Lipases Rancidity Proteinases Casein Potential health risks Enzymatic Browning Arctic Apples Proteolytic enzymes Refrences

1. 1
Food Spoilage Due to enzymes
Zohaib HUSSAIN
sp13-bty-001
Presentation Number 1
COMSATS Institute of Information Technology Abbottabad

2. 2
What is microbial food spoilage?
• Microbial food spoilage occurs
as a consequence of either
microbial growth in a food
• Release of extracellular and
intracellular enzymes in the
food environment
Signs of spoilage
• In normal tissues, the rates of new
cell growth and old cell death are
kept in balance
– Changes in color
– Changes in odor
– Changes in texture e.g slime
formation
– Accumulation of gas or foam
– Accumulation of liquid

3. 3
Spoilage by microbial growth occurs
much faster than spoilage
by microbial extracellular
or intracellular enzymes in the absence
of viable microbial cells.

4. 4
 Lipases
 Rancidity
 Proteinases
 Casein
 Potential health risks
 Enzymatic Browning
 Arctic Apples
 Proteolytic enzymes
 Refrences

5. 5
Lipases
•Lipase activity shown by psychotrophs isolated from milk
and milk products e.g Flavobacteria and Pseudomonas
species
•Microbial lipases are heat stable.
•Lipase activity in milk leads to the release of medium and
short-chain fatty acid from triglycerides. (Hydrolytic
rancidity)
•Hydrolysis of as little as 1-2 % triglycerides leading to
rancid off flavor.
•Milk naturally also contains high levels of indigenous lipase,
•It is likely that indigenous as well as microbial lipases are
important in development of lipolytic rancidity in milk.

6. • Milk is heated to destroy
milk lipases but not the
bacterial heat-stable
lipases.
• Assay methods depend
on the release of free
fatty acids due to
hydrolysis of milk fat
• ELISA is also used to
measure lipases of
Pseudomonas Spp. 6

7. Rancidity
• Microbial rancidity refers to a process in which
microorganisms, use their enzymes such as lipases to break
down fat.
• Rancidification or rancidity, causes a substance to become
rancid, that is, having a rank, unpleasant smell or taste.
• Consuming rancid food products is unlikely to cause
immediate illness or harm,
• Reduce the nutritional value of food, and some vitamins are
highly sensitive to degradation.
• Produce potentially toxic compounds associated with long-
term harmful health effects concerning advanced aging,
neurological disorders, heart disease, and cancer 7

8. Proteinases
• The major cause of bitterness in milk and milk products is
the formation of bitter peptides due to the action of
proteinases.
• Proteinase activity has been detected in Pseudomonas
Serratia and Bacillus species.
• Heat stability of proteinases from several bacterial species
was investigated by Griffiths et al. (1981).
• Strict quality control is therefore critical in UHT milk
products to ensure that heat-stable proteinases do not cause
bitter off flavors.
• The most investigated source of bitter peptides is the casein.
8

9. • Even when present as low as
1ng/ml in raw milk can
reduce the acceptance quality
of milk during normal
storage.
• So it is very important to use
a sensitive assay to predict
the shelf life of dairy
products.
• Laboratory tests for these
proteinases include: ELISA,
Flurescamine assay
9

10. Casein
• Casein phosphoproteins (αS1, αS2, β, κ).
• These proteins are commonly found in mammalian milk
making up 80% of the proteins in cow milk
• Casein major component of cheese
• Use as a food additive, to a binder for safety matches
• As a food source
• Casein supplies amino acids, carbohydrates
• And the two inorganic elements calcium and phosphorus
10

11. Potential Health Risks
• Populations with greater than 10% of the protein in their diet
from casein
• We were at risk of cancer due to casein acting as a cancer
promoter.
• A Casein allergy, when your body's immune system
mistakenly thinks the protein is harmful and produces allergic
(IgE) antibodies for protection.
• The interaction triggers the release of body chemicals
• Such as histamine that cause symptoms
• Swelling of the lips, mouth, tongue, face, or throat
• Skin reactions such as hives, a rash, or red, itchy skin
sneezing, runny nose, itchy eyes, coughing,etc 11

12. The China Studyis a
book written about a
large-scale study done
with the support of the
Chinese government
and provincial
governments across
China.
America's best-selling
books about nutrition.

13. Enzymatic Browning
• Fruits and vegetables turning brown when damaged/cut is
exposed to air (enzyme-involved oxidation)
• Enzyme involved is polyphenol oxidase (PPO).
• PPO converts polyphenol, which is naturally present in all
kinds of fruits and vegetables, into a brown pigment called
melanin.
• PPO is naturally separated from polyphenol in the intact
cells.
• Damage or cut destroys cell structure and mix the PPO and
polyphenol together.
• PPO converts polyphenol into melanin pigment. Therefore
brown surfaces are formed. 13

14. • Arctic Apples apples that contain a nonbrowning trait
introduced through biotechnology.
• They were developed through a process of genetic
engineering and precision breeding by Okanagan Specialty
Fruits
• Specifically, gene silencing reduces the expression
of polyphenol oxidase (PPO), thus preventing the fruit
from browning. First of its type.
14

15. Proteolytic Enzymes
• Proteolysis Cells contain
proteolytic enzymes which
hydrolyse proteins into amino
acids, which is responsible for
the ageing and spoilage of
foods.
• Suitable action of proteolytic
enzymes on meat produces
tendering effect, which
improve meat quality.
• However undesirable action of
this enzyme causes spoilage of
meat. 15

16. 16
Refrences
file:///C:/Users/worldlinks/Downloads/microbial-and-biochemical-spoilage-of-foods-an-
overview.pdf
http://www.sciencedirect.com/science/article/pii/0958694695000739
file:///C:/Users/worldlinks/Downloads/MANUSCRIPT_PATEL_3.pdf
http://aem.asm.org/content/70/10/5715.full.pdf+html
https://en.wikipedia.org/wiki/Lactobacillales#Metabolism
https://www.google.com.pk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-
8#q=microbial+enzymes+definition
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3784079/
http://www.ncbi.nlm.nih.gov/pubmed/11350200
http://www.sciencedirect.com/science/article/pii/S0273230001914667
https://en.wikipedia.org/wiki/Rancidification
https://www.google.com.pk/search?q=psychotrophs&oq=psychotrophs
https://en.wikipedia.org/wiki/Casein#Health_issues
http://blogs.webmd.com/food-and-nutrition/2016/02/5-superfoods-for-men.html
https://www.google.com.pk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-
8#q=lactic%20acid%20bacteria%20in%20food%20spoilage
http://faculty.weber.edu/coberg/class/3853/3853%20MOs%20and%20Food%20Spoilage
%20notes.htm
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822015000100173
https://www.google.com.pk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-
8#q=enzymatic%20degradation%20food%20contamination
http://www.britannica.com/topic/food-preservation
http://edblog.hkedcity.net/te_tl_e/wp-content/blogs/1685/uploads/FST/Food%20Booklet
%209%20eng.pdf
https://www.google.com.pk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-
8#q=enzymes%20in%20carbohydrate%20metabolism%20for%20lactic%20acid%20production
http://link.springer.com/article/10.1007/BF00399499
https://en.wikipedia.org/wiki/Polyphenol_oxidase
https://en.wikipedia.org/wiki/Arctic_Apples