DAIRY MICROBIOLOGY

 

Starter Culture & Fermented Dairy Products

Compiled by: - Mr. Abhay Pandey

 

Q.A group of active and desirable microorganisms capable of bringing about desirable changes in the milk product through the process of fermentation is called

A. Starters

 

Q.Starter cultures produces____ from lactose (milk sugar), which in most cases cause or assist in the coagulation of milk protein by lowering pH value.

A.Lactic acid

 

Q.Organisms possess some claimed health benefit for those who consume them is called

A. Prebiotics

 

Q.The age-old indigenous fermented milk of India which has managed its popularity in Indian diet despite changing lifestyles and food habits

A. Dahi

 

Q. All Lactoccus lactis species belongs to the group (acc. to growing tamperature)

A.Mesophilic

 

Q.Streptococcus salivaris ssp thermophilus is mainly used for the preparation of

A. Yoghurt

 

Q.These organisms are normally used along with lactic acid bacteria (LAB) in multiple or mixed strain cheese starter cultures, which produces flavour compounds

A. Leuconostoc

 

Q.These organisms are generally used in preparation of therapeutic fermented

milk products in combination with yoghurt, acidophilus milk or yakult starter cultures.

A.Bifidobacteria

 

Q. White mould ,used in manufacture of surface mould ripened cheeses is

A. Penicillium cammemberti

 

Q.The best method of heat treatment of reconstituted skim milk for propogation of starter cultures is

A.Tyndalization

 

Q.The starter culture added to the milk for preparation of fermented milk

A.Bulk starter culture

 

Q.Starter culture from Netherlands Dairy Research Institute is called

A.NIZO

 

Q.Most of the commercial cultures are in the form

A.Freeze-dried form

 

Q.The main purpose of using production systems for bulk starter culture preparation is to

A.Control contamination from bacteriophage

 

Q.The system in which all inoculations take place through a barrier of chlorinated water and Re-usable, collapsible polythene bottles are used at each stage.

A.Lewis system

Q.The starter culture is available in more concentrated form in large volumes such that the product can be inoculated directly into the production milk in___system

A.Direct Vat Inoculation

 

QThe concept of rotational operating system is that the regular change of a culture would prevent the build-up of a_______ and thus avoid starter failure because they are virulent against one host type

A.Bacteriophage

 

Q.The operating system which is based on the identification of a small number of highly characterized single strain phage resistant bacteria.

A.Non-rotational

 

Q.Lactic acid bacteria producing large quantities of ethanol, co2 as well as lactic acid when grown on lactose or glucose are considered as

A.Heterofermentative organisms

 

Q.Citrate is metabolized by Lactococcus lactis ssp lactis biovar diacetylactis for production of

A.Diacetyl

 

Q.In protein metabolism the enzymes acting on______ peptide bonds are known as peptide hydrolases

A.Peptide Bonds

 

Q.The enzymatic hydrolysis of milk proteins results in the liberation of _______free amino acids

A.Amino acids

 

Q.During the manufacture of yoghurt vitamins like niacin and______, are actively synthesised by the starter cultures

A.Folic Acid

 

Q.Many organisms require____ as a growth factor because it functions as a coenzyme in many different biochemical reactions

A.Folacin

 

Q.Antimicrobial substances that are naturally present in milk

A.Immunoglobulins

 

Q.The major effect of antibiotic residues in yoghurt milk is to cause breakdown the_____in between S. thermophilus and L. bulgaricus

A.Symbiotic relationship

 

Q.When an organism adversely affects the environment of another organism it is said to be

A.Mutualism

 

Q.A good starter should have the ability to produce_____ at vigorous and steady rate

A.Lactic Acid

 

Q.Lactic acid bacteria are ___ for catalase test

A.Negative

 

Q.The activity test used mainly for mesophilic type of cultures

A.Horral Elliker’s test

 

Q.The creatine test makes it possible to quickly secure general information on the comparative amounts of acetyl methyl carbinol plus______

A.Acetaldehyde

 

Q.The tests that require high degree of training and experience

A.Organoleptic tests

 

Q.The starters that could protect consumers from harmful bacteria either by a rapid acidification or by the production of antimicrobials (bacteriocins) is called.

A.Functional starters

 

Q.Assessment of potential probiotic bacterial strains is based on

A.Adherence to human intestinal cells

 

Q.The probiotic bacteria that remains within the gastrointestinal tract for any significant period of time.

A.L. rhamnosus GG

 

Q.The only purified bacteriocin approved for use in products intended for human consumption.

A.Nisin

 

Q.Spontaneous loss of vitality inherent in starter itself is due

A.Loss of Enzymes

 

Q.Green flavour defect is due to under development of _____ as result of repeated transfer of culture before adequate development

A.Leuconostocs

 

Q.CO2 is produced by certain strains of_____ and in case of cottage cheese these may contribute to the floating curd defect

A.Leuconostocs

 

Q.Bacteriophages are widely distributed in nature & most abundant in ______part of animals

A.Intestines

 

Q.Without a _____, viruses cannot carry out their life-sustaining functions or reproduce

A.Host cell

 

Q.The medium deficient in ____ion, if used for maintaining starter cultures, prevent phage attack as these ion helps in phage adsorption to host cell

A.Calcium

 

Q.A modified hybridization assay is available for detection of bacteriophage, which employs DNase protection and slot blot methods to measure quantitatively the concentration of soluble and bacteriophage-encapsulated DNA in fluid samples

 A. DNase protection and Slot blot methods

 

 

Q.Varying the_______ of certain cultures can influence the flavour profile and other attributes of the final product.

A.Incubation temperature

 

Q.The best preservation method useful for extended periods of storage

A.Freeze drying

 

Q.Bulk starters are always prepared at

A.Production site

 

Q.The optimum growth temperature of Mesophilic cultures

A.21-35 degree C

 

Q.Most popular and widely used form of starter cultures

A.Liquid

 

Q.The solids content in reconstituted skim milk used for liquid starter propagation

A.10-12% SNF

 

Q.Destruction of bacterial cells due to an increased concentration of electrolytes and other solutes inside the cell and in the outside suspending medium can be prevented by adding

A.Cryo-protective agents

 

Q.In freeze drying the organisms are frozen and then water is removed by

A. Sublimation

 

Q.The freeze dried cultures are packed ______as the presence to avoid damage to bacterial cells.

A.In the absence of oxygen

 

Q.The undesirable properties (e.g. mycotoxin or antibiotic production by cheese moulds) present in organisms may be eliminated by techniques such as

A.Gene disruption

 

Q. Many properties essential for successful starter activity is controlled by

A.Plasmid DNA

 

Q.The genetic exchange mediated by a bacterial virus (bacteriophage) is called.

A.Transduction

 

Q.Transfer of naked DNA of one bacteria to another bacteria is called

A.Transformation

 

Q.The genetic exchange mediated by physical contact between two bacteria

A.Conjugation

 

Q.The genetic material characteristically more unstable

A.Plasmids

 

Q.The organism often plasmid free or contain small number of Plasmids

A.St.salivarius sp.thermophilus

 

Q.Engineering of ______ strain that contributes to the formation of lactose-free and naturally sweetened foods is now a reality

A.L. lactis

 

Q.A steam distillate of the culture of any or all of the following species of bacteria grown on a medium consisting of skim milk usually fortified with 0.1% citric acid is called

A.Starter Distillates

 

Q.The Liquid Butter flavours which are Generally Recognized as Safe (GRAS) ingredients and can be labeled as

A.Natural flavours

 

Q.The bacterial distillate has a diacetyl content of.

A.1369- 2666 mg/kg

 

Q.The synthetic distillates contains____ which replaces souring by starter cultures

A.Edible fats

 

Q.A balanced butter flavour can be obtained by adding other important aroma substances, such as, and certain lactones.

A.Acetaldehyde

 

Q.Fermented milks with slimy consistency are popular in

A.Scandinavia

 

Q._______ is an example of milk-wheat based fermented food

AKishk

 

Q.Most popular fermented milk made using themophillic starter is

A.Yoghurt

 

Q.Yoghurt is called as Zabady in

A.Egypt

 

Q.Stimulator compound produced by S. thermophilus that helps L.bulgaricus.

A.Formic acid

 

Q.Symbiosis in yoghurt culture have been know to produce higher amount of a flavour compound called

A.Acetaldehyde

 

Q.The non-essential culture in yoghurt could be

A.L .acidophilus

 

Q.The optimum temperature for Lactobacillus delbrueckii subsp. bulgaricus

A. 45C

 

Q.As per FAO/WHO, full fat yoghurt has

A. > 3.0% fat

 

Q.Normal shelf-life of yoghurt at refrigeration temperature is

A.2-3 weeks

Q.The most suitable time-temperature combination for heat treatment for milk intended for yoghurt manufacture is

A.85 C for 20 min

 

Q.The ideal rate of inoculation of yoghurt starters is;

A.2.0%

 

Q.Homogenization of milk affects the quality of yoghurt by;

A.Increased whey syneresis

 

Q.Over incubated yoghurt has more of ______ type of lactic acid

A.D (-)

 

Q.Normal shelf-life of thermized yoghurt at refrigeration temperature is

A.4-6 weeks

 

Q.The major flavour compound in yoghurt is;

A.Acetaldehyde

 

Q.Liquid yoghurt has total solids content of _______

A.Less than 9%

 

Q.Calcium content ion yoghurt

A.150-200 mg%

 

Q.Minerals in yoghurt has higher availability due to presence of

A.Latic acid

 

Q.Which type of cancer may be prevented more easily by consumption yoghurt

A.Colon cancer

 

Q.The whey separation defect in yoghurt can be minimized by

A.Higher protein content

 

Q.The oldest and most popular fermented milk in India is

A.Dahi

 

Q. According to BIS standards the coliform count in dahi should not exceed -------------per gram.

A.10

 

Q.---------------------- is a diacetyl producing dahi starter culture

A.Lactococcus diacetylactis

 

Q.In winter dahi ---------------------- dominate.

A.Streptococci

 

Q.---------------------processing step improves the mouthfeel of the dahi.

A.Homogenization

 

Q.Which is the most convenient packaging material for set dahi in case of commercialization ?

A.Polystyrene cups

Q. ---------------- step can minimize the unwanted microflora in dahi

A.Heat treatment

 

Q.The sweetened variety of dahi popular in eastern India is

A.Mishti doi

 

Q.The unsweetened steamed yoghurt is called

A.Bhapadoi

 

Q.Too high incubation temperature can result into -----------------flavour defect in

A.Sour

 

Q.Gassiness in dahi can be due to

A.Bacillus contamination and Coliform contamination

 

Q.The definition of true butter milk

A.fluid left after churning cream

 

Q.The flavour is produced by ....….. in butter milk.

A.Leuconostoc

 

Q.The optimum for incubation during CBM(continuous butter milk)production is

A. 21C

 

Q.The major flavour compound in CBM is

A.Diacetyl

 

Q.Good quality CBM stored at less than 5C should have shelf-life of

A.2 weeks

 

Q.What is the key metabolite in citrate fermentation pathway for diacetyl?

A.Alpha-acetolactate

 

Q. The diacetyl in CBM is most stable at pH;

A.4.6

 

Q.Richness of flavour can be improved in CBM by

A.Double stage homogenization

 

Q.The ion that affects flavour in cultured butter milk

A.Mg

 

Q.The term probiotic was coined by

A.Lilly & Stillwell

 

Q.To test the capability of probiotic to establish in intestine, it is tested for ……… in vitro.

A.EPS production

 

Q.The health effect of a probiotic organism is;

A.Strain specific

 

 

Q.The most acceptable guidelines for probiotics is given by;

A.WHO

 

Q.The probiotic culture L.casei Shirota belongs to a company called

A.Yakult Honsha Ltd.

 

Q.The acidophilus product containing yeasts as one of the cultures

A.Acidophilin

 

Q.During the process of probiotic product manufacture, maximum attention is given at;

A.Viability of culture

 

Q.The optimum temperature for acidophilus milk is

A.37 C

 

Q.The plain bifidus milk has

A.Vinegar type flavour

 

Q.The probiotic culture L.rhamnosus GG belongs to

A.Valio

 

Q.During the process of fermentation, ...........decreases in concentration

A.Lactose

 

Q.Vitamin important in uptake of dietary calcium

A. Vitamin D

 

Q.Some probiotic bacteria have been reported to cause …………….. in   immunocompromized subjects

A. Bacteremia

 

Q.The unique polysaccharide found in kefir grains is

A.kefiran

 

Q.Kefir comes under the category of ---------------type fermentation

A.Acid-alcohol

 

Q.Generally Kefir grains contains -----------------group of microorganisms

A.Lactic acid bacteria , yeasts and acetic acid bacteria

 

Q.The viability of Kefir grains can be maintained by

A.Transferring them daily into fresh milk and allowing them to grow

 

Q. Koumiss is traditionally made from ------------------------milk

A.Mare milk

 

Q.In comparison to mare’s milk cow milk has lower ----------------------content

AWhey protein

 

Q.Traditionally koumiss has been used for the treatment of ----------------------

A.Pulmonery tuberculosis

 

Q.Koumiss starter mainly comprises of

A.L.. bulgaricus and Saccharomyces lactis

 

 

 

 

 

References:-

1.      ICAR E- course

2.      NDRI class notes

3.      Previous year asked questions