on the sensory characteristics of the final product, ensuring its acceptability during commercialization and consumption. Furthermore, chlorophyll and carotenoids, abundant in algae, possess well-documented antioxidant properties, contributing to the product’s health benefits without compromising its sensory appeal.

Microalgae are considered a good source of pigment as they can synthesize natural pigments at higher concentrations, these natural pigments have antioxidant properties beneficial in the prevention of cancer and cardiovascular disease equations25,26,27. Table 4 presents the concentrations of pigments chlorophyll a, chlorophyll b, and carotenoids in labneh samples enriched with S. platensis or C. vulgaris in compared with control after zero time and 21 days of refrigerated storage. The concentration of the detected pigments increased by increasing the concentration of added S. platensis or C. vulgaris. It is also noted that there is no obvious difference between the effect of S. platensis and C. vulgaris on the content of labneh samples from pigments at the same concentration.

Table 4 The concentration of photosynthetic pigments in different labneh treatments enriched with Spirulina platensis or Chlorella vulgaris and control sample after 0 and 21 days of refrigerated storage.
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Total phenolic compounds

Table 5 illustrates the content of labneh from phenolic compounds after 0 and 21 days of refrigerated storage. The concentration of phenolic compounds content increased by increasing the concentration of added microalgae compared with the control sample. It is also noted that the concentration of phenolic compounds in different labneh samples was higher after 21 days of refrigerated storage than the concentrations after 1 day of refrigerated storage. The results also show that the concentration of phenolic compounds in labneh samples fortified with C. vulgaris was higher than those fortified with S. platensis. Besides being functional compounds, the fortification of dairy products with phenolic compounds increases the rate of consumer demand10.

Table 5 The concentration of phenolic compounds and DPPH radical-scavenging activity in different labneh treatments enriched with Spirulina platensis or Chlorella vulgaris and control sample after 0 days and 21 days of refrigerated storage.
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Antioxidant activity

Microalgae are considered a potential source for safe and effective bioactive compounds such as pigments, and phenolic compounds which effectively participate in their antioxidant properties. The current study shows (Table 5) that the antioxidant activity of labneh samples determined as DPPH radical-scavenging activity (%) increased by increasing the concentration of S. platensis or C. vulgaris in comparison with the control sample. It is also noted that the antioxidant scavenging activity in different labneh samples was higher after 21 days of refrigerated storage than the antioxidant scavenging activity at the zero-day of refrigerated storage, and the antioxidant scavenging activity in labneh samples fortified with C. vulgaris was higher than those fortified with S. platensis. Moreover, no signs of spoilage appeared on the stored labneh which may be back to the increased content of cheese in flavonoids, phenolic compounds, and antioxidants10.

Texture analysis

Previous studies showed that supplementation of dairy products with microalgae can affect their texture properties46. Data presented in Table 6 shows the curd tension of different labneh samples expressed as weight in grams required to get a knife out of the curd, and it also shows curd syneresis expressed as weight in grams of separated serum at different periods 30, 60, and 90 min. The presented data shows that the addition of S. platensis or C. vulgaris at different concentrations increased the curd tension and curd syneresis in comparison with the control sample. The curd tension in labneh samples fortified with C. vulgaris was higher than those fortified with S. platensis. However, the curd syneresis in samples fortified with S. platensis was higher than those fortified with C. vulgaris.

Table 6 Curd syneresis and curd tension of different labneh treatments enriched with Spirulina platensis or Chlorella vulgaris and control sample after coagulation.
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Rheological parameters

Rheological properties are mechanical properties resulting in deformation and the flow of material in the presence of stress, these properties are very effective tools in evaluating the variations in constituent materials and mixture proportions on texture and sensory properties. Rheology plays a crucial role in understanding the texture of dairy products60. These products exhibit a range of behaviors, from liquids like milk to solids like cheese. Some, like yogurt, possess characteristics of both. Generally, dairy products are categorized as fluids/semi-solids or solids61.

In the current study, rheological properties such as hardness, springiness, cohesiveness, gumminess, and chewiness were used to characterize the textural changes in different labneh treatments due to the addition of microalgae at different concentrations.

Hardness is the force (Newtons, N) required to achieve a certain deformation, indicating the resistance of the food to deformation. Springiness measures how quickly a deformed food item returns to its original condition after the removal of the force, measured in millimeters, reflecting the food’s elasticity. Cohesiveness is a measure of the strength of the food’s internal bonds, expressed as a percentage (%), showing how well the components of the food stick together. Gumminess is the force (in Newtons, N) needed to break down a semi-solid food to a state ready for swallowing, indicating the food’s resistance to being broken down in the mouth. Lastly, chewiness is the energy (in Newton millimeters, N*mm) needed to chew a solid food to a state ready for swallowing, representing the food’s resistance to being chewed. These parameters, crucial in the study of food texture, can be automatically calculated using specific software, allowing for a more objective and precise analysis of food texture62.

Table 7 shows the rheological parameters of labneh samples fortified with S. platensis or C. vulgaris at different concentrations compared with the control sample after 1 and 21 days of refrigerated storage. Fortification of labneh with S. platensis or C. vulgaris had a significant effect on the rheological properties. Hardness, springiness, Gumminess, and chewiness decreased with increasing S. platensis or C. vulgaris concentration, but cohesiveness values increased in comparison with the control sample. Concentration of 1% S. platensis or C. vulgaris had a very negative impact on the rheological parameters of the resultant labneh. It is also noted that the decrease in rheological parameters in labneh samples fortified with C. vulgaris was higher than in labneh samples fortified with S. platensis. All the rheological parameters decreased after 21 days of refrigerated storage except the springiness of samples containing C. vulgaris increased after 21 days of refrigerated storage.

Table 7 Rheological properties of different labneh treatments enriched with Spirulina platensis or Chlorella vulgaris and control sample after one and 21 days of refrigerated storage.
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Microbiological analysis

A comprehensive microbiological evaluation was conducted on labneh samples from various treatments to create a detailed picture of their microbial profile. Notably, no coliform bacteria were detected in any of the samples, indicating effective sanitary practices during production and contributing to overall product safety.

Viability of the starter culture

Labneh samples were analyzed for the viability of the starter culture during coagulation along 21 days of refrigerated storage. As shown in Fig. 2 viable counts of the starter culture (log cfu/ml) decreased in all labneh samples after 1 day of refrigerated storage except the labneh sample containing 0.25% S. platensis was higher (8.32 log cfu/ml). It is also noted that during the storage time of up to 21 days, the viable counts were almost constant except labneh sample containing 1% C. vulgaris, and the control sample decreased to 6.44, and 6.86, log cfu/ml, respectively. Both S. platensis and C. vulgaris had a beneficial effect on the viability of the starter bacteria, this may be due to their higher content of nutrients such as protein, essential fatty acids, vitamins, and minerals10,63.

Fig. 2
figure 2

Viability of the starter culture after coagulation and the refrigerated storage for 21 days in labneh samples fortified with Spirulina platensis or Chlorella vulgaris in comparison with the control sample. ns; nonsignificant differences. HSD; Tukey’s honestly significant difference at a significant level of α at 0.05.

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Figures 3 and 4 show the total bacterial count and counts of yeasts and molds, respectively, during the refrigerated storage period. The total bacterial count and the counts of yeasts and molds increased during the refrigerated storage period to up to 14 days, then decreased after 21 days. It is also noted that the labneh sample containing 1% C. vulgaris contained a lower total count and counts of yeasts and molds compared with other labneh samples and control samples. Coliform bacteria were not detected in all labneh samples during the storage period.

Fig. 3
figure 3

Total bacterial count during 21 days of refrigerated storage in labneh fortified with S. platensis or Chlorella vulgaris in comparison with the control sample. ns; nonsignificant differences. HSD; Tukey’s honestly significant difference at a significant level of α at 0.05.

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Fig. 4
figure 4

Counts of yeasts and molds during 21 days of refrigerated storage in labneh samples fortified with Spirulina platensis or Chlorella vulgaris in comparison with the control sample. ns; nonsignificant differences. HSD; Tukey’s honestly significant difference at a significant level of α at 0.05.

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The reduction in the microbial community may be due to the content of bioactive compounds (flavonoids, steroids, tannins, saponins, and alkaloids) in the fortified labneh that was directly proportional to the antioxidant and antimicrobial activities. As previously stated, these bioactive compounds had antioxidant and antimicrobial properties64. Several probable mechanisms have been suggested for the bioactive compounds. They can damage the enzymatic processes involved in energy production during finishing or destruction of the permeability block of the cell membrane by varying the physiological state of the cells or affecting synthesis of the structural components65. Thus these bioactive metabolites were reported to have various antimicrobial activities66.

Sensory evaluation of fortified labneh

All labneh samples were sensory evaluated during 21 days of refrigerated storage. As shown in Table 8, the addition of both S. platensis and C. vulgaris at 0.25% or 0.5% had no negative impact on the flavor, taste, body, and texture of the labneh samples compared with the control sample. However, the concentration of 1% for both types of microalgae had a very negative impact on the acceptability and all sensory parameters compared to other treatments and control samples with unpleasant flavor, and it also caused weakness of the resultant curd with the appearance of the wheying-off defect in compared with other treatments and control sample. Furthermore, S. platensis had a very similar effect with C. vulgaris on the organoleptic characteristics of the resultant labneh at all concentrations.

Table 8 Effect of the supplementation with Spirulina platensis or Chlorella vulgaris on the sensory characteristics of labneh during the refrigerated storage period.
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The addition of S. platensis or C. vulgaris into the labneh had an obvious effect on the color of all treatments compared to the control sample where the color of these treatments changed from green to blue due to the concentration of added microalgae (Supplementary Fig. 1). This characteristic was acceptable by panelists at concentrations of 0.25 and 0.5% of added microalgae. However, it was not acceptable at a concentration of 1%. It is also possible to add some herbs such as Thymus vulgaris or Mentha to match the resultant color with the taste at concentrations of 0.25 and 0.5% of added microalgae.

Chemical composition of whey

Whey is the byproduct resulting from the milk curd after coagulation67. Data presented in Table 9 shows the chemical composition of whey samples resulting from different labneh treatments, and control samples. Whey separated from the labneh sample containing 0.25% S. platensis had a higher moisture content (91.5%) compared with whey of the control sample 90.06%. However, the moisture content decreased to 90.48, and 90.75% in whey of labneh samples containing 0.5%, and 1% S. platensis respectively. On the other hand, the whey of the labneh sample containing 0.25% C. vulgaris had a lower moisture content (89.73%) compared with the whey of the control sample. However, the moisture content increased to 91.5%, and 96.65% in the whey of labneh samples containing 0.5, and 1% C. vulgaris respectively. There is an inverse relation between moisture and total solids contents, where the whey sample contained higher moisture content (96.65%), contained lower total solids content (3.35%), and also the whey sample contained lower moisture content (89.73%), contained higher total solids content (10.27%). Additionally, most of the whey samples contained the same fat ratio (0.1%) except the whey samples resultant from labneh samples contained 0.25, & 1% S. platensis and 0.5% C. vulgaris contained 0.2%.

Table 9 Labneh yield, and chemical composition of whey separated from different labneh treatments in comparison with control.
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There is a variation in whey content from protein with different concentrations of S. platensis, and C. vulgaris. As shown in Table 9, the protein ratios were 1.18, 1.79, and 1.5% in whey of labneh containing 0.25, 0.5, and 1% S. platensis, respectively. These ratios were 1.91, 1.45, and 0.7% in the whey of labneh contained 0.25, 0.5, and 1% C. vulgaris, respectively, while the whey of the control contained 1.75%. It is also noted that the whey content from carbohydrates in all samples was lower than the whey of the control sample, where the carbohydrate contents were 4.7, 5.5, and 4.74% in the whey of labneh contained 0.25, 0.5, and 1% S. platensis, respectively, and 5.38, 5.06, and 1.09%, in whey of labneh contained 0.25, 0.5, and 1% C. vulgaris, respectively, while the whey of control contained 6.05%.

Data in Table 9 also show that the ash content in whey samples increased by 2.41, 2.12., 2.81, and 2.88% in the whey of labneh samples contained 0.25, 0.5, and 1% S. platensis, and 0.25% C. vulgaris, respectively. However, it decreased to 1.78, and 1.46% in the whey of labneh samples contained 0.5, and 1% C. vulgaris, respectively.

The yield of labneh

Table 9 shows the yield of different labneh treatments. The concentration of 0.25% from S. platensis, and C. vulgaris, the yield decreased to 27.23, and 28.06%, respectively compared with the control sample yield (31.26%). At a concentration of 0.5% from S. platensis, and C. vulgaris, the yield increased to 31.7, and 37.4%, respectively. However, higher yield values (40.26, and 45.06%) were noted at a concentration of 1% from S. platensis, and C. vulgaris, respectively. This increase in yield values at a concentration of 1% microalgae resulted from keeping the higher moisture content in the curd as previously shown in Table 1.

While the addition of microalgae powders significantly improved the nutritional profile and sensory characteristics of reduced-fat labneh, the underlying mechanisms remain partially unexplored. The observed enhancements could potentially be attributed to the coagulation activity or pH modulation properties of the microalgae. Certain microalgae strains, particularly those rich in polysaccharides or specific proteins, have been shown to exhibit cheese-like coagulation activity68,69. This activity could interact with milk casein during labneh production, influencing curd formation kinetics and ultimately contributing to improved texture and yield70. Furthermore, microalgae metabolites and cell wall components might influence the cheesemaking process by modulating pH. Studies on cheese production suggest that pH changes can significantly impact texture, moisture content, and starter culture activity71. Future research should explore these possibilities by analyzing curd formation kinetics and final cheese yield with varying microalgae concentrations. Additionally, a more detailed examination of pH changes throughout the cheesemaking process with different microalgae inclusions would provide valuable insights into their potential role in enhancing labneh quality.

To ensure the safety and consumer acceptance of microalgae-enriched labneh, it is crucial to employ cultivation and processing methods that adhere to relevant guidelines. This not only safeguards the final product but also fosters consumer trust. In our study, the absence of coliform bacteria in the final labneh, as confirmed by the microbiological evaluation, provides preliminary evidence of the safety measures employed during microalgae processing.

Ultrastructural investigations

To understand how microalgae incorporation affects the microstructure of labneh during storage, we compared samples with and without microalgae at two key time points: 0 days (initial state) and 21 days (storage period). The 0-day microalgae sample serves as a control for the 21-day microalgae sample, as both contain microalgae. This allows us to isolate the effect of storage time on the microstructure. Importantly, comparing the 0-day microalgae sample to the control (labneh without microalgae) at 0 days revealed initial changes in microstructure due to the presence of microalgae itself.

The untreated control of fresh labneh

The untreated control of fresh labneh exhibits a complex microstructure, as revealed by SEM images at varying magnifications (Fig. 5A,F). At lower magnification, the surface appears relatively smooth with some protrusions and pores. These observations are consistent with a well-compacted protein network, potentially indicating good stability and textural properties. Interestingly, closer inspection at higher magnifications (Fig. 5C,D,F) reveals a more intricate landscape with crevices, elevations, and distinct globular structures. These globular structures, likely representing fat globules or protein aggregates surrounded by other milk solids, may vary in size and shape depending on factors like fat content, homogenization processes, and interactions between fat and protein fractions. It’s important to note that a completely smooth surface might not always be desirable. Slight roughness from casein micelles or fat globules can contribute positively to the textural perception of the final product. Therefore, the observed surface characteristics of the control labneh, with its balance of smooth and rough features, suggest well textural properties.

Fig. 5
figure 5

SEM micrograph of fresh reduced-fat labneh without microalgae at zero time.

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The untreated control after 21 days

After 21 days of storage without microalgae supplementation, the SEM images of the labneh (Fig. 6) reveal changes in the microstructure compared to the control. At lower magnification (Fig. 6A), there appears to be increased aggregation and compaction of protein clusters compared to the fresh labneh (Fig. 5A). This observation suggests a possible ongoing process of syneresis during storage. Furthermore, a closer examination at higher magnifications (Fig. 6B,C,D) demonstrates a heterogeneous surface topology with variations in particle sizes and shapes. These observations are consistent with a dynamic evolution in the protein network and fat globule distribution within the labneh matrix over the storage period. Figures 6E,F provide further details of this heterogeneity, revealing smoother regions alongside areas with more prominent protein aggregates. These findings suggest that storage without microalgae may induce alterations in the microstructure of the labneh, potentially impacting its textural properties.

Fig. 6
figure 6

SEM micrograph of reduced-fat labneh without microalgae after 21 days.

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Comparing these observations with those at zero-time investigations, it is evident that the microstructure of the labneh has evolved significantly over the 21 days of storage. At zero time, the microstructure was relatively uniform; however, storage has led to particle agglomeration and texture modification. This highlights the pivotal role of storage time in influencing the textural attributes and overall quality of reduced-fat labneh.

Spirulina platensis-fortified labneh

After manufacturing, Fig. (7A & B) depict a uniform and compact microstructure of the fresh labneh when incorporated with 0.25% S. platensis (at zero time). This suggests that the microalgae at this concentration could enhance the texture and consistency of the labneh, this was corroborated by the findings of positive sensory attributes at this concentration. Figures 7C,D show a less compact structure with visible separation between particles when the labneh is incorporated with 0.50% S. platensis. This indicates that this concentration might not be optimal for maintaining the desired textural attributes of the labneh. However, Fig. 7E,F reveal an irregular and highly porous structure of the labneh when incorporated with 1% S. platensis. This aligns with the negative impacts on sensory qualities at this concentration.

Fig. 7
figure 7

SEM micrograph, depicting fresh reduced-fat labneh. The samples were prepared with the incorporation of 0.25% (A & B), 0.50% (C & D), and 1% (E & F) of Spirulina platensis and captured at zero time.

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After 21 days of storage, Fig. 8A,B) depict isolated and sporadic algal particles in the labneh when incorporated with 0.25% S. platensis. This suggests minimal integration of the microalgae at this concentration, indicating that the microstructure of the labneh remains relatively stable over time. At 0.50% S. platensis, SEM images (Fig. 8C,D) show increased particle density and a more complex structure. This indicates a pronounced incorporation of the microalgae, leading to a heterogeneous texture in the labneh after 21 days of storage. Figure 8E,F reveal an intricate structural network in the labneh when incorporated with 1% S. platensis, suggesting extensive integration of the microalgae, which significantly altering the microstructure of the labneh over the storage period in comparison with zero time.

Fig. 8
figure 8

SEM micrograph, depicting the reduced-fat labneh prepared with the incorporation of 0.25% (A & B), 50% (C & D), and 1% (E & F) of Spirulina platensis, after 21 days of storage.

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Comparing these observations with the investigations at zero-time, it is evident that the microstructure of the labneh has evolved significantly over the 21 days of storage. At zero time, the distribution of S. platensis was relatively uniform; however, storage has led to particle agglomeration and texture modification. This highlights the pivotal role of storage time and S. platensis concentration in influencing the textural attributes and overall quality of reduced-fat labneh.

Chlorella vulgaris-fortified labneh

Regarding, C. vulgaris, the images of SEM images (Fig. 9A,B) depict a relatively smooth surface with sporadic, isolated spherical structures when the labneh is incorporated with 0.25% C. vulgaris after manufacturing (at zero time). This suggests minimal interaction or integration of the microalgae at this concentration. At 0.50% (Fig. 9C,D), the SEM images show an increase in surface roughness and complexity when the labneh is incorporated with 0.50% C. vulgaris. This indicates a higher degree of incorporation and interaction between the labneh and the microalgae, leading to a more heterogeneous texture in the labneh.

Fig. 9
figure 9

SEM micrograph, depicting fresh reduced-fat labneh. The samples were prepared with the incorporation of 0.25% (A & B), 0.50% (C & D), and 1% (E & F) of Chlorella vulgaris and captured at zero time.

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The SEM investigation (Fig. 9E,F) reveals abundant spherical structures densely packed on the surface when the labneh is incorporated with 1% C. vulgaris. This suggests optimal incorporation and interaction at this concentration, significantly altering the microstructure of the labneh. These observations suggest that as the concentration of C. vulgaris increases, there is enhanced integration into the labneh matrix leading to increased surface complexity and heterogeneity. This could potentially influence the textural, nutritional, and sensory attributes of reduced-fat labneh.

After 21 days of storage, labneh enriched with C. vulgaris (Fig. 10A,B) showed a noticeable heterogeneity in texture and structure when the labneh was incorporated with 0.25% C. vulgaris. This suggests a moderate distribution of the microalgae within the labneh matrix, indicating that the microstructure of the labneh evolves over time. At 0.50% C. vulgaris, Fig. 10C,D show increased structural complexity and density of labneh. This indicates enhanced interaction between the labneh and the microalgae, leading to a more heterogeneous texture in the labneh after the storage period. Compared to the control at 0 days, SEM analysis revealed that incorporating 1% C. vulgaris significantly alters the microstructure of the labneh over the storage period (21 days). This is evident by the increased surface roughness and complexity observed in the microalgae-supported labneh at 21 days (Fig. 10E,F) compared to the initial state (Fig. 9).

Fig. 10
figure 10

SEM micrograph, depicting the reduced-fat labneh prepared with the incorporation of 0.25% (A & B), 0.50% (C & D), and 1% (E & F) of Chlorella vulgaris, after 21 days of storage.

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Comparing these observations with the investigations at zero time, it is evident that the microstructure of the labneh has evolved significantly over the 21 days of storage. At zero time, the microstructure was relatively uniform; however, storage has led to particle agglomeration and texture modification. This highlights the pivotal role of storage time and C. vulgaris concentration in influencing the textural attributes and overall quality of reduced-fat labneh.

The previous microstructural investigation provided visual evidence supporting the current research findings on the impact of different concentrations of S. platensis and C. vulgaris on the sensory and nutritional attributes of reduced-fat labneh. Consequently, highlights the importance of optimizing the concentration of microalgae for labneh enrichment and underscores the potential of microalgae in functional food applications.

Correlations and potential mechanisms

Our research suggests that incorporating microalgae, specifically S. platensis and C. vulgaris, into the production of reduced-fat labneh can significantly enhance its nutritional quality. However, Fig. 11 provides a visual summary of the potential mode of action of microalgae on fortified labneh based on our study. The action mechanisms are likely related to the inherent properties of microalgae, which are known to be rich in essential nutrients such as proteins, amino acids, and unsaturated fatty acids. This is supported by the nutritional profiles of both S. platensis and C. vulgaris and the positive correlations observed in our study between microalgae content and these nutrients72,73,74.

Fig. 11
figure 11

A visual summary of the potential mode of action of microalgae on fortified labneh.

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It was noted an increment in antioxidant activity in labneh enriched with microalgae, suggesting a transfer of bioactive compounds like phenolic acids and carotenoids from the microalgae to the final product, thereby enhancing its free radical scavenging ability73. Additionally, the viability of the starter culture bacteria improved during storage in the presence of microalgae. This could be due to the nutrient-rich environment provided by the microalgae, which may also act as prebiotics.

Our evaluation also revealed potential textural modifications in the labneh, which could be attributed to the interaction of microalgae proteins and polysaccharides with milk casein proteins during gelation. These components may act as gelling agents, influencing the viscosity and mouthfeel of the labneh. Microalgae proteins are known to contain up to 70% protein, including all 20 essential amino acids, which can fulfill human dietary requirements and contribute to the gelation process in food products75. Additionally, the physicochemical properties of microalgae proteins and polysaccharides could potentially alter the rheological properties of labneh, such as its viscosity76.

The sensory attributes of labneh, including flavor and aroma, can vary depending on the species and concentration of microalgae, as well as processing techniques. While some studies report minimal sensory differences, others suggest potential changes that need to be evaluated through consumer sensory tests. Consumer acceptance of microalgae as a novel food ingredient shows a preference for lower inclusion levels due to the impact on color and taste, with freshwater algae generally preferred over marine species due to less pronounced fishy flavors77. Additionally, the physicochemical properties of microalgae-enriched foods indicate that higher concentrations of microalgae may lead to strong colors that are not typically associated with certain food products, which could affect consumer acceptance78. Therefore, sensory evaluation is crucial to determine the acceptability of microalgae-enriched labneh and identify any potential modifications needed to meet consumer preferences79,80.

It is important to note that further research is required to establish definitive cause-and-effect relationships between microalgae addition and the observed changes in labneh. Isolating specific microalgae components and conducting in vitro experiments will help elucidate their individual effects on labneh properties. Future studies should also include detailed textural and rheological analysis to better understand the specific changes associated with microalgae addition.

Ultimately, The current work shares insights across multiple domains. In health and nutrition, the rising demand for reduced-fat dairy products amid concerns about diet-related diseases prompts exploration into methods for enhancing their nutritional profiles, potentially by incorporating microalgae rich in omega-3 fatty acids and antioxidants, garnering attention from researchers, health professionals, and consumers globally. Sustainability considerations highlight microalgae’s promise as a resource-efficient food source, suggesting their integration into dairy products like labneh could advance discussions on sustainable food production and mitigate environmental impacts associated with conventional agriculture. Furthermore, in food science and technology, research on the biochemical, microbial, and ultrastructural attributes of reduced-fat labneh fortified with microalgae presents avenues for product innovation, appealing to food scientists, technologists, and industry professionals seeking to develop novel, nutritious offerings in other dairy products. Finally, the proposed investigation could enhance the nutritional content while preserving the traditional sensory qualities.

Conclusion

This study innovatively explored fortifying reduced-fat labneh with S. platensis and C. vulgaris microalgae at optimal concentrations (0.25% and 0.50%). The enriched labneh exhibited enhanced sensory attributes, a significantly improved nutritional profile with increased essential nutrients, unsaturated fatty acids, antioxidant pigments, and boosted overall antioxidant activity. Importantly, both microalgae improved starter culture viability during storage. These findings highlight the potential of microalgae as a novel approach to simultaneously improve the nutritional and sensory quality of reduced-fat labneh. Future research could explore microalgae blends for synergistic effects and in vivo/in vitro studies to assess the bioactivity of the enriched product.

While there is a correlation in the sense that both microalgae can enhance the properties of labneh at certain concentrations, future research endeavors should explore the optimization of microalgae mixtures to achieve specific sensory and textural characteristics, and their potential in functional food applications. This could lead to the development of innovative, nutritious, and sensory-appealing dairy products, contributing to the growing field of functional foods. To further advance this field, studies investigating the shelf life and stability of enriched labneh under various storage conditions, as well as an assessment of the impact of microalgae enrichment on potential allergenicity and safety aspects, are of paramount importance. These investigations not only hold significance for commercial production but also underscore the importance of consumer health considerations.