PHENOLIC COMPOSITION AND BIOACTIVITY OF CASTANHOLA ALMOND FLOUR

The castanhola (Terminalia catappa Linn) fruit is an exotic species that contains peel, pulp, and almond as edible fractions. Almonds stand out for their pleasant taste, appreciable nutritional content (proteins, lipids, and vitamins), and high energy value. Nonetheless, it is a food source unknown to the general public, a factor that justifies its underutilization in human consumption. Furthermore, there is a lack of research regarding its bioactive compounds’ identification and quantification, such as vitamins, phenolic compounds, and carotenoids, responsible for beneficial properties to human health. Thus, this study aimed to evaluate the phenolic profile and the antioxidant activity of castanhola almond flour (CAF). The CAF production consisted of de-pulping the fruits and drying the nuts in a forced air circulation oven at 60 ºC for 48 h, followed by manual cracking to remove the almonds that were ground in a crusher and sieved. The CAF was portioned in vacuum-packed polypropylene bags and stored frozen until use. Initially, the methanolic extract of CAF was obtained by a methanol solution (70%) in ultrasound for 60 minutes. The total phenolic content (TPC) and phenolic compounds profile of CAF measurements applied Folin-Ciocalteu colorimetric method and liquid chromatography coupled to a diode arrangement detector (HPLC-DAD), respectively. The antioxidant activity assays were DPPH and FRAP. The TPC in CAF extract was 415.72 ± 14.14 mg GAE per 100 g. Overall, 12 phenolic compounds, including three phenolic acids, six flavanols, two flavonols, and one anthocyanin, were identified and quantified in this food matrix for the first time. As the most abundant group in the CAF extracts, the content of flavanols was 15.48 ± 1.58 mg 100 g-1, followed by phenolic acids (4.51 ± 0.12 mg 100 g-1) and anthocyanins (2.27 ± 0.02 mg 100 g-1). The phenolic compounds are a significant group of nutritional ingredients, considered the main bioactive compounds in plants with antioxidant capacity. In addition, the different groups of phenolic compounds promote other types of bioactivities, including anti-inflammatory (phenolic acids, flavonols, and anthocyanins), anticancer (phenolic acids and anthocyanins), antimicrobial properties (phenolic acids and flavonols). Hence, these compounds have received prominence for their potential beneficial effects on human health and for their release from the food matrix upon food processing. CAF results for DPPH assays were IC50 of 89.67 μg mL-1 of the sample. Previous research showed a high correlation between values of phenolic content and antioxidant activity. However, concerning the ABTS test, the CAF showed antioxidant potential below 50% and it was not possible to obtain the IC50 value. Thus, the high TPC of CAF suggest a promising scenario of its application in the food industry as a form of adding value to this unknown raw material, improving the quality and nutritional value of foods, and transforming them into antioxidants sources for the human diet.