CSS General Science and Ability Food Science Flashcards

24 sample cards from the Food Science deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. Why are anti-nutrients significant in food science, and give two examples.

   Anti-nutrients are compounds that interfere with nutrient absorption or utilization, reducing bioavailability. Examples: phytic acid (binds iron, zinc, calcium) and oxalic acid (binds calcium); also tannins and trypsin inhibitors.

2. What are the three main sensory attributes used to judge food quality?

   Appearance (color, shape, size, gloss), texture (mouthfeel and physical structure), and flavor (combined taste and aroma).

3. What gives flavor its full sensory profile, and what are the five basic tastes?

   Flavor is the combination of taste (tongue) and aroma (smell/olfaction), plus mouthfeel. The five basic tastes are sweet, sour, salty, bitter, and umami (savory).

4. What is the Maillard reaction and why is it important to food appearance and flavor?

   A non-enzymatic browning reaction between amino acids (proteins) and reducing sugars on heating, producing brown color and characteristic roasted/baked flavors (e.g., bread crust, seared meat, coffee).

5. Distinguish enzymatic browning from non-enzymatic (Maillard/caramelization) browning.

   Enzymatic browning is catalyzed by enzymes (polyphenol oxidase) reacting phenols with oxygen, browning cut fruit (apples). Non-enzymatic browning (Maillard and caramelization) requires heat and no enzymes, producing cooking colors and flavors.

6. What is caramelization?

   The non-enzymatic browning of sugars by heat alone (without amino acids), producing brown color and sweet, nutty, caramel flavors when sugar is heated to high temperatures.

7. Define a food additive and state the broad reasons additives are used.

   A food additive is a substance intentionally added to food to maintain or improve safety, freshness, taste, texture, nutritional value, or appearance. Used for preservation, sensory enhancement, processing aid, and fortification.

8. Distinguish a preservative from an antioxidant as food additives.

   A preservative inhibits microbial growth or spoilage to extend shelf life (e.g., sodium benzoate, nitrites). An antioxidant prevents oxidation of fats and color/flavor compounds, delaying rancidity (e.g., BHA, BHT, vitamin E/C).

9. Give two examples each of common chemical preservatives and natural preservatives.

   Chemical: sodium benzoate, potassium sorbate, sodium nitrite, sulphur dioxide. Natural: salt (sodium chloride), sugar, vinegar (acetic acid), spices, smoke.

10. Name two synthetic and two natural antioxidants used in foods.

    Synthetic: BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), TBHQ, propyl gallate. Natural: tocopherols (vitamin E), ascorbic acid (vitamin C), rosemary extract, beta-carotene.

11. What is rancidity, and what are its two main types?

    Rancidity is the deterioration of fats/oils producing off-flavors and odors. Types: oxidative rancidity (reaction of fats with oxygen) and hydrolytic rancidity (breakdown of fats by water/enzymes releasing free fatty acids).

12. List the major functional categories of food additives besides preservatives.

    Antioxidants, emulsifiers, stabilizers/thickeners, colorants, flavor enhancers (e.g., MSG), sweeteners, acidulants/pH regulators, leavening agents, and nutritional fortifiers.

13. What is an emulsifier and give a common example?

    An emulsifier stabilizes mixtures of two immiscible liquids (oil and water) by reducing surface tension, keeping them blended. Example: lecithin (from egg yolk or soy) in mayonnaise and chocolate.

14. What are the four main causes of food deterioration/spoilage?

    Microbial (bacteria, yeasts, molds), enzymatic (food's own enzymes), chemical (oxidation, rancidity, browning), and physical/biological (insects, rodents, moisture loss, mechanical damage).

15. Which microorganisms cause food spoilage, and which conditions favor their growth?

    Bacteria, yeasts, and molds. Growth is favored by warmth, moisture (high water activity), neutral pH, oxygen (for aerobes), and available nutrients. The 'danger zone' is roughly 5-60 degrees C.

16. What is water activity (aw), and why does it matter for spoilage?

    Water activity is the amount of free (unbound) water available for microbial growth and reactions, on a 0-1 scale. Lowering aw (by drying, salting, or adding sugar) inhibits microbial growth and extends shelf life; most bacteria need aw > 0.91.

17. How do enzymes cause food deterioration even without microbes?

    Naturally present enzymes continue acting after harvest/slaughter, causing over-ripening, softening, enzymatic browning, and off-flavors; blanching or heating denatures these enzymes to slow deterioration.

18. Define food adulteration and distinguish intentional from incidental adulteration.

    Food adulteration is lowering quality by adding inferior/harmful substances or removing valuable constituents. Intentional adulteration is deliberate (for profit, e.g., adding water to milk); incidental adulteration is unintentional contamination (e.g., pesticide residues, rodent hairs).

19. Give three classic examples of food adulterants and the foods they are added to.

    Water and starch in milk; brick powder or coloring in chili/red powder; argemone oil in mustard oil; chicory in coffee; chalk powder in flour; melamine in milk to fake protein content.

20. What are the main objectives of food preservation?

    To prevent microbial growth and enzymatic/chemical spoilage, extend shelf life, retain nutritional and sensory quality, ensure year-round availability, and reduce food waste and foodborne illness.

21. List the principal methods of food preservation by their underlying principle.

    By temperature: refrigeration, freezing, pasteurization, sterilization/canning. By moisture removal: drying/dehydration. By chemicals: salting, sugaring, pickling (acid), chemical preservatives, smoking. By other means: irradiation, fermentation, vacuum/MAP packaging.

22. Compare pasteurization and sterilization.

    Pasteurization uses mild heat (e.g., 72 degrees C for 15 s, HTST) to kill pathogens and reduce spoilage organisms without destroying all microbes; product needs refrigeration. Sterilization uses higher heat (e.g., canning, UHT ~135 degrees C) to destroy all microbes and spores for long shelf-stable storage.

23. How do salting, sugaring, and pickling preserve food?

    Salting and sugaring lower water activity through osmosis, dehydrating microbial cells and inhibiting growth. Pickling lowers pH using acid (vinegar/acetic acid or fermentation lactic acid), creating an environment hostile to spoilage microbes.

24. How do canning, freezing, and irradiation each preserve food?

    Canning seals food in airtight containers then heat-sterilizes it, killing microbes and excluding oxygen. Freezing lowers temperature below -18 degrees C, halting microbial growth and slowing enzyme/chemical reactions. Irradiation uses ionizing radiation (gamma, X-ray, electron beam) to kill microbes and pests without significant heating ('cold sterilization').

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