بررسی تاثیر تیمار های مختلف در کنترل قهوه ای شدن انجیر نیمه مرطوب (پرسی) رقم سبز استهبان

Iran is one of the most important fig producer countries around the world. Intermediate moisture fig is a processed product. One problem about intermediate moisture fig is that the color will be changed and transmute to brown during storage after processing. The purpose of this research was to study soaking temperature and time effects and to evaluate the effects of calcium chloride, cysteine, sodium metabisulphite and citric acid in various concentrations on prevention of semi-moisture fig browning at room temperature. Chemical compounds (protein, total sugar, fat, fiber and moisture) of fig samples were determined. In order to prepare product five different periods of time(3, 6, 9, 12, 15 min) and five different degrees of temperature (20, 40, 60, 80, 100°C) based on central composite rotational design were used. Samples were kept in room temperature for 2 weeks to evaluate the effects of soaking parameters on color and texture of product. After that moisture, color and texture of samples were determined. First different solution of calcium chloride (0.6, 1, 1.5, 2% w/w), citric acid (0.5, 1, 2, 3%w/w), cysteine (0.05, 0.07, 0.2, 0.5%w/w) and sodium metabisulphite (500, 800, 1000 and 1200 ppm ) were prepared. Dried figs were dipped in prepared solutions and water was used to evaluate control samples to optimize the time and temperature, then color of the samples were measured in specific period of time during four months. Results showed that temperature of 60°C and 3min interval provided 20% moisture in the product which assessed as the best moisture content for preserving color and texture. The most desirable L value was obtained using citric acid (1, 2, 3%w/w) and Calcium chloride (1.5%w/w). However sodium metabisulphite and cysteine in concentration of 0.07%, 0.05%, 0.2% showed significant difference with control, the results were not satisfactory. Results showed that using suitable temperature in rehydration of fig to inactivate poly phenol oxidase and chemical treatments to postpone and reduce the browning reaction rate were effective.