Análise pós-colheita de goiabas revestidas com fécula de mandioca e óleo essencial de canela

Guava is a perishable fruit susceptible to a large amount of post-harvest losses. Biodegradable coatings have been studied as an alternative to reduce these losses. This study aimed to evaluate the chemical composition of guavas ‘Pedro Sato’ coated with cassava starch with or without the essential oil of cinnamon, submitted to three treatments: control, starch and starch 2% + 2% essential oil of cinnamon 0.01% and stored at 25 ° C and 76 ± 5% RH for 8 days. The experimental design in a factorial 3x5 (3 treatments x 5 times analyzes, 0, 2, 4, 6 and 8) with 3 replicates of 3 fruits, were studied:  weight loss, pH, soluble solids, titratable acidity, sugars total and reducing sugars and ascorbic acid. The weight loss, pH and soluble solids content increased, while the acidity decreased in all treatments. Treatments starch and starch 2% + 2 cinnamon essential oil 0.01% on the eighth day had lower levels of total sugars than control. Reducing sugars increased in all treatments during the days of storage, while ascorbic acid decreased, but to a lesser extent in treatments starch 2% and starch + essential oil of cinnamon 0.01%. The starch 2% + essential oil of cinnamon 0.01% represents good alternative for post-harvest guava conservation, maintaining the chemical characteristics of the fruit without undesirable changes.A goiaba é um fruto perecível susceptível a uma grande quantidade de perdas na pós-colheita. Revestimentos biodegradáveis vêm sendo estudados como uma alternativa para reduzir essas perdas. Este trabalho teve como objetivo avaliar a composição química de goiabas ‘Pedro Sato’ revestidas com fécula de mandioca associada ou não ao óleo essencial de canela, submetidas a três tratamentos: controle, fécula 2% e fécula 2% + óleo essencial de canela 0,01%, e armazenadas a 25ºC e 76 % ± 5 UR, por 8 dias. Utilizou-se delineamento experimental em esquema fatorial 3x5 (3 tratamentos x 5 tempos de análises, 0, 2, 4, 6 e 8) com 3 repetições de 3 frutos, sendo avaliados: pH, sólidos solúveis, acidez titulável, açúcares totais e redutores e ácido ascórbico. O pH e o teor de sólidos solúveis aumentaram, enquanto a acidez diminuiu em todos os tratamentos. Os tratamentos fécula 2% e fécula 2% + óleo essencial de canela 0,01% apresentaram no oitavo dia teores de açúcares totais menores que o controle. Os açúcares redutores aumentaram nos três tratamentos durante os dias de armazenamento, enquanto o ácido ascórbico diminuiu, porém de forma menos acentuada nos tratamentos fécula 2% e fécula 2% + óleo essencial de canela 0,01%. A fécula 2% + óleo essencial de canela 0,01% representam uma boa alternativa para a conservação pós-colheita da goiaba, mantendo as características químicas do fruto, sem alterações indesejáveis

Mechanism of firmness loss in guava cv. Pedro Sato during ripening at room temperature

<div><p>Abstract Guava (Psidium guajava L.) is fruit with very short shelf life due to associated with the loss of firmness in the pulp and information on the activity of enzymes that degrade pectic substances, as well as the amount of pectin, is very contradictory and not clearly defined. This work showed that the firmness of the fruit decreased sharply on the first four days of ripening. The identified phenolic compounds had their content increased with fruit maturation. The addition of the enzymes cellulase and hemicellulase in the pectin extraction in fruits of Psidium guajava revealed higher contents of this polyssacaride that the ones reported in literature, highlighting pectin as the responsible for the firmness of these fruits at more adequate contents. β-D-glucosidase was identified as one of the responsible enzymes for the maturation of P. guajava fruits. Thus, studies about possible inhibitory effects of this enzyme in P. guajava fruits may reveal an important tool to reduce pectin release and early maturation of these fruits.</p></div

Modifications in the methods to extract pectin from cv. “Pedro Sato” guavas during ripening

<div><p>Abstract Guava is a highly perishable fruit due to its intense metabolism during ripening, with a shelf life of up to five days at room temperature. The loss of firmness during ripening is caused by the activity of hydrolytic enzymes that promote dissolution of the pectin constituents of the cell wall. Although guava is considered to be rich in pectin, the amounts reported in the literature do not exceed 2.4%, a content indicating it is not responsible for the firmness of guava. The aim of this study was to extract pectin from the guava pulp during 7 days of ripening by two methods (ethanol and EDTA extraction) and suggest modifications in the methods by adding to the extraction residue, cellulase and pectinase to degrade the cell wall structure of the fruit and obtain larger amounts of pectin, which would imply the participation of pectin in the maintenance of fruit firmness. It was possible to infer there were no differences in the pectin levels extracted by the two methods, due to sugar contamination. As from the new stage in the execution by the two methods, the extraction was more efficient: 9.10% of pectin with EDTA and 7.63% with ethanol. The pectin contents found were higher than those mentioned in the literature, better explaining their responsibility in fruit firmness.</p></div