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Nutritional Effects and Antimicrobial Activity of Kefir (Grains)

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J. Milk Sci. Biotechnol. 2018;36(1):1-13 J Milk Sci Biotechnol Vol. 36, No. 1 1
Received: March 17, 2018
Re vised : March 21, 2018
Accepted: March 21, 2018
These authors contributed equally to
this study.
*Corresponding author :
Kwang-Young Song
Dept. of Biological Engineering, Yanbian
University of Science & Technology,
Yanji, China, and Center for One
Health, College of Veterinary Medicine,
Konkuk University, Seoul, Korea.
Tel : +82-2-450-4121
Fax : +82-2-3436-4128
E-mail :
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Ying Shen
Dong-Hyeon Kim
Jung-Whan Chon
Hyunsook Kim
Kwang-Young Song
Kun-Ho Seo
Nutritional Effects and Antimicrobial Activity of Kefir
Ying Shen
, Dong-Hyeon Kim
, Jung-Whan Chon
, Hyunsook Kim
Kwang-Young Song
, and Kun-Ho Seo
1Dept. of Biological Engineering, Yanbian University of Science & Technology, Yanji, China
2Center for One Health, College of Veterinary Medicine, Konkuk University, Seoul, Korea
3Dept. of Food & Nutrition, College of Human Ecology, Hanyang University, Seoul, Korea
Kefir exhibits antimicrobial activity
in vitro
against gram-positive and gram negative
bacteria, as well as some fungi. The ability of LAB to inhibit the growth of closely related
bacteria is well known. This inhibition of pathogenic and spoilage microbes may be due
to the production of organic acids, hydrogen peroxide, acetaldehyde, diacetyl, carbon
dioxide, or bacteriocins. Lactobacilli are the major contributors to acid production and,
hence, a determining factor in the flavor development in kefir. Lactic acid, proteolytic
activity, and acetaldehyde are the essential flavor compounds in kefir. Both acid and
bacteriocins contribute to the antimicrobial activity of kefir and kefir grains. Kefir is rich
in proteins, calcium, vitamin B
, niacin, and folic acid. Many studies have investigated the
benefits of consuming kefir and have shown that it is a natural probiotic, which when
consumed regularly, can help relieve intestinal disorders, promote bowel movement, reduce
flatulence, and improve the overall health of the digestive system. Tibetan kefir, which is
different from traditional kefir, is produced in China. It has been reported to exhibit
antimicrobial activity that is nearly identical to that of traditional kefir. Kefir production
is considered a rapidly growing food industry in China.
kefir, kefir grains, nutritional value, antimicrobial activity, kefir’s production
Kefir production is mainly based on fermentation of milk with starter kefir culture and
kefir grains looks like little cauliflowers and contains a complex mixture of lactic acid
bacteria, acetic acid bacteria and yeast (Ot1es and Cagindi, 2003; Wojtowski
et al.
, 2003;
et al.
, 2004; Powell, 2006; Chen
et al.
, 2008; 周
et al.
, 2008; 王
et al
2009). The complex structure of microflora cause symbiotic relationship is responsible
for fermentation (Maeda
et al.
, 2004;
et al.
, 2005). Thus, the purpose of this review
paper was to suggest the basic information about kefir which had many function for
improving human health. This review contacted kefir’s history, the current industrial
status, kefir’s appearance including the descriptions about kefir grains, kefir’s overall
functions and its production in China. All the materials have been reorganized in the
published literature.
All about Kefir
1. History
The word kefir is derived from the Turkish word ‘keif’ which means ‘good feeling’. Kefir
Shen et al.
2J Milk Sci Biotechnol Vol. 36, No. 1
is known as a milk beverage of old world food. The drink originated in the Caucasus
Mountains in the former Soviet Union, in Central Asia and has been consumed for
thousands of years (Powell, 2006). The Caucasian people discovered that the fresh milk
carried in leather pouches would occasionally ferment into an effervescent beverage
et al.
, 2004). In their countries the kefir until now has been produced
primarily from sheep milk, whereas in Europe its production on a commercial scale is
limited basically to cow milk (Wojtowski
et al.
, 2003).
2. Industrial status
Besides that kefir originally spread through Russia, Eastern Europe, Middle East, the
west Germany, Switzerland, and Northern Europe. Recently, kefir is also popularized in
America, England, Canada, Japan, and so forth. For those countries which did not pay
much attention on kefir, have shown exceeding interests at kefir recently. In particular,
Germany will enlarge both the consumption and production of kefir in the future. In
China, industry of kefir is still at the very beginning step, and the annual yield is less
than 30,000 tons. Most kefir are predominantly imported (王
et al
., 2009).
3. Kefir and kefir grains
Kefir differs from other fermented dairy products in that it is the product of fer-
mentation of milk in the presence of a mixed group of microorganism confined to a
matrix of discrete ‘kefir grains’, which can be recovered for subsequent fermentation
et al
., 2008). Kefir is fermented only by kefir grains and its mother culture, and
kefir grains are the original contributor to kefir’s antimicrobial activity.
Kefir grain, is like small clusters of off-white gelatinous nodules. The grains are
insoluble in water and common solvents, gelatinous, and irregular in size, varying from
0.3∼3.5 cm in diameter. Each grain contains symbiotic consortia of bacteria and yeasts
held together by a matrix of proteins, lipids, and polysaccharides. This symbiosis is
responsible for kefir’s mouthfeel’ s like tangy and stringy, and accounts for many of its
health promoting and medicinal properties (Powell, 2006). These grains can be per-
severed by freezing, lyophilization, and refrigeration (Silva
et al.
, 2009).
4. Kefiran
Kefiran is a water-soluble polysaccharide gel, which constitutes between 24∼25% (m/m)
of the dry weight of the kefir grain. It is a matrix of fibrillar amorphous material. This
fibrillar matrix surrounds the bacteria and yeast in kefir grains, and holds the grains
together (Santos
et al.
, 2003). Kefiran polysaccharide has antibacterial, antimycotic and
antitumour activity (Micheli
et al
., 1999). It is also said that a number of Kefiran-
producing homofermentative LAB have been isolated from kefir grains, including
Lactobacillus kefirnofaciens
Leuconostoc mesenteroides
tococcus lactis
Kefiran has been studied extensively and has demonstrated anti-inflammatory and
immunomodulating properties in animal and human trials. It has also demonstrated
antibacterial and anti-mycotic properties (Diniz, 2003; Maeda
et al.
, 2004).
Nutritional Effects and Antimicrobial Activity of Kefir (Grains) J Milk Sci Biotechnol Vol. 36, No. 1 3
5. Health benefits
For kefir is a natural probiotic, it contains live active cultures of normal flora which
is made of very strong strains of microorganisms that help to over take pathogenic
organisms, repopulate the digestive tract and aid in digestion. It also claims that
consuming fermented milk foods can boost the immune system, alleviate symptoms of
diarrhea and chronic constipation, and lower the risk of colon cancer (Ot1es and
Cagindi, 2003).
The microbes in kefir grains are able to produce lactic acid, acetic acid, ethanol,
peptides, and other biologically active components that increase the storage capability
of milk and inhibit the growth of undesirable and pathogenic microbes (Witthuhn
., 2005). There are data to show that many lactobacilli are capable of producing a
wide range of antimicrobial compounds that may be used in the treatment and
prevention of vaginal infections (Farnworth, 2005).
Some studies refer to kefir’s antimicrobial activity and suggest that the probiotic might
influence the gastrointestinal disorders of humans, such as with ulcers and diarrhea
(Jamuna and Jeevaratnam, 2004).
6. Kefir vs yogurt
Yogurt contains transient beneficial bacteria that keep the digestive system clean and
provide food for the friendly bacteria that reside there. But kefir can actually colonize
the intestinal tract, a feat that yogurt cannot match. Kefir contains several major strains
of friendly bacteria not commonly found in yogurt,
Lactobacillus Caucasus,
species, and
species. Because the curd size of kefir
is smaller than yogurt, it is also easier to digest, which makes it a particularly excellent,
nutritious food for babies, the elderly and people experiencing chronic fatigue and
digestive disorders.
7. Production of kefir
Kefir can be made from any type of milk, cow, goat or sheep, coconut, rice or soy.
Although it is slightly mucous forming, the mucous has a "clean" quality to it that creates
ideal conditions in the digestive tract for the colonization of friendly bacteria.
There are several methods of producing kefir (Ot1es and Cagindi, 2003). Commonly
traditional and industrial processes are used and also food scientists are currently studying
modern techniques to produce a kefir with the same characteristics as those found in
traditional kefir.
Here are the two basic types of processes:
1) Traditional process
the traditional method of kefir making involves the direct addition of kefir grains to
milk, which has been pasteurised and cooled to between 200℃ and 250℃. Then, fer-
mented in 18∼24 hours at 20∼250℃ (room temperature). After this, the grains are
removed by filtering with a sieve and can be dried at room temperature and kept at
cold surroundings for being used in the next inoculation. Kefir is stored at 40
C for a
Shen et al.
4J Milk Sci Biotechnol Vol. 36, No. 1
time then is ready for consumption. The traditional process of kefir is shown in Fig. 1.
2) Industrial process
this method is almost the same as traditional process. First, to homogenize the
milk to 8% dry matter and held by heat treatment at 90∼95
for 5∼10
minutes. Then to cool at 18∼24
and inoculated with 2∼8% kefir cultures in
tanks. It costs 18∼24 hours to ferment. The coagulum is separated by pomp
and distributed in bottles. After maturing at 12∼14
or 3∼10
for 24 hours,
kefir is stored at 4
. The industrial process of kefir is shown in Fig. 2
S and Cagindi, 2003).
The optimal conditions for kefir’s fermentation has been proved to be: fermenting
temperature 23℃, incubating quantity 3%, time requirement 48h, concentration 12%.
Incubating temperature is the primary factor which affects fermentative activity.
Secondly, the milk concentration. Thirdly, the quantity of incubating kefir grains. At last,
incubating time makes the least influence on fermentative activity (
et al
., 2005)
Functions of Kefir
1. Physiological function of kefir
Owing to the probiotic microbial communities are different from the common yogurt,
the physiological functions of its products are superior than the common yogurt. Kefir
is rich in highly digestible lactoprotein and milk fat, in which probiotic microbial com-
Fig. 1. The traditional process of kefir.
Nutritional Effects and Antimicrobial Activity of Kefir (Grains) J Milk Sci Biotechnol Vol. 36, No. 1 5
Fig. 2. The industrial process of kefir.
munity hydrolyzes most of lactose in milk into human benefited L-lactic acid, with very
little D-lactic acid formed. It claims that kefir contains 2∼5% D-lactic acid, which is
further lower than that of common yogurt (contains about 25∼60% lactic acid). Since
human body is lack of metabolic enzyme of lactate, ingesting D-lactic acid is more easy
to suffer a acidic blood disease.
Therefore, kefir is a good diet for lactose intolerant individuals that have the inability
to digest significant amounts of lactose that is the predominant sugar of milk (Ot1es
S and Cagindi, 2003).
Meanwhile, with the function of L-lactic acid, it also improves the absorbability of
calcium, phosphorus, and iron. In addition, kefir is rich in water soluble vitamin B, like
vitamin B
, vitamin B
, vitamin B
, vitamin B
, niacin, and folic acid. As a result, kefir
is not only brings a high nutritional value, but also contribute to a better health and
increasing longevity (王
et al
., 2009).
2. Other beneficial properties
1) Impacts on immune system
Researches also claimed about their curative properties and consumed that fermented
milk foods can boost the immune system, alleviate symptoms of diarrhea and chronic
Shen et al.
6J Milk Sci Biotechnol Vol. 36, No. 1
constipation, and lower the risk of colon cancer have been popular, along with the
perception that commercial yogurt and kefir are inferior to those fermented at home
from natural starters (Lopitz-Ostoa
et al.
, 2006). Probiotics found in kefir have sti-
mulating effects on the immune system by improving phagocytosis and by increasing
the numbers of T-lymphocytes and NK cells. They also have an indirect effect on the
immune system by forming bioactive peptides in the process of fermentation (Heyman,
2000; Sanders, 2000).
2) Antitumor activity
Several studies have investigated the antitumor activity of kefir and polysaccharides
form kefir grain (Cevikbas
et al.,
1994; Furukawa
et al.
, 1990). And recent researches
demonstrated that kefir has a better function of antiatheroscloresis and antidiabetics,
and has the curative properties for tuberculosis. Besides, kefir contains capsular poly-
saccharide which inhibit the reproduction of cancer cells, so that reduce the incidence
of cancer.
3) Microorganisms’growing inhibition
Kefir can also decrease contents of serum cholesterol, strengthen functions of liver and
gall. Improving the functions of immune system and anti-aging. viable organism in kefir
grains forcefully inhibit production of such bacteria, like
Escherichia coli
. Therefore, frequently consumption of kefir can
maintain a superiority of probiotic community within human’s gastrointestinal tract.
Revolution in bowels” mentions that “intestinal disease is the root of all diseases”. A
healthy body should begin with healthy intestines. Consequently, the consumption of
kefir in a frequent way, a superiority of probiotic in intestines can be retained, and
reduce incidence of intestinal diseases, eventually obtain a healthy body and the aim
of longevity.
3. Nutritional values
The composition of kefir is variable and not well defined (Zubillaga
et al.
, 2001). It
depends on the source and the fat content of milk, the composition of the grains or
cultures and the technological process of kefir. The chemical composition of kefir is
shown in Fig. 3.
The nutrient composition of kefir is similar to that of milk, in addition to beneficial
bacteria and yeast, kefir contains vitamins, minerals and essential amino acids that help
the body with healing and maintenance functions. With kefir containing more vitamins
, B
and folic acid, kefir is also rich in vitamin K and amino acids and is an excellent
source of biotin, a B vitamin that aids in the assimilation of the other B vitamins. The
proteins in kefir are partially digested and are, therefore, more easily utilized.
Tryptophan, one of the essential amino acids abundant in kefir, is well known for its
relaxing effect on the nervous system. Kefir also offers an abundance of calcium and
magnesium, which are important minerals for a healthy nervous system. The high
phosphorous content contributes to the utilization of carbohydrates, fats, and proteins
Nutritional Effects and Antimicrobial Activity of Kefir (Grains) J Milk Sci Biotechnol Vol. 36, No. 1 7
Fig. 3. The chemical composition and the nutritional values of kefir.
by the body for cell growth, maintenance and energy (Saloff-Coste, 1996).
Kefir is a good source of essential amino acids, vitamins, and minerals, which helps
maintenance chemistry in our body (Fig. 3).
The numerous benefits of B vitamins are regulation of the kidneys, liver and nervous
system to helping relieve skin disorders, boost energy and promote longevity (Ot1es and
Cagindi, 2003). Propionibacteria may be added to the kefir grains to increase the
vitamin B
concentration of the beverage. This is beneficial as the presence of vitamin
in milk decrease as much as 95% during lactic acid fermentation. The micro-
organisms in kefir do not synthesize vitamin B
, but they stimulate its production in
mixed culture in the presence of propionic acid bacteria. Van Wyk (2002) reported
increases of vitamins B
in kefir enriched with
Propionibacterium freudenreichii
Antimicrobial Activity of Kefir
1. Microorganism living on kefir grains
Kefir and sphingomyelin isolated from the lipids in kefir have been reported to
stimulate the immune system in both
in vitro
in vivo
studies (Osada
et al.
, 1994;
et al.,
Kefir possesses antimicrobial activity
in vitro
against a wide variety of Gram-positive
and Gram-negative bacteria, as well as some fungi (Garrote, 2000).
Differences in the genus, species or strain of probiotic bacteria can contribute to
differences in traits such as stability, enzyme expression, carbohydrate fermentation
patterns, acid production, and colonizing ability. The composition of kefir varies drama-
Shen et al.
8J Milk Sci Biotechnol Vol. 36, No. 1
Fig. 4. Kefir grain. Off-white, looks like pieces of
coral or small clumps of cauliflower.
Fig. 5. Microorganism perched on kefir grains
culture medium, containing a complex mixture of
tically depending on a variety of factors, including the source of the milk, its fat content
and the composition of the grains or starters.
Kefir grains include LAB (
Lactobacilli, lactocci, Leuconostocs
), yeasts, acetic acid
bacteria and possibly other microorganisms. The predominant
in kefir
grains are
L. paracasei
paracasei, L. acidophilus
L. delbrueckii
ricus, L. plantarum
L. kefiranofaciens
. These strains account for 90% of the
population in the grains, but only 20% of the
in the final fermented
beverage. The remaining 80% of these LAB consists of
L. kefir.
Here is the Table for microorganisms associated with kefir and kefir grains:
Lactic acid bacteria
Enterococcus durans
Lactobacillus kefiranofaciens
Leuconostoc mesenteriodes
Streptococcus salivarius
Acetic acid bacteria
Candida pseudotropicalis
Mycelial fungi
Some coliforms are actively inhibited by kefir microorganisms, and pathogenic bacteria
such as
do not grow when they are introduced to kefir. Of all
the kefir starter microbial components, the microphilic homofermentative lactococci
and acetic acid bacteria are the most active against coliforms. The microbes in kefir
grains are able to produce lactic acid, acetic acid, ethanol, peptides, and other
biologically active components that increase the storage capability of milk and inhibit
the growth of undesirable and pathogenic microbes.
Van Wyk (2001) showed that kefir possesses an inhibitory activity against
lococcus aureus, Bacillus cereus, Escherichia coli
Clostridium tyrobutyricum
teria monocytogenes
. Studies have also indicated that yeasts such as
, when
Nutritional Effects and Antimicrobial Activity of Kefir (Grains) J Milk Sci Biotechnol Vol. 36, No. 1 9
separated from kefir, possess pronounced antimicrobial activiry against coliforms
(Powell, 2006).
The exact cause of the inhibition is not known, but may be due to the antagonistic
action of various species of LAB (Lactic Acid Bacteria). Lactic acid bacteria are also
capable of preventing the adherence, establishment, replication, and pathogenic action
of certain enteropathogens. The precise mechanism of this antagonistic activity is not
clear, but may include the activity of lactic acid or volatile acids, hydrogen peroxide,
carbon dioxide, acetaldehyde and diacetyl, or bacteriocin and bacteriocin-like pro-
ducts. Supposedly, some inhibitory compounds of the kefir beverage, such as bac-
teriocins, hydrogen peroxide, and organic acids might be responsible for killing patho-
genic microorganisms.
In addition, kefir might also promote competitive adhesion to the gastrointestinal
epithelium surface (Ot1es and Cagindi, 2003).
isolated from kefir showed
antimicrobial activity against
and verified that ingestion of kefir spe-
cifically lowered microbial populations of Enterbacteriaceae and
(Powell, 2006).
2. Antimicrobial activity of kefir (grains)
LAB must survive in the digestive system after they are consumed in order to produce
any beneficial effects. It has been shown that
Lactobacillus delbrueckii
consumed in fermented milk products like yogurt and kefir do survive the
passage through the upper gastrointestinal tract. Probiotics have been effective in the
treatment of people with inadequate lactose digestion, as they convert the lactose in
the lactic acid, rendering the milk they ferment almost lactose-free. Research has
shown that probiotic can contribute to the general health of their host by resisting
colonization of the digestive system by harmful microorganisms, contributing to the
nutrition of the host, and affecting immunomodulation.
A decrease in the pH of the kefir beverage is caused by the accumulation of organic
acids, primarily lactic acid and acetic acid, produced as major end-products of
carbohydrate metabolism by LAB. Accumulation of lactic acid and a subsequent
decrease in pH results in a broad-spectrum inhibitory activity against Gram-positive
and Gram-negative bacteria.
The undissociated forms of lactic and acetic acid penetrates the microbial cell
membrane. This results in acidification of the cytoplasm and the formation of inhibi-
tions, especially against enzymes, by salt excesses. At a higher intracellular pH these
acids dissociate to produce hydrogen ions, which interfere with important metabolic
functions such as oxidative phosphorylation and substrate translocation. The antimi-
crobial effect of lactic or acetic acid depends on the pKa value of the acid, as well as
the pH of the external environment. These acids are known to inhibit
E. coli
. At a pH 5.0, acetic acid inhibits the growth of
Salmonellae typhimurium.
synergism between lactic and acetic acid has been reported for the inhibition of
E. coli
spp. (Garrote
et al.
, 2000). Lactic acid is a stronger acid than acetic acid
and in well-buffered foods with a pH of 4∼6, acetate has a stronger antimicrobial effect
as a greater portion of the acid is undissociated.
Shen et al.
10J Milk Sci Biotechnol Vol. 36, No. 1
Brown sugar was the most effective carbohydrate source with antimicrobial action,
mainly against
C. albicans
, for kefir grains promoted the hydrolysis of non-reducing
sugars, which are converted into organic acids and substances capable of producing
inhibition halos with pathogenic microorganisms (Yuksekdag
et al
., 2004).
Kefir’s Research and Production in China
1. Tibetan kefir
In China, there is such a kind yogurt that the production is very resemble to that of
kefir’s. People immerse Tibetan kefir grains in milk, after acidification of the milk,
separate the grains. Also, it claims that long time drinking Tibetan kefir beverage can
boost people’s immune system, complement vitamins, retard aging, allay tiredness,
particularly good for people who suffering a gastrosia, or nephropathy. This kind
Tibetan kefir looks very similar to kefir grains. They are both off-white, colloidal lump,
and there lives various microorganisms on the surfaces. Research has shown that
compared microbial community structures of kefir and Tibetan kefir by using
PCR-DGGE, bacteria community showed a 78∼84% similarity among different Tibetan
kefir, and 50∼70% among kefir from different regions. DGGE profiles of yeast indicated
80∼92% similarity of yeast community among 3 Tibetan kefirs, and a 50∼75% similarity
among kefir from different regions (周
et al.
, 2008).
According to Fig. 8 and Fig. 9, it is seen that compared with kefir grain, the
microorganism density of the outer surface of Tibetan kefir grain is larger.
2. Development of various kefir’s products and outlook of kefir’s research in China
Kefir is an amazing yogurt, which is the secret of longevity in the Caucasus residents,
because of its unique nutritional and health function abnormalities prevalent in foreign
countries. However, kefir production in China is severely hampered. The reason is that
kefir ferment on high-priced imports and the foreign agent produced by fermentation
of kefir flavor and texture are not suitable for domestic consumption habits.
China’s large population, the demand for fermented health drinks straight up, while
China’s current annual sales of kefir beverages is less than small countries such as
Sweden and Finland, mainly due to kefir ferment rely on imports, prices high, a single
species and fermentation, the impact of active instability.
There are many companies produced new kefir fermentation agent industrialization,
which both lowered the price of kefir and produced high quality that can be com-
parable to foreign products. Plus kefir can be easily made at home. Therefore, an
effective solution to the foreign monopolies, import prices are too high and fermented
beverages are not suitable for Chinese tastes and so on. Consequently, it will promote
the industrialization of kefir in China.
Kefir’s high nutritional values, containing about tryptophan, minerals, and vitamins,
Nutritional Effects and Antimicrobial Activity of Kefir (Grains) J Milk Sci Biotechnol Vol. 36, No. 1 11
Fig. 6. Kefir grains from Belgium. Fig. 7. Tibetan kefir grains from Tibet.
Fig. 8. Outer surface of Tibetan kefir grain
Fig. 9. Outer surface of kefir grain (×3,000).
which help human body get rid of many diseases. Such as intestinal diseases, cancer,
etc. Due to the microorganisms living on the surface of kefir grain, kefir possesses an
inhibitory activity against
Staphylococcus aureus, Bacillus cereus, Escherichia coli
Clostridium tyrobutyricum
Listeria monocytogenes
. Meanwhile, studies have also
indicated that yeasts such as
, when separated from kefir, possess pro-
nounced antimicrobial activity against coliforms, as well as some fungi, so as to lower
the risk of colon cancer. Therefore, it is recommended to consume kefir for being in
good shape. As the industrialization of kefir will be promoted in China, more and more
Chinese can benefit from this nutritional food as well.
This research was supported by Basic Science Research Program through the National
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... The protein composition of kefir varies as it depends on the source of milk, the components of the grains or cultures, and the process of kefir fermentation [27]. Otles (2003) [21] and Gamba et al. (2020) [33] reported lower protein contents for traditional kefir samples made from kefir grains (3.22% and 4.54%) compared to kefir samples prepared by the present study at 5.69% to 5.87%. ...
... and differed significantly across kefirs produced from cow's milk and almond milk mixtures at different ratios (p<0.005). Notably, the fat content of cow's milk kefir in this study corroborated earlier reports showing cow's milk kefir having fat contents between 1.34 % to 3.5% [26,27,32]. According to Dinkçi et al. (2015) [3], 3% (w/v) inoculation of kefir grains in 100% cow's milk produced milk kefir with 2.83% of fat. ...
... According to Dinkçi et al. (2015) [3], 3% (w/v) inoculation of kefir grains in 100% cow's milk produced milk kefir with 2.83% of fat. Likewise, a 10% (w/v) inoculum used by Gamba [27] showed that a 100 g cow's milk kefir samples contained 3.5g of fat. ...
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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<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<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.
... Besides to the free amino acid compositions of the kefir brew that varies during the fermentation process like; glutamic acid, isoleucine, phenylalanine, methionine, lysine, and threonine [11]. Tryptophan is one of the essential amino acids and a predominant amino acid in kefir, that has a vital role in the nervous system function [7,11]. ...
... kefir is a good source of many vitamins that are not metabolically produced in the human body, that we usually obtain from food. The most important of these vitamins present in kefir are: thiamine, pyridoxine, folic acid, biotin, vitamin C and Carotene ( Figure-3)., which in turn play an important role in maintaining and regulating body functions and reinforcement of the immune system [7,11,23]. ...
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Symbiosis is a coordination pattern within different microorganisms, which are capable of readjusting the imbalance of the intestinal microbiota; as a consequence of unhealthy lifestyles. A diet that rich in sugar, salt, and saturated fat is the main cause for change in the microbial equilibrium; which is responsible for gut homeostasis, that contribute to several universal epidemic diseases. Kefir grains constrain an invisible world within them; that are clusters of complex symbiotic system of beneficial microbial mixture consisting mainly of bacteria and yeasts, which is considered as a probiotic. Kefir brew is a nutraceutical dairy product, that is produced during the fermentation process as a result of the action of probiotics on the milk. Kefir brew has an ability to modulate the intestinal microbiota balance, and enhance its action. Routinely consumption of kefir brew attains a great promotion to the human health. In this review, we will discuss the mechanism by which consumption of kefir brew probiotics will modulate this imbalance system and accordingly restrain these diseases. Furthermore, we will highlight the symbiotic system of kefir brew and its significant actions on the human body; including the ability to promote the immune system in order to inhibit tumor formation or cancer progression.
... Different temperature conditions can also affect the variety and number of microflora found in kefir grains [3]. [4] explained that kefir is better than yogurt, especially for microflora diversity. The microorganisms were not found in yogurt but had a good role in gastrointestinal health, including Lactobacillus caucasus, Leuconostoc, and Acetobacter species. ...
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Keywords: ABSTRACT Kefir, Antioxidant, Eleutherine sp, Infusa Bawang dayak (Eleutherine palmifolia(L) Merr) is a local plant of Kalimantan (Indonesia) which is traditionally a spice and medicinal plant. The infusa of the bulb is exceptionally rich in phenolic and flavonoid as a phytochemicals compound. As a natural product, it has an excellent potential candidate to be the source of phenolic compounds for kefir manufactured into functional food products. The physicochemical, microbiological, and sensory quality was determined for kefir drink supplemented with bawang dayak (Eleutherine palmifolia(L) Merr) infusa at different concentrations (0, 1, 2, and 3%). Based on the study's results, kefir drink supplementation with bawang dayak (Eleutherine palmifolia(L) Merr) infusa maintained the nutritional, microbiological, and sensory quality of kefir drinks. A functional characterization exceptionally increases the phenolic compounds and DPPH scavenging activity of the kefir drink. The phenolic content of kefir drink is 90.21-113.22 mg GAE/g). Furthermore, DPPH scavenging activity was 46.46-49.91%. The antioxidant activity of bawang dayak (Eleutherine palmifolia(L) Merr) infusa showed its specific nutritional value and therefore had the potential as a source of natural antioxidants. This work is licensed under a Creative Commons Attribution Non-Commercial 4.0 International License.
... Khamir menghasilkan alkohol dan CO 2 (Hidayat, Pagada, & Suhartini, 2006). Kefi r bermanfaat untuk menjaga sistem kekebalan tubuh, menghambat pertumbuhan tumor, menjaga sistem pencernaan, membantu metabolisme kolesterol, dan sebagai antimikroba (Shen et al., 2018). ...
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Penelitian ini bertujuan untuk mengetahui antibakteri masker kefir susu kambing pada Staphylococcus epidermidis dan menghitung jumlah koloni Bakteri Asam Laktat (BAL) dan khamir. Uji antibakteri dilakukan dengan metode difusi sumuran. Antibakteri masker kefir ditunjukkan dengan adanya zona hambat yang terbentuk di sekitar sumuran. Spread plating dilakukan untuk menghitung koloni bakteri asam laktat dan khamir. Medium MRSA dan PDA diinkubasi pada suhu 37ºC selama 2-3 x 24 jam. Jumlah koloni yang tumbuh dihitung menggunakan metode Standard Plate Count dengan jumlah koloni 30-300, dan dinyatakan dalam satuan CFU/g. Hasil penelitian menunjukkan bahwa masker kefir mempunyai sifat bakteriostatik. Kemampuan antibakteri masker kefir susu kambing pada Staphylococcus epidermidis disebabkan karena di dalam supernatan masker kefir terdapat senyawa antibakteri. Hal ini ditandai dengan terbentuknya zona irradikal. Rerata koloni BAL pada masker kefir susu kambing A dan B adalah 1,5×109 dan 1,2×1010 CFU/g. Rerata jumlah koloni khamir pada masker kefir susu kambing A dan B adalah 2,1×1010 dan >3,0×1010 (3,9×1010) CFU/g.ANTIBACTERIAL OF GOAT’S MILK KEFIR MASK ON Staphylococcus epidermidis IN VITROThis study was aimed at determining the antibacterial goat’s milk kefir mask on Staphylococcus epidermidis and the number of Lactic Acid Bacteria (BAL) and the number of yeast colonies. The antibacterial test was carried out using the diffusion method of the wells. The antibacterial activity in the kefir mask is shown by the presence of inhibitory zones that form around the well. Spread plating was done to calculate the colonies of lactic and yeast acid bacteria. MRSA and PDA medium were incubated at 37ºC for 2-3 x 24 hours. The number of growing colonies is calculated using the Standard Plate Count method with the number of colonies of 30-300 and expressed in units of CFU/g. The results showed that kefir masks had bacteriostatic properties. The antibacterial ability of goat’s milk kefir mask was since the kefir supernatant contained antibacterial compounds. This is indicated by the formation of an nonradical zone. The mean of BAL colonies in goat milk masks A and B was 1.5 × 109 and 1.2 × 1010 CFU/g. The average number of yeast colonies in Goat milk masks A and B was 2.1 × 1010 and> 3.0 × 1010 (3.9 × 1010) CFU/g.
... This activity may be due to biologically active molecules such as bacteriocins, organic acids, bioactive peptides or others. The studies show that the microorganisms which are found in kefir may be used to prevent and treat vaginal infections, gastrointestinal disorders and for healing skin lesions (Shen et al., 2018). ...
Kefir is a fermented milk beverage and known to have positive effects on gut microbial diversity and human health. In this study, digested and undigested kefir samples were compared for changes in their antihypertensive, antidiabetic, antioxidant and antimicrobial activities. Results showed that the amount of total phenolic substances, 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging (DPPH) activity, and the angiotensin‐converting enzyme inhibitor (ACE‐I) activity increased from 43.76 ± 0.005 mg gallic acid equivalents (GAE)/L, 4.20 ± 0.55%, and 9.91 ± 3.90% in undigested kefir to 668.16 ± 3.332 mg GAE/L, 63.06 ± 0.64%, and 98.88 ± 0.42% in digested kefir, respectively. While the dipeptidyl peptidase IV‐inhibitory (DPPIV‐I) activity of undigested kefir increased by 19.11 ± 7.35% after digestion, the optical density of the ferric‐reducing antioxidant power (FRAP) decreased from 1.188 ± 0.05 to 0.278 ± 0.009, and the protein amount decreased from 101.4 mg L−1 to 12.42 mg L−1 in digested kefir. No antimicrobial effect was observed in undigested kefir, whereas, digested kefir samples were active, but only against Escherichia coli. These results show that the gastrointestinal digestion processes of kefir generally increase the number of bioactive molecules, and the digestion process must be taken into account to determine the biological capability of foods. After the in vitro static gastrointestinal digestion processes of kefir, the amounts of total phenolic compound, 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging (DPPH) activity, angiotensin‐converting enzyme inhibitor (ACE‐I) activity, dipeptidyl peptidase IVinhibitory (DPPIV‐I) activity, and antimicrobial activity dramatically increased; however, FRAP activity decreased after the gastric digestion. The increasing of the activities, except DPPIV, is continued after intestinal digestion. The digestion process gave the actual biological capability of kefir.
... The grains are separated from the milk using sieves, and the beverage is stored at 4°C. Kefir grains can be reused in the manufacture of new products, as they remain stable for long periods and the microbiota is renewed due to the symbiosis (Shen et al., 2018). ...
The objective of the present chapter was to demonstrate the state of the art in the recent advances in nutritional and functional components of dairy products research. In this chapter, the main mechanisms responsible and essential for a better understanding of nutritional and functional values of the components of milk and dairy products are highlighted. It also includes a discussion about the positive impacts of fermented milk, cheese, butter, ice cream, and dairy desserts components on the consumer's health.
Kefir is a fermented dairy product with well recognized probiotic properties. Recently, consumer interest in fermented products with probiotic microorganisms has increased due to the accumulating evidence of the effects of kefir microorganisms on the modulation of gut microbiota and their antimicrobial activity. Although the health properties of kefir have been reviewed in other works, the present review addresses the antimicrobial effects of kefir microbiota and associated compounds. The antimicrobial activity of kefir microorganisms could derive from different mechanisms. The microorganisms' capacity to adhere to the intestinal epithelium, preventing the adhesion of pathogens, and their immunomodulation properties are among the mechanisms suggested. Bacteria and yeast isolated from kefir have been shown to have in vivo and in vitro antimicrobial activity against enteropathogenic bacteria and spoilage fungi. However, most reports have focused their approach on single-strain antimicrobial properties; evaluation of antimicrobial activity of cocultures of kefir microbiota and their potential mechanisms of action has been neglected. Kefir microbiota and associated compounds have shown promising antimicrobial effects; however, more research needs to be done to discern the mechanisms of action.
The rise of antibiotic resistance in Salmonella has necessitated the need for alternative ways of preventing and controlling infections. Fermented products have been recognised to have prophylactic and therapeutic properties against diseases. This study focused on the analysis of antagonistic effect of two different traditional kefir grains on Salmonella Arizonae and Salmonella Typhimurium after 24 and 48 h fermentation. Kefir supernatants were analysed for ethanol, organic acid and protein composition using gas chromatography, high performance liquid chromatography and shotgun proteomics, respectively. Salmonellae were rapidly eradicated in kefir possibly due to action of lactic acid as kefir cell-free supernatant contained high concentrations of lactic acid ranging from 83.59 to 229.92 mm. Other molecules with recognised antibacterial activities including carbonyl compounds, histone and cathelicidin were detected in the soluble phase that could have provided synergistic effect with the organic acids.
Kefir is an acidic and low alcoholic beverage produced by fermentation of milk, fruit juice or sugary water with kefir grains and its consumption is associated with prophylactic and therapeutic properties including its antagonistic effect on enteric pathogenic bacteria. Kefir grains have several bacteria and yeast species encased in an extracellular polysaccharide matrix. The beverage is consumed due to its attributed health benefits conferred by probiotics. Kefir drink has bactericidal and bacteriostatic effects on enteric bacterial pathogens. The mechanisms of kefir on bacterial pathogens involve destabilisation of the cell membrane, cell lysis, degradation of nucleic acid, inhibition of protein synthesis and binding onto yeasts. Exopolysaccharides, organic acids, peptides, S-layer proteins, and others are responsible for these antagonistic mechanisms. Other prophylactic and therapeutic properties of kefir include anti-inflammatory, constipation-alleviating, reversal of lactose intolerance and general gastrointestinal tract improvement. This can lead to better health, and consequently resistance to infection.
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The experimental material were kefirs produced from sheep, goat and cow milk, the fat content of the kefirs being 6.89, 3.64 and 4.29%, respectively. Fat in the kefir from sheep milk contained the least middle-chain saturated acids (48.82%) and the largest amounts of linoleic and α-linolenic acids (2.74 and 1.04%, respectively). Fat in the kefir produced from goat milk contained the largest amounts of short- and middle-chain saturated acids (17.49 and 52.67%, respectively), as well as the smallest amounts of monounsaturated acids (19.58%). In turn, fat in the kefir from cow milk contained the largest amounts of monounsaturated acids (27.30%) and the smallest amounts of short-chain saturated acids, linoleic acid and α-linolenic acid (8.58, 1.56 and 0.49%, respectively). The profile of saturated fatty acids in the fat of the investigated kefirs does not indicate differences among them in terms of cholesterogenic properties. On the other hand, the profile of unsaturated fatty acids shows clearly that kefir produced from sheep milk can have a considerably more advantageous effect on the health of the consumer than kefirs produced from goat or cow milk.
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Kefir is fermented milk only made from kefir grains and kefir cultures as no other milk culture forms. Kefir grains are the mixture of beneficial bacteria and yeast with a polysaccharide matrix. During fermentation lactic acid, CO<sub>2</sub>, ethyl alcohol and aromatic compounds that make its unique organoleptic properties are occurred. Kefir is used for the treatment or control of several diseases for many years in Russia. It is begun to consume in some areas of the world, southwestern Asia, eastern and northern Europe, North America and Japan for its nutritional and therapeutic aspects. This paper attempts to review the consumption, process, chemical and nutritional composition and the health benefits of kefir.
BDF1雌マウスの右腋窩部皮下に移植したLewis肺がん細胞の増殖と臓器に及ぼすヨーグルトおよびケフィールの経口投与の影響を検討した。Lewis肺がん細胞を7.2×105/匹移植した1日後から9日間連続してケフィールの凍結乾燥物を2g/マウス体重kgずつ胃内に投与したマウスの移植部位の腫瘍重量は, 無処理の対照区のマウスに比べて有意に軽く, 62%の腫瘍増殖抑制率を示した。この腫瘍増殖抑制率は, 抗がん剤であるPSKを0.5g/マウス体重kgずつ投与した場合より高い値であった。また, 担がん状態に陥ることによって肥大化した脾臓はPSKの投与によって, 増加した白血球数はケフィールおよびPSKの投与によって, その肥大化と増加が抑制され, 対照区との間に有意の差が認められた。
Kefir is a fermented milk that is produced by adding Kefir grains, consisting of bacteria and yeasts, to milk. The aim of this study was to determine the microbial population at different stages of traditional Kefir production and Kefir grain mass cultivation. Seven different selective growth media, morphological and biochemical characteristics were used for the isolation and identification of the microbes. The microbial numbers during Kefir production varied between 4.6×103 and 2.6×108. A Zygosaccharomyces sp. was isolated from traditional Kefir grains and after the culturing conditions applied during the mass cultivation Candida lambica and C. krusei were present. Although these two species are present in other fermented milks, this study is the first to report their presence in Kefir. Species of Leuconostoc, Lactococcus, Lactobacillus and Cryptococcus were isolated from traditional grains. Lactobacillus plantarum was present in the mass cultivated grains, but not in the traditional Kefir grains.
Kefir is a fermented milk drink produced by the actions of bacteria and yeasts contained in kefir grains, and is reported to have a unique taste and unique properties. During fermentation, peptides and exopolysacchar- ides are formed that have been shown to have bioactive properties. Moreover, in vitro and animal trials have shown kefir and its constituents to have anticarcinogenic, antimutagenic, antiviral and antifungal properties. Although kefir has been produced and consumed in Eastern Europe for a long period of time, few clinical trials are found in the scientific literature to support the health claims attributed to kefir. The large number of microorganisms in kefir, the variety of possible bioactive compounds that could be formed during fermenta- tion, and the long list of reputed benefits of eating kefir make this fermented dairy product a complex probiotic.
The use of functional foods (probiotics and prebiotics) has been demonstrated to be effective for the treatment or control of several diseases. Further well designed trials to examine the effects of different probiotic components are required. It is important to establish separate functions and to gain further insight into the underlying mechanisms that include competitive exclusion and modification of colonic microflora. For a very long time Russians have used kefir for the treatment of a wide range of illnesses. This paper attempts to review the use of probiotic and functional foods in different diseases, with a special emphasis on kefir.
Kefir is a milk-derived product prepared by the incubation of kefir ‘grains’ with defatted milk. Various studies have been published on the therapeutic effects of kefir. However, few controlled studies and little information on the antibacterial, antifungal and antitumoural activities of kefir have been published. Therefore, these activities associated with kefir were investigated. The daily intraperitoneal administration of 0.50 mL kefir for 20 days to mice; containing transplanted fusiform cell carcomas resulted in a significant decrease in tumour size. Kefir-induced disappearance of tumoural necrosis was also evident. With respect to the antibacterial activity of kefir, the greatest activity was exhibited against gram-positive coccus, staphylococcus, and gram-positive bacillus. Kefir ‘grains’ showed higher antibacterial activity than kefir. Kefir also demonstrated antifungal activity against Candida, Saccharomyces, Rhodotorula, Torulopsis, Microsporum and Trichopyton species. The results demonstrate that kefir possesses antibacterial, antifungal and antineoplastic activities, and provides credence to the folklorec use of kefir for a variety of infectious and neoplastic diseases.
Changes in certain microbiological, physicochemical, and sensory parameters of kefir were studied during refrigerated storage. Kefir batches were prepared using 1% and 5% added kefir grains, and samples for analysis were taken 24 h after inoculation and then after 2, 7, 14, 21, and 28 days of storage at 5 ± 1 °C. After fermentation for 24 h after inoculation, lactobacilli and lactococci were present at levels of 108 cfu/ml, and yeasts and acetic acid bacteria were present at levels of 105 and 106 cfu/ml, respectively. The lactic acid flora decreased by about 1.5 log units between days 7 and 14 and then stabilized at that level. Yeast and acetic acid bacterial counts, lactose, and pH all remained constant over the storage period, while the total fat content and dry matter decreased. The percentage inoculate did exert an influence, and the sample batches made using 1% added kefir grains had higher lactic acid bacterial counts, lactose, and pH, while the sample batches made using 5% added kefir grains had higher yeast and acetic acid bacterial counts and viscosity. The total fat and dry matter contents were similar in both sample batches. Sensory analysis of the kefir samples revealed maximum acceptability levels in the first 2 days of storage.
Numerous nutrition surveys conducted in recent years in South Africa indicated that malnutrition, including micronutrient deficiencies, poses enormous socio-economic problems. Government intervention ranges from feeding schemes to mandatory fortification of basic foodstuffs with, inter alia, folate. The need for affordable fortified foodstuffs prompted this study, the aim being to produce a Kefir beverage “naturally” fortified with folate and vitamin B12. Since propionibacteria (PAB) are well-established producers of these two vitamins and were found to grow well in the presence of lactic acid bacteria, inclusion of PAB into the Kefir grains would achieve this aim. In order to facilitate routine vitamin B12 and folate analyses of large sample numbers, sample extraction and purification methods and HPLC assay techniques were developed. Excellent sample stability was achieved using a KCN extraction buffer (B12 assays) and phosphate buffers, followed by nitrogen flushing and storage at –20oC (folate assays). Solid phase extraction ensured sample purification. A variable wavelength detector (VWD) was used during the B12 assays, while both the VWD, followed by a fluorescence detector were used to detect four different folate vitamers typically present in foodstuffs. The HPLC results were compared with those obtained for replicate samples assayed using microbiological assays, the standard assay methods. Good agreement between the two techniques validated the HPLC analyses. Seventeen Propionibacterium freudenreichii strains were screened for vitamin B12 and folate production capacity. Strain J15 consistently produced the highest vitamin B12 levels and was among the best folate producers. The highest vitamin B12 levels were achieved with a glucose-based rich growth medium (B12 medium), periodic fluctuation of microaerophilic and anaerobic cycles and a growth temperature of 30oC. However, strain J15 was the best producer even in the poorer YEL and Whey media with lactate as the energy source, under aerobic conditions and when cultivated at 35oC. This strain was, therefore, selected for combination with Kefir grains in order to effect inclusion with a view to produce a folate and vitamin B12 fortified Kefir beverage. The vitamin B12 production capacity of strain J15 exceeded that of strains J17 (American Type Culture Collection), an internationally recognised vitamin B12 producer, and J19 (All Russian Collection of Microorganisms), a superproducer of the vitamin. Several protocols were used to achieve inclusion of PAB into Kefir grains. The best results in terms of inclusion and vitamin levels were achieved with multiple reactions of the Kefir grains with a reconstituted freeze-dried J15 culture. PCR assays of extracted DNA verified the presence of strain J15 in these grains. Freeze-drying of the Kefir grains after a suitable reaction period with the PAB strain also resulted in retention of the PAB culture in the grains. Further refinement of the HPLC assays is recommended with respect to the sample purification technique (folate) and the inclusion of an autosampler, with the requisite precautions to prevent oxidation and photolytic degradation (vitamin B12). Further research is required to further increase the levels of PAB cells incorporated into the Kefir grains. Since the best results were achieved by reacting Kefir grains twice with reconstituted freeze-dried PAB culture, multiple reaction of Kefir grains with PAB culture should be investigated. This method offers a definite avenue for increasing PAB cells included in Kefir grains to sufficiently high levels to ensure adequate vitamin B12 and folate production within 12 – 24 h, the normal duration of a Kefir fermentation. Evaluation of the entire PAB culture collection (Food Science, University of Stellenbosch) may identify a strain that is a better vitamin B12 producer than strain J15. Studies will also have to be performed to assess the bioavailability of the vitamin B12 and folate in the fortified Kefir.