Back to: Food and Nutrition SS 2
Additives to the preservative foods can be antimicrobial. These inhibit bacterial or fungal growth, including mould or antioxidants, such as oxygen absorbers, which inhibit the oxidation of food components.
Adding preservatives is the chemical method of food preservation. Conventional antimicrobial preservatives include calcium propionate, sodium nitrite, sodium nitrate, sulphites (sulphur dioxide potassium hydrogen sulfite, sodium bisulfite, etc.), and disodium EDTA. BHA and BHT are antioxidants.
Pickling is a food preservation method used in an edible antimicrobial liquid. Pickling can be broadly divided into two categories: chemical pickling and pickling by fermentation.
Canning includes cooking food, sealing it in sterile canisters or pots, and boiling the containers as a method of sterilisation to destroy or weaken any remaining bacteria. Foods have varying degrees of natural spoilage protection and may require the final step in a pressure cooker.
No preservatives are added to High-acid fruits like strawberries and only a short boiling period, while marginal fruits such as tomatoes require longer boiling and the addition of other acidic components. Feeding stuffs with low acidity, such as vegetables and meats, require canning pressure.
Food preserved through canning or bottling is at immediate risk of spoilage after opening the can or bottle.
It is defined as heat treatment of food material at 72°C for 15 seconds, 63°C for 30 minutes, or 90°C for 0.5 seconds, followed by quick cooling to 7°C. High-temperature-short-time (HTST) treatments are favoured over low-temperature-long-time (LTLT) treatments because they cause less damage to the nutrient composition and sensory properties of meals.
Microbes are completely eliminated during sterilisation. Fruits and acidic vegetables, such as tomatoes, can be sterilised at 100°C for 30 minutes; however, non-acidic veggies must be sterilised at 116°C for 30 minutes.
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