Effect of packaging on the quality of minimally processed long bean (Vigna sesquipedalis L.)

M. Razali, H. Aminuddin, A. Noor Azizah and M. Habsah

Abstract

Long beans (Vigna sesquipedalis L.) were cut into 3–4 cm long and packed in three different types of packaging namely 500 ml round-shaped polypropylene (PP), airtight polyvinyl chloride (aPVC) and non-airtight polyvinyl chloride (nPVC) containers. Samples were stored at 2 °C and evaluated every 3 days of the 14 days of storage. Quality observation was based on physical and chemical changes, rate of respiration and ethylene production. The shelf life of minimally processed (MP) long bean was 14 days at 2 °C. Changes in total titratable acidity (TTA), ascorbic acid (AA) content, CO2 concentration and the rates of O2 consumption and ethylene production of MP long bean were reduced significantly (p <0.05) when stored at 2 °C. There were significant (p <0.05) differences in the percentage of weight loss, pH and concentrations of O2 and CO2 among types of packaging used, but the TTA, AA content and the rate of ethylene production were not significantly (p >0.05) different. The percentage of weight loss of MP long bean increased significantly (p <0.05) (1.34%) when packed in nPVC and stored at 2 °C and caused the samples to dehydrate. The symptom was not seen in samples packed in PP or aPVC containers. MP long bean softened and became soggy quickly. This might be due to condensation of water vapour as the by-product of the respiration process and reduction in O2 concentration in packages that encouraged alcoholic fermentation. Microbiological analysis of MP long bean indicated the reduction in coliform contamination, but the count of yeast and mould increased during storage period. Therefore, for a commercial purpose, packing of MP long bean in PP container is a better choice and more suitable as compared to aPVC and nPVC, since the freshness of the product can be maintained for a longer period.

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