Search

Neste trabalho, foram avaliados os efeitos de ácidos e filmes na prevenção do escurecimento do pericarpo de lichia. Lichias 'Bengal' foram colhidas com o pericarpo completamente vermelho e submetidas aos seguintes tratamentos: imersão em ácido cítrico 100 mM, por 5 minutos; imersão em ácido clorídrico (HCl) 1 N, por 2 minutos; imersão em fécula de mandioca 30 g/L, por 5 minutos, e filme de policloreto de vinila (PVC) de 14 µm de espessura, além do controle, não tratado.Os frutos de todos os tratamentos foram acondicionados em bandejas de poliestireno (220 mm x 140 mm x 40 mm), armazenados em câmara fria a 5 ± 1,2°C e 90 ± 5% de UR e avaliados a cada 4 dias, durante 20 dias. A fécula de mandioca e o ácido cítrico não foram eficientes em prevenir ou retardar o escurecimento do pericarpo da lichia. O filme de PVC manteve a coloração vermelha do pericarpo somente até o quarto dia de armazenamento. O HCl foi efetivo em prevenir o escurecimento do pericarpo dos frutos durante todo o período experimental sem prejudicar a qualidade pós-colheita. The effects of acids and films in preventing the pericarp browning of lychee were evaluated. `Bengal' lychees with pericarp completely red were harvested and treated as follows: immersion in citric acid 100 mM for 5 minutes, immersion in hydrochloric acid 1 N for 2 minutes, immersion in cassava starch 30 g/L for 5 minutes and the film of polyvinyl chloride (PVC) 14 mm thick, and a control, untreated. The fruits of all treatments were placed in polystyrene trays (220 mm x 140 mm x 40 mm), stored in a chamber at 5.0 ± 1.2° C and 90 ± 5% UR, and were evaluated every 4 days, for 20 days. The cassava starch and citric acid were not effective in preventing or delaying the browning of the lychee pericarp. The PVC maintained the red color of the pericarp only until the fourth day of storage. The HCl was effective in preventing the pericarp browning throughout the experimental period without spoiling the post-harvest quality.

A 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. Lychee (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.

Phenotypic plasticity in response to environmental variation occurs at all organizational levels and across temporal scales within plants. However, the magnitude and functional significance of this plasticity is little explored in perennial species. We examined the influence of different light regimes and nitrogen (N) availability on the morphological and physiological plasticity of coffee seedlings ( Coffea arabica L.). Potted plants were grown under 100% and 50% of full sunlight and were fertilized with Hoagland’s solutions containing 0, 16 or 23mM N. Most leaf traits responded to light with a classic 100% vs. 50% dichotomy [e.g., compared with those grown under 100% of full sunlight, 50% leaves had a thinner palisade mesophyll and a lower leaf mass per area (LMA) for improved light capture]. The outer periclinal cell walls in both epidermises exhibited thick epicuticular wax and three distinct layers. Chloroplasts of the mesophyll cells were densely occupied by thylakoids and starch grains. These characteristics were observed most clearly in plants supplemented by nitrogen or in those grown in shade conditions. Large starch granules were observed, but no membrane injuries were observed in either treatment. The plasticity index was high for the physiological traits that are associated with photoprotection and the maintenance of a positive carbon balance under 50% of full sunlight but was low for most morpho-anatomical features.

Um dos maiores problemas na pós-colheita da lichia é o escurecimento do pericarpo, o qual tem sido atribuído à degradação da antocianina. O objetivo do trabalho foi avaliar o efeito de diferentes doses de ácido ascórbico na prevenção do escurecimento do pericarpo e na manutenção da qualidade pós-colheita de lichia. Frutos de lichieira 'Bengal' com o pericarpo completamente vermelho foram imersos em solução com diferentes doses de ácido ascórbico (0; 5; 10; 15 e 30 mM), por 5 minutos. Após secagem à temperatura ambiente, foram acondicionados em bandejas de poliestireno, armazenados em câmara fria a 5 ± 1,2°C e 90 ± 5% de UR e avaliados a cada 4 dias, durante 12 dias. Observou-se que a perda de massa fresca foi maior nos frutos não tratados com ácido ascórbico. Independentemente da dose, o ácido ascórbico teve pouco efeito na retenção da cor vermelha do pericarpo de lichia. A atividade das enzimas polifenoloxidase e peroxidase no pericarpo foi maior com as menores doses de ácido ascórbico (0; 5 e 10 mM), entretanto observou-se escurecimento a partir do quarto dia no pericarpo dos frutos tratados com este ácido. O ácido ascórbico também não foi eficiente na manutenção da qualidade interna dos frutos. One of the biggest problems in postharvest of lychees is the pericarp browning, which has been attributed to anthocyanins degradation. The purpose of this work was to evaluate the effect of different doses of ascorbic acid to prevent pericarp browning and on the maintenance of postharvest quality of lychees. Fruits of 'Bengal' lychee with completely red pericarp were immersed in solution with different doses of ascorbic acid (0, 5, 10, 15 and 30 mM) for 5 minutes. After dried, the fruits were packed in polystyrene trays, stored in cold chamber at 5 ± 1,2°C e 90 ± 5% de RH and evaluated every other 4 days for 12 days. It was observed that the loss of fresh weight was higher in non-treated with ascorbic acid fruits. Independently of the dose, the ascorbic acid had little effect on the retention of the red color of the lychee pericarp. The polyphenoloxidase and peroxidase activities in the lychee pericarp was increased with lower doses of ascorbic acid (0, 5 and 10 mM), however, there was pericarp browning after the fourth day in the fruits of all treatments in ascorbic acid. Ascorbic acid was not efficient in maintaining the internal quality of fruit.

A novel trypsin inhibitor was purified from the seeds of Peltophorum dubium (Spreng.). SDS-PAGE under reducing conditions showed that the inhibitor consisted of a single polypeptide chain (ca. 20 kDa). The dissociation constants of 4 x 10(-10) and 1.6 x 10(-10) M were obtained with bovine and porcine trypsin, respectively. This constant was lower (2.6 x 10(-7) M) for chymotrypsin. The inhibitory activity was stable over a wide range of temperature and pH and in the presence of DTT. The N-terminal sequence of the P. dubium inhibitor showed a high degree of homology with other Kunitz-type inhibitors. When fed to the insect Anagasta kuehniella, in an artificial diet (inhibitor concentration 1.6%), the inhibitor produced approximately 56% and delayed the development of this lepidopteran. The concentration of inhibitor in the diet necessary to cause a 50% reduction in the weight (ED50) of fourth instar larvae was approximately 1%. The action of the P. dubium trypsin inhibitor (PDTI) on A. kuehniella may involve inhibition of the trypsin-like activity present in the larval midgut, resistance of the inhibitor to digestion by midgut enzymes and bovine trypsin, and association of the inhibitor with a chitin column and chitinous structures in the peritrophic membrane and/or midgut of the insect.