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Enzylatic lipolysis in food product

Technical information Food refrigeration and freezing Enzymatic Reactions

Enzymatic Reactions

Storage at low temperatures may reduce the activity of enzymes in the tissues, but may not inactivate them. In raw foods, enzymes (enzymes catalyzing hydrolytic cleavage), such as lipase (ether carboxylic hydrolases), phospholipase (phosphatid cleaving enzymes), proteases (hydrolases, dissecting peptide bonds) and other can remain active during frozen storage. Hydrolytic enzymes can produce a deterioration in the quality of products, which are not represented thermal treatments before freezing; however, blanching vegetables or cooking of meat inactivates these enzymes.

Lipase and phospholipases, hydrolyse ether bonds triglycerides, phospholipids, respectively; the hydrolysis of fats can lead to undesirable taste and structural changes. Some lipase may remain active in the frozen food systems maintained even when -29C. Lipase activity is manifested in the accumulation of free fatty acids. Freezing can focus lipolysis breaking lysosomal membranes that releases of hydrolytic enzymes, especially at low rates and under fluctuating temperatures.

During storage, issuance of short-chain fatty acids can lead to hydrolytic rancidity, producing off flavors and can interact with proteins, forming complexes that affect the texture.

Enzymes that catalyse the hydrolysis of proteins, peptides and amino acids; in the meat is endogenous enzymes that are considered useful, tenderising muscles in rigor mortis (Sista et al., 1997). Air conditioning meat freezing preserves the quality of the textures, but also has a lower tendency to drip on the thawing.

The "Browning " of plant tissue caused by enzymatic oxidation of phenol compounds in the presence of oxygen. The destruction of cells by ice crystals can start enzymatic Browning on facilitating contact between o-diphenol oxidase enzyme and its substrate. In oxido-reductases are of paramount importance because their effect leads to an unpleasant smell and bleaching of pigment in vegetables and Browning in some fruits.

In fruit and vegetable tissues, endogenous pectin methyl esterases catalyzes the removal methoxyl groups of pectins. In the case of frozen strawberries, these enzymes produce gelation during storage. Hydrolytic enzymes, such as chlorophylases and anthocyanases present in plants, could be a catalyst for the destruction of pigments in the frozen tissues, affect the color, if they are not inactivated blanching...

 
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