Non-enzymatic browning refers to a type of browning that does not require catalysis by enzymes. Such as Maillard reaction, ascorbic acid oxidation, pheophytin browning and so on. Non-enzymatic browning is the main browning reaction that occurs in the manufacture and storage of fruit and vegetable products.

(1) Changes in non-enzymatic browning consequences of vegetable products

The composition and content of free amino acids in fruits and vegetables vary with the type of fruits and vegetables. These amino acids react with carbonyl compounds such as sugars, ascorbic acid and oxidation products in fruit and vegetable products to cause browning. Among the amino acids, the browning activity of tryptophan, hydroxyproline, histidine, lysine, and aspartic acid is strong. With the progress of the browning reaction, the amino nitrogen is reduced. The change in the amino nitrogen content varies with the temperature. Take 6 months of storage as an example: 5 ° C is reduced by 10% or less; 20 ° C is not more than 15%; 40 ° C is 16% to 28%, and concentrated juice is 30% to 60%. The reduction rate of amino nitrogen varies depending on the type of fruits and vegetables, and the reduction of mandarin and pineapple is particularly remarkable. The amino acids with obvious decomposition are asparagine, glutamine, glutamic acid and the like. Promote non-enzymatic browning, as well as organic acids and metal ions. Tartaric acid is more active than citric acid browning; tin, iron and aluminum ions can promote browning; while fructose is most reactive in sugar. In addition, oxidized ascorbic acid can also promote browning at 3 to 6 mg of 100 ml. Therefore, it is necessary to prevent the formation of the above non-enzymatic browning conditions as much as possible in production and storage.

Non-enzymatic browning causes the following harmful changes to the product:

1, the nutritional value is reduced

After browning of fruit and vegetable products, vitamin C is destroyed, which will greatly reduce its nutritional value and physiological effects. Through browning, some essential amino acids and sugars in the beverage are destroyed; the products of amino acid, protein and sugar are not hydrolyzed by the enzyme, so the utilization rate of nitrogen and carbon by the human body is reduced. Therefore, the result of browning greatly reduces the nutritional value of fruit and vegetable beverages.

2. Increase in carbon dioxide and acid substances

The browning produced by the reaction of α-amino acids with sugar or ascorbic acid produces carbon dioxide. The rate of carbon dioxide evolution is proportional to the amount of unsaturated dicarbonyl compound. When the reducing sugar reacts with the amino acid, various reducing aldehydes are formed, which are easily oxidized to an acidic substance, which gradually causes a decrease in the pH of the product.

3, resulting in the reduction of product value or even loss of goods

Fruit and vegetable color is one of the main indicators for reviewing the quality of fruit and vegetable products. Non-enzymatic browning not only darkens the color of the product, but also produces fluorescent intermediates in the browning reaction. In this way, the sense of the product causes irreparable damage.

(2) Control of non-enzymatic browning

Completely eliminate browning of juices and jams and tea drinks

There are many reasons for the browning of juices and beer, most of which are caused by the extremely precursory substances of tannins and by the browning caused by sunlight. Some manufacturers use some antioxidants in beer, such as the use of VC and sodium sulfite in large quantities. Any antioxidant can prevent the browning of juice and beer, which will not help. They did not expect VC and sodium sulfite to have no browning resistance at all, and the antioxidants were only below 5 mgL. Because the plant contains ascorbate oxidase, when the tissue of the fruit and vegetable is destroyed and it is in contact with air, the ascorbic acid can be quickly destroyed. Moreover, ascorbic acid itself can be oxidized to cause browning. Ascorbic acid can be decomposed into dehydroascorbic acid and finally form furfural and carbon dioxide. In neutral or alkaline solution, ascorbic acid is very unstable and easy to brown; at pH <5.0, the rate of oxidation to dehydroascorbic acid is slow; but in the range of pH 2.0 to 3.5, browning is inversely proportional to pH. .

Most manufacturers add sulfite and VC as antioxidants in juice tea beverages, and do not mention the toxicity of sulfite and the side effects after consumption. It is worth mentioning that oxidative browning of juice and beer added to VC Different from the oxidative browning of other tannins and enzymes, they are browning caused by the oxidation of anthocyanins. The color reaction is not blackening, but the inherent pigment disappears and eventually becomes brick red. The brown precipitate, especially the heating of the juice, makes the browning more eclipsed, which is a problem that the juice industry has not solved so far. After VC is added to the juice and beer, VC will be rapidly oxidized to form the intermediate product H2O2. H2O2 will cleave the pyran ring by nucleophilic attack on the anthocyanin C-2 position, thereby producing a colorless ester. Degradants, which decompose and polymerize under heating conditions, eventually leading to a brownish precipitate in the juice. This reaction is also very obvious in the tea beverage. In the leaching of the tea juice, if VC is added as an antioxidant, the reaction is that the fresh green color of the tea soup is immediately lost, and the color is very light, and it appears to be somewhat hairy. White, the surface looks "oxidation browning is suppressed", in fact, this is the colorless formation of the rapid oxidation of VC, the formation of the intermediate hydrogen peroxide and the anthocyanin C-2 in the tea soup. The ester degradation product eclipses the tea soup. Under high temperature conditions, the colorless ester degradation product decomposes and decomposes under high temperature conditions, eventually forming a brown precipitate. It can be seen that the anthocyanins in VC and beer can also cause oxidative browning of beer, and finally form the aging of beer.

So how do you eliminate the browning of juices and beer and tea drinks?

1. Use tannase to eliminate tannins from juices and beer and tea beverages.

2. Remove the heavy metal ions that eliminate juice and beer and tea beverages, and cut off the browning path.

3. Use VB family antioxidants. The Na salt of VB has the ability to chelate and calcium and magnesium ions, which can rapidly decompose calcium scale in a very short period of time and become a soluble substance. Specific application: Because the Na salt of VB can chelate and heavy metal ions, thus cutting off the oxidation pathway, the Na salt of VB is a very good antioxidant, which can remove the aging flavor of beer and reduce the rebound of beer double-bending. It is also the most advanced antioxidant in beer.

Vb-Na antioxidant is a natural antioxidant factor and its derivative extracted from edible plants. It belongs to the vitamin B family and is a new natural antioxidant fresh-keeping stabilizer which is complexed with its unique multiplicative substances. Widely used in the juice and beer and tea beverage industries to prevent the oxidation of juice and beer and tea beverages, control the diacetyl recovery during beer storage, improve non-biological stability and flavor stability, and prolong the shelf life of juices and beer and tea beverages. Both have extremely significant effects.

Product status: white crystalline powder, moisture-absorbing, soluble in water.

Main ingredients: Vitamin B and other natural substances

Anti-browning Vb-Na antioxidants usage and dosage:

Usage: Try to add Vb-Na antioxidant before the raw fruit is crushed or before the pasteurization of juice jam production, add 510000. First calculate the amount of Vb-Na antioxidant to be added, then dissolve the Vb-Na antioxidant with an appropriate amount of water, quickly add it to the pulverized pulp and mix well.

For juice drinks, the amount of Na-Vb added should be calculated according to the total weight of the final juice drink of 2 ~ 5 / 10000! For example: 50 tons of thick paste plus water with 500 tons of juice drinks, should Calculate the amount of Na-Vb added according to 2 to 5/10000 of 500 tons.

Please use 2~5/10000 for a gradient test in the laboratory test! In order to get a reasonable economic addition. Suggested addition amount 3/10000

For questions about browning, please contact Wang Jian: 13901024290, (010) 69409663