Читать книгу Dry Beans and Pulses Production, Processing, and Nutrition - Группа авторов - Страница 90

The aggregate moisture content of bean seed is the most important consideration during harvest and storage. Seeds with moisture content above 18% are subjected to excessive damage during storage and in the processing line, due to physical susceptibility to mechanical forces and microbial spoilage from molds. However, seeds with moisture content below 15% are increasingly sensitive to impact damage. Dry beans have been studied widely with respect to storage stability and quality (McCurdy et al. 1980; Uebersax and Bedford 1980; Dhahir 1987; Rani et al. 2013). Respiration rates of beans decrease with moisture concentrations as beans mature (Swanson et al. 1977), with none detected at beans of <18% moisture.

Beans stored at too low moisture exhibit increased clumping and splitting upon canning due to seed coat and cotyledon rupture, while storage at high initial moisture encourages discoloration, off‐flavor development, loss of water uptake capacity, and mold growth. Morris and Wood (1956) reported that beans with moisture content above 13% deteriorated significantly in both flavor and texture after six months at 77 °F and became unpalatable within 12 months. Burr et al. (1968) reported that beans stored at high moisture showed a significant increase in their required cooking time while low moisture did not lose their cooking quality.

McCurdy et al. (1980) evaluated and compared different moisture equilibration and moisture determination methods with dry beans and indicated significant variation among individual dry beans for all methods of moisture equilibration, especially with direct addition of water, but observed no significant differences among the methods of moisture analysis. Storage A moisture content of 14.1% (a_w = 0.755) or less was recommended when storing pinto beans for microbial stability. It was recommended that a mean and coefficient of variation for moisture content of a representative sample should be used to define the actual condition of the beans.