INFLUENCE OF DRYING TEMPERATURE ON TOTAL PHENOLIC CONTENT AND ANTIOXIDANT CAPACITY OF GRAPE SEEDS
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Grape seed, which is an organic waste arise from production of wine, juice and molasses, is considered as a functional food ingredient in food formulations because of its rich content of bioactive compounds. This study was performed in order to evaluate the effect of air-drying temperature on the bioactive compounds of grape seeds. In the study, total phenolic content and antioxidant activity of grape seeds that are dehydrated at different drying temperatures (40, 50 and 60 degrees C) were determined. When comparing the fresh grape seeds with the corresponding dehydrated samples, it was shown that the drying operation led to reduction of total phenolic contents and the total phenolic contents decreased with an increase of the drying temperature. According to ABTS radical scavenging method, Trolox Equivalent Antioxidant Capacity (TEAC) was found to be highest for fresh grape seeds and presented lower values for grape seeds dried at three different temperatures. As a result of the study, it was demonstrated that grape seed is a powerful antioxidant source and it has still high antioxidant activity after drying process. However, drying at low temperatures was put forward to be advantageous in order to reduce the losses of phenolic components.