Enzyme reactions

Enzyme Reactions

Enzymes are powerful biological catalysts that enable specific reactions in food, biochemistry, and industrial processes. Each enzyme has a preferred substrate and functions best under optimal pH, temperature, and substrate concentration. Enzyme specificity can be classified into four types: absolute (one substrate), group (functional similarity), linkage (specific bond type), and stereochemical (molecular shape or isomerism).

Commercial enzymes like amylase or protease often contain traces of other enzymes. The purer the enzyme, the higher its cost—particularly for analytical applications. In food processing, substrate-based categories such as starch, protein, and fat are more relevant than chemical classifications.

Starch breakdown is typically performed by α- and β-amylase. α-Amylase (an endo-enzyme) breaks bonds within the chain, while β-amylase (an exo-enzyme) works from the ends. Cellulose, made of β-linkages, requires cellulases, which do not act on starch. Other complex carbohydrates like pentosans, β-glucans, and pectins are broken down by enzymes such as pentosanase, β-glucanase, and pectinase important for dough texture or juice viscosity.

Proteases break down proteins into amino acids. They can be endo or exo-acting, like trypsin or papain, and their activity depends on pH and specific amino acid targets. Types include alkaline, acid, thiol, and metallo-proteases.

Fat splitting enzymes include lipase, esterase, and lipoxygenase. Lipases release fatty acids from triglycerides, esterases act on water soluble esters, and lipoxygenases oxidize plant pigments such as carotenoids.

Finally, some enzymes influence natural processes like browning in fruit. Polyphenol oxidase, for example, causes enzymatic browning in cut apples. With targeted enzyme use, such effects can be enhanced, controlled, or prevented.

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