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HNSC 1200 Unit 4
Terms in this set (50)
Contrast the importance of water vs. protein and vitamin C
- the body needs 50x more water than proteins and 5000x more water than vitamin C
When does water freeze? How does this affect food texture?
- Water freezes at 0 degrees celsius and water expands when frozen resulting in a texture change in frozen foods
What is water activity? How does this property affect food perishability?
- water activity refers to the amount of available water in food vs. the bound water and foods with higher water activity are at higher risk of microbial spoilage
Which substances determine the physical property of water hardness? How can this pottery affect vegetables?
- mineral salts
- hard water can affect plant pigments when cooking vegetables
- example: red cabbage can turn green when boiled in hard water
Differentiate between temporarily hard water and permanently hard water
1) Temporarily hard water
- contain bicarbonate salts and can be softened by boiling
2) Permanently hard water
- contains magnesium and calcium sulfates and cannot be softened by boiling but can be softened by the exchange of sodium ions for the calcium and magnesium ions
What are the chemicals generally found in water and what's their importance?
1) Fluorine - important in teeth and bone formation
2) Chlorine - added to kill harmful microorganisms
3) Ozone - added to control bacterial growth
4) Nitrates - present in fertilizers, manure and sewage
5) Lead - may be found from old lead pipes but lead can be dangerous in water
6) Organic chemicals - pesticide contamination
What are the roles of water in food preparation?
1) Water acts as an important solvent
- sugars and many flavour compounds are dissolved in water
2) Water is used as a cooking medium
3) Water is part of hydrolysis
- starch undergoes hydrolysis to form simple sugars
4) Water acts as an ingredient in some foods
5) Water promotes essential chemical changes
- when water is added to products such as cakes and muffins, carbon dioxide is released and the product leavens
6) Water is used as a cleaning agent
Outline the role of water in the making of potato chips
1) Water is used to wash the potatoes to remove dirt and other substances
2) Water is used to rinse the potatoes once the skin has been removed
3) Water is used to rinse the potatoes after they have been sliced
What are carbohydrates? How are they produced? Where are they generally found?
- carbohydrates are macromolecules than consist of carbon, oxygen and hydrogen
- carbohydrates are produced by green plants through the process of photosynthesis and light is what drives the reaction (scientists cannot reproduce this reaction)
- carbohydrates are generally found in cereals, legumes, starchy foods, fruits, sugars, jams, and milk products
What are the ways we classify carbohydrates?
- simple sugars with one unit
- simple sugars with two units
- simple sugars with 3-10 units
- complex sugars with many units
What are the two classifications for polysaccharides?
1) Homoglucans (homopolysaccharides)
- composed of the same type of monosaccharide
2) Heteroglucans (heteropolysaccharides)
- composed of different types of monosaccharides
Differentiate between hexoses and pentoses
- Hexoses contain 6 carbons while pentoses contain 5 carbons
What are the building blocks of fibres/gums as well as starches
- hexose sugars such as glucose, fructose and galactose are the building blocks of starch
- pentose sugars like ribose and xylose are the building blocks of fibres and gums
What are the important monosaccharides and disaccharides we need to know?
Outline the properties of glucose
- glucose is the most abundant sugar in the world and is found in fruits, plant juices and honey
- glucose is the form of sugar that circulates in the blood and is broken down in the body to give 3 products, energy, water and carbon dioxide
- glucose is the monomer of many complex polysaccharides like starch and cellulose
Outline the properties of fructose
- sweetest of all common sugars and is found in fruits, plant juices and honey
- very soluble and does not crystallize easily
Outline the properties of galactose
- not normally found in food in its free form but can be found in its free form in fermented milk products like yogurt
- basic unit of some complex carbohydrates such as vegetable gums
Outline the properties of sucrose
- comprised of a glucose and fructose chemically bonded to each other and its common name is table sugar
- extracted from sugar cane and sugar beets
- present with other sugars in fruits, honey and vegetables
Outline the properties of maltose
- consists of two glucose molecules chemically bonded to each other
- product of starch hydrolysis
- important for production of malted beverages such as beer
- found in germinating grain and corn syrup
Outline the properties of lactose
- milk sugar
- consists of glucose and galactose chemically bonded
- only found naturally in milk and milk products
Outline the properties of starch
- plant's storage form of glucose which provides animals and plants with energy
What are the two types of the starch molecule?
1) Amylose - has a linear chain structure
2) Amylopectin - highly branched structure
What is gelatinization?
- process of starch granules swelling when heated in water and this process is responsible for the thickening that occurs when a starch pudding or sauce is cooked
Outline the properties of dextrins
- homoglucans derived from starch
- brown in colour
- produced commercially when starch molecules are partially broken down by enzymes, acid or dry heat
- formed from cornstarch when corn syrup is made, when bread is toasted or when flour is heated
- can be used as fat replacers in food products
Which has more thickening power, starch or dextrins?
- starch has greater thickening power
Outline the properties of glycogen
- homoglucan and the animal storage form of glucose
Which is more branched, starch or glycogen?
- glycogen is more branched than starch
How does glycogen relate to carbohydrate digestion and storage?
- during digestion, carbohydrates are hydrolyzed and the resulting glucose is absorbed in the blood for energy and excess glucose is converted into either fat or glycogen
- glycogen is stored in the liver and muscles temporarily until hydrolyzed
What are plant fibres?
- complex polysaccharides
Differentiate between soluble and insoluble plant fibres
Soluble plant fibres form gel-like solutions when mixed with water while insoluble plant fibres will absorb water and swell
What are the types of plant fibres?
5) Vegetable Gums
Outline the properties of cellulose
- composed of many glucose molecules linked together by beta bonds to form a linear chain
- can be used to replace some of the fat in a food product
Outline the properties of hemicellulose?
- greatest effect in baked goods
- improves mixing quality, reduces mixing energy, aids in incorporation of protein and improves loaf volume in bread dough
Outline the properties of beta-glucans
- composed of glucose units that are linked together by beta bonds
Outline the properties of pectins
- found in both cell walls and in space between plant cells
- pectin is a pectic molecule common in fruits and is responsible for forming gels in various jams and jellies
- commercially produced from apple cores or citrus peel
Outline the properties of vegetable gums
- long chain polysaccharides
- various hexose and pentose sugars are the building blocks
- produces a thickening effect when dissolved in water
- helps retain water and reduce evaporation rates
- used as fat replacers
Name 5 examples of vegetable gums
1) Seaweed extracts
2) Plant seed gums
3) Plant exudates
4) Microbial gums
5) Modified Cellulose
What are the forms of modified cellulose?
1) Carboxymethylcellulose - bulking agent in low calorie foods and in fruit fillings
2) Methyl Cellulose - used in reformed potato products and in coating to reduce oil absorption
How is corn processed into more convenient forms?
- corn is grounded to make cereals and tortillas
- corn is processed to make snack foods like corn chips
- corn is extracted into cornstarch which can then be hydrolyzed to produce corn syrup
How is wheat processed into more convenient forms?
- wheat kernel is composed of bran, germ and endosperm and the bran and germ are removed during milling and the endosperm is made into flour
- durum wheat is milled to from semolina which is used to make pasta
What are the raw materials used for been manufacturing and what are their roles?
1) Cereal grains like malted barley, rice and corn which supply the carbohydrates for fermentation
2) Saccharomyces yeast to ferment the carbohydrates into ethyl alcohol
3) Carbon dioxide to purge oxygen from beer and enhance foaming
4) Hops to intensify flavour and colour
What are the steps in making beer?
1)Malted barley and other cereals are mixed with water and cooked to produce a mash
- This process gelatinizes the starches and makes them more susceptible to fermentation
- The liquid portion of the mash is high in fermentable sugars and is known as wort
2) The wort is transferred into a brew kettle and hops are added and then the resulting mixture is brewed and the hops residue is allowed to settle
3) The wort is drawn from the kettle and then cooled and inoculated with yeast for fermentation
4) Fermentation takes about 9 days and produced an alcohol content of about 4.6% as well as some carbon dioxide
5) After fermentation is complete, the beer is chilled and passed through filters to remove the yeast and any excess materials
6) Beer is then stored in tanks for several months, which allows further settling of materials and development of flavour compounds
7) Additional carbon dioxide is added during storage which helps purge the beer of any oxygen
8) After storage the beer is given a last filtration and then bottled under pressure and pasteurized to prolong shelf life
What are prebiotics?
indigestible dietary carbohydrates that promote the growth of potentially beneficial bacteria
What are FOS?
- fructo-oligosaccharides are naturally occurring sugars found in a variety of plant foods and they have prebiotic properties
What are the benefits of FOS?
1) Lower cholesterol and triglyceride levels
2) Reduce pH of feces
3) Reduce CHO and lipid absorption
4) Reduce toxic metabolites
What is insulin?
insulin is a natural plant extract composed of linear fructose chains with mostly one terminal glucose unit
- insulin is found together with fructo-oligosaccharides
Metabolic Summary of Insulin
- insulin is not digested in the mouth, stomach or intestine or excreted in feces
- in the large intestine, insulin undergoes anaerobic fermentation by bacteria
- insulin contributes approx 1.5 calories per gram of insulin consumed
What are the potential health benefits of insulin?
1) Increases bioavailability of essential minerals like calcium and magnesium
2) May reduce the risk of colon cancer
3) Reductio in cholesterol and blood lipids
4) Prevention of gastrointestinal tract infections
5) Increased growth of bifidobacteria
When can insulin be used to modify food texture?
- insulin can be used in low fat foods to modify texture in order to provide a creamy mouth feel
- present in yogurt, cheese, whipped cream baked goods and more
What are other examples of carbohydrate prebiotics?
3) Oligosaccharides that contain xylose, mannose, galactose and maltose
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