Читать книгу Dry Beans and Pulses Production, Processing, and Nutrition онлайн

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The seed coat affects water absorption; however, the precise mechanism is unknown. Research on soybeans shows that the water absorption rate depends on the calcium content, seed coat surface, micropyle structure, and initial moisture content (Saio 1976; Hsu 1983). In studying the structural components, Sefa‐Dedeh and Stanley (1979a) found seed coat thickness, seed volume, and hilum size, along with protein content, to be the primary factors involved in water uptake. Thinner seed coats appear to absorb water more rapidly during initial soaking (0–6 hours). Siah et al. (2014) investigated the effect of soaking, boiling, and autoclaving (pressure cooking) on the phenolic contents and antioxidant activities of Australian grown broad/faba bean genotypes differing in seed coat color. A significant amount of active compounds was shown to leach into the soaking and cooking medium. Boiling was a better method in retaining active compounds in beans than autoclaving.

Seed coat color varies greatly among legumes due to compositional differences (discussed below). The seed coat must remain intact during storage and handling and must hydrate uniformly to enable swelling of the seed constituents during soaking and cooking procedures. Excessive seed coat rupture or sloughing will result in diminished culinary quality. This is particularly a concern with the sensory detection of tough free skins during maceration and excessive starch leaching during cooking or canning.