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

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