Food Freezing Honor

Household Arts

Requirements

1. What are the advantages and disadvantages of frozen foods?

   Answer: Advantages: long shelf life (months), preservation of nutrients (vitamins), convenience (quick preparation), reduced waste, retention of flavor, safety against microbial contamination. Disadvantages: change in texture (especially of fruits and vegetables), loss of some water-soluble vitamins (C), freezer space, and the cost of the electricity to keep them. — Freezing at -18°C inhibits microbial and enzymatic activity; vitamin C is the most lost (up to 50% in 6 months); a household freezer consumes about 30 kWh/month; research from USP shows that industrially frozen vegetables preserve more vitamins than fresh ones from the market (which spend days in transport) — an interesting paradox, in effect.

2. Define the following terms:
   • Scald/blanch
   • Quick freezing
   • Freezer burn

   Answer: 1) Scalding/blanching: plunging the vegetables into boiling water for 1 to 3 minutes and then into ice water — this inactivates the enzymes that spoil color, flavor, texture, and nutrients during freezing. 2) Quick freezing: lowering the food's temperature below -18°C within a few hours, forming small ice crystals that preserve the texture and prevent the rupturing of the cells. 3) Freezer burn: the drying out and oxidation of the surface of the food caused by poorly sealed packaging, leaving white or grayish spots, dry texture, and bad flavor. — Blanching deactivates peroxidase and catalase (enzymes that oxidize vegetables); small crystals (from quick freezing) do not rupture cells — unlike slow freezing, which destroys them; freezer burn occurs when air enters the packaging and dehydrates the food — common in poorly wrapped meats in the Brazilian household freezer, in effect.

3. What types of foods cannot be frozen?

   Answer: Should not be frozen: lettuce and raw greens (they wilt), raw tomato (it turns to mush), eggs in the shell (they crack), mayonnaise and creams (they separate), raw potatoes (they darken), prepared gelatins (they lose texture), soft cheeses (ricotta, cottage), bananas (they darken), and canned foods still sealed (the can may burst). Freezing changes the texture or spoils them completely. — The high moisture in these foods forms large crystals that rupture the cells; emulsions (mayonnaise) separate when frozen; potato and banana darken through an enzymatic reaction (PPO); the egg cracks from the expansion of water when freezing; standards published by Embrapa Alimentos and the Brazilian Society of Food Science and Technology, in effect.

4. Which containers are most suitable for freezing foods? Why should glass or styrofoam containers not be used?

   Answer: Suitable: plastic bags made for the freezer (thick), plastic containers with lids (BPA-free), vacuum packaging, and aluminum foil. Ordinary glass is not suitable because it can crack with the expansion of water when freezing (use only proper tempered glass); styrofoam insulates but absorbs odors and fats, and releases microplastics in direct contact with food. — Freezer-safe bags (Ziploc Freezer) withstand down to -40°C; BPA-free containers are the American FDA standard; vacuum packaging extends durability 3-5x; tempered glass like Pyrex withstands thermal variation; styrofoam (polystyrene) releases styrene on contact with fatty foods according to an Anvisa alert, in effect.

5. What essential points should be considered when selecting foods to be frozen?

   Answer: Points: freshness (the fresher, the better the result), proper ripeness (fruits at their peak, neither too green nor too ripe), absence of defects (no bruised or spoiled parts), reliable origin (no contamination), type of food (some do not freeze well), and portion size (small portions freeze faster and thaw better). — Old food keeps its poor quality in the freezer (it does not improve); the ideal ripeness point is that of fresh consumption; small portions follow the 4°C/h rule (crossing the bacterial danger zone quickly); the Embrapa and ANVISA standard recommends 0-4°C before the freezer and -18°C after 24h for ideal frozen food quality, in effect.

6. Demonstrate how to properly sanitize the freezer where the foods will be stored.

   Answer: Empty the freezer, unplug it, and let it defrost (do not force it with sharp objects). Clean the interior with a damp cloth in water + baking soda (1 spoon per liter), dry it well, turn it back on, wait for it to reach -18°C, and reorganize the foods. Do a complete sanitization every 6 months; clean up spills immediately after they occur. — Baking soda neutralizes odors naturally without leaving a chemical residue; defrosting with a sharp object can puncture the gas tubing (a high repair cost); the freezer reaches -18°C in 4-6 hours after restarting; regular cleaning reduces cross-contamination — a standard principle of Anvisa and the Health Surveillance of Brazil in all states, in effect.

7. Why is it important to label the containers of frozen foods? What materials should be used for this purpose? What information should be on the label?

   Answer: 1) Why labeling is important: the label allows identifying the content (what it is), controlling the shelf life by the freezing date, and organizing its use; without a label, control is lost and food forgotten in the freezer is wasted. 2) What materials to use: adhesive labels suitable for the freezer (they resist moisture), permanent markers (they do not fade), masking tape, and a marker. 3) What information should be included: the name/content of the food, the freezing date, the portion size (how many it serves), and preparation instructions. — Frozen meats last 3-12 months, vegetables 8-12 months, prepared dishes 2-3 months; ordinary ink fades with freezer moisture; freezer-safe adhesive labels are from 3M or Avery; date + name + portion is the SBA (Brazilian Society of Nutrition) standard — the basis of Brazilian household food management, in effect.

8. What is ascorbic acid and what is its use in freezing fruits?

   Answer: Ascorbic acid is vitamin C (C₆H₈O₆), a natural substance used as a food antioxidant. In freezing fruits (especially apple, banana, pear, peach), it prevents darkening from enzymatic oxidation (PPO). Dissolve 1 teaspoon in 4 liters of water and soak the cut fruits for 2-5 minutes before freezing them. — Polyphenol oxidase (PPO) is the enzyme that darkens cut fruits; vitamin C blocks the reaction by reducing the iron in the medium; lemon juice has the same effect (also rich in vit C); the Embrapa Tropical Agroindustry standard for preserving Brazilian fruits such as mango, pineapple, and papaya, in effect worldwide today.

9. How should the following foods be thawed and served:
   • Fruits
   • Greens
   • Vegetables
   • Pasta

   Answer: 1) Fruits: thaw in the refrigerator or consume them still cold (in juices, smoothies, and desserts) — do not let them thaw completely so they do not turn to mush; serve them right after the ideal point. 2) Greens (leaves): use them still frozen, throwing them directly into the sauté, soup, or cooking, without thawing first, so they do not wilt or lose color; serve immediately after preparation. 3) Vegetables: cook them straight from the freezer, without thawing, for 5 to 10 minutes (in boiling water, steamed, or sautéed), which preserves color, texture, and nutrients; serve them hot. 4) Pasta: heat it straight from frozen, without thawing — prepared dishes (lasagna, spaghetti, gnocchi) go straight into the oven or microwave until well heated inside; raw pasta can be cooked directly in boiling water; serve as soon as it is hot. General rule: never refreeze a food that has already been thawed. — Thawing on the counter favors bacteria between 5-60°C (the danger zone); microwave defrost creates hot spots — cook immediately afterward; refreezing loses texture and increases microbial risk; the Anvisa standard: "thawing in the refrigerator is the safest method" — a principle applied in all Brazilian manuals, in effect.

10. Freeze 2 types of vegetables and then prepare and serve them as a demonstration.

    Answer: You choose 2 vegetables (carrot, broccoli, green beans, cauliflower, peas): wash them well, cut into uniform pieces, blanch in boiling water for 2-3 min, plunge into ice water (to stop the cooking), drain, and freeze in a plastic bag. To serve: cook straight from the freezer for 5-10 min or sauté. Present the dish to the instructor with an explanation of the process. — Blanching deactivates the enzymes that spoil color and texture in the freezer; the thermal shock in ice water stops the cooking and fixes the color; freezer-safe bags last up to 1 year; vegetables preserve 90% of their vitamins if frozen within 6 months according to Embrapa Hortaliças — the basis of modern Brazilian cooking, in effect today.

11. Freeze one type of fruit in syrup.

    Answer: Choose a fruit (strawberry, mango, peach, pineapple). Prepare a syrup with 4 cups of water + 1 cup of sugar (40% sugar), boil for 1 min, and cool. Wash, peel, cut, and arrange the fruits in a container. Cover with the cold syrup, leaving 2 cm of space (expansion). Seal with an airtight lid and freeze at -18°C. It lasts 8-12 months in the freezer. — Syrup prevents darkening (oxygen does not reach the fruit) and improves texture upon thawing; the 40% ratio is the Embrapa standard for Brazilian fruits; the 2 cm space is essential — without it the expansion of water breaks the container; mango and peach are the fruits that best preserve their texture in syrup according to food tests, in effect.

12. Freeze one type of fruit without using any kind of sweetener.

    Answer: Choose a fruit (strawberry, raspberry, mango, blueberry). Wash it well, drain, cut (if large), spread in a single layer on a tray lined with parchment paper, freeze for 2 hours (individual freezing). Then transfer to freezer-safe plastic bags, remove the air, and freeze at -18°C. It keeps its shape and flavor for 8-12 months. — This method (IQF — Individually Quick Frozen) prevents the fruits from sticking together and allows using small quantities; it is how industrial fruits are frozen; ascorbic acid (vitamin C) can be sprayed on to prevent darkening without sweetening; the Embrapa Tropical Agroindustry standard for Brazilian fruits, in effect.

13. Freeze 2 types of prepared dishes (e.g., lasagna, stroganoff, etc.). What special precautions should be taken during the preparation of these foods?

    Answer: Prepare the lasagna and stroganoff normally, cool them completely within 2 hours, divide into portions (individual containers), cover well, and freeze. Precautions: never freeze them hot (it creates large ice crystals), use containers suitable for freezer-to-oven use (e.g., tempered glass), label with the date, and thaw in the refrigerator 24h before reheating in the oven or microwave. — Cooling quickly avoids the bacterial danger zone (5-60°C); Pyrex containers withstand going back and forth from freezer to oven (380°C); dishes with sauce keep better than dry ones; the Embrapa Alimentos standard: "cool within 2h, freeze within 4h after cooking" — the basis of modern Brazilian food safety, in effect.

14. Present the shelf life of each of the foods from requirements 10 to 13.

    Answer: Shelf life in the freezer at -18°C: blanched vegetables (req. 10): 8-12 months; fruit in syrup (req. 11): 8-12 months; fruit without sweetener (req. 12): 6-8 months (it oxidizes and loses color faster); prepared dishes with sauce such as lasagna/stroganoff (req. 13): 2-3 months (the texture worsens). Always write the freezing date on the label and respect the deadline to ensure quality. — Times from Embrapa Alimentos and the USDA Food Safety; after the deadline the food is still safe but loses quality (texture, flavor, vitamins); vacuum packaging extends it 3-5x; a freezer with temperature fluctuation shortens the deadline; the Anvisa standard requires a date label on every frozen food, for modern Brazilian quality, in effect.