To these can be added in modern times, to pasteurize (UHT) treatments heating with infrared, microwave and ohmic heating.
Chemical changes that occur during food processing are numerous, and they can be desirable, undesirable, of questionable consequence or a combination thereof.
Thermal treatment lead to desirable changes, such as protein coagulation, starch swelling, textural softening and formation of aroma components and these changes can influence sensory properties, functional properties and/or nutritive value.
Changes induced by processing in food proteins relate mainly to their denaturation, binding of flavor-active and lipid oxidation products to them and modifications brought about intentionally by derivation and enzymatic treatment.
Among lipid constituents of foods, both polar and non-polar components are affected by processing. While many of the changes that occur in food lipids are experienced during their production, many of these effects are system-dependent.
Carbohydrates also undergo changes during milling, cooking, drying, freezing and storage. Carbohydrates present in food are either in the polymeric, oligomeric or simple form. Many of the characteristics of carbohydrates in foods and their physio-chemical changes during processing are dictated by structural characteristics. Complex carbohydrate constituent of foods and the source material from which they are derived also affect many of their properties.
However undesirable changes also occur, such as losses of vitamins and minerals, formation of thermal reaction components of biopolymers, and in minimal processing terms, losses of fresh appearance, flavor and texture.
Yet gradually some ill effects of processing on food compositions and wholesomeness started to come to light, for example the Maillard interaction between carbonyl and amino compounds and their subsequent cyclization and polymerization, caramelization reactions that lead to the formation of heterocyclic compounds, polycyclic aromatic molecules, nitrosamine and such other toxic, carcinogenic and mutagenic molecules during processing.
Although these are known to be produced in trace quantities the consumer has become aware of the lurking danger.
Food processing can result in several changes and advantages, some of which are substantial:
*Lessened hazards from microbial pathogens
*Lessened spoilage (microbial, enzymatic)
*Inactivation of heat-labile, anti-nutritional substance
*Increase a variety of foods, some with enhanced sensory properties - bakeries, confectionary, meat analogs, fermented foods.
Food changes during Processing
