Milk kefir (MK) and water kefir (WK) are traditionally produced from different unique probiotic-containing semi-soft particles known as milk kefir grains and water kefir grains. There is significant ...confusion between these kefir grains, even in peer-reviewed scientific publications. Even though both grains have some similarities, they have significant differences in structure, microbial content, and impact on the finished beverage product.
This review compares the two probiotic kefir grains and examines the similarities and differences in these two grains and the products made from them. Microbiological, chemical, and functional properties for two grains are examined.
The two different fermented beverages produced from these grains have different physical and chemical characteristics and different microbiological composition. MK and WK also have different functional properties. During the COVID-19 pandemic, the consumption of natural probiotic-containing foods was suggested as beneficial for improving gut health and, consequently, overall health. MK and WK contain broad spectra of probiotic microorganisms, which may help improve overall health and immunity. Consequently, MK and WK may help protect against COVID-19 and especially in the elderly. While milk kefir provides significant amounts of protein as well as probiotics and prebiotics, water kefir can be a significant probiotic and prebiotic source for vegans and people who are allergic to dairy products. Both of these grains are important for their potential health benefits.
•Milk kefir and water kefir grains are two unique probiotic starter cultures.•Kefir grains were naturally formed via the symbiotic relationships of inherent microorganisms.•Beverages prepared from these grains are wholly unique among probiotic products.•Each kefir product has significant health promoting properties.•Water kefir has great potential as a probiotic product for those who are allergic to dairy ingredients as well as to vegans.
•Bacterial and fungal genes of kefir grains were sequenced.•Lactobacillus genera were highly associated with protein digestion ability in GK.•Volatiles in GK was highly correlated with the bacteria ...and yeasts in kefir grains.
Microbial diversity in kefir grains is responsible for the production of goat milk kefir with unique peptides composition and volatile profile. High-throughput sequencing technique was used to analyze bacterial and fungal diversity of three different kefir grains which were originated from China, Europe Germany and United States. Peptides and volatile profile in goat milk kefir were determined by proteomic platform and Gas Chromatography-Ion Mobility Spectrometry, respectively. Clustering analysis indicated that the different content of Lactobacillus genera in different kefir grains was highly associated with the proteolytic ability in goat milk kefir. Contents of volatile compounds in goat milk kefir were also correlated to the bacteria and fungi in kefir grains (especially for Lactobacillus spp. and Saccharomyces spp.). The innovation of this study was to find a new way in exploration of the correlation of microbiota in kefir grains with the proteolytic ability and volatile profile of goat milk kefir.
Aims
Although kefir has been known for centuries, there is confusion between the two types of kefir grains, for example, milk kefir (MK) grain and water kefir (WK) grain. This study aimed to unravel ...the differences and similarities between WK grain and MK grain.
Methods and Results
Microbiological analyses, identification of grains microbiota and enumeration of microbiological content of the grains as well as scanning electron microscope (SEM) imaging, dry matter, protein, ash, and mineral content, and colour analyses were carried out for the two types of grains. As a result, significant differences were found in microbiological content, chemical properties and colours (p < 0.05). Additionally, SEM images revealed the different intrinsic structures for the microbiota and the structure of the two types of grains.
Conclusions
MK grain has more nutritional content compared to WK grain. Despite not as widely known and used as MK grain, WK grain is a good source for minerals and health‐friendly micro‐organisms such as lactic acid bacteria and yeasts. WK grain is possibly suitable for vegans and allergic individuals to fulfil nutritional requirements. Moreover, in this study, the variety of WK grain microbial consortia was wider than that of MK grains, and this significantly affected the resultant WK products.
Significance and Impact of the Study
This is the first study that comprehensively compares two different kefir grains in microbial, chemical and physical properties.
Display omitted
•The microbial dynamics and volatilome profile in kefir production have been studied.•A microbial shift was observed during the production of backslopped kefir.•Backslopped kefir ...samples showed higher pH, protein, lactose and ash content.•Backslopped kefir was correlated with cheesy, buttery, floral and fermented odors.•This is the first report on volatilome profile of the backslopped kefir.
Kefir is a well-known health-promoting beverage that can be produced by using kefir grains (traditional method) or by using natural starter cultures from kefir (backslopping method). The aim of this study was to elucidate the microbial dynamics and volatilome profile occurring during kefir production through traditional and backslopping methods by using five kefir grains that were collected in Bosnia and Herzegovina. The results from conventional pour plating techniques and amplicon-based sequencing were combined. The kefir drinks have also been characterized in terms of their physico-chemical and colorimetric parameters. A bacterial shift from Lactobacillus kefiranofaciens to Acetobacter syzygii, Lactococcus lactis and Leuconostoc pseudomesenteroides from kefir grains in traditional kefir to backslopped kefir was generally observed. Despite some differences within samples, the dominant mycobiota of backslopped kefir samples remained quite similar to that of the kefir grain samples. However, unlike the lactic acid and acetic acid bacteria, the yeast counts decreased progressively from the grains to the backslopped kefir. The backslopped kefir samples showed higher protein, lactose and ash content and lower ethanol content compared to traditional kefir samples, coupled with optimal pH values that contribute to a pleasant sensory profile. Concerning the volatilome, backslopped kefir samples were correlated with cheesy, buttery, floral and fermented odors, whereas the traditional kefir samples were correlated with alcoholic, fruity, fatty and acid odors. Overall, the data obtained in the present study provided evidence that different kefir production methods (traditional vs backslopping) affect the quality characteristics of the final product. Hence, the functional traits of backslopped kefir should be further investigated in order to verify the suitability of a potential scale-up methodology for backslopping.
Water kefir is a sparkling, slightly acidic fermented beverage produced by fermenting a solution of sucrose, to which dried fruits have been added, with water kefir grains. These gelatinous grains ...are a symbiotic culture of bacteria and yeast embedded in a polysaccharide matrix. Lactic acid bacteria, yeast and acetic acid bacteria are the primary microbial members of the sugary kefir grain. Amongst other contributions, species of lactic acid bacteria produce the exopolysaccharide matrix from which the kefir grain is formed, while yeast assists the bacteria by a nitrogen source that can be assimilated. Exactly which species predominate within the grain microbiota, however, appears to be dependent on the geographical origin of the grains and the fermentation substrate and conditions. These factors ultimately affect the characteristics of the beverage produced in terms of aroma, flavour, and acidity, for example, but can also be controlled and exploited in the production of a beverage of desired characteristics. The production of water kefir has traditionally occurred on a small scale and the use of defined starter cultures is not commonly practiced. However, as water kefir increases in popularity as a beverage – in part because of consumer lifestyle trends and in part due to water kefir being viewed as a health drink with its purported health benefits – the need for a thorough understanding of the biology and dynamics of water kefir, and for defined and controlled production processes, will ultimately increase. The aim of this review is to provide an update into the current knowledge of water kefir.
•Water kefir is a sparkling, acidic fermented beverage produced by fermenting a sucrose solution, to which dried fruits and water kefir grains are added.•Lactic acid bacteria, yeast and acetic acid bacteria are the primary microbial members of the sugary kefir grain.•Which species predominate within the kefir grain appears dependent on the geographical origin of the grains and substrate and fermentation conditions.•Water kefir is seen as a vegan alternative to milk kefir and purported health benefits related to the presence live microorganisms.•As water kefir increases in popularity there is a need for a thorough understanding of the biology and dynamics of water kefir fermentation.
Sugary kefir beverage is produce by fermenting raw sugar solution with kefir grains, the latter consisting of polysaccharide and microorganisms. This beverage, with great consumption in countries ...such as USA, Japan, France, and Brazil, represents a promising market to functional cultured drinks. This paper reviews the microbial diversity and interaction, kinetics, safety, and bioactivities of sugary kefir fermentation. The literature reviewed here demonstrates that sugary kefir possesses a similar microbial association relative to traditional milk kefir fermentation, especially among lactic acid bacteria and yeast species, such as Lactobacillus, Leuconostoc, Kluyveromyces, Pichia, and Saccharomyces. However, a selective pressure at species level is generally observed, as, for example, the stimulation of Saccharomyces species metabolism, leading to a high content of alcohol in the final product. This also seems to stimulate the growth of acetic acid bacteria that benefit of increased ethanol production to acetic acid metabolism. Existing reports have suggested important bioactivities associated with sugary kefir beverage consumption, such as antimicrobial, antiedematogenic, anti-inflammatory, antioxidant, cicatrizing, and healing activities. Other alternative non-dairy substrates, such as fruits, vegetables, and molasses, have also been tested for adaptation of kefir grains and production of functional beverages with distinct sensory characteristics. This diversification is of crucial importance for the production of new probiotic products to provide people with special needs (lactose intolerance) and vegan consumers.
•Survey on microbial composition and kinetics of sugary kefir fermentation.•Manufacturing, safety, and bioactivities of sugary kefir beverage are reviewed.•Update of non-dairy kefir beverages in the word.•Alternatives sources of non-dairy, probiotic products are proposed.
Kefir is a symbiotic microbial blend of lactic acid bacteria, yeast, and acetic acid bacteria anchored to a polysaccharide matrix, endowing remarkable health benefits. The increase in the number of ...lactose intolerant, vegan and vegetarian consumers, led, in recent years, to develop fruit or vegetable-based healthy formulas. This review has been conceived to be a complete collection of different classes of non-dairy kefir products. Fruit or vegetable-based are used as substrates for milk or water kefir grains fermentation. The microbiological, chemical-physical, technological, and sensory aspects were discussed for each formulation. Moreover, when available, other potential health benefits were reported and discussed.
•Alternative substrates for kefir fermentation were analysed and discussed.•Non-dairy kefir beverages show different features compared to milk-based product.•Like traditional one these products are rich in probiotic microorganisms.•Fruit or vegetable-based fermented drink possess antioxidant activity.•Grains can be used for multiple fermentations reducing production cost.
Kefir is a dairy product that can be prepared from different milk types, such as goat, buffalo, sheep, camel, or cow via microbial fermentation (inoculating milk with kefir grains). As such, kefir ...contains various bacteria and yeasts which influence its chemical and sensory characteristics. A mixture of two kinds of milk promotes kefir sensory and rheological properties aside from improving its nutritional value. Additives such as inulin can also enrich kefir's health qualities and organoleptic characters. Several metabolic products are generated during kefir production and account for its distinct flavour and aroma: Lactic acid, ethanol, carbon dioxide, and aroma compounds such as acetoin and acetaldehyde. During the storage process, microbiological, physicochemical, and sensory characteristics of kefir can further undergo changes, some of which improve its shelf life. Kefir exhibits many health benefits owing to its antimicrobial, anticancer, gastrointestinal tract effects, gut microbiota modulation and anti-diabetic effects. The current review presents the state of the art relating to the role of probiotics, prebiotics, additives, and different manufacturing practices in the context of kefir's physicochemical, sensory, and chemical properties. A review of kefir's many nutritional and health benefits, underlying chemistry and limitations for usage is presented.
Kefir milk, known for its high nutritional value and health benefits, is traditionally produced by fermenting milk with kefir grains. These grains are a complex symbiotic community of lactic acid ...bacteria, acetic acid bacteria, yeasts, and other microorganisms. However, the intricate coexistence mechanisms within these microbial colonies remain a mystery, posing challenges in predicting their biological and functional traits. This uncertainty often leads to variability in kefir milk's quality and safety. This review delves into the unique structural characteristics of kefir grains, particularly their distinctive hollow structure. We propose hypotheses on their formation, which appears to be influenced by the aggregation behaviors of the community members and their alliances. In kefir milk, a systematic colonization process is driven by metabolite release, orchestrating the spatiotemporal rearrangement of ecological niches. We place special emphasis on the dynamic spatiotemporal changes within the kefir microbial community. Spatially, we observe variations in species morphology and distribution across different locations within the grain structure. Temporally, the review highlights the succession patterns of the microbial community, shedding light on their evolving interactions.Furthermore, we explore the ecological mechanisms underpinning the formation of a stable community composition. The interplay of cooperative and competitive species within these microorganisms ensures a dynamic balance, contributing to the community's richness and stability. In kefir community, competitive species foster diversity and stability, whereas cooperative species bolster mutualistic symbiosis. By deepening our understanding of the behaviors of these complex microbial communities, we can pave the way for future advancements in the development and diversification of starter cultures for food fermentation processes.
•Sucrose, demerara, brown, fructose, coconut sugar, and honey as sucrose-substitute.•Sheep milk kefir with sucrose-substitutes had higher Lactobacillus counts.•Sucrose-substitutes increased the ...antagonistic activity against foodborne pathogens.•Sucrose-substitutes improved the fatty acid profile, and bioactive compounds levels.•Sheep milk kefir with sucrose-substitutes had higher antiproliferative activity.
The effect of different types of sugar (sucrose, demerara, brown, fructose, coconut sugar, and honey) on sheep milk kefir was evaluated. Microbial counts (Lactobacillus, Lactococcus, Leuconostoc, yeast), antagonistic activity against foodborne pathogens, microstructure (scanning electron microscopy), and antiproliferative activity of cancer cells were evaluated. Furthermore, the antioxidant activity (DPPH), inhibitory activity of angiotensin-converting enzyme (ACE), α-amylase, and α-glucosidase, lactose content, lactic and acetic acids and ethanol, fatty acid profile and volatile organic compounds were determined. The addition of sugars increased the Lactobacillus population (up to 2.24 log CFU/mL), metabolites concentration, antagonistic activity against pathogens, antioxidant activity (11.1 to 24.1%), ACE inhibitory activity (27.5 to 37.6%), α-amylase inhibition (18 to 37.4%), and anti-proliferative activity. Furthermore, it improved the fatty acid profile and volatile compounds. The results suggest that the replacement of sucrose with different types of sugar constitute an interesting option to be used in sheep milk kefir formulations.
PDF
