Concentrated apple juice detection

Concentrated fruit juice is made by using a low-temperature vacuum concentration method after the fruit is squeezed into its original juice, which evaporates a portion of the water. When preparing 100% fruit juice, an equal amount of natural water lost during the concentration process must be reduced into the concentrated fruit juice raw material to produce a product with the color, flavor, and soluble solid content of the raw water fruit flesh. Nutritional concentrated fruit juice contains a large amount of dietary fiber. Fruit cellulose is the main component of plant cell walls, not a nutrient. However, after ingestion by the human body, it absorbs water and expands, adsorbs harmful ingredients in food, stimulates gastrointestinal peristalsis, helps digestion, accelerates excretion, shortens the time for harmful substances to remain in the body, and ultimately achieves the goal of preventing gastrointestinal diseases. It has positive significance for preventing gastrointestinal cancer. Cellulose is also known by nutritionists as the seventh nutrient after the six major nutrients of protein, carbohydrates, fat, inorganic salts, vitamins, and trace elements. Non enzymatic browning is one of the chemical reactions that have the greatest impact on the quality and color changes of fruit juice products during heating and long-term storage. The known chemical processes of non enzymatic browning in fruit juice mainly include the following reaction mechanisms: Maillard reaction, caramelization reaction, ascorbic acid reaction, polyphenol oxidation condensation reaction. In citrus juice, reducing sugars, amino acids, and ascorbic acid are the main substrates of non enzymatic browning. Among them, the Maillard reaction is an important cause of browning during juice heating and long-term storage. The degradation of ascorbic acid is generally believed to be the main reaction leading to browning during citrus juice storage. Amino acids are considered an important cause of browning, and the presence of phenolic substances can also lead to fruit juice browning. [1] The Maillard reaction is a complex process that involves the reduction of sugars and amino compounds such as free amino acids, peptides, and proteins to undergo a carbonyl amino reaction, followed by a series of rearrangements, dehydration, condensation, and polymerization reactions to produce a dark brown substance. This reaction is a continuous and interconnected process that is widely present in food heating and storage. John Hodge3 et al. formally named this reaction Mailardreaction and described and summarized the reaction process. Danehy, Martins, and Zheng Wenhua et al. supplemented and developed this reaction. Buera et al. demonstrated and emphasized the importance of the Maillard reaction in fruit juice browning, but due to the high acidity of citrus juice, Clegg et al. believed that the sugar amino acid reaction of the Maillard reaction type had a smaller effect on orange juice browning. The reaction process can be divided into initial stage, intermediate stage, and final stage, including glycosamine condensation, molecular rearrangement, degradation of rearranged products through three different pathways, and the reaction of polyhydroxyunsaturated compounds. Amino acids, as important reactants involved in the Maillard browning reaction in fruit juice, play an important and diverse role. Their amino groups act as nucleophilic reagents in the reaction, accelerating the decomposition of sugars and promoting the formation of melanin. Meanwhile, the properties of amino compounds affect the rate of Maillard reaction, and it is generally believed that basic amino acids have high browning activity, including aminoacetic acid, tryptophan, lysine, and tyrosine; Cysteine, aspartic acid, and glutamic acid are considered low browning active amino acids; Among them, lysine has 2 amino acids and has been proven to be the most active amino acid in browning reaction. Its model browning degree is 2-3 times that of other amino acid models, and its activity is 5-15 times that of other amino acids