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HNSC 1200: Unit 4
Terms in this set (67)
What is the most abundant nutrient?
The water content of food can be impacted by?
Give an example
- food processing
- ex. raw apple = 84% water, while dried apple is 32%
What are the Physical and Chemical Properties of Water? (5)
- made up of two hydrogen atoms bonded with one hydrogen atom
- Water freezes at 0oC and will expand once frozen.
- Water boils at 100oC at normal atmospheric pressure (near sea level)
- At high altitudes, the boiling point is lowered and it takes longer to cook foods
- Foods with high water activity are at higher risk of microbial spoilage
What is Water hardness? (3)
List its 2 subgroups
- The presence of mineral salts determines water hardness
- Hardness causes scale build up on equipment and pipes
- Hard water is usually alkaline—can affect plant pigments when cooking vegetables (e.g., red cabbage can turn green when boiled in hard water)
- Temporarily hard water
- Permanently hard water
Temporarily hard water (2)
- contains bicarbonate salts
- can be softened by boiling
Permanently hard water (3)
- contains calcium and magnesium sulfates
- cannot be softened by boiling because the minerals are not precipitated by heat
- can be softened by exchanging sodium ions for the calcium and magnesium ions (results in very high levels of sodium)
What are 6 chemicals found in water?
- Fluoride: may be added for teeth and bone formation
- Chlorine: often added to kill microbes, and ozone because it doesn't have an after taste like chlorine
- Nitrates: may be present, from fertilizers, manure and sewage
- Lead: may be found, from old lead pipes
- Organic chemicals: ex. pesticide contamination
- High levels of microorganisms: from animal or human waste resulting in food borne illness
What is water's role in food preparation? (6)
- Water is an important solvent.
- Water is used as a cooking medium (boiling and steaming)
- Water is part of the chemical reaction known as hydrolysis
- Water acts as an ingredient in some foods.
- Water promotes certain chemical changes
- Water is used as a cleaning agent for food and equipment in food processing
Describe: Water is an important solvent (dissolving) (3)
- Many flavour molecules are dissolved in water, e.g., coffee, tea
- Sugars are dissolved in water, e.g., fruit juices, syrups
- Starch granules are first dispersed in water and then the mixture is heated. The starch granules absorb water to produce a thickened pudding or sauce
Describe: Water is used as a cooking medium (boiling and steaming)
- acts as a vehicle for heat transfer
Describe: Water is part of the chemical reaction known as hydrolysis
- Water breaks a chemical bond, splitting the substance into two or more new substances. ex. when starch undergoes hydrolysis to form simple sugars such as glucose.
Describe: Water acts as an ingredient in some foods
- ex. low fat frozen desserts, low calorie margarines
Describe: Water promotes certain chemical changes
- ex. activation of chemical leavening agents (baking powder, baking soda). Left dry these agents do not react. When water is added, carbon dioxide is released which leavens products such as cakes and muffins
Describe: Water is used as a cleaning agent for food and equipment in food processing
- Removes soil, residues and microorganisms depending on the rigour used in washing
Waters role in potato chips (3)
- used to wash the potatoes to remove dirt
- used to rinse the potatoes once the skin has been removed
- This water will contain starch from the potatoes
- contain carbon, hydrogen and oxygen, so are often abbreviated CHO
- produced in green plants via photosynthesis - H20 and CO2 combine to form glucose
- Light is needed to provide the chemical energy to hold the bonds between the atoms in a glucose molecule together
- animals and humans can obtain some energy when the plant is eaten
What are 6 carbohydrate foods?
- Cereal grains and flours: ex. wheat, rye, corn, rice.
- Legumes: ex. peas, beans, lentils.
- Starchy roots, tubers or stems: ex.potatoes, yams, cassava, celery.
- Fruits: ex. oranges, apples, bananas.
- Sugars, honey, jams, molasse
- Milk products
Classification of Carbohydrates
List the 4 units and the amount of simple sugars each one contains
- classified according to the number of basic sugar (saccharide)
- Monosaccharides: simple sugars, 1 unit.
- Disaccharides: simple sugars, 2 units.
- Oligosaccharides: simple sugars, 3-10 units.
- Polysaccharides: complex sugars, many units
What are the 3 Monosaccharides?
What are the building blocks of starches? (4)
Hexose sugars (6 carbon)
What are the building blocks of fibres and gums? (3)
Pentose sugars (5 carbon)
What is the most abundant sugar in the world?
Where can glucose be found?
- fruits, plant juices and honey, often present with other sugars
What is the form of sugar that circulates in the body?
What 3 products is glucose broken down into in the body?
- carbon dioxide
Glucose is: (2)
- the basic unit of complex carbs such as starch and cellulose
- a major component of corn syrup which is formed by hydrolysis of starch. Corn syrup and crystalline glucose are widely used in the baking industry.
Fructose is: (3)
- found in fruits, plant juices and honey
- the sweetest of all common sugars
- very soluble and does crystallize easily
Galactose is: (4)
- Not normally found in its free form in foods
- Forms a bond with glucose to produce lactose (milk sugar).
- Some galactose is found in free form in fermented milk products (e.g., yogurt) where hydrolysis of lactose has occurred
- Galactose is the basic unit of some complex carbohydrates such as vegetable gums
What are the 3 Disaccharides?
- Sucrose (glucose + fructose)
- Maltose (glucose + glucose)
- Lactose (glucose +galactose)
Sucrose is: (3)
- Table sugar
- extracted from sugar cane and sugar beets
- Present with other sugars in fruits, honey and vegetables
Maltose is: (2)
- Found in germinating grain and corn syrup. A product of starch hydrolysis
- Important for production of malted beverages such as beer
Lactose is: (2)
- Milk sugar
- Only found naturally in milk and milk products
- Include raffinose and stachyose commonly found in dried beans
- Not digested by humans but broken down by bacteria in intestinal tract resulting in gas formation
What are the 4 Polysaccharides?
Complex CHO/polysaccharides are chains of sugar units linked together
- is a PLANT'S storage form of glucose
- can be branched or unbranched
- is water insoluble (so cannot wash away from plant via rain)
- provides plants with energy and humans/animals with energy when eaten, as we can digest starch
- Basic storage form of carbohydrates in plants: found in abundance in seeds, roots and tubers
- Consists of only glucose molecules
What are the 2 kinds of starch molecules? (4)
- amylose: has a linear chain structure
- amylopectin: has a highly branched structure
- most natural starches consist of amylose and amylopectin
- normal starch consist of 25% amylose and 75% amylopectin
What is Gelatinization?
- a process of starch granules swelling when heated in water
- is responsible for the thickening that occurs when a starch pudding or sauce is cooked
- polysaccharides that are derived from starch
- Produced commercially when starch molecules are partially broken down by enzymes, acid or dry heat (a process called dextrinization)
- Formed from cornstarch when corn syrup is made, when bread is toasted or when flour is heated/browned
- Dextrins have less thickening power than starch and are brown in colour
- Can be used as fat replacers in food products (e.g., salad dressings, frozen desserts, puddings).
- is the ANIMAL storage form of glucose
- longer and more branched then starch
- rapidly breaks down when the animal is slaughtered
- During digestion, carbohydrates (e.g., starch) are hydrolyzed to glucose which is absorbed into the blood
- Surplus (excess) glucose is converted into either fat or glycogen
- Glycogen is stored in the liver and muscles temporarily until hydrolyzed to help maintain blood glucose levels or used as fuel by muscles
List the 2 types
- The undigested residues of plants
- Soluble fibre
- Insoluble fibre
Soluble fibre: (2)
- dissolve in water.
- Form gel-like solutions when mixed with water. E.g., Oat bran, psyllium.
Insoluble fibre: (2)
- does not dissolve in water
- Will absorb water and swell. E.g., wheat bran
What are the 5 types of fibre?
- Vegetable gums/hydrocolloids
- Consists of many glucose molecules linked together by beta bonds to form a linear chain
- Most abundant type of fibre, make up plant cell wall material
- Can be used to replace some of the fat in a food product (e.g., sauces, salad dressings, frozen desserts).
- Also found in plant cell walls
- Heteroglucan*: Contain a variety of different monosaccharide building blocks, e.g., pentoses and hexoses.
- Greatest effect is in baked goods where they improve the water binding of flour
- In bread dough they improve mixing quality, reduce mixing energy, aid incorporation of protein and improve loaf volume.
- Polysaccharides composed of glucose units that are linked together by beta bonds
- Less linear than cellulose and more soluble in water
- Oats and barley are rich sources
- In the gastrointestinal tract, they form a viscous hydrated mass that traps bile acids and reduces the amount of cholesterol absorbed into the body (so may be of benefit for heart disease)
- Also decreases the rate of digestion of starch into glucose and the rate of absorption of glucose from the gastrointestinal tract into the bloodstream
- Therefore, beta-glucan may be good for diabetics as a means of controlling blood sugar levels
- Found in both cell walls and in space between plant cells. Aid in cementing plant cells together
- Galacturonic acid (a derivative of galactose) is the basic building block of pectic substances
- Pectin is a pectic molecule common in fruits and is responsible for forming gels in various jams, jellies and preserves
- Commercially, pectin is produced from apple cores or citrus peel
Vegetable gums/hydrocolloids: (5)
- Long chain polysaccharides
- Heteroglucan*: Various hexose and pentose sugars are the basic building blocks
- Dissolved in water, they produce a thickening or texture building effect
- Gums can help to retain water, reduce evaporation rates and modify ice crystal formation
- Widely used in the food industry as fat replacers (ice cream, low calorie salad dressings, low fat foods).
What are 5 examples of gums/hydrocolloids?
- Seaweed extracts: agar, alginate, carrageenan
- Plant seed gums: locust bean gum, guar gum
- Plant exudates: gum arabic (used to stabilize carbonated drinks), gum tragacanth
- Microbial gums: xanthan gum (used for cloud stabilization in orange juice), dextran
- Modified cellulose: Carboxymethylcellulose, which is used as a bulking agent in low calorie foods and in fruit fillings
Methyl cellulose is used in reformed potato products and in coatings & batters to reduce oil absorption.
What 3 high carbohydrates foods are often processed into more convenient forms?
- Ground to make cereals and tortillas
- Processed to make snack foods (e.g., corn chips)
- Extracted into cornstarch
- Cornstarch can be hydrolyzed to produce corn syrup (glucose + dextrin).
Wheat kernel is composed of:
- bran (outer layer, high in vitamins, minerals and fibre)
- germ (the sprouting part high in vitamins and fat)
- endosperm (high in carbohydrates)
- bran and germ are removed during milling and the endosperm is made into flour
- 75% of the wheat produced world-wide is used to produce flour, while the remainder is used to produce cereal, pasta, animal feed, wheat germ and wheat germ oil
Durum wheat: (2)
- Milled to form "semolina" (coarse flour) used to make pasta (gluten protein is what gives pasta dough its elasticity)
- Canadian durum wheat is exported all over the world
What are the 5 raw materials for beer manufacturing?
- cereal grains such as malted barley, rice, and corn which supply the carbohydrates (maltose and glucose) for fermentation
- saccharomyces yeast to ferment the carbohydrates into ethyl alcohol
- carbon dioxide (to purge oxygen from beer and enhance foaming)
- hops (to intensify flavour and colour)
What are the 4 steps for making beer?
- malted barley and other cereals are mixed with water cooked to produce a MASH. This process gelatinizes the starches and makes them more susceptible to fermentation
- liquid portion of the mash is high in fermentable sugars and is known as WORT
- The wort is transferred into a brew kettle and hops added. The mixture is brewed and the hops residue is allowed to settle
- The wort is drawn from the kettle through the bed of hops, which partially filters the wort.
- The wort is then cooled and inoculated with yeast for fermentation
How long does fermentation take?
- takes about 9 days and produces an alcohol content of approximately 4.6% as well as some amounts of carbon dioxide
What happens after fermentation is complete? (5)
- the beer is quickly chilled and passed through filters to remove the yeast and any suspended materials
- The beer is then stored in tanks for several months, which allows further settling of finely suspended materials and development of flavour compounds
- Additional carbon dioxide is added during storage, which also helps purge the beer of any oxygen that may be present. This is necessary because the presence of oxygen in the beer can destroy flavour and reduce shelf life
- After storage the beer is given a last fine filtration to yield a sparkling clear beverage
- The beer is then bottled (known as racking) under pressure and pasteurized to prolong shelf life
What are Prebiotics?
- Indigestible dietary carbohydrates which are able to stimulate the growth of potentially beneficial bacteria / probiotics
What are Fructo-oligosaccharides?
- have prebiotic properties
- They are naturally occurring sugars found in a variety of plant foods (such as bananas, tomatoes, onions, garlic, wheat, barley and rye) as well as honey and brown sugar
Which beneficial bacteria use Fructo-oligosaccharides as food? (4)
- it is not able to feed harmful bacteria
What are other potential benefits of Fructo-oligosaccharides? (4)
- Lower cholesterol and triglyceride levels.
- Reduce the pH of feces
- Reduce CHO and lipid absorption
- Reduce toxic metabolites
What is inulin? (2)
- A natural plant extract composed of linear fructose chains with mostly one terminal glucose unit
- Inulin is found together with fruto-oligosaccharides
What is the metabollic summary of inulin?
- Inulin is not digested in the mouth, stomach or small intestine
- In the large intestine, inulin undergoes complete anaerobic fermentation by bacteria
- Therefore contributes approximately 1.5 calories per gram inulin consumed
- No inulin is excreted in the stool
What are 5 potential benefits of inulin?
- Increases bioavailability of minerals such as calcium, magnesium and iron
- May reduce the risk of colon cancer
- Reduction in cholesterol and blood lipids
- Prevention of gastrointestinal tract infections
- Increased growth of bifidobacteria
What are 6 benefits of the increased growth of bifidobacteria?
1. Produces nutrients such as B-group vitamins, folic acid
2. Produces digestive enzymes
3. Reduces food intolerance
4. Improves nutrient management
5. Reduces liver toxins, i.e., blood amines and ammonia
6. Competitive elimination of pathogenic microorganisms.
In what foods can inulin be used in? (3)
- low fat foods to modify texture to provide a creamy mouth feel
- used in products such as yogurt, cheese, whipped cream, frozen desserts, baked goods
- processed meats
What are 3 other examples of carbohydrate prebiotics?
- Oligofructose- oligosaccharide containing fructose, ex. raftilose
- Lactulose (disaccharide consisting of fructose chemically bonded to galactose)
- Oligosaccharides that contain xylose, mannose, galactose and maltose.
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