Читать книгу Dry Beans and Pulses Production, Processing, and Nutrition - Группа авторов - Страница 91

As is consistent with all biological systems, bean quality degradation occurs faster at relatively higher temperatures (Burr et al. 1968; Bradford et al. 2018). Uebersax and Bedford (1980) reported that navy bean quality deteriorates during storage with increases in relative humidity (RH) and temperature, both for dry and subsequently processed beans. Stable quality was obtained in navy beans stored at 75% RH or less with temperatures of 20°C (70°F) or lower. Mold growth occurred on beans stored at 20°C (70°F) and 30°C (85°F) when the relative humidity was greater than 75% (16% moisture). Deterioration rates based on seed discoloration and mold growth was minimized in beans stored at 55°F under relative humidity ranging from 75% to 86%. The influence of increased storage temperature became greater at higher relative humidity.

Chemical and biological changes occur during dry bean storage. Dhahir (1987) reported increased total protein and pectin solubility for cold water, but decreased soluble protein, soluble solids, and pectin solubility in hot water and alkaline solution for dry beans (navy, black, pinto, and kidney) stored for 9 months at 18% moisture at 5°C, 20°C, and 35°C. Additionally, three bean cultivars of navy (Seafarer), pinto (Oletha), and kidney (Montcalm) were stored at three different storage temperatures (5°C, 20°C, and 35°C) with moisture levels of 10–18%. As storage temperature and moisture content increased, both the cooking time and processed bean firmness (shear force) increased. Results demonstrated a high correlation between cooking time and shear force.

Beans are typically stored with good cooking and processing quality up to one year; however, they are commonly held as carryover beyond one season. Storage beyond one year presents higher risks of quality deterioration due to physiological changes that can result in adverse storage‐induced defects, e.g., hard‐to‐cook phenomena and seed discoloration (Uebersax and Siddiq 2012).