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The effects of maturity (green-unripe, red-ripe, and purple-fully ripe) and heat treatment (blanching at 90±5°C for 2 mins and steaming at 105±5°C for 5 mins) on the antioxidant content and activity of Philippine bignay (Antidesma bunius (Linn.) Spreng cv. ‘common’) flesh and seeds were investigated. The total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) were determined using the Folin-Ciocalteau assay, aluminum chloride assay, and pH differential technique, respectively, and the antioxidant activity was determined using DPPH, ABTS, and FRAP assays. Results showed that the antioxidant content and activity of bignay increased with maturity. Fully ripe flesh and seeds were found to have the highest antioxidant content and activity regardless of the heat treatment applied. The TPC (8.06±0.15 mg gallic acid equivalents (GAE)/g), TFC (8.10±0.06 mg quercetin equivalents (QE)/g), TAC (4.07±0.03 mg cyanidin-3-glucoside equivalents (CGE)/L extract), and antioxidant activity (ABTS 10.37±0.04 , DPPH 9.60±0.10, FRAP 24.37±0.53 Trolox equivalents (TE)/g) of fully ripe seeds were superior when blanched. On the other hand, the TPC (40.73±0.04 mg GAE/g), TFC (31.54±0.15 mg QE/g), TAC (20.93±0.12 mg CGE/L extract), of fully ripe flesh were superior when not heat-treated while its antioxidant activity (ABTS 34.19±0.19, DPPH 14.01±0.02, FRAP 87.78±1.22 (TE)/g) was highest when blanched but did not vary significantly compared to unheated samples. This study suggested that bignay ‘common’ variety was a good source of antioxidants particularly the flesh at fully ripe stage. Blanching had shown to enhance its antioxidant activities.

Cereal grains and products provide calories globally. The health benefits of cereals attributed to their diverse phenolic constituents have not been systematically explored. Post-harvest processing, such as drying, storing, and milling cereals, can alter the phenolic concentration and influence the antioxidant activity. Furthermore, cooking has been shown to degrade thermo-labile compounds. This review covers several methods for retaining and enhancing the phenolic content of cereals to develop functional foods. These include using bioprocesses such as germination, enzymatic, and fermentation treatments designed to enhance the phenolics in cereals. In addition, physical processes like extrusion, nixtamalization, and parboiling are discussed to improve the bioavailability of phenolics. Recent technologies utilizing ultrasound, micro- or nano-capsule polymers, and infrared utilizing processes are also evaluated for their effectiveness in improving the phenolics content and bio-accessibility. We also present contemporary products made from pigmented cereals that contain phenolics.

This study aimed to determine the influence of maturity stages and processing methods (blanching and steaming) on the antioxidant profile and in vitro antioxidant activities of bignay (Antidesma bunius (Linn.) Spreng var. Kalabaw) flesh and seeds. Bignay fruits of three maturities (unripe, half ripe, and fully ripe) were collected from Laguna, Philippines. Each maturity stage was subdivided into three lots. One lot underwent blanching at 90 ± 5°C for 2 minutes, and another underwent steaming at 105 ± 5°C for 5 minutes while the last did not undergo treatment. Seeds of the samples were then separated from the flesh. Both seeds and flesh were freeze-dried, extracted, and analyzed for antioxidant contents (total phenolic content, total flavonoid content, and total anthocyanin content) and antioxidant activity by DPPH, ABTS, and FRAP assays. Results show that both the maturity and processing methods significantly affect the antioxidant content and activity of the samples. Moreover, except for the FRAP assay done on flesh samples, all assays showed that there is significant interaction between the effect of maturity and processing method on the antioxidant contents and activity of bignay flesh and seeds. Results also show that fully ripe flesh and seeds yielded greater antioxidant content and antioxidant activity than their half-ripe and unripe counterparts; whereas, blanched flesh and seeds generally had higher antioxidant activities than their unprocessed and steamed counterparts.

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