Influence of the use of acids and films in post-harvest lychee conservation

Abstract

RESUMO Influência da utilização de ácidos e filmes na conservação pós-colheita de lichiaA lichia (Litchi chinensis Sonn.) possui alto valor comercial no mercado, entretanto, apresenta vida útil pós-colheita curta, por causa do rápido escurecimento do pericarpo. O objetivo deste trabalho foi avaliar a vida útil pós-colheita de lichias 'Bengal', armazenadas após tratamento com ácido clorídrico e ácido cítrico, associados a fécula de mandioca e embalagem plástica. Frutos com pericarpos uniformemente vermelhos foram submetidos aos tratamentos: 1-( imersão em ácido cítrico 100 mM por 5 minutos + fécula de mandioca 30 g/L por 5 minutos); 2-( imersão em ácido clorídrico 1 M por 2 minutos + fécula de mandioca 30 g/L por 5 minutos); 3-( imersão em ácido cítrico 100 mM por 5 minutos + filme de policloreto de vinila (PVC ,14 µm de espessura)); e 4-( imersão em ácido clorídrico 1 M por 2 minutos + filme de PVC). Durante 20 dias, os frutos foram avaliados quanto à perda de massa fresca, cor do pericarpo, pH, teor de sólidos solúveis e acidez titulável da polpa, vitamina C do pericarpo e da polpa e atividades de polifenoloxidase e peroxidase do pericarpo. O tratamento com ácido clorídrico associado ao PVC foi o mais efetivo na manutenção da cor vermelha e o que melhor conservou as características de qualidade dos frutos. A fécula de mandioca associada ao ácido cítrico e ácido clorídrico não reduziu a perda de massa e não impediu o escurecimento do pericarpo de lichia. Influence of the use of acids and films in post-harvest lychee conservation 1 Palavras-chave: Litchi chinensisLychee (Litchi chinensis Sonn.) has a high commercial value; however, it has a short shelf-life because of its rapid pericarp browning. The objective of this study was to evaluate the shelf-life of 'Bengal' lychee fruits stored after treatment with hydrochloric acid and citric acid, associated with cassava starch and plastic packaging. Uniformly red pericarp fruits were submitted to treatments: 1-(immersion in citric acid 100 mM for 5 minutes + cassava starch 30 g L -1 for 5 minutes), 2-(immersion in hydrochloric acid 1 M for 2 minutes + starch cassava 30 g L -1 for 5 minutes), 3-(immersion in citric acid 100 mM for 5 minutes + polyvinyl chloride film (PVC, 14 µm thick)) and 4-(immersion in hydrochloric acid 1 M for 2 minutes + PVC film). During 20 days, the fruits were evaluated for mass loss, pericarp color, pH, soluble solids and titratable acidity, vitamin C of the pulp and pericarp and activities of polyphenol oxidase and peroxidase of the pericarp. The treatment with hydrochloric acid associated with PVC was the most effective in maintaining the red color of the pericarp for a period of 20 days and best preservation of the fruit. The cassava starch associated with citric acid, and hydrochloric acid did not reduce the mass loss and did not prevent the browning of lychee fruit pericarp.

Uso de embalagem e da refrigeração no armazenamento de lichias “Bengal”

“…It was also found that these levels decreased significantly during storage. The reduction of the titratable acidity values over the days was also observed by Silva et al (2012), Liang et al (2013) and , in litchi, regardless of the treatment used. Also in Table 2, it was found that the SS/TA ratio was not affected by the treatments, but there was effect of the storage time in this parameter, with an increase in values.…”

Combined effect of acids and shellac coating on pericarp browning, enzymatic activities, and biochemical attributes of litchi fruit during storage

“…Ascorbic acid oxidizes rapidly in the presence of oxygen and application of coatings limits the gaseous exchange that consequently reduces the oxygen gas concentration inside the fruit and prevents the ascorbic acid oxidation. Silva et al (2012) observed smaller reductions in ascorbic acid content of cassava treated with HCl and Zhou et al (2008) also reported better retention of ascorbic acid in shellac‐coated pear fruits.…”

“…However, HCl‐treated litchi fruits showed superiority over other treatments as minimum POD activity was seen in higher concentration of HCl (0.5 M) in combination with shellac wax (48.10 unit/min/g FW) followed by HCl 0.25 M + shellac (50.20 unit/min/g FW). Silva et al (2012) recorded that combined effect of PVC film and hydrochloric acid resulted in lower POD enzymatic activity in litchi fruit pericarp.…”

Exogenous Application of Oxalic Acid Delays Pericarp Browning and Maintain Fruit Quality of Litchi cv. “Gola”

“…; Silva et al . ). Similarly, various anti‐browning agents like calcium chloride, Iso‐ascorbic acid, 4‐hexylresorcinol and citric acid have also been found effective to control browning in apple, pear, loquat and mango (Monsalve‐Gonzalez et al .…”

“…Previously, SO2 was used commercially to control pericarp browning in litchi, but sulfur residues left in fruit caused harmful effects on consumer's health (Sivakumar et al 2005;Kudachikar et al 2007). Therefore, other substitutes such as citric acid with cassava starch, hydrochloric acid with PVC film, chitosan in combination with ascorbic acid and N-acetyl cysteine have also been reported to delay pericarp browning in litchi (Liu et al 2006;Sun et al 2010;Silva et al 2012). Similarly, various anti-browning agents like calcium chloride, Iso-ascorbic acid, 4-hexylresorcinol and citric acid have also been found effective to control browning in apple, pear, loquat and mango (Monsalve-Gonzalez et al 1995;Buta and Abott 2000;Ding et al 2002;Guerrero-Beltran et al 2005).…”