This study compared the effect of application of edible coating on or before ultraviolet treatment on postharvest longan fruits. The treated longan fruits were examined for weight loss, respiration rate, surface color changes, enzymatic activities (PPO, POD, and PAL), and total phenolic contents throughout the 7 storage days at ambient temperature. In addition, coat homogeneity was examined and cell structure of longan flesh at the end of storage was observed. The results showed that when UV was applied before coating (i.e., chitosan or carrageenan), it had relatively lower PPO and PAL activities and retained higher TPC in longan pericarp. However, the changes in enzymatic activities did not affect the surface lightness and browning index as they were more influenced by the type of coating, in which combination treatments with carrageenan showed higher surface lightness and lower browning index compared to treatment combinations containing chitosan. However, when UV treatment preceded coating, the combinations of UV plus chitosan coating produced lower PPO and PAL activities and retained better cell structure with less damage than the combinations of UV plus carrageenan coating. UV plus carrageenan coating showed relatively higher weight loss and respiration rate, with cell structure exhibiting bigger intercellular spaces at the end of storage. Therefore, application of UV treatment followed by chitosan coating was found to be the best treatment combination for controlling enzymatic activities and reducing senescence rate of longan fruits.

The effect of chitosan/carrageenan and glycerol as edible coating materials in preserving the fresh longan fruits stored at ambient temperature was evaluated. The concentration of coating components played an important role in the process of controlling quality changes and quantity losses. Changes in fruits' weight loss, respiration rate and color were used as a measure of the coating's effectiveness. Results have shown that increase in the chitosan or carrageenan concentration led to significant (p < 0.05) decreases in water loss, weight loss and respiratory rate in coated fruits. However, in carrageenan-coated fruits, high increase in concentration (> 1.19%) of the carrageenan resulted in slight increases in water and weight losses. From the multiple response optimization analysis, a combination of 1.29% (w/v) chitosan with 0.42% glycerol and 1.49% (w/v) carrageenan with 0.03% glycerol were predicted to give the desired coating because they were able to preserve the longan by showing minimal quality changes and quantity losses. Efecto de los recubrimientos comestibles a base de chitosano y carragenano en los frutos de longan (Dimocarpus longan) después de la cosecha RESUMEN El presente estudio se propuso evaluar el efecto de materiales de recubrimiento comestibles a base de chitosán/carragenano en la conservación de frutos de longan frescos, almacenados a temperatura ambiente. La concentración de los componentes de recubrimiento desempeñó un rol importante en el proceso de control de los cambios de calidad y las pérdidas de cantidad. Los cambios en el peso, la tasa de respiración y el color fueron utilizados como medida de la eficacia del recubrimiento. Los resultados mostraron que al aumentar la concentración de quitosano o carragenano se redujo significativamente (p < 0.05) la pérdida de agua, la pérdida de peso y la tasa respiratoria en los frutos con recubrimiento. Sin embargo, en los frutos cubiertos con carragenano, el elevado aumento en su concentración (> 1.19%) produjo un ligero aumento del agua y pérdida de peso. El análisis de optimización de respuesta múltiple permitió pronosticar que la combinación de 1.29% (w/v) quitosano con 0.42% de glicerol y 1.49% (w/v) de carragenano con 0.03% glicerol producirían el recubrimiento deseado, pues pudieron conservar el longan con mínimos cambios en la calidad y mínimas pérdidas de cantidad.

BackgroundFood flavor appreciation is one of the first signals along with food appearance and texture encountered by consumers during eating of food. Also, it is well known that flavor can strongly influence consumer’s acceptability judgment. The increase in the consumption of snail meat across the world calls for the need to research into the aroma compounds responsible for the distinctive aroma notes of processed snail meat.ResultsThe odorants responsible for the unique aroma notes in thermally processed giant African snail meats were evaluated by means of aroma extract dilution analysis (AEDA), gas chromatography–olfactometry (GC–O) and odor activity values (OAVs) respectively. Results revealed significant differences in the aroma profiles of the raw and thermally processed snail meats. Whilst the aroma profile of the raw snail meat was dominated with the floral-like β-ionone and β-iso-methyl ionone, sweaty/cheesy-like butanoic acid, and the mushroom-like 1-octen-3-one, the boiled and fried samples were dominated with the thermally generated odorants like 2-methylpyrazine, 2,5-dimethylpyrazine, 2-acetylthiazole and 2-acetylpyridine.ConclusionFinally, results have shown that sotolon, 2-acetyl-1-pyrroline, 2-furanmethanethiol, 2-methylbutanal, 1-octen-3-one, octanal, furanone, 2-methoxyphenol, 2-acetylpyridine, 2-acetylthiazole, and 2-methylpyrazine contributed to the overall aroma of the thermally processed snail meat.

No abstract