Food Groups & Shelf Life
Fats & Oils
Color
GMF & Texture
Rancidity & Antioxidants
100
What is the difference between a food and a nutrient?
A food is any substance, natural or artificial ( processed, semi-processed, or raw) intended for human consumption (does not include things such as tobacco or drugs), while a nutrient is a component of food meant to provide energy, maintenance, or growth or repair of tissues. Things such as proteins, lipids, carbohydrates, and vitamins, minerals, and water are nutrients.
100
What is the difference between a saturated fatty acid, a mono-unsaturated fatty acid, and a poly-unsaturated fatty acid?
A saturated fatty acid has only single C to C bonds. A mono-unsaturated fatty acid has only one double C to C bonds and the rest of the C to C bonds are single bonds. A poly-unsaturated fatty acid has more than one double C to C bonds.
100
What is the difference between a dye and a pigment?
Artificial or coloring agents from a different natural source is referred to as a dye (synthetic). Coloring materials that are naturally presented in food are referred to as pigments (natural).
100
Define genetically modified food.
Food derived from or produced from a genetically modified organism.
100
What is an antioxidant, and what are they primarily used for?
A substance that delays the onset or slows the rate of oxidation, and they are used to extend the shelf-life of foods.
200
Define shelf life.
Self life is the period of time that food can go before changes in smell, taste, texture, and appearance cause the product to be undesirable or unfit for consumption.
200
Which is more stable unsaturated hydrocarbons or saturated hydrocarbons, and why?
Saturated hydrocarbons are more stable due to the single bonds.
200
Explain why synthetic colorants in food is a concern in the international community.
Every nation has its own set of laws, and some nations do not have the restrictions or inspections on synthetic colorants in food that other nations have. Since international trade is continuing to grow, many nations are concerned with the health hazard that some synthetic colorants in food being purchased from other nations posses.
200
What are 2 benefits to genetic modification and 2 concerns of genetic modification.
Benefits: Enhanced yield of crops, better taste, more nutritious, longer shelf life, & faster and larger growing livestock Concerns: Job of average farmer, hormones and other products in the food that can be transferred to humans who consume the food, and increase in allergies.
200
Name two common antioxidants and their sources.
Vitamin E - found in wheat germ, nuts, seeds, whole grains, green leafy vegetables, and vegetable oils (like canola & soybean). Vitamin C - found in citrus fruits, green peppers, broccoli, green leafy vegetables, strawberries, and potatoes. B-carotene - found in carrots, squash, broccoli, sweet potatoes, tomatoes, and peaches. Selenium - found in fish, shellfish, red meat, eggs, grains, chicken, and garlic.
300
List 3 factors that effect shelf life (excluding pH change) and explain how they effect shelf life.
-Change in water content: If moist foods have a loss of water they become dry (undesirable & sometimes unfit for consumption), or when a dry food absorbs water it gives rise to microbial degradation. -Light: This gives energy for photo-chemical reactions, which lead to rancidity, loss of color, and oxidation of nutrients. -Air contact: Increase exposure to air can lead to a decrease in nutrients, discoloration, and rancidity. -Temperature: As temperature increases, the degradation of food increases, texture is possible effected as well.
300
List two advantages and two disadvantages of hydrogenating fats and oils.
Advantages: The product becomes a semi-solid, rate of oxidation decreases (which makes the product more stable), texture of the product can be controlled. Disadvantages: The product is not as healthy for the heart, partial saturation can lead to creation of trans fats (much harder to metabolize), and increases LDL cholesterol.
300
List 3 factors that affect the color stability of anthocyanins, carotenoids, chlorophyll, and heme.
Colors of light absorbed by the pigments Oxidation Temperature change pH change.
300
Distinguish between the following types of dispersed systems: suspensions, emulsions, and foams in food.
Suspensions: solid particles suspended in a liquid. Emulsions: stable blend of two immiscible liquids. Foams: gas bubbles trapped in a liquid medium.
300
What are flavonoids and what are their claimed affects?
Flavonoids are a class of natural antioxidants, and have been claimed to have positive health benefits such as preventing cancer, lowering blood sugar levels, and lowering LDL cholesterol.
400
Describe 3 traditional methods used by different cultures to extend the shelf life of foods.
-Salting -Pickling -Fermentation -High Sugar Content
400
List the three primary things required for the hydrogenation process (not including an unsaturated fat &/or oil).
A High temperature (around 200 degrees C) Pressure A metal catalyst (usually nickel, but there are others).
400
List what color(s) Anthocyanins, Carotenoids, Chlorophyll, and Heme are responsible for, and a source for each.
Anthocyanins: red, pink, purple, and blue. Found in berries. Carotenoids: yellow, red, and orange. Found in algae, carrots, and bananas. Chlorophyll: green. Found in all plants. Heme: Red. Found in red blood cells.
400
Describe what a dispersed system is.
A dispersed system is a kinetically stable mixture of one phase in another largely immiscible phase.
400
What are some advantages and disadvantages of synthetic antioxidants?
Advantages: More effective (generally) at reducing the rate of rancidity, are less expensive (generally) than natural antioxidants, avoids a potential concern of an unwanted color or aftertaste of food caused by natural antioxidants. Disadvantages: Consumers perceive natural antioxidants to be safer because they are natural, some can reduce the risk of cancer and heart disease by inhibiting free radicals, policies regarding the labeling and safe use of food additives can be difficult to implement and monitor (especially internationally), some natural antioxidants can serve a plethora of purposes such as being a precursor to vitamin A, production of hormones, and collagen.
500
What is the difference in chemical composition of lipids (fats & oils), carbohydrates, & proteins.
Lipids (fats & oils): Form three long-chain fatty acid (carboxylic acid) molecules and one glycerol molecule. Carbohydrates: The simplest carbohydrates are monosaccharides and they contain one carbonal group (C double bonded to O) and at least two hydroxyl (-OH) groups, and have a C:H:O ratio of 1:2:1. Proteins: Made up of at least 2-amino acids and have peptide bonds.
500
Explain in depth how the length of hydrocarbon chains, the degree of unsaturation, and the effect of an unsaturated fat or oil being trans- or cis- has on melting point.
The longer the hydrocarbon chain the greater the mass which causes there to be more Van der Waal forces, which makes the melting point higher. The greater the degree of unsaturation (more double & triple carbon to carbon bonds) the lower the melting point, because there is less contact and fewer Van der Waal forces. Also this creates a more crooked structure which is harder to compact, also lowering the melting point. Since a cis- fat has the hydrogens on the same side the structure is more crooked than that of a trans- fat, and so a cis- fat will (in general) have a lower melting point and a trans- fat will have a higher melting point.
500
Compare and contrast non-enzymatic browning (Mallard reaction) and caramelization (these cause the browning of food), and the factors that effect them.
Mallard: A chemical reaction between an amino-acid and a reducing sugar (will typically require heat). Very long description look at pg. 436 for confirmation of the correct answer. Caramelization: For foods with high carbohydrate content and low nitrogen content. If required look at pg. 435 for confirmation of the correct answer. Effecting factors: pH level, temperature, and concentration of sugar content.
500
Describe the action and structure of emulsifiers. Also what kind of energy is needed to create and emulsion?
An emulsifier will help the different phases to mix. An emulsifier will generally have a hydrophilic polar head and a hydrophobic non-polar tail. Mechanical energy is needed to make an emulsion (mixing & churning).
500
What are additives and what are some advantages and disadvantages of using additives?
An additive is a chemical compound that slows the rate of deterioration of food. Advantages: Prolong shelf life, reduces mold and bacteria growth in cheese and breads, reduces the growth of microorganisms in carbonated drinks, and can be used to make meats cured. Disadvantages: Can be hazardous to health if not strictly regulated and inspected, allergies, many inconclusive studies with cancer being a possible side effect of consumption of large quantities of additives, and may be bad for health if someone is eating an "irregular" diet (for example a low-sodium diet).
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