Color, physicochemical parameters and antioxidant potential of whole grape juices subject to different UV-C radiation doses

Abstract

Knowing that moderate stress such as UV radiation can activate defense mechanisms in plants, the use of UV-C radiation appears as hypothesis of a promising technique that would help to stimulate and enhance beneficial compounds for health, through a clean and healthy technology. In this study, the possible induction of secondary metabolism, the increase in the content of phytochemical compounds and physicochemical changes through the use of UV-C radiation were evaluated on whole grape juices produced with Vitis labrusca grapes, cultivar Isabel Precoce. Grapes were harvested, sanitized, exposed to UV-C radiation at doses of 0, 2, 4 and 6 KJ m , and then the juices were prepared and packed into amber glass bottles at room temperature. Analyses were performed at 0, 30, 60, 90 and 120 days of storage. Based on results obtained and conditions in which the experiment was performed, UV-C treatment in grapes caused abiotic stress in the fruits, affecting color, titratable acidity, soluble solids/titratable acidity ratio, vitamin C and percentage of protection against oxidation. Application of UV-C did not change levels of phenolic compounds in fruit juices or the percentage of scavenging free radicals, pH and soluble solids.Index terms: Phenolics; antioxidant activity; vitamin C. RESUMOSabendo que estresses moderados como a incidência de radiação UV podem ativar mecanismos de defesa nos vegetais, o uso da radiação UV-C surge como hipótese de uma técnica promissora que ajudaria a estimular e a potencializar compostos benéficos para a saúde, por meio de uma tecnologia limpa e saudável. Neste estudo, avaliou-se a possível indução ao metabolismo secundário, o incremento do teor de compostos fitoquímicos e as alterações físico-químicas, por meio do uso da radiação UV-C em sucos de uva integrais produzido com uvas Vitis labrusca, cv. Isabel Precoce. As uvas foram colhidas, sanitizadas, submetidas à exposição à radiação UV-C, nas doses 0; 2; 4; e 6 kJ m -2 e, em seguida, destinadas à elaboração de sucos, que foram acondicionados em frascos de vidro âmbar e armazenados à temperatura ambiente, sendo as análises realizadas nos dias 0, 30, 60, 90 e 120 dias de armazenamento. Com base nos resultados obtidos e nas condições em que foi realizado o experimento, verificou-se que o tratamento UV-C nas uvas provoca um estresse abiótico nas frutas, afetando a coloração, acidez titulável e relação sólidos/acidez titulável, vitamina C e porcentagem de proteção contra a oxidação. A aplicação da radiação UV-C não resultou em alterações nos teores de compostos fenólicos dos sucos, nem na porcentagem de sequestro de radicais livres, não alterando também o pH e sólidos solúveis.

Evaluation of the toxicity and hypoglycemic effect of the aqueous extracts of Cnidoscolus quercifolius Pohl

“…The phytochemical analysis of the aqueous extract of C. quercifolius revealed the presence of phenols, flavones, flavonols, xanthones, catechins, triterpenoids, and tannins. Studies have shown that flavonoids, when ingested on a regular basis through diet, can help prevent chronic non-communicable diseases due to their antioxidant, anti-inflammatory, anti-hyperglycemic, anticarcinogenic and antiatherogenic effects, as well as antibacterial and antiviral activities ( 28 , 29 ). Triterpenoids are metabolites that also have an antidiabetic potential, which act to increase the release of insulin, modifying glucose metabolism, inhibiting hyperglycemic factors, and inhibiting or stimulating enzyme synthesis ( 30 ).…”

O Physico-chemical properties of mango pulp and cajarana blends

“…During the last decades, the population is increasingly looking to insert plant products with a high content of vitamins, anthocyanins and phenolic compounds into their usual diet, this interest comes from several studies that report that the consumption of these components can bring health benefits (Corbo et al, 2014;Henrique et al, 2016;Buniowska et al, 2017).…”