Microbial Spoilage of Food MCQs 50 Score: 0 Attempted: 0/50 Subscribe 1. : The main cause of food spoilage is: (A) Enzymatic activity (B) Microbial growth (C) Physical damage (D) Chemical oxidation Show All Answers 2. : Which microorganism is mainly responsible for souring of milk? (A) Yeast (B) Lactic acid bacteria (C) Mold (D) Coliform bacteria 3. : The term “putrefaction” refers to: (A) Breakdown of carbohydrates (B) Decomposition of proteins (C) Oxidation of fats (D) Formation of alcohols 4. : Slime formation on meat is mainly caused by: (A) Molds (B) Yeasts (C) Bacteria (D) Viruses 5. : Which bacteria are most common in refrigerated spoilage of meat? (A) Pseudomonas species (B) Clostridium species (C) Lactobacillus species (D) Bacillus species 6. : “Flat sour spoilage” in canned food is caused by: (A) Clostridium botulinum (B) Bacillus stearothermophilus (C) Bacillus coagulans (D) Clostridium sporogenes 7. : The “swelling” of canned foods is due to: (A) Gas formation by microorganisms (B) Moisture loss (C) Chemical reaction (D) Freezing 8. : Yeasts spoil food primarily by: (A) Producing toxins (B) Fermentation of sugars (C) Breaking down proteins (D) Oxidizing fats 9. : Mold spoilage in bread is commonly caused by: (A) Penicillium and Aspergillus (B) Clostridium and Bacillus (C) Lactobacillus and Leuconostoc (D) Salmonella and Shigella 10. : Which type of microorganism causes “ropiness” in bread? (A) Bacillus subtilis (B) Pseudomonas fluorescens (C) Rhizopus stolonifer (D) Penicillium expansum 11. : “Black rot” in eggs is caused by: (A) Pseudomonas (B) Proteus (C) Clostridium (D) Salmonella 12. : The spoilage of canned acidic foods is mostly caused by: (A) Bacillus coagulans (B) Clostridium botulinum (C) Lactobacillus (D) Yeasts and molds 13. : The microorganism responsible for butter rancidity is: (A) Pseudomonas putida (B) Lactobacillus casei (C) Clostridium butyricum (D) Bacillus cereus 14. : “Surface taint” on butter is caused by: (A) Pseudomonas putrefaciens (B) Bacillus cereus (C) Saccharomyces cerevisiae (D) Penicillium glaucum 15. : “Green rot” in eggs is caused by: (A) Pseudomonas fluorescens (B) Bacillus subtilis (C) Aspergillus niger (D) Clostridium botulinum 16. : The “souring” of canned food without gas production is called: (A) Putrefaction (B) Flat sour spoilage (C) Swelling (D) Ropiness 17. : The “cloudiness” in fruit juices is caused by: (A) Yeasts (B) Bacteria (C) Molds (D) Coliforms 18. : Meat slime develops faster at: (A) Low humidity (B) High humidity (C) Freezing temperature (D) Dry conditions 19. : The bacteria that cause “sweet curdling” of milk are: (A) Bacillus cereus (B) Alcaligenes viscolactis (C) Lactobacillus bulgaricus (D) Streptococcus lactis 20. : “Sour cream” is produced by: (A) Lactic acid bacteria (B) Yeasts (C) Molds (D) Coliforms 21. : “Pink discoloration” in cheese is due to: (A) Serratia marcescens (B) Bacillus subtilis (C) Lactobacillus plantarum (D) Rhizopus nigricans 22. : The spoilage of canned meat by hydrogen swell is due to: (A) Clostridium species (B) Bacillus species (C) Lactic acid bacteria (D) Molds 23. : “Rancidity” in fats and oils is caused mainly by: (A) Yeasts (B) Lipolytic bacteria (C) Lactic acid bacteria (D) Proteolytic molds 24. : The “rope spoilage” of pasteurized milk is caused by: (A) Bacillus subtilis (B) Clostridium sporogenes (C) Pseudomonas fluorescens (D) Micrococcus luteus 25. : “Black spot” on cured meat is caused by: (A) Penicillium (B) Aspergillus niger (C) Rhizopus (D) Mucor 26. : The “musty odor” in spoiled grains is due to: (A) Molds (B) Yeasts (C) Bacteria (D) Protozoa 27. : Fish spoil rapidly because: (A) High water activity and neutral pH (B) Low protein content (C) High salt content (D) Low microbial load 28. : “Sulphide spoilage” in canned foods produces: (A) Rotten egg smell (B) Sweet taste (C) Sour odor (D) No smell 29. : “Mold bloom” on cheese surface is due to: (A) Penicillium and Aspergillus (B) Lactobacillus (C) Bacillus (D) Clostridium 30. : “Soft rot” in vegetables is caused by: (A) Erwinia carotovora (B) Pseudomonas aeruginosa (C) Clostridium botulinum (D) Bacillus cereus 31. : The main cause of microbial spoilage in frozen foods is: (A) Psychrotrophic bacteria (B) Thermophilic bacteria (C) Mesophilic bacteria (D) Yeasts only 32. : “Sticky surface” of cured meat is due to: (A) Micrococcus and Staphylococcus (B) Clostridium (C) Pseudomonas (D) Lactobacillus 33. : The presence of coliforms in food indicates: (A) Poor hygiene or contamination (B) Presence of toxin (C) Pasteurization (D) High acidity 34. : “Blue mold rot” on citrus fruits is caused by: (A) Penicillium italicum (B) Aspergillus flavus (C) Rhizopus stolonifer (D) Fusarium oxysporum 35. : “Black mold rot” on fruits is caused by: (A) Aspergillus niger (B) Rhizopus stolonifer (C) Penicillium digitatum (D) Mucor pusillus 36. : “Souring” of canned foods is mostly due to: (A) Lactic acid bacteria (B) Yeasts (C) Molds (D) Clostridium 37. : “Swelling” of cans without spoilage odor indicates: (A) Chemical reaction (B) Microbial contamination (C) Mold growth (D) Physical damage 38. : “Gassy spoilage” in canned vegetables is caused by: (A) Clostridium species (B) Bacillus subtilis (C) Lactobacillus species (D) Yeast 39. : “White patches” on bread are caused by: (A) Rhizopus stolonifer (B) Penicillium expansum (C) Aspergillus flavus (D) Mucor mucedo 40. : “Slimy” spoilage of cooked meat is caused by: (A) Lactic acid bacteria (B) Pseudomonas species (C) Staphylococcus aureus (D) Yeasts 41. : “Souring” of meat is caused by: (A) Lactic acid bacteria (B) Clostridium (C) Bacillus (D) Yeast 42. : The spoilage of canned foods without visible microbial growth is called: (A) Flat sour spoilage (B) Hidden spoilage (C) Swelling (D) Putrefaction 43. : “Pink slime” in bottled beverages is due to: (A) Serratia marcescens (B) Pseudomonas fluorescens (C) Bacillus subtilis (D) Aspergillus niger 44. : The spoilage of pickles is mainly due to: (A) Yeasts and molds (B) Lactic acid bacteria (C) Coliform bacteria (D) Clostridium 45. : “Ropy” slime formation in beer is due to: (A) Pediococcus (B) Listeria (C) Bacillus (D) Pseudomonas 46. : Spoilage in butter often begins on: (A) Surface (B) Core (C) Bottom (D) Sides 47. : The main spoilage organisms in vacuum-packed meats are: (A) Lactic acid bacteria (B) Aerobic molds (C) Yeasts (D) Pseudomonas species 48. : “Sulfur stinker” spoilage in canned foods is caused by: (A) Clostridium nigrificans (B) Bacillus coagulans (C) Listeria monocytogenes (D) Lactobacillus plantarum 49. : “Fruity odor” in spoiled wine is due to: (A) Yeasts producing esters (B) Lactic acid bacteria (C) Molds (D) Bacillus species 50. : “Putrid odor” in spoiled fish is mainly due to: (A) Production of trimethylamine (B) Yeast fermentation (C) Mold growth (D) Lactic acid formation