Physico-chemical characterization of stored black beans ( Phaseolus vulgaris L.)

Abstract

Selected physical and chemical characteristics were studied on black beans ( Phaseolus vulgaris L.) after 2 years of storage under refrigerated hypobaric conditions (RHC) and ambient conditions (AC). Black beans stored under RHC of 4.5°C, 50–60% relative humidity and atmospheric pressure of 125 mm Hg exhibited quality factors characteristic of fresh beans, such as shorter cooking time, smaller quantities of solids loss, electrolytes leached, and percentage of hardshell than beans stored at AC of 23–25°C and 30–50% relative humidity. Additionally, beans stored under RHC demonstrated greater germination rate (93%) than beans stored at AC (72%). Beans stored at AC exhibited quality factors characteristic of hard-to-cook (HTC) beans. Percentage water absorption indicated a faster initial hydration rate in beans stored under RHC compared to beans stored at AC until after 12 h of soaking, when both reached a similar hydration rate. Moisture content of beans stored under RHC was similar to that of beans prior to storage, while the moisture content of beans stored at AC was significantly lower. Crude protein, crude fat, and ash concentration of beans prior to storage and beans stored for 2 years under RHC or AC were not significantly different. The electrophoretic profile of the main protein of beans, globulin G1, was not altered by the storage conditions. The combined effect of refrigeration and hypobaric storage conditions demonstrated potential for maintaining the fresh quality of beans in storage for up to 2 years.