Oils and Fats: Properties and Uses
37 Questions
5 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which type of rancidity is light induced?

  • Enzymatic oxidation
  • Oxidative Rancidity
  • Photooxidation (correct)
  • Hydrolytic Rancidity

    • Hydrolytic rancidity is associated with the development of disagreeable flavor in oils and fats.

    True

    What is the term used for the conversion of triplet state oxygen to singlet state oxygen?

    Photooxidation

    The reactivity of singlet state oxygen (1O2) is ______ times greater than that of triplet state oxygen (3O2).

    <p>1500</p> Signup and view all the answers

    Match the following components with their type of sensitization:

    <p>Chlorophylls = Type II sensitizer Riboflavin (vitamin B2) = Type I sensitizer Heavy metals = Type II sensitizer Mb (myoglobin) = Type I sensitizer</p> Signup and view all the answers

    Which of the following is NOT a type of oxidative rancidity?

    <p>Hydrolytic Rancidity</p> Signup and view all the answers

    What role do sensitizers play in photooxidation?

    <p>They activate oxygen to singlet state oxygen.</p> Signup and view all the answers

    Freezing completely prevents rancidity development in oils and fats.

    <p>False</p> Signup and view all the answers

    What is one application of Sucrose fatty acid ester (Olestra)?

    <p>Used as a frying medium in savoury snack foods</p> Signup and view all the answers

    Sucrose monostearate is only used in baked products.

    <p>False</p> Signup and view all the answers

    What are carbohydrate-based fat replacers created from?

    <p>Cereal, grain, and/or starches such as corn, potato, and tapioca.</p> Signup and view all the answers

    Hydrocolloids provide ______ to foods.

    <p>thickness</p> Signup and view all the answers

    Match the following carbohydrate-based fat replacers with their characteristics:

    <p>Polydextrose = Needs more liquid and provides a thick mouthfeel Sorbitol = Acts as a sweetener and can cause laxative effects Modified food starches = Acts as an anti-staling agent Gums = Provides structure and emulsion in food</p> Signup and view all the answers

    What flavor is associated with crude soybean oil?

    <p>Grassy</p> Signup and view all the answers

    Type II lipoxygenase is highly specific and acts on oils only after free fatty acids have formed.

    <p>False</p> Signup and view all the answers

    What are the flavors associated with reverted soybean oil?

    <p>Grassy, beany, buttery, melony, tallowy, painty, fishy</p> Signup and view all the answers

    The enzyme that catalyzes the oxidation of unsaturated oils is called _____ .

    <p>lipoxygenase</p> Signup and view all the answers

    Which of the following aldehyde compound gives a pronounced green bean odor?

    <p>3-cis-hexenal</p> Signup and view all the answers

    Match the following lipoxygenase types with their characteristics:

    <p>Type I lipoxygenase = Highly specific, attacks cis-cis-1,4-pentadiene group Type II lipoxygenase = Less specific, operates at higher ppm Both Type I and Type II = Catalyze oxidation of unsaturated oils</p> Signup and view all the answers

    Which of the following oils was the first modified oil for improved oxidative stability?

    <p>Low-linolenic canola oil</p> Signup and view all the answers

    What is the optimum pH for Type I lipoxygenase activity?

    <p>9</p> Signup and view all the answers

    Fat replacers are designed to increase the fat and calorie content of food.

    <p>False</p> Signup and view all the answers

    What is the product of the reaction between singlet oxygen (1O2) and an unsaturated fatty acid (RH)?

    <p>Hydroperoxide (ROOH)</p> Signup and view all the answers

    What is Olestra derived from?

    <p>Sucrose polyester derived from soybean, corn, cottonseed or sunflower fatty acids.</p> Signup and view all the answers

    All non-triglyceride components of oils are classified as polar compounds.

    <p>True</p> Signup and view all the answers

    The ideal fat replacer should mimic the attributes of fat while significantly reducing its __________ content.

    <p>calorie</p> Signup and view all the answers

    Carotenoids can act as quenchers for singlet oxygen, preventing photooxidation.

    <p>True</p> Signup and view all the answers

    Match the following types of substances with their characteristics:

    <p>Fat-like substances = Not absorbed or partly absorbed by humans Olestra = Sucrose polyester yielding no calories Low DS compounds = Hydrophilic, digestible, absorbable High DS compounds = Lipophilic, non-digestible, non-absorbable</p> Signup and view all the answers

    What happens to oil palm fruits that contain chlorophyll when they are not harvested at the mature stage?

    <p>They contribute to photooxidation.</p> Signup and view all the answers

    What are the characteristics of modified oils created through plant breeding and genetic engineering?

    <p>Improved nutritional properties, oxidative stability, and physical properties</p> Signup and view all the answers

    Flavour reversion occurs in oils with high levels of ______ fatty acids, such as linolenic acid.

    <p>polyunsaturated</p> Signup and view all the answers

    Olestra contains 9 kcal/g and is fully absorbed by the human digestive system.

    <p>False</p> Signup and view all the answers

    Match the following types of oils with their susceptibility to flavour reversion:

    <p>SB oil = Susceptible to flavour reversion Corn oil = Least susceptible to singlet O2 attack Fish oil = Susceptible to flavour reversion Rapeseed oil = Susceptible to flavour reversion</p> Signup and view all the answers

    What is the induction period (IP) in the context of oxygen uptake?

    <p>Both A and B</p> Signup and view all the answers

    SFAE stands for __________ fatty acid esters.

    <p>sugar</p> Signup and view all the answers

    Phenolic antioxidants such as BHA and BHT effectively protect oils from photooxidation.

    <p>False</p> Signup and view all the answers

    What unpleasant change occurs in oils containing 18:3 when exposed to air?

    <p>Development of objectionable or off-flavours.</p> Signup and view all the answers

    Study Notes

    OILS & FATS

    • Topics in oils and fats include rancidity, frying, and novel oils & fats, including fat replacers.

    Rancidity

    • Rancidity is the development of unpleasant flavors in oils/fats resulting from specific chemical reactions.
    • Types of rancidity include hydrolytic and oxidative rancidity.
    • Oxidative rancidity, also called autooxidation, is further categorized as photooxidation, flavor reversion, and enzymatic oxidation.

    Frying

    • Deep frying has increased in use since the past 40 years, especially in the U.S., W. Europe, and Asian Countries.
    • Common fried products include potato chips & crisps, doughnuts, expanded snack products, fried dishes, roasted nuts, fast foods, and convenience frozen foods.
    • Oil pick-up (amount of oil absorbed by the product) varies from 6% for roasted nuts to as much as 40% for potato chips.

    Novel Oils & Fats

    • New types of oil and fats are developed by genetic engineering or plant breeding modifications.
    • This modification can result in oils that have different fatty acid compositions, in particular in regard to improving nutrients, oxidative stability or physical and technological properties.

    Fat Replacers

    • Fat replacers are substances used to replace fat.
    • Ideal fat replacers create qualities of fats and significantly reduce the fat and calorie content of foods.
    • Fat replacers can be either fat-like substances not absorbed by humans or protein/carbohydrates that mimic fat qualities.
    • One example is Olestra, a sucrose polyester.
    • Also considered are carbohydrate-based fat replacers such as modified food starches, hydrocolloids and polyols.

    Stability of Frying Oils & Fats

    • Stability is measured using accelerated tests, including active oxygen method (AOM or Swift test), oven/Schaal test and Rancimat / OSI.
    • Various oils have varying stability characteristics. The stability of different frying oils is measured by means of these tests and specific data tables are available.

    Mechanism of Deep Oil/Fat Frying

    • Frying is a dehydration process that transfers heat rapidly. Water evaporates inside the food altering its texture, color and organoleptic (sensory) qualities.
    • Food surface becomes dry and porous, this is related to oil absorption.

    Changes in Oil during Frying

    • Darkened color, increased viscosity, decreased smoke point, increased foaming, and increased gum formation are visible changes during frying.

    Overview of Chemical Changes during Deep Frying

    • Reactions are initiated by steam and moisture from the frying process.
    • Various chemical reactions lead to the formation of volatile compounds such as aldehydes, alcohols, ketones, cyclic compounds, dimers, and trimers.
    • Additionally, Hydrolysis leads to formation of fatty acids, glycerol and partial glycerides.
    • Oxidative Reactions (autoxidation) lead to the formation of hydroperoxides (HPs), free radicals, and various volatile degradation products.
    • Thermal degradation reactions result in new C-C linkages and formation of cyclic monomers and polymers.
    • Gumming and foaming of oils can also occur during frying.

    Removal of Volatiles from Frying

    • Volatiles (e.g., antioxidants, fatty acids and others) are removed from the frying system.
    • Various reactions can occur, autoxidation, and formation of degradation products will occur if oil contacts air.

    Modified Oil Types

    • Canola oil, high oleic sunflower oil and safflower oils are examples of novel or modified oils.

    Tests for Heat Abuse of Oils

    • Tests involve detecting volatile and non-volatile decomposition products (NVDPs).
    • These tests usually involve chemical and physical changes in the oil such as changes in color, viscosity, foaming and levels of fatty acids (and other compounds).

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Oils & Fats - FST663 Chapter 1 PDF

    Description

    Explore the chemistry and applications of oils and fats in this quiz. Topics include rancidity, frying techniques, and novel oil developments. Test your knowledge on how these factors affect food quality and preparation.

    More Like This

    Rancidity and Preventive Measures Quiz
    3 questions

    Rancidity and Preventive Measures Quiz

    RobustForesight5015 avatar
    RobustForesight5015
    Understanding Rancidity in Foods
    3 questions

    Understanding Rancidity in Foods

    RobustForesight5015 avatar
    RobustForesight5015
    Lipid Peroxidation and Rancidity
    4 questions

    Lipid Peroxidation and Rancidity

    LuckyMilwaukee avatar
    LuckyMilwaukee
    Fats and Rancidity Quiz
    9 questions

    Fats and Rancidity Quiz

    JubilantDiopside1201 avatar
    JubilantDiopside1201
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser