THE INFLUENCE OF REFRIGERATION TIME AND OF SUGAR ADDITION ON ASCORBIC ACID CONTENT IN SOME NATURAL JUICES

Abstract

Following some studies concerning the main factors influencing the concentration of vitamins within food raw materials, especially ascorbic acid, this work tries to make evident the influence of the refrigeration temperature and of the sucrose addition on content of this vitamin in three types of natural juice. The biological material was represented by black currant, raspberry and quince natural juices, obtained from these fruits by means of a crushing out process. For each type of juice, samples without addition and samples with 5% and 10% sucrose addition were made up. The ascorbic acid determination was carried out from fresh juice as well as from juice kept in refrigerator, at certain time intervals (24, 48, 96 and 168 hours). The storage of these juices under refrigeration conditions has determined percentage reductions of vitamin C content of these ones. Thus, after 168 hours of storage, in the three types of analyzed juices the highest loss of vitamin have been registered in samples without sucrose addition, and the least ones in samples with 10% addition. The comparison of vitamin C values in the three analyzed juices, subjected to 168 hour- refrigeration process, has emphasized that the highest loss of ascorbic acid have been in quince juice, and the least one in black currant juice.