UVC light modulates vitamin C and phenolic biosynthesis in acerola fruit: role of increased mitochondria activity and ROS production.

The effects of ultraviolet-C light (UVC) on vitamin C and phenolic compounds in acerola during postharvest storage were investigated in order to elucidate the mechanism inducing the antioxidant systems. The fruits, stored at 10 °C for 7 days after a hormetic UVC irradiation (two pulses of 0.3 J/cm2), showed significantly less degradation of vitamin C and phenolic compounds than the control without the UVC challenge. UVC activated the L-galactono-1,4-lactone dehydrogenase (GalDH), a key enzyme for vitamin C biosynthesis, and altered the composition of phenolic compounds, through phenolic biosynthesis, in acerola during postharvest storage. UVC also induced reactive oxygen species (ROS) productions at immediate (day 0) and late (day 7) times during postharvest storage through the mitochondrial electron transport chain and NADPH oxidase, respectively. Results suggest that UVC helps in the retention of vitamin C and phenolic content in acerola by altering ascorbic acid and phenolic metabolism through an increase in mitochondrial activity and a ROS-mediated mechanism. Data showed the beneficial effects of UVC on maintenance of nutraceutical quality in acerola during postharvest storage and supplied new insights into understanding the mechanism by which UVC irradiation enhance the antioxidant system in fruits.

The influence of pulsed light exposure mode on quality and bioactive compounds of fresh-cut mangoes.

This study investigated the effect of pulsed light (PL) on the respiratory rate, quality (firmness, color and soluble solid content), bioactive compounds (ascorbate and carotenoid) and total antioxidant activity of fresh-cut "Tommy Atkins" mangoes. Fresh-cut mangoes were subjected to PL treatments: control (0P), 1 pulse (1P; 0.7 J cm-2), 4 successive pulses (4P; 2.80 J cm-2) and 1 pulse per day for 4 days (1P4D; 2.80 J cm-2) before storage for 7 days at 6 °C. The 1P and the 4P treatments reduced fresh mass loss during storage, while 4P-treated samples also showed a slower decline of yellow color, as shown by parameter b and overall better visual appearance. After 7 days of storage, total ascorbate content was 40% higher in the 1P4D treatment than in control, whereas total carotenoid content (0.894 mg g-1 FM) and total antioxidant activity (144 µmol trolox 100 g-1 FM) were the highest in the 4P-treated samples. Results suggest that PL mode of application is more important than the fluence or final dose received by fresh-cut mangoes; moreover, 4P is an effective method to preserve, or even improve quality of fresh-cut mangoes.

Understanding the physiological effects of UV-C light and exploiting its agronomic potential before and after harvest.

There is an abundant literature about the biological and physiological effects of UV-B light and the signaling and metabolic pathways it triggers and influences. Much less is known about UV-C light even though it seems to have a lot of potential for being effective in less time than UV-B light. UV-C light is known since long to exert direct and indirect inhibitory and damaging effects on living cells and is therefore commonly used for disinfection purposes. More recent observations suggest that UV-C light can also be exploited to stimulate the production of health-promoting phytochemicals, to extent shelf life of fruits and vegetables and to stimulate mechanisms of adaptation to biotic and abiotic stresses. Clearly some of these effects may be related to the stimulating effect of UV-C light on the production of reactive oxygen species (ROS) and to the stimulation of antioxidant molecules and mechanisms, although UV-C light could also trigger and regulate signaling pathways independently from its effect on the production of ROS. Our review clearly underlines the high potential of UV-C light in agriculture and therefore advocates for more work to be done to improve its efficiency and also to increase our understanding of the way UV-C light is perceived and influences the physiology of plants.

Qualidade pós-colheita da banana 'Prata Catarina' submetida a diferentes danos mecânicos e armazenamento refrigerado / Postharvest quality of 'Prata Catarina' banana submitted to different mechanical damages and refrigerated storage

Objetivou-se avaliar o efeito dos danos mecânicos provocados por impacto, corte e abrasão sobre a qualidade de banana 'Prata Catarina', submetida ao armazenamento refrigerado (14°C ±1ºC e 84% ±5% de UR durante 21 dias). Os frutos foram provenientes de um pomar comercial, localizado no município de Limoeiro do Norte-CE. O experimento foi instalado em delineamento inteiramente ao acaso, no esquema de parcelas subdivididas no tempo, tendo-se, nas parcelas, as amostragens ao longo do tempo e, nas subparcelas, os quatro tratamentos: testemunha ou ausência de dano mecânico (T1), impacto (T2), abrasão (T3) e corte (T4), com quatro repetições de dois frutos cada. Os danos por impacto e abrasão foram os que proporcionaram maior velocidade de amadurecimento, sendo que o dano por impacto proporcionou maior atividade da enzima polifenoloxidase. As bananas 'Prata Catarina' que não sofreram danos podem ser comercializadas por até 21 dias de armazenamento (14°C ± 1ºC e 84% ±5% UR), sem perda da qualidade.

The aim of this study was to evaluate the effect of mechanical damages caused by impact, cut and abrasion on the quality of 'Prata Catarina' banana subjected to cold storage (14°C±1°C and 84%±5% RH for 21 days). The fruits were from a commercial orchard in the city of Limoeiro do Norte-CE. The experiment was conducted in a completely randomized design in split plot in time, taking up the samples in portions over time and in the subplots the four treatments: control or absence of mechanical damage (T1), impact (T2), abrasion (T3) and cut (T4), with 4 replicates of 2 fruits. Damages by impact and abrasion were the ones which provided the highest speed of ripening, and the damage caused by impact provided greater polyphenoloxidase enzyme activity. 'Prata Catarina' bananas that suffered no damage can be marketed until 21 days of storage (14°C±1°C and RH 84%±5%), without loss of quality.

Effects of clarification on physicochemical characteristics, antioxidant capacity and quality attributes of açaí (Euterpe oleracea Mart.) juice.

The effects of a clarifying process using pectinases and chitosan on the physicochemical characteristics, antioxidant capacity and quality attributes of açaí fruit (Euterpe oleracea Mart.) juice were evaluated. Clarification of acaí pulp resulted (P ≤ 0.05) in a 50 % loss of total anthocyanin (4.2730 mg/100 mL) and 29 % reduction in antioxidant capacity (33.60 µM FeSO4/g). A high association (P ≤ 0.05) was found between the decrease of antioxidant capacity and total anthocyanin loss. The use of pectinases associated with chitosan as an aid for clarification of açaí juice proved to be highly effective and resulted in a clear juice with a brighter purple to red color that was free of lipids, insoluble solids, and others substances that cause hazes. The obtained clarified açaí juice is a genuinely high-value anthocyanin-rich product that could be used as colorant and functional ingredient to fruit juices and soft drinks.

Antioxidant metabolism during fruit development of different acerola (Malpighia emarginata D.C) clones.

The present research work describes the major changes in the antioxidant properties during development of acerola from five different clones. Ripening improved fruit physicochemical quality parameters; however, total vitamin C and total soluble phenols (TSP) contents declined during development, which resulted in a lower total antioxidant activity (TAA). Despite the decline in TSP, at ripening, the anthocyanin and yellow flavonoid content increased and was mainly constituted of cyanidin 3-rhamnoside and quercetin 3-rhamnoside, respectively. The activities of oxygen-scavenging enzymes also decreased with ripening; furthermore, the reduction in vitamin C was inversely correlated to membrane lipid peroxidation, indicating that acerola ripening is characterized by a progressive oxidative stress. Among the studied clones, II47/1, BRS 237, and BRS 236 presented outstanding results for vitamin C, phenols, and antioxidant enzyme activity. If antioxidants were to be used in the food supplement industry, immature green would be the most suitable harvest stage; for the consumer's market, fruit should be eaten ripe.

Toxicity of hydrolyzed vicilins toward Callosobruchus maculatus and phytopathogenic fungi.

Studies have shown that vicilins (7S storage proteins) from seeds were able to bind to the surface of the Callosobruchus maculatus larval midgut and to the peritrophic matrices of the midguts of Diatraea saccharalis and Tenebrio molitor , inhibiting larval development. Vicilins were also shown to inhibit yeast growth and bind to yeast cells through the association with chitin-containing structures. The present work studies the association of peptides from vicilins of genotypes of Vigna unguiculata (susceptible and resistant to bruchid) with acetylated chitin and the toxicity of vicilin fragments and chitin-binding vicilin fragments to C. maculatus and phytopathogenic fungi. Hydrolysis of vicilins with alpha-chymotrypsin results in a complex mixture of fragments that were separated by chitin-affinity chromatography. Chitin-binding peptides from both genotypes were toxic to C. maculatus larvae, and alpha-chymotrypsin-hydrolyzed vicilins were deleterious to the above insect and to Fusarium oxysporum , Colletotrichum musae , and Saccharomyces cerevisiae fungi.