Delaying the harvest induces bioactive compounds and maintains the quality of sweet potatoes

We have identified the best harvesting periods, related to higher bioactive compound content and post-harvest quality, for minimally processed sweet potatoes with orange pulp and cream pulp. Quality loss in minimally processed sweet potatoes occurred due to browning in cv. Mãe de Familia and ESAM1 and to whitening in cv. Paraná. Both Mãe de Família and ESAM1 presented higher peroxidase and polyphenol oxidase activities at 120 days, and cv. Paraná contained high levels of provitamin A. β-carotene was the major carotenoid (up to 99%) in orange pulp. All cultivars harvested at 150 and 180 days and minimally processed showed the best visual quality, the highest bioactive compound content, and no microbial infection. Delaying the harvest also increase the antioxidant activity in orange roots, which was associated with a high content of carotenoids and phenolic compounds, resulting in an increase in the nutritional quality of the product. PRACTICAL APPLICATIONS: Postharvest techniques can improve the visual and phytochemical quality of vegetables and extend their shelf life. The present research provides the best harvesting periods for minimally processed cream and orange sweet potato roots with higher postharvest qualities. Delaying the harvest resulted in a product with better visual quality, higher levels of bioactive compounds, which are highly beneficial to health, for example, ß-carotene, and no microbiological contamination. Our results may contribute to improvements in the current knowledge about harvesting times for sweet potato growers who aim to produce high quality, minimally processed products with a longer shelf life.

Biogenic Amines and the Antioxidant Capacity of Juice and Wine from Brazilian Hybrid Grapevines

Some biogenic amines (BAs) are used as quality markers in grape-derived products. The prolife of 9 BAs was determined in juices and wines elaborated from hybrid grapes. Low levels of histamine, tyramine and cadaverine were found. Juices elaborated from 'BRS Rúbea' showed the highest tyramine levels (1.56 mg/L), while no histamine was found in wines elaborated from 'Seleção 34' and its higher content was detected in 'BRS Carmem' (3.55 mg/L). Juices elaborated from 'BRS Violeta' showed elevated content (472.88 mg/L) of total phenolic compounds (TPC) and mono-hydrated serotonin (6.20 mg/L), and wines elaborated from 'Violeta' presented a high serotonin mono-hydrate content (23.63 mg/L) and high antioxidant activity with FRAP test (77.24 mmol FeSO₄/L). Juices elaborated from hybrid grapes 'BRS Violeta' and wines from 'BRS Violeta', 'Seleção 34' and 'Seleção 13' had high levels of bioactive compounds, emphasizing the great potential of these cultivars for winemaking.

Nutritional value and antioxidant compounds during the ripening and after domestic cooking of bananas and plantains

Genotypes of bananas and plantains have been studied for biofortification purposes, mainly due to content of resistant starch (RS) and polyphenols. This study aims to identify banana and plantain genotypes with a high content of resistant starch, phenolic compounds and minerals, and to evaluate the impact of the ripening stage and domestic thermal processing to select superior genotypes with high levels of functional compounds. In this study, it was used bunches of bananas and plantain genotypes. The phenolic compounds profiles were determined by HPLC-DAD in pulps and peels. The resistant starch and the minerals (K, Na, Zn, Cu and Fe) were evaluated in pulps and peels of unripe fruit. The results of phenolic compounds were studied in three ripening stages, and after thermal processing (ripe stage) of two genotypes, which were most promising for biofortification studies. Resistant starch and minerals were analysed in the unripe fruits. The peel biomass showed the highest values of phenolic compounds and minerals. The total starch content in the pulp varied from 42.3% ('FC06-02') to 80.6% ('Pelipita'). Plantains and cooking bananas presented the highest contents of starch and resistant starch (stage 2 - green with yellow traces). The pulps of the dessert genotypes 'Khai' and 'Ouro da Mata', and cooking genotype 'Pacha Nadam' stood out due to their minerals high contents (P, K and Fe; Zn and Fe; Ca, Mg and Zn, respectively). The dessert bananas (e.g., 'Ney Poovan') and cooking bananas (e.g., 'Tiparot') had the highest concentrations of phenolic compounds, mainly in ripe fruit (stage 5 - yellow with green). In addition, the thermal processing of Musa spp. fruit led to increasing these secondary metabolites, mainly the cooking of fruit with peel by boiling, which should be preferred in domestic preparations.