Starch retrogradation and stale breadStarch retrogradation is the recrystallisation of gelatinised starch molecules during cooling and storage; it's the primary cause of bread becoming stale. After baking, amylose and amylopectin chains realign into ordered structures, expelling bound water and causing crumb firming and loss of perceived freshness even when microbial spoilage is absent. The rate and extent depend on starch composition, moisture level, storage temperature and

pH and microbial growth Acidity is a primary environmental control point for microbial activity in food systems. pH influences enzyme function, membrane integrity and nutrient availability, so lowering pH inhibits many spoilage organisms and pathogens while enabling desirable fermentative microflora in controlled processes. The mechanism is biochemical: hydrogen ion concentration alters protein folding and transport across cell membranes, slowing metabolic reactions and reduc

Osmosis in marinades Osmosis governs the movement of water and small solutes between marinade and muscle tissue, affecting flavour penetration and moisture balance. Salt and acidic components create osmotic gradients that encourage diffusion of soluble flavour compounds into tissue while drawing water either out or in depending on relative concentrations. Enzymatic marinades add proteases that locally degrade proteins to increase tenderness, but enzymes act primarily near the

Emulsions: mayonnaise and hollandaise Mayonnaise and hollandaise are classic oil-in-water emulsions where dispersed oil droplets are stabilised by emulsifiers—egg yolk lecithin in mayonnaise, and lecithin plus partially denatured egg proteins and acid in hollandaise. Stabilisation occurs when amphiphilic molecules orient at the oil‒water interface, reducing interfacial tension and allowing fine droplets to be suspended within a continuous phase. Temperature, shear rate, dropl

Starch gelatinisation Starch gelatinisation is the fundamental physical change that thickens sauces, binds batters and gives cooked grains their mouthfeel. When starch granules are heated in water, they absorb liquid, swell and—once a critical temperature range is reached—lose crystalline order. Amylose leaches out and amylopectin swells, increasing viscosity and forming a semirigid gel upon cooling. Key variables are starch type, concentration, heating profile and shear. Pot

Protein denaturation in eggs Egg protein denaturation is a predictable structural transition chefs exploit for coagulation, emulsification and texture setting. Native egg proteins—ovalbumin, ovotransferrin and others—have folded tertiary structures; heating or mechanical shear unfolds these proteins, exposing hydrophobic regions and reactive amino acids so they form new intermolecular bonds and a network that traps water.Denaturation is influenced by temperature ramp, salt, p

Most people see a deep brown crust and call it “caramelised.” Technically, that is often wrong. **A Maillard crust is not the same as caramelisation.** The Maillard reaction occurs when **amino acids and reducing sugars** react under heat. It creates hundreds of new flavour and aroma compounds, producing notes that can be roasted, nutty, savoury, meaty, toasted, or intensely complex. This is what helps give a properly seared steak, roasted coffee, toasted bread, fried chicken