Common Food Additives

Why This Matters

Understanding food additives is fundamental to mastering food science because these compounds demonstrate core principles you'll be tested on repeatedly: chemical stability, microbial control, colloidal chemistry, and sensory science. When you see an ingredient list on a food label, you're looking at a carefully engineered system where each additive serves a specific functional purpose—and exam questions will expect you to explain why that additive was chosen and how it works at the molecular level.

Don't just memorize additive names and their uses. Know the mechanism behind each category: Why does an antioxidant prevent rancidity? What makes an emulsifier work at the oil-water interface? How do pH control agents create an environment hostile to pathogens? When you understand the underlying chemistry, you can predict additive behavior in novel situations—exactly what FRQ prompts will ask you to do.

---

Additives That Control Microbial Growth and Spoilage

These additives target the biological and chemical processes that cause food to deteriorate. By manipulating water activity, pH, or directly inhibiting microbial enzymes, they extend shelf life without altering the fundamental character of the food.

Preservatives

• Sodium benzoate and potassium sorbate inhibit microbial metabolism—they're most effective in acidic environments (pH < 4.5) where they exist in their undissociated, membrane-permeable form
• Target organisms include bacteria, molds, and yeasts—these preservatives disrupt cellular enzyme function and nutrient transport systems
• Regulatory limits (GRAS status) ensure safe consumption levels; commonly found in pickles, soft drinks, and condiments

Antioxidants

• Prevent lipid oxidation by scavenging free radicals—this stops the chain reaction that produces off-flavors and rancidity in fats and oils
• BHT (synthetic) vs. ascorbic acid (natural) represent two approaches; both donate hydrogen atoms to stabilize reactive oxygen species
• Protect color, flavor, and nutritional quality—particularly important for preserving fat-soluble vitamins like A and E

pH Control Agents

• Citric acid and sodium bicarbonate regulate acidity/alkalinity—affecting both microbial safety and chemical reaction rates during processing
• Low pH environments inhibit pathogen growth—most foodborne bacteria cannot survive below pH 4.6, making acidification a preservation strategy
• Influence texture and leavening in baked goods; sodium bicarbonate releases $CO_2$ when combined with acids

---

Additives That Modify Texture and Structure

These compounds work through colloidal chemistry principles—they stabilize emulsions, increase viscosity, or prevent unwanted physical changes during storage and processing.

Emulsifiers

• Lecithin and mono/diglycerides are amphiphilic molecules—their hydrophilic heads and hydrophobic tails position at oil-water interfaces to reduce surface tension
• Stabilize immiscible phases in products like mayonnaise, margarine, and ice cream by preventing coalescence of dispersed droplets
• HLB (hydrophilic-lipophilic balance) values determine whether an emulsifier favors oil-in-water or water-in-oil emulsions

Stabilizers and Thickeners

• Xanthan gum and carrageenan increase viscosity—they form hydrogen bonds with water molecules, creating gel networks that trap liquid
• Prevent phase separation in sauces, dairy products, and soups by slowing particle movement through the continuous phase
• Pseudoplastic behavior (shear-thinning) allows products to pour easily but maintain body at rest—critical for consumer acceptance

Anti-Caking Agents

• Silicon dioxide and calcium silicate absorb moisture—they coat particle surfaces to prevent water bridges that cause clumping
• Maintain free-flowing properties in powdered products like salt, spices, and coffee creamer
• Concentration typically 1-2% by weight; must be food-grade with controlled particle size for effectiveness

---

Additives That Enhance Sensory Properties

These additives target consumer perception—taste, appearance, and overall palatability. They don't preserve food but make it more appealing and satisfying.

Artificial Sweeteners

• Aspartame and sucralose provide sweetness without caloric load—they bind to sweet taste receptors with much higher affinity than sucrose (200-600× sweeter)
• Aspartame contains phenylalanine—requires warning labels for individuals with phenylketonuria (PKU)
• Heat stability varies significantly; sucralose withstands cooking temperatures while aspartame degrades, limiting their applications

Food Colors

• FD&C certified colors and caramel color enhance visual appeal—color strongly influences flavor perception and purchase decisions
• Natural vs. synthetic sources have different stability profiles; synthetic dyes typically offer more consistent hue and better light stability
• Certification and labeling requirements vary by country; some colors approved in the US are restricted in the EU

Flavor Enhancers

• Monosodium glutamate (MSG) activates umami receptors—it amplifies savory taste without contributing its own distinct flavor profile
• Synergistic effects with nucleotides like inosinate and guanylate can reduce required MSG concentration by 10-15×
• Yeast extract provides natural glutamates—allows "clean label" formulation while achieving similar flavor enhancement

---

Additives That Improve Nutritional Value

These compounds address public health goals by fortifying foods with nutrients that may be lacking in typical diets or lost during processing.

Nutritional Additives

• Vitamins and minerals are added to restore or enhance nutritional profiles—mandatory fortification programs target widespread deficiencies (iodine in salt, vitamin D in milk)
• Bioavailability considerations affect which chemical form is used; ferrous sulfate absorbs differently than ferric pyrophosphate in iron fortification
• Stability during processing and storage must be evaluated—some vitamins degrade with heat, light, or oxygen exposure, requiring protective encapsulation

---

Quick Reference Table

---

Self-Check Questions

1. Which two additive categories both extend shelf life but through different mechanisms—one by directly inhibiting microorganisms and one by creating unfavorable environmental conditions?

2. Explain why lecithin is effective in mayonnaise production. What molecular property allows it to stabilize the oil-water emulsion?

3. Compare BHT and ascorbic acid as antioxidants. What do they share functionally, and how do they differ in terms of origin and consumer perception?

4. An FRQ asks you to reformulate a high-sodium soup while maintaining flavor intensity. Which additive category would you investigate, and why does it work without adding sodium chloride?

5. A powdered drink mix is clumping during storage. Identify the additive category that addresses this problem and explain the mechanism by which it maintains free-flowing properties.