Enhancement quality and storage time of apple concentrate by usingL-ascorbic acid

Between all the vitamins, ascorbic acid is destroyed with oxidation process, as well as in the extracts, juices and foods this vitamin is oxidized when exposed to air. The amount of oxidation is greatly accelerated by heating and alkali materials. Concentrate is a form of fruits that most of its main constituents or solvents are eliminated. Usually, by concentrating the juice in a solution or suspension and turning it into powder or extract, the concentrate is formed. The advantage of concentrate production is that by eliminating water, the weight of the food is reduced, and therefore its transportation is easier and less costly. Apples concentrate has always been a concern for juice and concentrate producers. Apple is quite economical due to lower prices and good brix. On the other hand, apple concentrate is used as the base for all types of beverages and juices in factories. It is also used in the production of apple vinegar. Considering the large volume of production of apple concentrate in industrial units, its quality is decreased over a period of time (between one and three months) depending on the conditions of production. In this research, it has been determined that L-ascorbic acid (vitamin C) can improve the quality and maintance of apple concentrate. L-Ascorbic acid (made in China), gelatin and Bentonite (Iran Barite Co.) were used. Apple concentrate was carried out in the classic method (using filter materials and vacuum filters) at Azarakam Urmia Co. Perlites were provided from Zomorrod puyesh Urmia Co. Amylase and pectinase enzymes were used with the DSM mark. To control the turbidity of apple concentrate samples, a turbidometer instrument (H2A-N2100 HACH Co., United States) was used by. The DR2800 spectrophotometer (HACH Co., United States) was used to check the color and clarity of apple concentrates.
The color of apple concentrates samples was measured by spectrophotometer at a wavelength of 440 nm. To do this, the apparatus was first calibrated with distilled water at 100, and then the apple concentrate (filtered with filter paper) was transported to the cell and the absorbance amount was recorded. The clarity of apple concentrates samples was measured by spectrophotometer at a wavelength of 640 nm. To do this, the apparatus was first calibrated with distilled water at 100, and then the apple concentrate was transported to the cell and the transmittance amount was recorded. The turbidity of apple concentrates samples was measured by the turbidometer instrument. To do this, the apparatus was first calibrated with distilled water at 100, and then the apple concentrate was transferred to the instrument cell and the turbidity amount was recorded. Apple concentrates quality (clarity and color enhancement and turbidity decrease) was improved by flocculation and precipitation of concentrate by adding of 1- bentonite-gelatin mix, and 2- bentonite-gelatin-L-ascorbic acid mix. The mix solution of bentonite, gelatin, and L-ascorbic acid was added to apple concentrate in the four separated stages including; 1: to the mash enzyme tank, 2: to the crude apple juice, 3- to the fining tank (in single-stage), and 4- to the fining tank (in two-stage). The ratio of bentonite, gelatin, and L-ascorbic acid in the mix solution was optimized by experimental analysis. The quality of treated apple concentrates by bentonite,
gelatin, and the L-ascorbic acid mix was analyzed by spectrophotometer and turbidimeter. The results showed that the samples treated with bentonite-gelatin-L-ascorbic acid mix had higher quality character than samples treated with the bentonite-gelatin mix, so L-ascorbic acid had a significant effect on the apple concentrate quality. Also, the results showed that adding of bentonite-gelatin-L-ascorbic acid mix to the samples in the fining tank (in single-stage) improved apple concentrate than other three stages. According to the results adding of bentonite-gelatin-L-ascorbic acid mix to the samples cause to stable quality of apple concentrate for 90 days. The results showed that the addition of ascorbic acid to apple juice before pasteurization due to the short duration of production in the production process and the decrease of ascorbic acid activity due to pasteurization had no significant effect on the apple concentrate, but adding the ascorbic acid in the pasteurized juice created a significant effect in all product quality parameters, which include: shortening the filtration time, shorter drainage time and lower consumption of perlite.