Comprehensive Guide to Food Preservation Principles and Additives
Common Terms Related to Food Preservation
Additives: Materials added to food to assist in manufacturing and preservation, as well as to improve nutritive value, palatability, and eye appeal.
Aging: Changes in tenderness that occur in meats following slaughter.
Antioxidants: Substances that retard the oxidative rancidity of fats.
Emulsifying Agents: Substances that aid in the uniform dispersion of oil in water.
Fermentation: The transformation of metabolism compounds without the use of oxygen.
Freeze Drying: A method of drying where the material is frozen and a high vacuum is applied. The cooking effect of evaporation keeps the material frozen while moisture distills off as a vapor.
Maillard Reaction: Also known as the browning reaction or non-enzymatic browning; it is a reaction between amino acids and sugar that produces a brown color.
Pasteurization: A mild heat treatment designed to destroy many vegetative forms of bacteria.
Stabilizers: Substances that maintain the equilibrium of emulsions containing fat and water.
Diluted Brine: Ingredients dissolved in a small amount of brine before being mixed with the remaining liquid.
Curing Brine: A prepared stock of saturated salt that can be dissolved by stirring into a specific amount of water.
Fish Sauce: Locally referred to as "patis," this is drawn off from the liquefaction of a salt mixture.
Marmalades: Preserves made from citrus fruits; bitter oranges are noted for making the best marmalade.
Introduction to Food Preservation: Principles, Importance, and Value
Definition and Function: Food preservation prevents the growth of microorganisms (such as yeasts) and other microbes. While some methods introduce benign bacteria or fungi, most aim to slow the oxidation of fats that cause rancidity.
Visual Deterioration: Preservation includes processes that inhibit visual decay, such as the enzymatic browning reaction seen in apples after they are cut during preparation.
Multi-Method Processes: Many preservation techniques involve more than one method. For example, turning fruit into jam involves:
Boiling: Reduces moisture content and kills bacteria.
Sugaring: Prevents the re-growth of microbes.
Sealing: Uses an airtight jar to prevent recontamination.
Sustainability: Traditional preservation methods often have a lower energy input and carbon footprint compared to modern methods.
Value and Importance of Food Preservation
Adds Variety: Preserved foods allow for items to be consumed out of season, such as using canned or dehydrated peas during hot summer months when fresh peas are unavailable.
Increases Shelf Life: Fruits and vegetables like pineapples and cherries can be maintained for long durations using various preservation methods.
Increases Food Supply: Preservation ensures a larger amount of food is available for consumption over time.
Decreases Wastage: Processing and preserving excess foods that would otherwise spoil adds to the existing food supply.
Decreases Dietary Inadequacies: Preserved foods help overcome regional food shortages. For instance, Middle-East countries with arid soil that cannot grow vegetables overcome this shortcoming by importing fresh and preserved fruits and vegetables.
Principles and Categories of Food Preservation
Commercial Goal: The purpose of commercial food preservation is to maintain wholesomeness, nutritive value, sensory quality, and safety by controlling microbial growth and undesirable chemical, physical, and physiological changes.
Bactericidal Methods: These methods destroy or kill spoilage agents. An example is thermal processing, such as canning.
Bacteriostatic Methods: These methods do not eliminate bacteria but prevent their growth by inactivating them. Examples include drying and freezing; microorganisms may remain present but cannot harm the food while inactivated.
Basic Methods of Preventative Action
Microbial Decomposition Prevention:
Keeping microorganisms out through sanitary handling.
Removal of microorganisms.
Hindering microbial growth and activity using low temperatures, drying, or chemicals.
Killing microorganisms using heat.
Prevention of Self-Decomposition:
Destruction or inactivation of food enzymes through blanching.
Prevention or delay of purely chemical reactions, such as using antioxidants to prevent oxidation.
External Factors: Adequate packaging is required to prevent damage from insects, animals, or mechanical causes.
Understanding Food Spoilage
Definition: Food spoilage is the process in which food quality deteriorates to the point it is inconsumable.
Causes: Spoilage results from microbial attack, enzymatic digestion, chemical degradation, and physical injury.
Types: Microbial food spoilage is a specific type caused by the activity of microorganisms. Self-decomposition can be illustrated by the internal breakdown of fruits like oranges.
Systematic Overview of Food Additives and Preservatives
Food Additives: Substances added to food to preserve flavor or enhance taste, appearance, and other qualities.
Historical Examples: Pickling with vinegar, salting (e.g., bacon), preserving sweets, and using sulfur dioxide in wines.
Food Preservatives: Specific additives capable of inhibiting, retarding, or arresting fermentation, acidification, or other decomposition caused by microbes.
Primary Categories of Preservatives
Antimicrobials: Stop the growth of molds, bacteria, and yeast.
Antioxidants: Slow the oxidation of fats to prevent rancidity.
Rot Inhibitors: Specifically target the prevention of rot in produce.
Specific Chemical and Natural Preservatives
Dimethyl Dicarbonate: An additive that inhibits certain enzymes to prevent microbial growth. It is primarily used in beverages, often alongside sulfur dioxide in wine. It is also found in sodas, iced teas, and sports drinks.
Sodium Benzoate and Benzoic Acid: These kill bacteria and microbes, particularly in acidic conditions. They are used in salad dressings, pickles, milk products, and meats.
Methylcyclopropene: A gas sprayed onto fruit crates (e.g., apples and grapes) to inhibit ethylene gas, the hormone responsible for ripening. It can preserve apples for up to year and bananas for up to month.
Calcium Sulfate: Acts as an acidity regulator and flour stabilizer. Since some foods require specific acidic conditions to stay fresh, this helps achieve the desired environment.
Sodium Nitrite: Responsible for the pink color in hot dogs, bacon, and lunch meats like bologna. It works by killing bacteria and spoilage-causing microbes.
BHT (Butylated Hydroxytoluene): An antioxidant that prevents the oxidation of fats. It is commonly found in cereals, baked goods, and snacks.
Sorbic Acid: An antimicrobial agent available as calcium sorbate or potassium sorbate. It occurs naturally in plants but is used synthetically in frozen pizza, fountain sodas, and oatmeal cookies.
Natural Preservatives: Lemons, garlic, and sea salt possess antimicrobial activities. They are used in salads, oats, soup, kale, and broccoli.
Carrageenan: Used in meat and dairy products because of its ability to bind strongly to food proteins and its preservative properties.