CONCENTRATION OF ANTIOXIDANT ACTIVITY AND NUTRITIONAL QUALITY OF FREEZE-DRIED BLACKBERRY BEFORE FREEZING

Abstract

The blackberry (Rubus sp.) has a high antioxidant potential, mainly due to the representative contents of total phenolic compounds, flavonoids and the high content of anthocyanins. The objective of this work was to evaluate the physicochemical characteristics and antioxidant activity of blackberry in natura, frozen pulp and pre-lyophilized for freezing. For this, the fruits were sanitized and separated into in natura samples, frozen for 90 days with pre-drying by freeze-drying, before freezing, for 90 days. All samples were evaluated for their physicochemical composition - moisture, crude protein, crude fats, fiber, carbohydrates, minerals, total soluble solids (ºBrix), pH and titratable acidity. The pulps were prepared after freezing time in a 4:1 ratio (fruit:distilled water), and then the pulps were dried, crushed and the concentration of phenolic compounds and flavonoids was measured. A significant difference was observed for soluble solids, crude protein content, total carbohydrates and flavonoids for the lyophilized treatment compared to the frozen one, and the pulp with freeze-dried blackberries did not differ from the contents of the fruit in natura. Therefore, the freeze-drying process of blackberries, prior to freezing, proved to be more appropriate, because it better preserved the nutrients, and can be used as an alternative method to avoid the loss in the composition of the post-harvest blackberry, since the fruit is found in mid-November and December.