How foods are produced, processed, fermented, cured and manufactured, and what those processes change.
Dutch-process cocoa is treated with alkali to raise its pH. It is usually darker, less acidic, and smoother-tasting than natural cocoa, but alkalization can substantially reduce flavanols. The acidity difference can also matter in recipes that rely on baking soda.
Plain instant, old-fashioned, and steel-cut oats can be nutritionally very similar. Processing mainly changes particle size, texture, cooking time, and how quickly starch is digested.
Freezing itself does not destroy nutrients. Peas, corn, green beans, broccoli, spinach, and berries can retain vitamins and minerals at levels comparable to refrigerated fresh produce; meat and poultry change little nutritionally. Blanching and storage explain many differences.
Heating or pasteurizing honey can lower enzyme activity, raise HMF when treatment is intense, and delay crystallization by helping filtration and controlling yeasts. That does not make raw honey a radically different source of nutrition, and pasteurized honey is still not safe for children under one year because ordinary processing does not reliably destroy botulism spores.
Extra-virgin olive oil is essentially 100% fat. A standard olive-oil reference provides about 884 kcal/100 g, with roughly 73 g monounsaturated, 13.8 g saturated and 10.5 g polyunsaturated fat. A tablespoon weighing about 13.5 g supplies around 119 kcal. “Extra virgin” describes how the oil is produced and its chemical and sensory quality, not a lower-calorie version of olive oil.
Yolk color is driven mainly by carotenoids in the hen's diet: the pigment type, amount and combination all matter. Yellow corn and yellow-orange plant pigments such as marigold can deepen yolk color. A darker yolk does not by itself prove that an egg is fresher, more nutritious or produced under a particular housing system.
Aquafaba is the liquid left from cooking chickpeas or found in a can. It is not plain water: soluble proteins, carbohydrates and other compounds migrate out of the beans and give the liquid enough surface activity and viscosity to stabilize foams and emulsions.
Canned legumes are not nutritionally inferior simply because they are canned. Once both forms are cooked, protein, fiber and carbohydrate are broadly similar. Added sodium is often the biggest difference, and draining and rinsing can reduce it substantially.
Raw Atlantic cod is about 82 calories, 17.8 g protein and less than 1 g fat per 100 g. Dried salted cod concentrates protein and sodium as water is removed; desalting then changes the composition again.
Roasting does not empty a nut of nutrition. Protein, minerals, and the broad fatty-acid profile change relatively little, while heat-sensitive compounds such as some tocopherols, thiamin, carotenoids, and polyphenols can fall—especially with hotter or longer roasting.
Seitan is essentially cooked, hydrated wheat gluten. That lets it pack roughly 20–30 grams of protein into 100 grams with little fat, but there is no universal seitan number: water, starch, broth, and seasoning can move the label substantially.
Aging does not magically add protein or fat to cheese; it removes water. That is why aged cheeses can exceed 350–400 calories and 25 grams of protein per 100 grams while many fresh cheeses land around 170–250 calories and 12–18 grams protein.