EVALUATION OF TOTAL PHENOLIC CONTENT AND ANTIOXIDANT ACTIVITY DURING SHELF LIFE OF YOGURT ADDED WITH TAMARIND (Tamarindus Indica) PULP PROCESSED BY OHMIC HEATING

The use of emerging technologies can favor the production of dairy products that are more nutritionally and sensorially appealing. The aim of this study was to evaluate the effect of an alternative thermal processing of tamarind pulp using ohmic heating (OH) on the antioxidant activity and total phenolic compound content in yogurts. Tamarind pulp (5%) was processed using OH under different electric fields: 60V (6.67 V/cm; T1), 120V (13.33 V/cm; T2), and also by pasteurization (75°C/3 minutes; TP), and then added to the yogurt. An untreated sample (TC) was used as a control. Antioxidant activity (AA) was assessed through the percentage (%) of DPPH free radical reduction and total phenolic content (TPC) by the reaction with Folin-Ciocalteu reagent on days 0 and 21 of refrigerated storage. It was observed that the TPC increased after 21 days of storage, with the highest levels found in T1 (2.022mg GAE/100g) and TP (1.911mg GAE/100g), with no significant difference (p>0.05) between them. Additionally, TC (1.817mg GAE/100g) and T2 (1.750mg GAE/100g) did not differ from TP (p>0.05). The highest antioxidant activity was observed on day 0 in TC (43.35%), significantly differing (p<0.05) from the other treatments - T2, TP, and T1 (36.73%, 24.9%, and 17.49%, respectively). After 21 days of storage, there was a reduction in antioxidant activity in all treatments, indicating a possible degradation of other bioactive antioxidant compounds during the period, since the TPC increased. T1 (17.0%) and T2 (14.83%) did not show a significant difference compared to TC (16.66%; p>0.05), while TP had the lowest value (6.38%; p<0.05). Thus, it is concluded that reduced electric fields can be applied as an alternative to the thermal treatment of tamarind pulp, as it allowed for greater preservation of TPC and favored, over the storage period, its extraction and greater preservation of AA.