IIB. Defects in Milk

Question 1

• caused by the growth of lactic acid bacteria and result from small amounts of acetic and propionic acids

Answer 1

souring

Question 2

LacLacLeuEnt
PedStrepEntKleib

Answer 2

Lactococcus, Lactobacillus, Leuconostoc, Enterococcus
Pediococcus, Streptococcus, Enterobacter, Kleibsiella

Question 3

• results from growth of Lactococcus lactis and due to methylbutanal

Answer 3

malty

Question 4

• growth of lactic acid bacteria which produce exocellular polymers that increase viscosity of milk

Answer 4

ropy texture

Question 5

• associated with the growth of coliforms, yeasts, or spore-formers

Answer 5

gassy defects

Question 6

• Lactobacillus brevis and Lactobacillus casei subsp. pseudoplantarum associated with
___________ in retail mozzarella cheese

Answer 6

gas production

Question 7

• Lactobacillus casei subsp. casei – produces a _____________ in mozzarella cheese

Answer 7

soft-body defect

Question 8

• Lactobacillus delbrueckii subsp. bulgaricus cause _____________ in cheese

Answer 8

pink discoloration

Question 9

• Lactococcus spp. _________ produced by these bacteria cause fruity off-flavor in Cheddar cheese

Answer 9

esterase

Question 10

• esters that contribute to fruity flavor in cheese

Answer 10

ethyl hexanoate and ethyl butyrate

Question 11

• Bacillus cereus spoilage bacteria in
_________ milk

Answer 11

pasteurized

Question 12

• chymosin-like protease causes
__________ in fluid milk

Answer 12

coagulation

Question 13

• any enzyme produced by Bacillus cereus which degrades the fat globule membrame resulting in the aggregation of the fat in cream that gives a bitty cream defect

Answer 13

phospholipase C

Question 14

• Bacillus circulans and Bacillus mycoides capable of spoiling ____________ milk

Answer 14

heat-treated

Question 15

• Bacillus stearothermophilus – the major __________ species in milk

Answer 15

heat-resistant

Question 16

• Bacillus subtilis and Bacillus megaterium ___________bacteria isolated from UHT-processed milk

Answer 16

less heat-resistant

Question 18

• Clostridium sporogenes cause __________ or bursting of cans

Answer 18

swelling

Question 19

• Clostridium tyrobutryricum, Clostridium sporogenes, and Clostridium butryricum – cause _________ in cheese

Answer 19

gas formation

Question 20

• Candida spp. cause spoilage in
fermented or yeasty flavor observed in
Cheddar cheese because of high levels of ethanol, ethyl acetate, and ethyl butyrate

Answer 20

True

Question 21

• caused by plant-pathogenic microorganisms initiating
infection of otherwise healthy and uncompromised products

Answer 21

Active spoilage

Question 22

• opportunistic microorganisms gain access to internal tissues via damaged epidermal tissue, lesions caused by plant pathogens, or by natural openings

Answer 22

Passive Spoilage

Question 23

• enzymes that cause depolymerization of the pectin chain

Answer 23

Pectinase

Question 24

• enzymes that degrade cellulose to glucose
• attack native cellulose by cleaving cross-linkages between chains

Answer 24

Cellulase

Question 25

• Clostridium thermosaccharolyticum – cause swelling in _______ vegetable due to large amount of hydrogen and carbon dioxide produced

Answer 25

canned

Question 26

• Fruits have higher water activity to support the growth of xerophilic (grow at low Aw) or osmophilic (grow at high Aw) fungi.

Answer 26

True

Question 27

• Erwinia rots found in _______

Answer 27

pears

Question 28

ZygoHansenCanDeb PichiaPenAspEuro

Answer 28

Zygosaccharomyces, Hanseniaspora, Cadida, Debaryomyces Pichia, Penicillium, Aspergillus, Eurotium

Question 29

• Alicyclobacillus acidoterrestris bacterium that cause spoilage in ___________

Answer 29

pasteurized juice

Question 30

• bloody bread – result from growth of the red-pigmented bacterium Serratia marcescens in breads

Answer 30

True