THE COMPARISON OF ACID ASCORBIC CONTENT DURING PROCESSING OF SOME VEGETABLES AND FRUITS

In this work there was searched the ascorbic acid content variation in four plant species during processing. The biological material was represented by: green onion, spinach leaves, pear fruits (from vegetable farms around Suceava town) and kiwi fruits (from supermarket). The ascorbic acid content was determined through a method based on reduction (by the ascorbic acid) of 2.6-Dichlorphenol-indophenol to the corresponding leucoderivate. Through grinding and one hour exposure to air at 20-22°C, the largest reduction in ascorbic acid content was in pear fruits (50%), and the lowest one in spinach leaves (11.7%). By means of thermal processing (boiling) the ascorbic acid content of the analyzed species has changed in different proportions. Thus, as compared to fresh samples, in boiled ones the vitamin C content has decreased most in pear fruits (by 52.6%) and least in spinach leaves (by 38.5%). Under the same conditions, in green onion sample the ascorbic acid mean content has increased by 10.8%, compared to fresh sample. In the fruit species, under thermal processing conditions, the ascorbic acid mean content was different as against heat-unprocessed samples. Thus, at kiwi fruits both in samples poached with sugar and without sugar, the total content of ascorbic acid (from product and boiling liquid) was superior to the heat-unprocessed samples. In contrast, at pear fruits, under the same experimental conditions, the total content of ascorbic acid was lower than in heat-unprocessed samples.