Kefir Fermentation Research Articles

Comparison of Fermentation Kinetics of Milk Kefir and White Rice Kefir at Low Temperatures: Exploring the Effects on Product Quality

Kefir fermentation has been extensively studied because of its potential to develop novel functional drinks and its various biological activity. This study investigates the comparative fermentation kinetics of milk kefir and white rice kefir at low temperatures, addressing a gap in current research. Utilizing a comprehensive research methodology, including sample preparation, fermentation processes, and various analyses, the study explores the distinct patterns observed in the fermentation kinetics, physicochemical properties, and microbiological characteristics of both kefir types. The results highlight significant differences influenced by low temperatures, emphasizing the need to consider specific attributes for each kefir type in low-temperature fermentation. The findings contribute novel insights into optimizing fermentation conditions and enhancing product quality. The results offer additional perspectives on the influence of fermentation temperature on microbial dynamics, physicochemical properties, and health-related aspects in various fermented products. This study advances our understanding of kefir fermentation, providing valuable implications for the production of high-quality and functional beverages.

Probiotic Growth Pattern and Physicochemical Evaluation of Water Kefir Fermentation

Probiotics are live-friendly microorganisms that can confer a health benefit on the host if it is consumed in sufficient amounts. Water kefir is a probiotic-rich fermented beverage that contains multi-species of live cultures. Brown sugar and palm sugar were used for water kefir fermentation due to their high sucrose and mineral contents. The objective of this study was to determine the probiotic growth pattern of water kefir and to evaluate the physicochemical parameters, including the pH changes, lactic acid content, reducing sugar content, and total soluble solids. The fermented water kefir was collected at every 6-hour interval, until the end of 72 hours of fermentation. The growth curve was determined by enumerated probiotics on De Man, Rogosa, and Sharpe (MRS) agar, Yeast Extract-Peptone-Dextrose (YPD) agar, and Gluconobacter (GM) agar plates, respectively. MRS, YPD, and GM agar plates were used to enumerate lactic acid bacteria, yeast, and acetic acid bacteria, respectively. The result showed increased probiotic growth as fermentation time increased with different phases observed from the growth curve. The stationary phase of probiotics was recorded at 30-42 h and was recommended as the optimal harvesting point. Besides, longer fermentation time produced lower pH values and lower total soluble solids while higher lactic acid and higher reducing sugars. At the end of fermentation, the concentration of lactic acid and reducing sugars were 2.16 ± 0.09 g/L and 13.66 ± 0.14 mg/mL, respectively. In conclusion, probiotics from water kefir fermentation are suggested to be best harvested between 30-42 hours and can be used for self-consume or downstream processing.

Powdered water kefir: Effect of spray drying and lyophilization on physical, physicochemical, and microbiological properties

This study addresses the challenge of optimizing powdered water kefir's fermentation and preservation processes to enhance its physical-chemical, microbiological, and technological characteristics. The main objective was to determine the best fermentation conditions and evaluate the efficacy of different drying methods. The optimal fermentation conditions were 5 % kefir grains, 10 % brown sugar, and an incubation temperature of 25 °C. Remarkably, the microbiological analysis revealed high abundances of Zymomonas mobilis (grains: 94.31 % and beverage: 91.68 %), Sporolactobacillus spathodeae (grains: 3.00 % and beverage: 5.42 %), and Liquorilactobacillus satsumensis (grains: 1.47 % and beverage: 0.62 %) among bacteria, and Lachancea fermentati (grains: 95.54 % and beverage: 67.53 %), Wickerhamomyces anomalus (grains: 3.00 % and beverage: 26.77 %) among fungi. The study innovatively demonstrates that lyophilization preserves the viability of these microorganisms, making it a promising method for producing stable, probiotic-rich powdered kefir. Although spray drying resulted in a logarithmic reduction of 3 logs CFU/g, it maintained sufficient microorganism counts, proving its viability as an alternative drying method. These methods retain the ideal physical-chemical properties and expand the accessibility and practical applications of water kefir. This research underscores the potential for powdered water kefir to deliver health benefits conveniently and versatilely, paving the way for broader industrial and academic applications.

In Vitro Antitumor and Antioxidant Capacity as well as Ameliorative Effects of Fermented Kefir on Cyclophosphamide-Induced Toxicity on Cardiac and Hepatic Tissues in Rats.

Fermented prebiotic and probiotic products with kefir are very important to slow down and prevent the growth of tumors and to treat cancer by stimulating the immune response against tumor cells. Cyclophosphamide (CPx) is widely preferred in cancer treatment but its effectiveness in high doses is restricted because of its side effects. The aim of this study was to investigate the protective effects of kefir against CPx-induced heart and liver toxicity. In an experiment, 42 Wistar albino rats were divided into six treatment groups: the control (Group 1), the group receiving 150 mg/kg CPx (Group 2), the groups receiving 5 and 10 mg/kg kefir (Groups 3 and 4) and the groups receiving 5 and 10 mg/kg kefir + CPx (Group 5 and 6). Fermented kefirs obtained on different days by traditional methods were mixed and given by gavage for 12 days, while a single dose of CPx was administered intraperitoneally (i.p.) on the 12th day of the experiment. It was observed that alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatinine kinase-MB (CK-MB), ischemia modified albumin (IMA) and Troponin I values, which indicate oxidative stress, increased in the CPx-administered group, and this level approached that of the control in the CPx + kefir groups. Likewise, as a result of the kefir, the rats' CPx-induced histopathological symptoms were reduced, and their heart and liver tissue were significantly improved. In conclusion, it was observed that kefir had a cytoprotective effect against CPx-induced oxidative stress, hepatotoxicity and cardiotoxicity, bringing their biochemical parameters closer to those of the control by suppressing oxidative stress and reducing tissue damage.

Dynamics of peptides released from cow milk fermented by kefir microorganisms during fermentation and storage periods

This study investigates the changes in peptides released during the fermentation and storage of cow milk with a kefir culture using porous graphitized carbon-liquid chromatography-tandem mass spectrometry (PGC-MS/MS). A comprehensive inventory of 695 distinct milk peptides from 98 milk proteins was determined, with 523 characterized within 24 h of fermentation. The quantitative evaluation of released peptides throughout the kefir fermentation process unveiled noteworthy variations. A total of 50 discrete bioactive peptides with various biological functions were determined throughout the fermentation stages. After fermentation, we identified 26 bioactive peptides within the resulting beverage, maintaining their stability throughout storage. In addition, during the storage periods, three new bioactive peptides emerged. The composition of bioactive peptides underwent alterations during fermentation but remained relatively constant during storage. Our study sheds light on the proteolytic activity of potential enzymes released into the milk samples from kefir cultures, contributing to the beverage's evolution during storage.

Dynamic alterations of flavor, functional nutrients, and microbial community during fermentation of different animal milk kefirs

Kefir is a traditional dairy beverage, usually made from cow or goat milk fermented with kefir grains, and has many health benefits. To elucidate the fermentation patterns of animal milk kefirs during the fermentation process and find the optimal milk types, cow, camel, goat, and donkey milk were fermented with kefir grains for 0, 1, 3, 5, and 7 days. Volatile and non-volatile metabolites and microbial changes were dynamically monitored. The results showed that volatile flavor substances were massively elevated in four kefirs on days 1–3. Lipids and carbohydrates gradually decreased, while amino acids, small peptides, and tryptophan derivatives accumulated during fermentation in four kefirs. Besides, four kefirs had similar alterations in Lactobacillus and Acetobacter, while some distinctions existed in low-abundance bacteria. Association analysis of microorganisms and volatile and non-volatile metabolites also revealed the underlying fermentation mechanism. This study found that appropriately extending the fermentation time contributed to the accumulation of some functional nutrients. Furthermore, goat and donkey milk could be the better matrices for kefir fermentation.

Chemical, microbial, and volatile compounds of water kefir beverages made from chickpea, almond, and rice extracts

This study aims to assess the microbial, nutritional, volatile, and sensory characteristics of rice, almond, and chickpea water kefir beverages during refrigerated storage. Plant-based kefirs contained significant amounts of lactic acid bacteria and yeasts. The microbial content of kefirs was stable during 14-day refrigerated storage. Lactic acid, acetic acid, and tartaric acid are commonly detected organic acids in kefir samples. Almond and chickpea kefirs were rich in potassium mineral. Almond kefir had the highest ethanol content among plant-based kefirs, followed by chickpea and rice-based kefirs. Ethyl acetate, acetic acid, propionic acid, hexanoic acid, and benzenemethanol were identified as key volatile compounds in almond kefir and chickpea kefir samples using a GC–MS detector during water kefir fermentation. According to sensory analysis results, significant differences are present for all test parameters except odor. Almond kefir was the most accepted, while the other two kefir samples were below the general acceptance level (P < 0.05).

Modelling the dynamics of microbial populations and Salmonella spp. in milk kefir

Kefir is a fermented dairy product based on the fermentation of milk by bacteria and yeasts. It is produced by adding kefir grains, consisting of a consortium of microorganisms, to milk in order to start a natural fermentation (Garofalo et al., 2020). Kefir is well recognized for its potential health value as a source of probiotics, however, there have been concerns about the potential growth of pathogenic microorganisms in kefir and the potential health hazards associated (Leite et al., 2013) A mathematical model was developed to describe the evolution of microbes present during kefir fermentation and the potential growth of Salmonella spp. as one example of a potential food safety hazard. For this, equations previously described in the scientific literature were combined and adapted to the milk kefir matrix. To assess the safety of the product, the growth of Salmonella was predicted considering its interaction with the medium and the other species. The drop in pH; generation of yeasts metabolites such as ethanol; and buffer capacity was described and considered when modelling Salmonellas’ kinetics. Interaction between the pathogenic species and the background microflora was included in the model. Parameters of some well-described systems were taken from literature. Alongside, some other parameters describing specific assets from the system were estimated using experimental data of microbial population kinetics during kefir fermentation. The growth of yeasts, lactic acid bacteria, Salmonella together with the pH were experimentally collected at critical processing times and fitted to the mathematical model by minimizing the residual sum of squares (RSS). Confidence intervals of 95 % were calculated. For further validation, the output of the model was contrasted with an independent data set. It was concluded that Salmonella is able to increase its population during the first hours of the kefir fermentation process. Inactivation can be apportioned to the drop of pH as a consequence of the LAB metabolism, once the pH reaches values below 4. After this no growth of Salmonella seems to be found in milk kefir as confirmed by the model. No residual population of the pathogen is observed. This suggests that by controlling the growth and metabolism of the background microflora, safety can be assured in milk kefir. This process was successfully described by a novel mathematical model and the estimation of its´parameters.

Non-targeted metabolomics unveils metabolic spectrum characteristics and core metabolite interaction networks in water kefir fermentation

Water kefir, a traditional beverage highly valued by consumers, is known for its abundance of probiotics and a wide range of beneficial substances. However, the complex scientific challenges of understanding the interactions among the microbial community in this stable symbiotic drink have not been fully researched. This study aims to fill this gap by using non-targeted metabolomics methodologies, specifically UHPLC-QE-MS and GC-TOF-MS platforms, to explore the metabolomic landscape throughout the fermentation stages of water kefir. This research reveals important metabolic biomarkers, including N-acetyl-l-aspartic acid, β-alanine, and O-acetylserine. These biomarkers are involved in various metabolic pathways such as alanine, aspartate, and glutamate metabolism, as well as cysteine and methionine metabolism, during the fermentation process of water kefir. An important finding is the presence of a positive correlation between amino acids and organic acids within the correlation network. This indicates a synergistic relationship that promotes favorable interactions among these essential components. Furthermore, this study provides a detailed metabolic network depicting the process of water kefir fermentation. This network establishes a solid foundation for further exploration of the intricate metabolic mechanisms governing water kefir fermentation.

Physicochemical characterization and antibacterial activity of Brazilian artisanal milk kefir

Milk kefir has an acidic taste and creamy consistency and results from the fermentation of milk by the microorganisms present in kefir grains. Milk kefir is known worldwide for its health benefits attributed to various bioactive compounds, including organic acids, bioactive peptides, and bacteriocins. This study evaluated the physicochemical composition of Brazilian artisanal milk kefir samples and studied the antibacterial activity of kefir beverage and of microorganisms isolated from kefir against potentially pathogenic bacteria. During the 24 and 48 h kefir fermentation, reducing sugars and pH decreased and lactic acid concentration increased. Kefir fermented in 48 h completely inhibited the bacterial growth of Staphylococcus aureus, Salmonella enterica and Escherichia coli. Of the 29 microorganisms isolated from kefir, 10 strains (34.5%) showed inhibitory activity against S. aureus, Bacillus cereus, Streptococcus mutans, Klebsiella pneumoniae, S. enterica and E. coli. These strains showed inhibition zones of 12-40 mm against potentially pathogenic bacteria tested. Based on the antagonist capacity of the microorganisms isolated from milk kefir, these strains have potential to be used as food preservatives and as probiotic agents.

Process understanding and monitoring: A glimpse into data strategies for miniaturized NIR spectrometers

BackgroundThe implementation of process analytical technologies (PAT) has gained attention since 2004 when its formal introduction through the U.S. Food and Drug Administration was introduced. Manufacturers that need to evaluate the employment of new monitoring systems could face different challenges: identification of suitable sensors, verification of data meaning, evaluation of several statistical strategies to obtain insights about data and achieve process understanding and finally, the actual possibilities for monitoring. Kefir fermentations were chosen as an example because of the chemical and physical transformations that occurred during the process, which could be common to several other fermentation processes. In order to pave the way for monitoring establish the information contained in the data and find the right tools for extracting them is of extreme importance. Strategies to identify different experimental conditions in the spectra acquired with a miniaturized NIR (1350-2550 nm) during process occurrence were addressed. ResultsThe study aims to offer insights into good practices and steps to pave the way for process monitoring with handheld NIR data. The main aspects of interest for batch processes in preliminary evaluations were investigated and discussed. On the one hand, process understanding and, on the other, the possibilities for process monitoring and endpoint determination were examined. The combination of different statistical tools allowed the extraction of information from the data and the identification of the link between them and the chemical and physical changes during the process. In addition, insights into the spectra characteristics in the studied spectroscopic range for kefir fermentation were reported. SignificanceThe capabilities for miniaturized NIR spectra to represent and statistical strategies to characterize different experimental conditions in a real case fermentation occurrence were proved. The strengths and limitations of some of the common approaches to catch changes in fermentation condition were highlighted. For the various statistical approaches, the chances offered in the research and development stages and to set the scene for monitoring and end-point detection were explored.

Multi-omics characterization of the microbial populations and chemical space composition of a water kefir fermentation.

In recent years, the popularity of fermented foods has strongly increased based on their proven health benefits and the adoption of new trends among consumers. One of these health-promoting products is water kefir, which is a fermented sugary beverage based on kefir grains (symbiotic colonies of yeast, lactic acid and acetic acid bacteria). According to previous knowledge and the uniqueness of each water kefir fermentation, the following project aimed to explore the microbial and chemical composition of a water kefir fermentation and its microbial consortium, through the integration of culture-dependent methods, compositional metagenomics, and untargeted metabolomics. These methods were applied in two types of samples: fermentation grains (inoculum) and fermentation samples collected at different time points. A strains culture collection of ∼90 strains was established by means of culture-dependent methods, mainly consisting of individuals of Pichia membranifaciens, Acetobacter orientalis, Lentilactobacillus hilgardii, Lacticaseibacillus paracasei, Acetobacter pomorum, Lentilactobacillus buchneri, Pichia kudriavzevii, Acetobacter pasteurianus, Schleiferilactobacillus harbinensis, and Kazachstania exigua, which can be further studied for their use in synthetic consortia formulation. In addition, metabarcoding of each fermentation time was done by 16S and ITS sequencing for bacteria and yeast, respectively. The results show strong population shifts of the microbial community during the fermentation time course, with an enrichment of microbial groups after 72h of fermentation. Metataxonomics results revealed Lactobacillus and Acetobacter as the dominant genera for lactic acid and acetic acid bacteria, whereas, for yeast, P. membranifaciens was the dominant species. In addition, correlation and systematic analyses of microbial growth patterns and metabolite richness allowed the recognition of metabolic enrichment points between 72 and 96h and correlation between microbial groups and metabolite abundance (e.g., Bile acid conjugates and Acetobacter tropicalis). Metabolomic analysis also evidenced the production of bioactive compounds in this fermented matrix, which have been associated with biological activities, including antimicrobial and antioxidant. Interestingly, the chemical family of Isoschaftosides (C-glycosyl flavonoids) was also found, representing an important finding since this compound, with hepatoprotective and anti-inflammatory activity, had not been previously reported in this matrix. We conclude that the integration of microbial biodiversity, cultured species, and chemical data enables the identification of relevant microbial population patterns and the detection of specific points of enrichment during the fermentation process of a food matrix, which enables the future design of synthetic microbial consortia, which can be used as targeted probiotics for digestive and metabolic health.

Improvement of kefir fermentation on rheological and microstructural properties of soy protein isolate gels

Soy protein isolate (SPI) has become a promising plant-based material as an animal protein products alternative. However, its application was limited due to the weak gelling properties. To investigate the effect of kefir fermentation on SPI gels properties, SPI-polysaccharide gels was produced by unfermented and kefir-fermented SPI using different concentration of KGM, chitosan, and calcium chloride in this study. Characterization of fermented SPI gels showed that fermentation by kefir grains can be applied to improve the textural strength, mechanical structure, and thermal characteristics of SPI gels. Compared to unfermented SPI gels, the water-holding capacity was remarkably enhanced to 63.11% and 65.71% in fermented SPI-chitosan gels. Moreover, the hardness of fermented SPI-KGM gels were significantly increased to 13.43 g and 27.11 g. And the cohesiveness and resilience of fermented-KGM gels were also improved than unfermented samples. Results of rheological characterization and thermogravimetric analysis revealed the strengthened mechanical features and higher thermal stability of fermented SPI gels. Additionally, the main role of hydrophobic interactions and secondary structure variations of SPI gels were demonstrated by intermolecular force measurements, Fourier-transform infrared spectroscopy, and X-ray diffraction. Moreover, the network structure was observed more compact and homogeneous performed by microstructural images in fermented SPI gels. Therefore, this research provided a novel approach combining multi-species fermentation with protein gelation to prepare SPI gel materials with improved nutrition and structural properties.

Use of reconstituted kefir consortia to determine the impact of microbial composition on kefir metabolite profiles

Kefir is fermented traditionally with kefir grains, but commercial kefir production often relies on fermentation with planktonic cultures. Kefir has been associated with many health benefits, however, the utilization of kefir grains to facilitate large industrial production of kefir is challenging and makes to difficult to ensure consistent product quality and consistency. Notably, the microbial composition of kefir fermentations has been shown to impact kefir associated health benefits. This study aimed to compare volatile compounds, organic acids, and sugar composition of kefir produced through a traditional grain fermentation and through a reconstituted kefir consortium fermentation. Additionally, the impact of two key microbial communities on metabolite production in kefir was assessed using two modified versions of the consortium, with either yeasts or lactobacilli removed. We hypothesized that the complete kefir consortium would closely resemble traditional kefir, while the consortia without yeasts or lactobacilli would differ significantly from both traditional kefir and the complete consortium fermentation. Kefir fermentations were examined after 12 and 18 h using two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS) to identify volatile compounds and high performance liquid chromatography (HPLC) to identify organic acid and sugar composition. The traditional kefir differed significantly from the kefir consortium fermentation with the traditional kefir having 15–20 log2(fold change) higher levels of esters and the consortium fermented kefir having between 1 and 3 log2(fold change) higher organic acids including lactate and acetate. The use of a version of kefir consortium that lacked lactobacilli resulted in between 2 and 20 log2(fold change) lower levels of organic acids, ethanol, and butanoic acid ethyl ester, while the absence of yeast from the consortium resulted in minimal change. In summary, the kefir consortium fermentation is significantly different from traditional grain fermented kefir with respect to the profile of metabolites present, and seems to be driven by lactobacilli, as evidenced by the significant decrease in multiple metabolites when the lactobacilli were removed from the fermentation and minimal differences observed upon the removal of yeast.

Financial Feasibility Analysis of the Inferior Robusta Coffee Beans Selling Using the Fermentation Method with Kefir Starter at CV. Asmak Kopi

This study aims to assess the financial feasibility of Kefir fermentation for inferior robusta coffee. The research design employed data collection methods. The study was conducted at CV. Asmak Kopi from August to December 2022. The study utilized data as the subject of investigation. The data used in this research consisted of primary and secondary data. Primary data was sourced from the coffee business entity CV. Asmak Kopi, including labor data, production costs, production types, and coffee prices. Secondary data used in the study was obtained from various government institutions, organizations, research studies, survey results, and other sources. The obtained data was quantitative and analyzed to determine financial feasibility, including analysis of production costs, break-even analysis, Internal Rate of Return (IRR) analysis, Benefit Cost Ratio (B/C Ratio) analysis, Payback Period (PP) analysis, Return on Investment (ROI) analysis, and Net Present Value (NPV) analysis. This quantitative analysis was presented in tabulated form, grouping and classifying the data to facilitate data analysis. Data processing was performed using calculators and Microsoft Excel software. Based on the research findings, the business of improving the quality of inferior robusta coffee through kefir fermentation at CV. Asmak Kopi is financially feasible. This is supported by the results of the financial feasibility test, indicating an IRR of 82.88%, B/C Ratio of 3.08, Gross B/C Ratio of 1.8, positive NPV, and a payback period shorter than the production lifespan. The sensitivity analysis also showed that a 50% increase in inferior material prices had no significant impact, indicating that the business is still viable. However, a 20% decrease in selling prices has a significant impact, and the product should not experience a price decrease of more than 20%. At a price decrease of 30%, the business is not feasible as it would result in losses. The business of improving the quality of inferior robusta coffee through kefir fermentation at CV. Asmak Kopi is feasible.

Use of mandarin and persimmon fruits in water kefir fermentation.

Water kefir is a non-dairy probiotic beverage. It is obtained by fermentation of water kefir grains with a sugar solution. This study aims to determine the properties of water kefir beverages obtained by fermentation of mandarin and persimmon-containing water for 42 h. According to microbiological results, both fruits containing water samples provided a high number of lactic acid bacteria and yeasts. Moreover, after fermentation, pH, Brix, and dry matter content did not significantly differ. On the other hand, fructose, maltose, and acetic acid contents of mandarin water kefir are significantly higher than persimmon water kefir (p < .05). Persimmon water kefir had higher total phenolic contents, twice as much as mandarin water kefir (p < .05). Both water kefirs had good color properties. The organoleptic acceptability of the fruit water kefirs was promising.

Preparation of lentil and quinoa protein complexes through protein–protein interactions and water kefir–assisted fermentation to improve protein quality and functionality

IntroductionIndustrial applications of lentil (LP) and quinoa (QP) proteins are limited due to their relatively poor water solubility. In this study, a combination of protein-protein interaction (PPI) and fermentation was used to improve the functionality and nutritional value of LP by conjugating them with QP. The reaction conditions between LP and QP for producing these conjugates were established.MethodsThe ratio of LP to QP was equal (50:50), and complexation was carried out at 25°C for 60 min. Fermentation of the solubilized LP-QP complexes (1%, w/v) for 5 days at 25°C with water kefir (5%, v/v) was carried out to enhance the protein quality and functionality of the LP-QP complexes.ResultsThe combined technique significantly enhanced protein digestibility, decreased the proportion of α-helices in the protein structure in favor of random coil components, and improved the phenolic content of the LP-QP complexes. Digestibility increased to 87%, up from 76% for unfermented LP-QP. Moreover, the LP-QP complexes produced using the combined technique generated a highly nutritional protein with a reduced saponin content.ConclusionThis research revealed that a combination of PPI and water kefir fermentation significantly enhances the nutritional and functional quality of LP, creating new opportunities for leveraging the growing popularity of plant-based proteins into high-value industrial applications.

Enhanced functionality of fermented whey protein using water kefir

ABSTRACT This research is part of an effort to enhance fermented whey proteins’ quality and nutritional value. In this research, we investigated the feasibility of using a natural fermentation approach on whey proteins. We determined the protein digestibility, non-nutritive compounds (including phenolic compounds and saponins), and microbiological quality of water kefir-fermented whey proteins. Due to the water kefir-induced fermentation of whey proteins, the protein digestibility improved from 88.48 to 94.33%. The protein quality of fermented whey proteins has been modified after the water kefir fermentation, as observed with the changes in the secondary protein structure components, especially α-helices (decreased from 10.58 to 8.52%) and random coil (increased from 12.25 to 17.33%). In addition, their water solubility, surface hydrophobicity, and surface charge changed significantly (P < .05) during the fermentation time; 88.44 to 94.11%, 387.23 to 272.7 a.u. and −30.06 to −34.93 mV, respectively. Furthermore, water kefir is an excellent source of fermenting microorganisms, including lactic and acetic acid bacteria and yeast. Thus, the water kefir fermentation approach could be an effective, practical, non-thermal approach for altering whey proteins.

Proximate Composition and Antimicrobial Activity of Kefir Produced from Cow’s and Almond Milk

Fermented foods are an important diet component of people around the world. Kefir, or fermented milk, is popular worldwide due to its high nutritional value, with cow's milk being the common substrate for traditional kefir fermentation. However, the scarcity of animal-based milk in some countries, plus cultural, religious, and health reasons, have seen non-dairy milk kefir from almond milk gaining popularity among consumers globally. This study aimed to evaluate and compare the proximate composition and anti-microbial activity of kefir produced from 100% cow or 100% almond or an equal (1:1) mixture of both kinds of milk. This study used the AOAC 2000 method for the proximate analysis, while the agar well diffusion method examined the anti-microbial activity of the milk samples against Escherichia coli, Staphylococcus aureus, and Salmonella typhi. Results revealed that the three kefir samples showed significantly different (p&lt;0.05) moisture, total dietary fiber, and fat contents and were within the CODEX acceptable range for kefir. All samples exhibited varying degrees of inhibition between the different pathogens. The diameters of the inhibition zone of the tested kefir samples were significantly different toward Salmonella typhi (p&lt;0.05), with the mixture of almond and cow milk notably producing better inhibition towards all tested bacteria. The above-said milk mixture also gave a better overall nutrient profile (lower fat and higher fibre). While almond milk might be a suitable substrate for kefir, it was not effectively inhibitory for all bacteria. The overall results thus conveyed the promising use of almond and cow milk mixture as an alternative substrate for kefir fermentation, further supporting its potential use as a probiotics source.

Chemical Evaluation and Probiotic Potential of Kefir Different Nutrient Media

Kefir is a gelatinous mass composed of bacteria and yeast. This study aims to develop beverages obtained from kefir grains’ fermentation in different nutrient media. Thus, kefir fermentation was performed in an aqueous solution of sucrose, whole milk, whole grape juice, and water-soluble coconut extract. The fermentation process was analyzed from grain growth, beverage yield, lactic acid determination, pH, total soluble solids, and microbiological analysis. The results showed the beverages had pH and lactic acid values following the legislation. Furthermore, it identified the probiotic potential of the coconut and milk water-soluble extract beverages.