Biochemical Aspects of food spoilage by enzymes like Lipase and Lipooxygenase, Rancidity and Antioxidants.

1. I.BIOCHEMICAL ASPECTS OF FOOD
SPOILAGE , II.ROLE OF LIPASE AND
LIPOXYGENASE, III.OXIDATIVE
RANCIDITY , IV. ANTIOXIDANT
Presented by : Meet Padhiyar
Reg. no. : 04-BSMS-02353-2020
M.Sc 2nd sem. Biochemistry
Presented to : Dr. Smita Singh
Asst. professor, Biochemistry, college
of basic science and humanities,SDAU

2. CONTENT
• Introduction of food spoilage
• The chief cause of food spoilage
• Role of Lipase
• Role of Lipooxygenase
• Oxidative rancidity
• Antioxidants

3. INTRODUCTION OF FOOD SPOILAGE
• Definition : Food spoilage means the original nutritional
value, texture, flavor of the food are damaged, the food
become harmful to people and unsuitable to eat.
• Food spoilage is a metabolic process that causes foods to
be undesirable or unacceptable for human consumption due
to changes in sensory characteristics.
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4. THE CHIEF CAUSE OF FOOD SPOILAGE
1. Physical Spoilage
2. Cause by Microorganisms like Bacteria,
Yeast, Moulds
3. Biochemical Spoilage by
• Enzymatic Reaction
• Non-enzymatic reaction
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5. 1. PHYSICAL SPOILAGE
• Physical spoilage is due to physical damage to food during
harvesting, processing or distribution and in Transportation.
• Food spoilage can be caused by physical factors, such as
temperature, moisture and pressure acting upon the foods.
• The damage increases the chance of chemical or microbial
spoilage and contamination because the protective outer
layer of the food is bruised or broken and microorganisms
can enter the foodstuff more easily.
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6. •Damage during
harvesting
•Damage during transport
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7. 2. CAUSE BY MICROORGANISMS LIKE BACTERIA,
YEAST, MOULDS
• In order to grow or multiply in number, all micro-organisms
need sufficient moisture, food and a favorable temperature.
• Food spoilage is a complex process and excessive amounts
of foods are lost due to microbial spoilage even with modern
day preservation techniques.
• It is impossible to eliminate available food for microbial
growth attention must be given to the control of other
conditions that encourage microbial growth.
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8. • MOULDS : They will grow on sweet foods such as jellies or
jams and They commonly occur on meats (even cured
meats), on cheese, milk and other protein foods.
• They require less moisture than yeasts and bacteria and
they are also adaptable many conditions of acidity and
temperature so, they are commonly involved in the spoilage
of food.
• Certain moulds such as Aspergillus flava, growing on cereal
grains and on peanuts have been found to produce toxins,
that have caused illness and death in animals.
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9. • Yeast : Yeasts are another type of microorganism that can
cause food spoilage, but are also used in many fermentation
operations.
• Yeasts are single-celled fungi that are round or cylindrical in
shape and three to five microns in size.
• Important yeasts in food include Candida spp., Dekkera
spp.. Saccharomyces spp.. and Zygosaccharomyces spp.
• Most sugar-containing foods are slightly acid, such as fruits
juices are particularly susceptible to spoilage by yeasts .
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10. • Bacteria : Bacteria are single-celled organisms that are one
to five microns in size.
• Spore-forming bacteria are usually associated with spoilage
of heat-treated foods because their spores can survive high
processing temperatures
• Bacteria that cause food borne illness include Escherichia
coli, Bacillus cereus, Salmonella spp., Campylobacter jejuni,
Clostridium spp., Listeria monocytogenes, and Vibrio spp.
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11. CONTROL OF MICROORGANISMS
• In acid foods, a boiling temperature maintained for a
relatively short period of time is adequate for the destruction
of bacteria.
• Bacillus and clostridium spores are resistant to heat and
require very high temperatures for their destruction.
• Heat in the presence of acid is highly destructive to bacteria.
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12. BIOHEMICAL SPOILAGE
• Most of the changes in foods are due to alteration in
biochemical properties of the food by microbes. These can
be due to carbohydrate, protein, lipid or pectin degradation.
1. Enzymatic reaction
2. Non enzymatic reaction
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13. 1. ENZYMATIC REACTION
• Enzymes are large protein molecules that act as biological
catalysts, accelerating chemical reactions without being
consumed.
• After the harvesting of fruits, enzymes remain active within
the cells. They continue to catalyse the biochemical
processes of ripening and may eventually lead to rotting.
Eg. : Banana
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14. 2. NON ENZYMATIC REACTION
• Additional causes of spoilage include non-enzymatic
reactions in food, such as oxidation.
• A number of chemical processes not involving enzymes may
result in food browning.
1. Maillard reaction
2. Ascorbic acid degradation
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15. 1. MAILLARD REACTION
• The Maillard reaction is a form of non-enzymatic browning
commonly associated with the desirable color and aromas
of cooked foods including bread, meat, roasted nut, coffee.
• The Maillard is a chemical reaction between amino acids
and reducing sugars that gives browned food its distinctive
flavor.
• Maillard reaction revolves around the study of thermally
generated compounds exhibiting mutagenic and/or
carcinogenic properties.
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16. 2. ASCORBIC ACID DEGRADATION
• Ascorbic acid present in fruits undergo oxidation with the
formation of a compound which produces a brown pigment
and causes discolouration.
• Ascorbic acid is used for the prevention of browning and
other oxidative reactions in food products as well as it acts
as removal of molecular oxygen in polyphenol oxidase
reactions.
• Citrus juices, especially their concentrates, develop
browning, which has been attributed to ascorbic acid
degradation.
• When ascorbic acid breaks down by acid catalysis, furfural
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17. ROLE OF LIPASE
• Lipase is an enzyme that breaks down triglycerides into free
fatty acids and glycerol.
• Lipases are present in pancreatic secretions and are
responsible for fat digestion.
• There are many different types of lipases :
1. Hormone-sensitive lipases are in adipocytes,
2. Lipoprotein lipase in the vascular endothelial surface,
3. Lysosomal lipase in lysosome
4. Gastric lipase in digestive juice
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18. ROLE OF DIFFERENT LIPASE
1 Hormone-sensitive lipase is found within fat tissue and is
responsible for degrading the triglycerides that are stored
within adipocytes
2 Lipoprotein lipase is found on the vascular endothelial
surface and is responsible for degrading triglycerides that
circulating from chylomicrons and VLDLs.
• Lipoprotein lipases includes pancreatic lipase, hepatic
lipase, and endothelial lipase .
3 Lysosomal lipase, breaks down lipids such as cholesteryl
esters and triglycerides.
4 Gastric lipase, Functions in the infant at a near-neutral pH to
aid in the digestion of lipids.
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19. ROLE OF LIPOXYGENASE
• Most common in plants they involved in a plant physiology
including growth and development, pest resistance, and
senescence or responses to wounding.
• Lipoxygenases isozymes are involved in the metabolism of
eicosanoids.
• LOXs are dioxygenases that catalyze the formation of
hydroperoxides from polyunsaturated fatty acids such as
linoleic acid and arachidonic acid.
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20. OXIDATIVE RANCIDITY
• Rancidification is the process of complete or incomplete
oxidation or hydrolysis of fats and oils when exposed to air,
light, or moisture or by bacterial action, resulting in
unpleasant taste and odour.
• Two types of Rancidity :
1. Hydrolytic Rancidity
2. Oxidative Rancidity
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21. 2. OXIDATIVE RANCIDITY
• It is refers to the objectionable flavours and odours caused
by oxidation of the unsaturated fatty acid chains of lipids by
atmospheric oxygen.
• It is also known as autoxidation, and associated with the
degradation by oxygen in the air.
• The double bonds of an unsaturated fatty acid can be
cleaved by free-radical reactions involving molecular
oxygen. This reaction causes the release of malodorous and
highly volatile aldehydes and ketones.
• Because of the nature of free-radical reactions, the reaction
is catalyzed by sunlight.
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22. ANTIOXIDANT
• Antioxidants are compounds that inhibit oxidation, a
chemical reaction that can produce free radicals and chain
reactions that may damage the cells of organisms.
• Their traditional role is, as their name suggests, in inhibiting
the development of oxidative rancidity in fat-based foods,
particularly meat and dairy products and fried foods.
• Antioxidants are increasingly important additives in food
processing.
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23.  There are many antioxidants present such as
anthocyanines, copper, flavanoids, tocopherols, licopene,
alicine, betacarotene and etc …
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24. • Antioxidants such as BHA, BHT and TBHQ and propyl
gallate are Synthetic antioxidants can extend the shelf life of
food.
• Butylated hydroxyanisole (BHA) and the related compound
butylated hydroxytoluene (BHT) are phenolic compounds.
• They are often added to foods to preserve fats and oils and
keep them from becoming rancid.
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25. THANK YOU