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.

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.

Bignay pomace is a processing byproduct that can be a source of bioactive compounds. However, a suitable dehydration method should be considered to efficiently valorize this waste material into high-value food ingredient and maximize its health-promoting properties. Bignay pomace was subjected to convection oven-drying and freeze-drying to investigate the effect of these pre-processing techniques on the physicochemical, bioactives, and antioxidant properties of the samples. Both drying methods significantly (p<0.05) changed the total phenolic and anthocyanin contents of bignay pomace while flavonoids and tannins were not significantly affected. Freeze-drying of samples resulted in higher phenolic content (1742 vs. 1273 mg gallic acid equivalent/100 g DW) and anthocyanin content (496 vs. 223 mg cyanidin-3-glucoside equivalent/100 g DW) than convection oven-drying. Freeze-drying also resulted in higher antioxidant properties based on DPPH, ABTS radical scavenging activity, and FRAP assays. Bignay pomace extract was analyzed through HPLC (with photo-diode array detector) for its phenolic profile and nine compounds were identified, with catechin and epicatechin as the dominant components. HPLC analysis also showed that while the drying process does not influence the phenolic profile of the samples, it significantly affected the concentration of phenolic compounds present. The results of this study showed that freeze-drying is a more viable method to retain the majority of bignay pomace’s functional properties compared to convection oven-drying. Graphical Abstract

The Philippines as a tropical country is home to several indigenous berries that offer enough supply of health-promoting bioactive compounds like vitamin C. Vitamin C is an important micronutrient in the human diet that is usually supplied by fruits and vegetables. The amount of this vitamin in different products varies depending on the species, variety, maturity, processing, and other conditions. In this study, the vitamin C contents of selected Philippine indigenous berries such as bignay and lipote were evaluated as affected by fruit maturity and processing treatment. Fruits of two bignay (Antidesma bunius (Linn.) Spreng), varieties, ‘Common’ and ‘Kalabaw’, as well as of lipote (Syzygium polycephaloides (C. B. Rob.) Merr.), at three maturity stages (unripe, half-ripe, and fully ripe) were acquired in Laguna, Philippines. Samples were subjected to two processing treatments: blanched (90 ± 5 °C, 2 minutes) and steamed (105 ± 5 °C, 5 minutes), while control samples did not undergo processing treatment. The flesh and seeds were separated, lyophilized, extracted, and subjected to quantification of vitamin C using reversed-phase high performance liquid chromatography. Results showed that the vitamin C levels of both fruits were significantly affected by maturity, processing, and their interaction (P < .05). In general, a concomitant increase in vitamin C content was noted as fruit maturity progressed for both flesh and seeds (0.3 to 1.7-fold increase). Lipote seeds on the other hand, had decreased vitamin C content as maturity progresses (0.6-fold decrease). Moreover, blanching the fruits resulted in the highest retention of vitamin C in the fruit samples (247% at most). The general findings of this study indicated that the utilization of these indigenous berries for future functional product development must be accompanied by the blanching - as a pretreatment process, of the fully ripe fruits to attain enhanced vitamin C contents. Graphical Abstract

Lipote (Syzygium polycephaloides (C. B. Rob.) Merr.) is a Philippine endemic tree whose berries have a potential for functional food development. This study aimed to investigate the effect of the maturity stage (unripe, half-ripe or fully ripe) and processing (blanching at 90±5°C for 2 mins and steaming at 105±5°C for 5 mins) on the antioxidant content (total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC)) and antioxidant activity by DPPH, ABTS, and FRAP assays, of lipote flesh and skin (referred herein as flesh) and seeds. Results showed that maturity and processing significantly affect the antioxidant contents and activities of fresh lipote flesh and seeds. Blanched lipote flesh generally had higher TPC, TFC, and antioxidant activities than their unprocessed and steamed counterparts. Blanched unripe flesh had the highest TPC (33.57±0.27 mg gallic acid equivalents [GAE]/g) and antioxidant activity measured by ABTS, FRAP, and DPPH assay (92.31±1.28 mg Trolox equivalents [TE]/g, 123.83±0.86 mg TE/g, and 74.02±0.33 mg TE/g, respectively) while blanched fully ripe flesh had the highest TFC (27.98±0.08 mg quercetin equivalents [QE]/g) and TAC (18.11±0.11 mg cyanidin-3-glucoside equivalents [C3GE]/g). Lipote seeds, especially unripe ones, have appreciable antioxidant contents and antioxidant activity, even greater than that of lipote flesh. Unprocessed unripe seeds had the greatest TPC, TFC and antioxidant activity by DPPH assay (123.56±0.94 mg GAE/g, 111.90±0.14 mg QE/g and 465.89±1.86 mg TE/g, respectively). It is recommended that blanching be used as a processing step to increase the antioxidant content of lipote flesh while lipote seeds should be investigated further for nutraceutical applications due to their high antioxidant properties.