Histological Development of the Green Bean Pod as Related to Culinary Texture.

Abstract

SUMMARY— The different tissues of the green pod exhibit a wide range in cellular structure and composition at edible maturities. Large substomatal spaces and intercellular spaces in outer parenchyma and thick‐walled hypodermis contribute to cell separation or sloughing when the beans are cooked. Cells of the outer parenchyma contain numerous starch granules, are thicker walled than the inner parenchyma cells, and usually are not torn as a result of freezing. Cells of the inner parenchyma are thin‐walled and form a compact, succulent tissue with only minute intercellular spaces. Slow rates of freezing result in radial cracks often extending into the young fiber sheath lying between the inner and outer parenchyma zones. With more rapid freezing small cracks sometimes appear only in close association with the immature fiber sheath cells. Prolonged immersion freezing usually results in radial splitting throughout all tissues without respect to differences in structure and composition. In pods overly mature for culinary use wall thickening and lignification of sheath sheath and sclereid caps contribute to toughness and stringiness. Other histological aspects of texture qualities involve growth environment and postharvest conditions.

Physico‐Chemical and Structural Characteristics of Vegetables Cooked Under Sous‐Vide, Cook‐Vide, and Conventional Boiling

“…In green beans, epidermal and hypodermal layer cells were observed (Figure b). As described by Reeve and Brown (), secondary walls were found in the hypodermal tissue of the bean pods. In raw samples, lines drawn in cytoplasmic regions (equivalent of the solute content) were more than in cooked ones.…”

An Electron Microscopy Study on the Texture of Fresh, Blanched and Sterilized Green Bean Pods (Phaseolus vulgarisL.)

“…In addition they contain large vacuoles and a large number of chloroplasts and starch granules (2). The cells of the inner parenchyma tend to be more uniform in size and shape, forming a more compact tissue (3,4). Only cells in the vascular tissues and the hypodermis contain secondary walls at edible maturity.…”

Desenvolvimento morfo-anatômico do fruto de Dalbergia nigra (Vell.) Fr. All. (Leg. - Papilionoideae)

“…A origem epidérmica desta região pericárpica parece ser comum na sub-família Papilionoideae (Kaniewsky, 1968;Kaniewsky & Wazinska, 1968;Reeve & Brown, 1968;Souza, 1984).…”