Food Science
Core concepts
Food science applies chemistry, microbiology, and engineering to food. Candidates should understand the macronutrient functions in food systems: proteins gel and coagulate, starches gelatinize and retrograde, fats emulsify and contribute mouthfeel, and water activity governs microbial growth. Know the danger zone (40°F–140°F / 4°C–60°C), the temperature ranges for psychrotrophs versus thermophiles, and the difference between spoilage organisms and pathogens. Preservation methods-thermal processing (blanching, pasteurization, commercial sterilization), freezing, dehydration, fermentation, irradiation, and modified atmosphere packaging-each act on a different mechanism. Also know Maillard browning versus caramelization, enzymatic browning in cut produce, and pH effects on gel formation (pectin gels need acid and sugar).
Traps
Questions confuse sterilization with pasteurization, or imply freezing kills microorganisms (it does not-it inhibits). Another common error is treating water activity and moisture content as identical. Watch for stems that describe browning and expect you to pick the wrong reaction: Maillard needs amino acids plus reducing sugars and heat; caramelization needs only sugar and heat.
Worked example
A processor wants to extend shelf life of cut apples. Rule of thumb: enzymatic browning comes from polyphenol oxidase acting on exposed tissue, so control options are heat (blanch), acid (lower pH), or exclusion of oxygen-not adding sugar, which drives water activity questions instead.
Rule of thumb
Name the mechanism (heat, water, pH, oxygen, temperature) before choosing the intervention.