CORRELATION ANALYSIS BETWEEN ANTIOXIDANT ACTIVITY AND TOTAL PHENOLICS OBTAINED FROM CASHEW APPLE BAGASSE
In Brazilian cashew apple industry, only 10 % to 20 % of cashew bagasse production is used, which represents low yields of processing and high quantities of rejected biomass. Despite their promising economic potential, cashew apples are still underutilized. The main purpose of this study was to apply an enzymatic maceration (281 UI.g-1 β-glucosidase from Aspergillus awamori) to obtain enriched phenolics extracts from cashew residue, based on previously data. A full factorial design 2^2 was applied to evaluate the effects of solvent/sample ratio (2:1, 2.5:1 and 3:1) and enzyme concentration (10 %, 15 % and 20 % related to dry matter) in the enhancement of phenolics and antioxidant capacity of the cashew bagasse extract. Total phenolic content (TPC) and antioxidant activity through 2,2'-azino-bis-3-ethyl benzthiazoline-6-sulphonic acid (ABTS) and oxygen radical absorbance capacity (ORAC) assays were performed. Flavonoids were identified by high performance liquid chromatography with diode array detection (HPLC/DAD). It was observed a strong correlation between TPC predicted by the model and the experimental data. Similarly, there was relationship among ABTS and ORAC predicted and experimental results. A linear relationship was confirmed between TPC and ABTS values (R = 0.965; p ≤ 0.05). According to response surface methodology, a solvent/sample ratio below 2.5:1 influenced positively the total phenolics content and antioxidant capacity of the extract. High levels of enzyme did not affect the responses for the proposed model. The best operation conditions was in the central point of the experimental design when the extract presented 294.3 mg of gallic acid equivalent per 100 g; 2.65 µM of Trolox equivalent per gram of extract for ABTS+ and 3.73 µM of Trolox equivalent per gram of extract for ORAC. Among the identified flavonoids, rutin, quercetin and isoquercetin were the major compounds.