Marcos José Trevisan

Mudanças na respiração e no coeficiente Q10 de goiaba relacionadas à temperatura

A goiaba (Psidium guajava L.) e um fruto tropical que apresenta rapido amadurecimento, o que a torna um produto muito perecivel. Temperaturas inapropriadas durante o armazenamento e comercializacao podem acelerar a perda da qualidade dos frutos. O objetivo desse trabalho foi avaliar a atividade respiratoria (AR), a producao de etileno (PE) e o coeficiente Q10 de goiabas em diferentes temperaturas de armazenamento. Goiabas do cultivar Paluma foram colhidas no estadio 1 de maturacao (casca verde escura) e armazenadas a 1, 11, 21, 31 e 41oC. A AR e a PE foram determinadas com 12, 36, 84 e 156 h de armazenamento. As taxas de AR e PE a 1 e 11oC foram as menores, atingindo valores ao redor de 0,16 e 0,43 mmol CO2 kg-1 h-1 e 0,003 e 0,019 µmol C2H4 kg-1 h-1, respectivamente. Quando as goiabas foram armazenadas a 21oC, observou-se aumento gradual em AR e PE, as quais alcancaram valores de 2,24 mmol CO2 kg-1 h-1 e 0,20 µmol C2H4 kg-1 h-1 apos 156 h de armazenamento. As maiores AR e PE foram observadas em goiabas armazenadas a 31oC. Apesar de alta AR, goiabas armazenadas a 41oC tiveram baixa PE, similarmente aquelas armazenadas a 11oC, indicando dano por alta temperatura. Na faixa de 1-11oC, o valor medio de Q10 foi de 3,0, enquanto esse valor quase duplicou na faixa de 11-21oC, atingindo 5,9. O Q10 decresceu nas faixas de 21-31oC e 31-41oC, apresentando valores de 1,5 e 0,8, respectivamente. Conhecendo-se a variacao do Q10, da taxa respiratoria e do comportamento do amadurecimento em resposta a diferentes temperaturas, as condicoes de armazenamento e comercializacao dos frutos podem ser otimizadas para reduzir as perdas na qualidade.

Effect of antioxidants in fresh cut radishes during the cold storage

The objective of this study was to evaluate the eff iciency of antioxidants in the cold storage of fres h cut radishes. The shredded roots were submerged in the respective treatments during 3 min (ascorbic acid or citric a cid) and stored at 5oC and 90% RH during 10 days. The radish treated with ascorbic acid showed the higher respi ratory rate in the first 4 h after the processing during the storage. The content of total soluble solids (TSS) wa s significantly higher in the treatment with citric acid. There was an increase in the content of ascorbic acid after two day of storage in the treatments with this antioxidant. Th e values of lightness (L*) were decreasing along th e storage. Citric acid treatments caused strongly red colorati on in the minimally processed roots. None of the tr eatments avoided the browning of the shredded radishes durin g the cold storage.

Influência do intervalo entre a colheita e a aplicação do 1-metilciclopropeno no controle do amadurecimento de mamão

The purpose of this work was to determine the influence of the interval between harvest and 1-MCP application on 1-MCP efficiency in delaying ripening in Golden papaya. Fruits were harvested from commercial orchards located in Linhares, ES, in a second stage of maturation, stored at 11±1oC and treated with 1-MCP (100 nL.L-1) 0, 1, 2 and 3 days after harvest. Treated and non-treated fruits were kept at 11±1oC for 6 days and, then, were stored at 22±1.5oC and 80-90%RH until complete ripening. 1-MCP delayed loss of firmness and skin color changes. Non-treated fruits reached ideal firmness for consumption between the 2nd and 4th day of storage at 22oC. Fruits treated with 1-MCP on the 2nd or 3rd day after harvest reached consumption stage between the 8th and 10th day of storage at 22oC. While fruits treated with 1-MCP one day after harvest reached optimum firmness for consumption on the 12th day of storage at 22oC, those treated on the harvest day did not softened. Though more subtly, skin color behaved in a similar way as firmness. There was a slight increase in soluble solids amounts in fruits along ripening. The lower the interval between harvest and 1-MCP application, the longer the 1-MCP efficiency in delaying ripening in Golden papaya. This is the key information when defining the application procedure for 1-MCP as a ripening regulator.

PONTO DE COLHEITA E QUALIDADE DE GOIABAS ‘KUMAGAI’ E ‘PALUMA’

ABSTRACTThis research aimed to study the influence of maturation on the quality of ‘Kumagai’ and ‘Paluma’ guavas. Healthy fruits of both cultivars harvested at five maturity stages defined on the basis of skin color, were selected for the absence of mechanical damage and rot and stored under environmental conditions (25±1oC and 85±5% RH). They were evaluated at the time of harvest and after reaching full maturity as the shelf-life, skin color, pulp firmness, ascorbic acid, soluble solids (SS) and titratable acidity (TA), as well as the SS/TA ratio and the flavor. The results indicated that cv. Kumagai guavas have longer conservation (6.8 days on average) than ‘Paluma’ (3.2 days on average) and that this period is influenced by ripening stage. Regardless of cultivar, guavas harvested in early stages of maturation kept more acid (0.71%) than that those harvested later (0.57%), with the aggravating circumstance that in cv. Kumagai, the harvest in stage 1, resulted in retention of the green color of the skin. The harvest of guava in early stages despite prolonging the shelf-life implies inferior fruit quality. On the other hand, the harvest in more advanced stages of maturation makes necessary the implementation of appropriate conservation techniques to the intrinsic characteristics of each variety, in order to ensure the quality of the fruit offered to the consumer.

Residues of carbosulfan and its carbofuran metabolites and 3-hydroxy-carbofuran in oranges

The objectives of this study were to evaluate the residues of the insecticide carbosulfan and its carbofuran metabolites and 3-hydroxy-carbofuran in orange compartments (whole fruit, bagasse and juice) and comparison between the residual levels found in fruits with the maximum residue level and the safety interval established by the Brazilian legislation. Two field experiments were carried out, both with the following treatments: a-check; b-one application of 10 g of carbosulfan . 100 L-1 of water; c-one application with twice the rate applied in treatment b; d-four applications with the same rate applied in treatment b. Samples were taken at (-1), zero, 1, 3, 7, 14, 21 and 28 days after the last or unique application. The quantitative determinations were done by gas chromatography technique, using a nitrogen-phosphorus detector. The carbosulfan metabolism to its carbofuran metabolite was rapid (3 days), being both analytes concentrated in the bagasse (peel + flavedo + albedo). However, the metabolism of carbofuran to 3-hydroxy-carbofuran was of low intensity or this metabolite was quickly dissipated. Carbosulfan residues and its metabolites did not penetrate into the fruit, thus not contaminating the juice. The use of the pesticide was adequate, with respect to fruit consumption, in relation to the Brazilian legislation.