Please use this identifier to cite or link to this item:
Development of a Suitable Process for Inhibition of Browning in Some Fruit Purees
- In this research, the first part was focused on finding techniques for efficient processing methods for inhibition of enzymatic browning in banana purees. In the second part, the focus was to study some suitable approaches for the control of nonenzymatic browning in tomato purees. Improvement of color in processed banana and tomato purees has been made by using familiar processes such as vacuum treatment and addition of browning inhibitors such as ascorbic acid, citric acid and malic acid. The degree of browning of the fruit products was determined by measuring the increase in absorbance at 420 nm in PD - 303 S Digital Spectrophotometer and TRSP-722 Grating Spectrophotometer. In order to control the quality of the processed foods, other physicochemical properties such as pH, acidity, ºBrix, moisture and ash contents as well as bacteriological examination were investigated. It was found that different processing methods for minimizing brown color formation affected the degree of browning and shelf-life of the products. Although 0.1% w/w ascorbic acid was suitable for the inhibition of enzymatic browning in banana puree, the method using 0.05%w/w ascorbic acid in conjunction with 0.05% w/w citric acid was more effective than ascorbic acid alone as the treated samples gave good color, flavor and texture. In heat preservation of banana puree, pasteurization at 70ºC for 10 minutes was found to be adequate for the control of browning. In processing of tomato puree, it was observed that immersion of tomatoes in 0.1%w/w ascorbic acid solution for 1 hour was effective in retaining the natural red color of tomatoes. Besides immersion, further addition of 0.1% w/w citric acid or malic acid to puree gave better color preservation and longer shelf-life of over one year. In open pan method, concentration temperature of 70-75°C for 5 hours was found to be suitable in order to meet the standard specification of ºBrix for tomato puree and to maintain the natural red color.