This document discusses kefir, a fermented dairy beverage produced by inoculating milk with kefir grains. Kefir grains contain various lactic acid bacteria and yeasts that ferment the milk sugars to produce kefir's characteristic sour taste, slightly alcoholic and yeasty flavor. Kefir provides probiotics and nutrients like protein, calcium and B vitamins. It is prepared by mixing pasteurized milk with kefir grains, incubating to ferment, then separating the grains to produce a drinkable consistency high in beneficial microbes and nutrients. Kefir grains can be preserved through drying or refrigeration and reused to make repeated batches of the probiotic fermented milk beverage.

1. Kefir – An Alternative
Fermented milk
Prepared BY
T.Achutharam
B.Tech (Dairy Technology)
College of Food and Dairy Technology
TANUVAS - Chennai

2. FERMENTATION
• Fermentation is one of the oldest and most economical method used
in food preservation.
• Fermentation enhance mineral bioavailability and digestibility of
roves protein and carbohydrates as well as improve organoleptic
qualities of product.
• A trend has been observed amongst customers towards minimally
processed, highly nutritious, health promoting and flavour
enriched food.
• The wholesome properties of fermented milks ( curd, Yoghurt, kefir,
Kumis..) with their nutritional value have driven a considerable
interest.

3. Kefir
Kefir is a traditional fermented dairy
product of middle east. It originated from
Caucasus mountain in former soviet union,
central Asia
Turkish word ‘Keyif’ which mean Good
feeling
It is a Viscous, Self carbonated beverage
with smooth, slightly foamy body and
whitish colour having very small quantity
of alcohol. Its is produced by fermentation
of milk with kefir grains or starter culture
obtained from the grains.

4. Kefir
• Kefir can be prepared any type of milk but
commonly cow milk is used.
• Milk of full fat/ low fat/ no fat, which is
pasteurized is used for the preparation of kefir.
• A good quality kefir has pourable consistency,
sour taste, marginally yeasty flavour and prickly
sensation of 𝐜𝐨 𝟐 .
• Lactic acid, ethanol, co2 and other flavour
compounds such as acetaldehyde, diacetyl and
acetoin are produced during fermentation.

5. Milk ( 3-4 %fat 8 -9% SNF)
Filtration
Preheating ( 50 – 60°C)
Homogenization (150 – 250 kg/cm 3
Heat treatment (90 -95°C/ 10-20 min)
Packaging ( cup/ tubs/Bottles)
Inoculation (kefir grains (4-5g/l amount may vary depending upon activity
Incubation (25 – 30°C/18- 20 hours)
Separation of grains ( sieving)
Maturation at 8 - 10°C / 10 – 12 hours (optional)
Storage ( 6 – 7° C)
Cooling ( 25 – 30°C)

6. Characteristics of Kefir
COMPONENTS 100g
Fat (%) 3.5 – 3.8%
Protein (%) 2.5 - 3.3%
Lactose(%) 3 – 4%
Water(%) 87 – 88%
Ethanol(g) 0.7 – 0.9 (depends on maturation
time )
Lactic acid (g) 0.7 - 1

7. Kefir grains
Kefir grains are yellowish white elastic, Slimy and irregular
shaped resembling cauliflower buds.
Size generally varies from 1-3 cm length and 1-6 cm in
diameter
Water 89-90%
Liquid 0.2%
Protein 3.0%
Sugar 6.0%
Ash 0.7%
Chemical Composition of Kefir grain

8. Kefiran
• Kefir is prepared from milk by inoculation with kefir grain which are a
composition of lactic acid bacteria and yeast.
• These microorganisms bind together with casein and complex
sugar by matrix of polysaccharides called Kefiran.
• Kefiran is reported to have antibacterial, anitumoral, antidiabetic
and immunomodulating properties as well as technological roles as
a thickener, gelling agent and emulsifier.
• Kefir grains grow in size 5 to 7% of the biomass is generally
separated from fermented milk and reused.

9. KEFIR GRAIN MICRO FLORA
Lactic Acid Bacteria 83-90%
Yeast 10-17%
Bacteria :
Leconostoc ssp,
Lactobcillus lactis cremoris
Acetobacter
lactobacillus kefiranofaciens
lactobacillus kefiri
Yeast
Sacharomyces cerevisae
Candida colliculosa
Candida inconspicua
Candida mangnoliae
kloekera spp
Candida famata
kluyveromices lactis
kluyveromices maxianus
Candida Kefir

10. Activation of Kefir grains
• Kefir grains are generally activated by inoculating in pasteurized
milk followed by incubation at room temperature at room
temperature for 24 hours.
• The grains are retrieved by sieving after fermentation and washed
with cooled sterile water.
• The procedure is repeated 3-4 times before being used for final
product preparation.

11. Preservation of Kefir Grains
• Kefir grains are mostly preserved by lyophilisation, dry or wet.
• Dried grains keep up their activity for 12-18 month while wet grains
8-10 days.
• Kefir grains are generally preserved in milk at refrigerated
condition for 3-5 day and subsequently it can be further reactivated
with replacement of milk

12. Characteristics Kefir Dahi
Culture Kefir grains Dahi culture
Texture Uniform due to sieving Smooth and sometimes
pasty
Flavour Yeasty with prickly
sensation
Diacetyl flavour
Milk Pasteurized whole milk Pasteurized whole
milk/partly Skimmed
milk
Maturation Done to obtain typical
flavour of kefir
Not done
Nature Probiotic in nature May or may not be
probiotic unless probiotic
organism are added
Consistency Mostly Pourable Pourable or set type
Immunomodulation Kefiran is major immune
modulating component
produced by kefir grains.
No Specific immune
modulating component is
present