FOOD PRESERVATIVES

Favorite Dish

Question: What is your favorite dish?

Task: List the ingredients of your favorite dish.

Preservatives: Identify which ingredients are preservatives.

Food Preservation

Definition:

The method of treating and coping with meals to stop or greatly slow down spoilage caused by microorganisms. Food preservation techniques can include refrigeration, canning, freezing, drying, and the use of food additives to maintain freshness and quality.

Food Preservatives

Definition:

Substances added to food to inhibit, retard, or arrest the process of fermentation, acidification, or other decomposition of food. Preservatives can be classified into natural and artificial categories according to their sources and mechanisms.

Natural vs. Artificial Preservatives

Natural Preservatives

  • Salt

    • Effect: Increases osmotic pressure, preventing the development of microorganisms. By drawing out moisture, it creates an environment that is less favorable for bacterial growth.

    • Mechanism: Inhibits cell growth or destroys organisms through dehydration.

  • Sugar

    • Effect: Helps remove water and inhibits microorganisms. Sugar does this through osmosis, which pulls water out of both the food and bacteria.

    • Mechanism: Uses osmosis to soak up water, reducing the water activity needed for bacterial proliferation.

  • Garlic

    • Properties: Known for its antibacterial properties. Can prolong the shelf life of various foods by fighting off bacteria.

    • Usage: Commonly used in making soups, dressings, pickles, and sauces for both flavor and preservation.

  • Onion

    • Properties: Contains antioxidants and antimicrobial properties that help prevent spoilage.

    • Usage: Widely used in cooking as a flavoring agent and for its preservative qualities.

  • Vinegar

    • Composition: Made through the fermentation of sugar and water, containing acetic acid, which is effective against many types of microbes.

    • Effect: Kills microbes and inhibits spoilage, making it a popular ingredient in pickling.

Artificial Food Preservatives

Types of Artificial Preservatives

  • Antimicrobial agents

  • Antioxidants

  • Chelating agents

Artificial Antimicrobial Agents

  • Nitrates

    • Source: Salts from sodium nitrate.

    • Usage: Used in curing meats to prevent the growth of Clostridium botulinum, enhancing food safety and shelf life.

  • Benzoates

    • Compound: Based on benzoic acid.

    • Usage: Sodium benzoate is extensively used in processed foods and beverages to extend their shelf life.

  • Propionates

    • Source: Compounds of propionic acid.

    • Usage: Commonly used in baked goods to inhibit mold growth, for example, calcium propionate.

  • Sorbates

    • Compound: Based on sorbic acid.

    • Usage: Potassium sorbate is used broadly in various products to preserve freshness.

Antioxidant Preservatives

Definition:

Preservatives that prevent reactions of food constituents with oxygen, thereby preventing spoilage and rancidity.

Examples of Artificial Antioxidants

  • BHT (Butylated Hydroxytoluene): Frequently used in snack foods, cereals, and animal foods to prevent spoilage.

  • BHA (Butylated Hydroxyanisole): A synthetic antioxidant primarily used for oils and fats to maintain stability and extend shelf life.

Chelating Agents

Definition:

Chemicals that bind metal ions to prevent their detrimental effects on food quality and flavor, often used to stabilize food textures.

Common Chelating Agent

  • EDTA (Ethylene Diamine Tetraacetic Acid): Prevents color deterioration in fats and sauces, enhancing visual appeal.

Characteristics of Food Preservation

  • Non-harmful to humans.

  • Inhibits microorganism growth, even in traces.

  • Maintains the quality and safety of food products.

Necessity of Food Preservation

  • Ensures food availability during scarcity.

  • Makes foods palatable and attractive, encouraging consumption.

  • Prevents spoilage from microorganisms effectively prolonging shelf-life.

  • Avoids undesirable changes in food, such as texture or taste degradation.

Osmosis

Definition:

The movement of water molecules from an area of high concentration to an area of low concentration across a semipermeable membrane, a key principle in both biology and food preservation.

Additional Osmosis Definition

Definition:

The movement of solvent from lower to higher solute concentration through a semipermeable membrane, critical for understanding how preservatives work at a molecular level.

Food Additives

Definition:

Substances added to food to preserve flavor or enhance other sensory qualities, critical for both consumer appeal and shelf stability.

Commonly Used Food Additives

Question: Can you name some food additives commonly used at home?

Food Colors

Purpose:

Added to replace lost colors or enhance appearance, contributing to consumer attraction and appeal.

Examples of Natural Dyes

  • Turmeric: A natural dye derived from turmeric root, imparting a yellow color (curcumin). Popular in curry powders.

  • Anthocyanin: A pigment that provides deep purple and blue colors in fruits such as grapes and blueberries, often used in beverages.

  • Carotenoids: Natural pigments providing red, yellow, or orange colors in foods. Commonly found in carrots, sweet potatoes, and other vegetables.

  • Chlorophyll:Chlorophyll is another natural pigment, found in all green plant

Reasons for Artificial Dyes

  • Cost-effective compared to natural colors.

  • Longer shelf life than natural alternatives, ensuring stability in products.

Antioxidants

Definition:

Preservatives that prevent or slow oxidation in food, protecting nutritional quality.

Emulsifiers

Definition:

Substances that combine oil and water-based ingredients that do not mix easily, crucial for many food products.

Types of Emulsions

  • Oil-in-Water

  • Water-in-Oil

Forming an Emulsion

Requirement:

An emulsifier and a force (like whisking) to mix oil and water, essential in products like mayonnaise or salad dressings.

What are Emulsifiers?

Function:

Added to stabilize emulsions and prevent separation in food products. They enhance texture and consistency.

How Emulsifiers Work

Mechanism:

Emulsifiers contain a hydrophilic end that is attracted to water and a hydrophobic end that is attracted to fat/oil, allowing them to mix immiscible substances.

Common Emulsifiers

  • Examples: Egg yolk, mustard.

  • Effect: These emulsifiers thicken the mixture and are useful property for many foods.

Stabilizing Agents

Definition:

Agents added to maintain or enhance food texture and characteristics, ensuring quality over time.

Examples of Stabilizing Agents

  • Agar: Derived from seaweed, used in various food products for gelling.

  • Pectin: A natural thickener used in jams and confectionery to achieve the desired consistency.

  • Xanthan Gum: A polysaccharide that improves texture and consistency in many food products.

  • Guar Gum: A versatile agent that works as a thickener, emulsifier, and stabilizer in a variety of food products.

Artificial Sweeteners

Definition:

Chemical compounds synthesized to provide sweetness without calorie value, offering alternatives to sugar.

Examples of Artificial Sweeteners

  • Saccharin: The first invented sweetener, providing intense sweetness with no calories.

  • Alitame: A high potency, stable sweetener that is used in various foods and beverages.

  • Aspartame: Highly sweet but unstable when heated, commonly found in sugar-free products.

  • Sucralose: A recent substitute for sugar that does not break down in the bloodstream, maintaining its sweetness in various applications.