Kefir

Question 1

describe kefir grains

Answer 1

white/yellow gelantinous grains

Question 2

what is kefir composed of

Answer 2

symbiotic mixture of: lactic acid bacteria, yeast, acetic acid bacteria

Question 3

what kind of matrix is kefir composed of in

Answer 3

exopolysaccharide matrix called (Kefiran)

Question 4

kefir is… acidic or ?

Answer 4

acidic fermented milk product

Question 5

name 2 methods of kefir production

Answer 5

1. russian method
2. the pure cultures

Question 6

describe russian method

Answer 6

using a series fermentation process, beginning with the fermentation of the grains.

Question 7

describe the Pure Cultures method

Answer 7

Isolated from kefir grains or commercial cultures.

Question 8

what milks types of kefir made from

Answer 8

pasteurised cow, ewe, goat, or buffalo milk.

Question 9

describe the 2 commercial industrial processing uses

Answer 9

direct to vat inoculation (DVI) or
direct to vat set (DVS) kefir starter cultures.

Question 10

what ratio is grains to milk

Answer 10

grains usually innoculated at 1-10% w/v

Question 11

time of fermentation

Answer 11

kefir obtained within 18-24 hr of fermentation.
kefir biomass increases and then may decrease (grains dissolve)

Question 12

what temperature of kefir fermentation

Answer 12

18-30 degrees c.

exopolysaccharide production is affect by temperature

Question 13

fermented kefir contains

Answer 13

bioactive peptides
bacteriocins
exopolysaccharides
organic acids.

Question 14

briefly name challenges in kefir production

Answer 14

diverse microflora of kefir grain, milk type, incubation time and storage conditions.

Question 15

describe kefir grains appearance

Answer 15

white to yellow gelantinous

Question 16

what size kefir grains

Answer 16

variable. varying from 0.3–3.5 cm in diameter).

Question 17

composed of microbial symbiotic mixture of

Answer 17

lactic acid bacteria
acetic acid bacteria
yeasts
fungi

in a polysaccharide matrix

Question 18

what are the 4 main groups of kefir

Answer 18

1. homo- fermentative LAB
2. hetero -fermentative LAB
3. lactose assimilating yeast
4. non-lactose assimilating yeast

Question 19

name bacterias

Answer 19

o Lactobacillus kefiri (80%; in final beverage)
o L. paracasei ssp. paracasei, L. acidophilus, L. delbrueckii ssp. bulgaricus, L. plantarum, and L. kefiranofaciens are predominant species (20% final beverage).
o Acetobacter aceti & A.rasens.
o S.cerevisiae, S.unisporus, Candida kefyr & Kluyveromyces marxianus sub sp. Marxianus

Question 20

describe the polysaccharide in kefiran

Answer 20

heteropolysaccharide composed of equal proportions of glucose and galactose and is mainly produced by Lactobacillus kefiranfaciens

Question 21

what is heteropolysaccharide composed of

Answer 21

equal proportions of glucose and galactose produced by Lactobacillus kefiranfaciens

Question 22

what is heteropolysaccharide produced by

Answer 22

Lactobacillus kefiranfaciens

Question 23

what does kefiran improve

Answer 23

viscosity and elasticity properties of acid milk gels and aids in gel formation

Question 24

what causes the smybiotic balance of bacterias in equilibrium

Answer 24

biomass production during fermentation

Question 25

the grain outer layer contains

Answer 25

LAB & yeast

Question 26

the grain inner layer contains

Answer 26

the quantity of lactobacilli are much higher

Question 27

describe the mechanisms of grain formation

Answer 27

symbiotic community where LAB, yeasts and AAB cohabit in a specific equilibrium o This balance between kefir microorganisms is evident by biomass production during fermentation the outer layer of the grain: LAB & yeast The inner layer of the grain: the quantity of lactobacilli were much higher Initially Lactobacillus & Saccharomyces start to auto-aggregate & co-aggregated into  small granules this aggregation is enhanced when the pH drops

Question 28

what do biofilm producers adhere to in grain formation

Answer 28

the surface. they continue to co-aggregate to become a 3D micro-colony.

Question 29

list chemical % of kefir

Answer 29

90% moisture, 3.0% protein, 0.2% lipid, 6.0% sugar, 0.7% ash, 1.0% lactic acid, 0.48% alcohol and 201.7–277.0 mL/L CO2

Question 30

microbial consortium is AKA

Answer 30

proteolysis

Question 31

what role does yeast have in proteolysis

Answer 31

establishing an environment that allows for the growth of kefir bacteria, as well as the production of several key metabolites such as: peptides, amino acids, vitamins, ethanol and CO2.

Question 32

what key metabolites does yeast contain

Answer 32

peptides, amino acids, vitamins, ethanol and CO2.

Question 33

what does lactic acid bacteria ferment/do in proteolysis

Answer 33

ferments the lactose to increase in lactic acid levels & as well as imparting the unique taste in kefir.

Question 34

what does lactic acid inhibit

Answer 34

inhibits microorganism growth owing to decrease in pH acting as a preservative.

Question 35

free fatty acids FFAs produced via... and what is it responsbile for

Answer 35

lipolysis in milk are responsible for the taste and aroma of kefir which was found to contain from 5 to 10 times more FFAs than milk.

Question 36

name amino acids in kefir and what role do they play

Answer 36

serine, threonine, alanine, lysine, valine, isoleucine, methionine, phenylalanine and tryptophan. major role in central nervous system

Question 37

name macro-elements in kefir and what role do they play

Answer 37

calcium, magnesium, potassium, and sodium that aid in the: utilisation of carbohydrates, fats and proteins for cell growth, maintenance, and energy

Question 38

name micro-elements in kefir and what role do they play

Answer 38

iron, zinc, and copper : cellular metabolism and blood production

Question 39

kefir acts against what bacteria and what does it do

Answer 39

pathogenic bacteria. inhibits spore formation and aflatoxin B1 produced by the fungus Aspergillus flavus

Question 40

name health benefits of kefir

Answer 40

1. antioxidant 2. antimicrobial 3. gastrointestinal function 4. cholesterol lowering 5. reduced bodyweight 6. anti-inflammatory 7. anticancer 8. probiotic 9. wound healing

Question 41

Conjugated linoleic acid (CLA)

Answer 41

native component in milk fat, can be increased in fermented milk through bioconversion of unsaturated fatty acids such as linoleic and linolenic acids by different LAB. CLA has anti-inflammatory, anti-atherogenic, and antioxidant properties.

Question 42

Bioactive peptides

Answer 42

are specific fragments of milk proteins that are released by proteolytic activity from caseins have been described for peptides released as a result of the activity of LAB in fermented milk products.

Question 43

what role does Bacteriocins do

Answer 43

are also among the beneficial peptides intrinsically synthesised by some LAB and their usefulness in preventing growth of undesirable & pathogenic microorganisms

Question 44

role of Extracellular PolySaccharide(EPS):

Answer 44

are complex extracellular carbohydrate polymers +ve interact with colonic microbiota