BIOCHEMISTRY OF FOOD SPOILAGE

1. BIOCHEMISTRY OF FOOD SPOILAGE Charul1, Jayanti Tokas2, Shalini Jain3 and Hariom Yadav4 1Department of Biochemistry, CCS HAU, Hisar, Haryana, India 2National Agri-Food Biotechnology Institute, Mohali, Punjab, India Email: yadavhariom@gmail.com

2. Proteins Vitamins Food Energy Building materials Lipids Carbohydrate Human Growth

3. FOOD GROUPS • Highly Perishable • Meat • Fruit • Milk • Vegetables • Eggs • Semi perishable • Potatoes • Nuts • Flour • Stable • Rice • Dry beans

6. Biochemistry of food spoilage Substrates Chemical reactions Chemical compounds Factors

7. Major causes of food spoilage Microorganisms • Insects • Rodents • Animals • Birds

8. LIGHT • Oxidation of food • Reversion flavor of soyabean • Sunlight flavor in milk • Rapid loss of Riboflavin, vitamin D, E and C • Greening of potato

9. Formation of excited triplet sensitizer (3Sen*) and its reaction with substrate via Type I and Type II reactions Sensitizer (Sharman et al., 2000)

10. Reversion flavor in soybean oil

11. Linolenic acid Linoleic acid 2-pentyl furan 2-pentenyl furan (Min, 2000)

12. Effect of chlorophyll on pentenyl furan peak areas (Callison, 2001)

13. Riboflavin Photosensitized Singlet Oxygen Oxidation of Vitamin D Vitamin D vitamin D-5,6 epoxide (King, 1996)

14. Head space oxygen of vitamin D2 samples with 15 ppm riboflavin stored in the dark from 1-8 hours (King and Min, 1998)

15. Effect of vitamin D2 and riboflavin concentrations on % headspace oxygen loss during storage in the light from 1 to 8 hours (King and Min, 1998)

16. Singlet Oxygen and Ascorbic Acid Effects on Dimethyl Disulfide and Off-Flavor inSkim Milk Exposed to Light Methionine Dimethyl Disulfide Postulated mechanism of dimethyl disulfide formation by singlet oxygen oxidation of methionine. (Jung et al., 1998)

17. Effects of time of exposure to fluorescent light on headspace volatile compounds and dimethyl disulfide of skim milk A - 2-butanone B - ethanol C - diacetyl D - dimethyl disulfide E - n-butanol (Jung et al., 1998)

18. Effects of ascorbic acid concentration on dimethyl disulfide (peak D) content in skim milk during light exposure for 1h. (Jung et al., 1998 )

19. Greening of potato Light Biosynthesis of chlorophyll Fixation of carbon dioxide Acetate Mevolenic acid Cholesterol

20. + Arginine (Kent et al., 2005)

21. Chlorophyll and solanine synthesis in potatoes Solanine Chlorophyll Light 23⁰C Dark (Ramaswamay et al., 1976)

22. Enzymes that cause food spoilage

23. ENZYMATIC BROWNING Polyphenol oxidase • Hydroxylation of monophenol to o-diphenol Phenolic substrate O2 Polyphenol oxidase O2 Phenolic substrate O2 O2 O2 O2 O2 • Dehydrogenation of o- diphenol to o-quinone

24. Oxidation of tyrosine by Phenolase and the formation of melanin pigment

25. Post-mortem changes in fish muscle due to autolytic degradation Autolysis (Green, 2011)

26. An overview of fruit ripening with particular emphasis on textural softening Protopectin → Soluble Pectin → Softening Decomposition (over matured fruit)

27. RANCIDITY Oxidative Rancidity Hydrolytic Rancidity Hydrolytic Rancidity Triacylglycerol Free fatty acids Glycerol (Volatile bad odor)

28. Oxidative Rancidity (Baysal and Demirdoven, 2006)

29. MAILLARD REACTION Glucosamine D-glucose Schiff Base

30. Melanoidins (Brown nitrogenous polymer)

31. Microbial Spoilage

32. BACTERIA Microbial Spoilage YEAST MOLDS

33. General pattern of microbial spoilage (Dalgaard, 1993)

34. Factors affecting growth of microbes • Intrinsic • Nutrients • aw • pH • Redox potential • Inhibitors • Extrinsic • Temperature • Humidity • Atmosphere • Implicit • Interactions of microorganisms

35. Fungal spoilage of starch-based foods in relation to its water activity (Abdullah et al., 2000)

36. MICROBIAL SPOILAGE – HOW DOES IT MANIFEST ITSELF? • Visible growth • Gas production • Slime • Enzymes • Off-flavours

40. Chemical changes caused by micro organisms • Degradation of carbohydrates • Degradation of N- compounds • Degradation of lipids • Pectin hydrolysis

41. Degradation of carbohydrates

43. Anaerobic Conversion of Lactic Acid to Acetic Acid and 1,2 Propanediol by Lactobacillus buchneri (Stefanie et al., 2001)

44. Lactic acid utilization by Lactobacillus buchneri, a potential spoilage organism in fermented cucumbers (Johanningsmeier , 2011)

45. Lactate utilization in time by L. buchneri at different pH (Stefanie et. al., 2001)

46. Degradation of N- compounds Proteolysis Putrefaction Proteinases Peptidases Proteins Polypeptides Amino Acids Cysteine desulfhydrase Methionine lyase Tryptophanase Decarboxylase H2S Methyl mercaptans Indole Cadaverine Putrescine Histamine Volatile products Bacterial Cell Amino Acids Cysteine Methionine Tryptophan Lysine Arginine Histidine

47. Reduction of trimethylamine oxide trimethylamine trimethylamine oxide Fishy odor • Pseudomonas • Shewanella • Bacillus • Clostridium

48. Degradation of lipids lipase Lipid oxdase Lipids Glycerol + Fatty acid Aldehyde , ketones • Pseudomonas • Micrococcus • Staphylococcus • Flavobacterium

49. Pectin Degradation Polygalacturonic acid + Methanol Pectin Galacturonic acid Apple rot Penicillium expansum  Soft and watery Dry and firm Moniliniafructigena

50. Slime production EPS