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Cutting The Preservation Of Fruits And Vegetables

Zhengzhou Miracle Machinery Co.,Ltd | Updated: Apr 21, 2017

cut fruit and vegetable anti-brown

In terms of fruits and vegetables, the main quality problem is browning, browning caused by poor appearance. Browning is not only fruits and vegetables, but also the prevalence of color in the whole food phenomenon. There are two types of browning reactions: one is in the oxidase catalyzed polyphenolic oxidation and ascorbic acid oxidation; the other is the need for enzyme browning.

Enzyme browning, must also have three conditions: the polyphenols, polyphenol oxidase and oxygen. These three conditions are indispensable. To prevent the occurrence of enzymatic browning, these conditions must be controlled to deal with.

To prevent the enzymatic browning of fruits and vegetables is more effective to inhibit the activity of polyphenols, followed by the prevention of fruit and vegetable raw materials and oxygen contact. Usually can be used to the appropriate heating method of phenol enzymes and all other enzymes lose their activities, so the production of fruits and vegetables often use raw materials blanching method enzyme. Chemical agents can also be used to inhibit the activity of the enzyme by adding a strong inhibitor of polyphenol oxidase. In addition, the regulation of pH can also achieve the effect of inhibition. The optimum pH range for phenolase oxidation is between 6 and 7, thus reducing the pH of the medium and inhibiting the catalytic activity of the enzyme. Finally, the oxygen can make the fruits and vegetables isolated from oxygen, browning can be suppressed.

Rather than enzymatic browning is much more complex, such as the Maillard reaction, ascorbic acid oxidation, pheasant chlorophyll browning and so on. Maillard reaction (ie, carbonylation reaction). It is an amine, amino acid, and a reaction between protein and sugar, aldehydes, ketones. Carbonyl compounds alone, there may be browning, and amino acids, proteins coexist, the more promoting effect. The reaction rate of browning is related to the structure of sugar and amino compounds involved in the reaction, the presence of water (substrate concentration), temperature and pH. Ascorbic acid oxidized browning. Because the plant contains ascorbate oxidase, when the fruit and vegetable tissue damage, and air contact, can make the rapid destruction of ascorbic acid. And ascorbic acid itself can be oxidized and cause browning. Chlorophyll de - browning. Green vegetables in the heat treatment, and chlorophyll coexistence of protein heat coagulation, so that chlorophyll free in the plant, chlorophyll into pheophytin, so that lost green and was brown.

The main way to avoid the non-enzymatic browning of fruits and vegetables is to use the product to protect against browning and low temperature storage. Maillard reaction is the main reaction of non-enzymatic browning in food processing, almost all the food can have the possibility of such a reaction. Traditionally, sulfites have been used to suppress browning, but the use of sulfites has some adverse effects on the human body. Citric acid combined with ascorbic acid can be a sulfite substitute.

cut fruit and vegetable color protection

In addition to enzymatic browning and non-enzymatic browning, there are mainly tannins and pigments can cause fruit and vegetable color change.

The discoloration caused by tannins is one of the most common discoloration phenomena in fruit and vegetable processing. ① browning caused by enzymes and tannins. ② tannin metal ion discoloration. Coke gallate acid tannin case trivalent iron ion blue-black, catechol-type tannin case trivalent iron ion greenish black. Tannins and tin are hot for a long time. Therefore, in the processing of fruits and vegetables to use less tin tin processing equipment. ③ tannin case change to black. This is the use of alkali peeled fruit and vegetable processing should pay special attention. ④ tannin in acidic conditions will form a pink pink "red powder". In the peanut endothelium contains a small amount of this substance.

Fruits and vegetables contained in the pigment is divided into water-soluble and non-water-soluble. General water-soluble pigment is a broad class of flavonoids, including anthocyanins and anthocyanins, non-water-soluble pigments for carotenoids and chlorophyll. These pigments are of an unstable nature and are easily discolored or discolored. Anthocyanin in the acidic to neutral range changes, the red will gradually tend to purple. The melanin will become gray and purple, and tin will become purple. Lanthocins in the alkaline conditions, the formation of chalcone substances, showing a yellow to brown. Lutein in acidic conditions such as iron ions turn green or blue. Lutein and aluminum chelate the role of the color caused by dark. In the production of asparagus and the use of onion products such as the use of aluminum equipment, will see this phenomenon of color darkening. Carotenoids cause discoloration. Β-carotene in the acidic instability, weak alkaline when more stable. At low concentrations of orange to yellow, high concentrations of orange-red. Heavy metal ions, especially iron ions can make it fade.