Food Chemistry Quiz – Test Your Knowledge of Food Science!

Lactic acid fermentation is a biochemical process in which glucose is converted into lactic acid by bacteria such as Lactobacillus. This process occurs in anaerobic conditions and is responsible for the sour taste in fermented dairy products like yogurt and cheese. The accumulation of lactic acid lowers pH, inhibiting the growth of harmful bacteria and preserving the food. This fermentation also enhances digestibility, improves texture, and develops complex flavors. Lactic acid fermentation is widely used in the production of kimchi, sauerkraut, and pickles. Its efficiency depends on temperature, bacterial strains, and substrate composition, influencing the final product’s taste and texture.

Antioxidants slow oxidation by neutralizing free radicals, which can damage food molecules and lead to spoilage. Oxidation is a chemical reaction that causes rancidity in fats, discoloration in fruits, and deterioration in food quality. Common antioxidants include vitamin E, vitamin C, and butylated hydroxytoluene (BHT). These compounds donate electrons to unstable molecules, preventing oxidative damage. Antioxidants also help maintain flavor, texture, and nutritional value in processed foods. Food manufacturers use antioxidants to extend shelf life and improve stability in oils, dairy, and meat products. Their effectiveness depends on concentration, temperature, and the presence of other reactive food components.

Capsaicin is the chemical compound responsible for the spiciness of chili peppers. It binds to pain receptors in the mouth, triggering a burning sensation by activating the TRPV1 receptor, which detects heat and irritation. The intensity of spiciness is measured using the Scoville Heat Unit (SHU) scale, with pure capsaicin reaching 16 million SHU. Capsaicin is fat-soluble, which is why dairy products help neutralize its effects better than water. Beyond its culinary use, capsaicin has medicinal properties, including pain relief and metabolism boosting. Its concentration varies among pepper species, influencing the perceived heat level in different cuisines.

Bacterial growth is the primary cause of food spoilage, leading to changes in texture, flavor, and safety. Bacteria thrive in warm, moist environments with a food source, multiplying rapidly. Spoilage bacteria, such as Pseudomonas and Lactobacillus, produce enzymes that break down proteins, fats, and carbohydrates, causing food to become slimy, sour, or discolored. Temperature control, such as refrigeration at 4°C (39°F) or freezing at -18°C (0°F), slows bacterial growth. Preservatives, proper packaging, and hygiene practices also help reduce spoilage. Understanding bacterial activity in food helps in extending shelf life and ensuring food safety through effective preservation techniques.

The Maillard reaction is a chemical reaction between amino acids and reducing sugars that occurs when food is heated above 140°C (284°F). This reaction produces hundreds of different flavor compounds and contributes to the characteristic brown color of baked bread, grilled meat, and roasted coffee. The reaction is influenced by temperature, pH, and moisture content. Higher temperatures accelerate the process, while excessive moisture slows it down. The Maillard reaction differs from caramelization, which involves the breakdown of sugars alone. Understanding this reaction helps in controlling flavor and texture in cooking, food processing, and the development of new food products.

Emulsifiers help stabilize mixtures of water and oil by reducing surface tension, preventing separation. They contain both hydrophilic (water-attracting) and hydrophobic (oil-attracting) ends, allowing them to form stable colloidal dispersions. Common emulsifiers include lecithin in egg yolks, which helps in mayonnaise and salad dressings, and mono- and diglycerides used in processed foods. Without emulsifiers, oil and water-based ingredients would separate, affecting the texture and consistency of foods. Emulsifiers are widely used in dairy, baked goods, and confectionery. Their effectiveness depends on concentration, temperature, and the presence of other food components that influence stability and texture.

Sodium benzoate is a widely used preservative that prevents microbial growth in acidic foods such as sodas, pickles, and fruit juices. It inhibits the metabolism of bacteria and molds by disrupting enzyme activity, reducing their ability to reproduce. The effectiveness of sodium benzoate is pH-dependent, working best in environments below pH 4.5. It extends shelf life by preventing spoilage and maintaining food safety. However, excessive consumption of preservatives has raised health concerns, including potential allergic reactions in sensitive individuals. Regulatory agencies set maximum allowable limits to ensure safety while preserving food quality and preventing microbial contamination.

Vitamin C is the most heat-sensitive vitamin because of its unstable chemical structure, which breaks down when exposed to temperatures above 70°C (158°F). Cooking methods such as boiling, frying, and roasting can degrade vitamin C content significantly. Water-soluble vitamins, including vitamin C, are also lost in cooking water during boiling. To preserve vitamin C, steaming or microwaving is recommended. Since vitamin C is essential for collagen synthesis, immune function, and antioxidant protection, its loss from cooking can impact nutritional intake. Eating raw fruits and vegetables is an effective way to maintain optimal vitamin C levels in the diet.

Food irradiation kills bacteria, molds, and parasites by exposing food to controlled doses of ionizing radiation, such as gamma rays or X-rays. This process breaks down microbial DNA, preventing reproduction and reducing foodborne illness risks. Irradiation extends shelf life without significantly altering texture, flavor, or nutritional content. It is commonly used for spices, dried fruits, and meat products to prevent contamination. Regulatory agencies ensure irradiation safety by setting dosage limits. Although effective, some consumers remain skeptical about irradiated foods. Understanding this process helps in appreciating its role in improving food safety and reducing waste in the supply chain.

Fats provide the most energy per gram, with approximately 9 kcal/gram, while carbohydrates and proteins provide only 4 kcal/gram. This is due to the high number of carbon-hydrogen bonds in fats, which release more energy upon oxidation. The human body primarily uses carbohydrates for quick energy, but fats serve as long-term energy storage. Since fats are more energy-dense, they are essential for endurance activities and metabolic functions. However, excessive fat consumption can lead to health issues such as obesity and cardiovascular disease. Understanding macronutrient energy values is crucial for designing balanced diets and managing caloric intake effectively.