PISA BASE QUESTION SERIES
ASSERTION and REASON type QUESTION
TEST ITEM :- 2
SUBJECT :- SCIENCE
Name of the Teacher: AJAY KUMAR BARHOLIYA
Subject : CHEMISTRY
Email: ajaykumarbarholia@gmail.com
Teaching Experience ; - 28 years
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 odor.
Specifically, it is the hydrolysis or autoxidation of fats into short-chain Aldehyde, ketones and free fatty acids, which are objectionable in taste and odor. When these processes occur in food, undesirable odors and flavors can result
Rancidity refers to the oxidation of unsaturated fats or oils in food that results in bad smells and bad taste. In simple words, when food has become unpleasant, it is termed rancid. When oxygen molecules interact with food and oil, the normal composition of the food is damaged which results in a change in taste and smell, and thus the food is not suggested to be consumed.
Rancidity is also known as Rancidification. It is a condition that is produced by the aerial oxidation of unsaturated fat which is present in food and other products that are noticeable by their terrible smell or taste.
When unsaturated fats are exposed to sunlight, it then converts to a hydroperoxide and breaks down to volatile aldehydes, esters, alcohols, hydrocarbons, ketones, etc., of which some of them have an unpleasant odor.
For e.g-
- An expired packet of chips smells different.
- The taste and smell of butter get changed when it is kept open for a long time.
Types of Rancidity
Rancidity is divided into three types:-
- Hydrolytic Rancidity
- Oxidative Rancidity
- Microbial Rancidity
Hydrolytic Rancidity
Hydrolytic Rancidity is defined as the smell or odor that occurs when free fatty acids are released and triglycerides are hydrolyzed. It generally causes an unpleasant smell. Triglyceride is a combination of three fatty acids, present in oily food. They release free fatty acids and produce glycerol when they react with water. These fatty acids form toxic compounds and may further undergo oxidative rancidification. Hydrolytic Rancidity occurs more quickly in the presence of enzymes like lipase and with moisture and heat. It results in the hydrolysis of the fats with the liberation of either one or more volatile fatty acids.
Oxidative Rancidity
Oxidative Rancidity is defined as a reaction that causes oxygen damage to a food substance. It occurs with unsaturated fats. The natural oil structure is damaged and interrupted by oxygen molecules in such a way that it changes its color, taste, and smell. It leads to the formation of toxic compounds like peroxides that damage Vitamin A and E in foods. In Oxidative Rancidity. The unsaturated fatty acids of glycerides are oxidized at their double bonds. Thus, this reaction causes the release of ketones, volatile aldehydes, and acids. It can be prevented by an oxygen-free atmosphere, light-proof packaging, and the addition of antioxidants.
Microbial Rancidity
Microbial Rancidity is that type of rancidity where microorganisms such as molds or bacteria use their enzymes like lipases to break down chemical structures of fat in oil-producing unwanted smells and taste. This process can be reduced by inhibiting microorganisms or by destroying them. It can also be reduced by pasteurization and the addition of antioxidant ingredients like vitamin E.
Prevention of Rancidity
There are many possible ways to prevent Rancidity. Some of them are:
The free radical pathway for the first phase of the oxidative rancidification of fats.
Antioxidants are often used as preservatives in fat-containing foods to delay the onset or slow the development of rancidity due to oxidation. Natural antioxidants include ascorbic acid (vitamin C) and TOCOPHEROLS (vitamin E).
Synthetic antioxidants include BUTYLATED HYDROXY ANISOL (BHA), BUTYLATED HYDROXY TOLUENE (BHT). The natural antioxidants tend to be short-lived so synthetic antioxidants are used when a longer shelf-life is preferred. The effectiveness of water-soluble antioxidants is limited in preventing direct oxidation within fats, but is valuable in intercepting free radicals that travel through the aqueous parts of foods. A combination of water-soluble and fat-soluble antioxidants is ideal, usually in the ratio of fat to water.
Antimicrobial agents can also delay or prevent rancidification by inhibiting the growth of bacteria or other micro-organisms that affect the process
Oxygen scavenging technology can be used to remove oxygen from food packaging and therefore prevent oxidative rancidification
The Rancimat method is carried out using an air current at temperatures between 50 and 220 °C. The volatile oxidation products are carried by the air current into the measuring vessel, where they are absorbed (dissolve) in the measuring fluid
- Antioxidants can be added to foods that contain oils and fats to slow down oxidative deterioration.
- To slow down the process of rancidification, food can be stored in airtight containers.
- Vacuum packing can be done to keep oxygen out.
- By adding inert gas such as nitrogen to the bag to replace oxygen.
- Food items can be kept in the refrigerator. It will reduce the rate of most reactions that take part in rancidity.
- By storing food in dark places.
Factors that affect Rancidity:
There are various factors that affect rancidity. Some of the factors are discussed below:
- Oxygen: The primary cause of rancidity is exposure to oxygen. Oxygen is more soluble in fats, which leads to food damage and oxidation by releasing free radicals.
- Microorganisms: Many microorganisms release an enzyme known as lipase which leads to hydrolysis of lipids. These microorganisms use their enzyme on food materials and destroy their chemical composition.
- Physical factors: Physical factors like Heat, light, temperature plays an important role in rancidification. Heat and light stimulate the process of oxidation and are the main source for the production of free radicals. Light promotes the decomposition of unsaturated fatty acids.
- Trace elements: The rate of rancidity can be increased by trace elements like Fe and Zn. This is another important factor that affects rancidity.
COMPETENCY BASED QUESTIONS
chapter :-1 chemical reaction
class 10
1. . Assertion :-
Oils and fatty substance when exposed to air, light, or moisture or by bacterial action, resulting in unpleasant taste and odor
.
Reason : Rancidification is the process of complete or incomplete reduction of fats and oils.
(iii) Assertion is true but the reason is false"
2. Assertion : fats and oils when exposed to air, light, or moisture or by bacterial action, resulting in unpleasant taste and odor.
Reason : The hydrolysis or autoxidation of fats into short-chain Aldehyde, ketones and free fatty acids, which are objectionable in taste and odor
(i) Both assertion and reason are true and the reason is the correct explanation of assertion".
3. Assertion :- Rancidity refers to the reduction of unsaturated fats or oils in food that results in bad smells and bad taste .
Reason : Fats and oils when exposed to air , resulting in change taste and odor the food is suggested to be consumed
:
. iv) Both assertion and reason are false.".
4. Assertion : :- Hydrolytic Rancidity occurs more quickly . Reason :- In the presence of enzymes like lipase and with moisture and heat . :
(i) Both assertion and reason are true and the reason is the correct explanation of assertion ".
5. Assertion :The unsaturated fatty acids of glycerides are oxidized at their double bonds .
Reason :Rancidification can be prevented by an oxygen-free atmosphere, light-proof packaging, and the addition of antioxidants .
i) Both assertion and reason are true and the reason is the correct explanation of assertion".
6. Assertion :microorganisms such as molds or bacteria use their enzymes for complete or incomplete reduction of fats and oils
.
Reason : The enzymes like lipases to break down chemical structures of fat in oil-producing unwanted smells and taste. .
(v) Assertion is false but reason is true ".
7. Assertion :Microbial Rancidity can also be reduced by pasteurization and the addition of antioxidant ingredients like vitamin E. .
Reason :microorganisms such as molds or bacteria use their enzymes for complete or incomplete reduction of fats and oils
(i) Both assertion and reason are true and the reason is the correct explanation of assertion".
8. Assertion : Synthetic antioxidants include BUTYLATED HYDROXY ANISOL (BHA), BUTYLATED HYDROXY TOLUENE (BHT). Use can be prevented Rancidification.
Reason :- The synthetic antioxidants are used As a short-lived prevention
(iii) Assertion is true but the reason is false.".
9. Assertion :- food can be stored in airtight containers .
Reason :- To slow down the process of rancidification
?
(i) Both assertion and reason are true and the reason is the correct explanation of assertion .".
10. Assertion :- The primary cause of rancidity is exposure to oxygen .
Reason :- Oxygen is more soluble in fats, which leads to food damage and oxidation by releasing free radicals
(i) Both assertion and reason are true and the reason is the correct explanation of assertion".
Reason :- which leads to hydrolysis of lipids ?
(i) Both assertion and reason are true and the reason is the correct explanation of assertion".
Reason :- Light promotes the decomposition of saturated fatty acids
(iii) Assertion is true but the reason is false".
Reason :- by trace elements like Fe and Zn. This is another important factor that affects rancidity
(v) Assertion is false but reason is true.".
Reason : Rancidification is the process of complete or incomplete reduction of fats and oils.
(iii) Assertion is true but the reason is false assertion".
Template
for preparation of Practice Items for Scientific Literacy
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Domain: Scientificliteracy |
Theme: RANCIDITY Unit
name: … |
Class :
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time: ..min Total
Credit: .. |
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Description
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Learning
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Scientific Literacy
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FRAMEWORK |
CHARACTERISTICS |
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Competency |
Scientific knowledge |
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Knowledge –system |
Physical system |
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Context |
GLOBAL |
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Cognitive demand |
Medium |
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Item Format |
open ended question |
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Proficiency Level |
4 |
Credit
Pattern :
Full
credit : …..
Partial
credit : ….
No
credit : 0
Description
of answer key and credits :
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Q1 Full credit – (c ) ………. No credit – any other answer /
missing. |
