Cotyledons structure

The seeds of dicotyledonous plants have two cotyledons, or seed leaves, which are part of the embryo. The cotyledons usually are the main storage tissue, although in some plants (such as castor bean) the endosperm also has a storage function. During development in the field, seeds gradually accumulate storage oils, proteins and carbohydrates (Table 3.1). In the seed, the cotyledon structure is relatively simple. The remainder of the embryo, the embryonic axis, consists mostly of undifferentiated cells, but provascular tissue can be detected that develops into vascular tissue in the seedling. 

The physical and chemical properties of dry beans are primary factors in determining subsequent final product quality. Dry bean seed structure is comprised of a seed coat and an embryonic cotyledon. Structurally, seed coat, cell walls, middle lamella and other cellular membranes greatly influence performance. Further, chemical components (carbohydrates, proteins, phytate, polyphenols and lignin) directly influence quality. 

Pascual-Albero, M.J., Perez-Munuera, I., and Lluch, M.A. 1998. Cotyledon structure of raw, soaked and roasted almond (Prunus amygdalus L.), Food Sci. Tech. Int., 4 189-197. 

FIGURE 10-3 Fat stores in cells, (a) Cross section of four guinea pig adipocytes, showing huge fat droplets that virtually fill the cells. Also visible are several capillaries in cross section, (b) Cross section of a cotyledon cell from a seed of the plant Arabidopsis. The large dark structures are protein bodies, which are surrounded by stored oils in the light-colored oil bodies. 

Figure 12.4 depicts the correlation between instrumental texture measured by the force required in a penetration test of cooked beans and the micro structure of hard and soft cotyledons. Individuals also discriminate between hard and soft beans as they are compressed between molars. In soft beans, individual cells, whose middle lamella have been dissolved during cooking, slide one past another during compression. Hard beans with rmdissolved cell walls cells feel tougher because they are fractured across the cotyledons. Think of how effortless it would be to tear down a brick wall that had no mortar binding the bricks. 

Linscheid, M., Wendisch, D. and Strack, D. (1980) The structures of sinapic acid esters and their metabolism in cotyledons of Raphanus sativus. Z. Naturforsch., 35c, 907. 

Figure 3. Structure of the sesame seed (A) and the oil drops in cotyledon (B).

Pig. 101.—Achenial fruits. I, Akene of Pulsatilla eut vertieally, showing adherent feathery style (si), pericarp (p), testa (<), endosperm (e), hypocotyl (h) and cotyledons (col) the last two structures making up the embryo 2, caryopsis of wheat showing beard of hairs above and position of embryo of seed below 3, utricle of Chenopodium cut vertically to show calyx (c), pericarp (p) and seed (s) regions 4, nut of an oak consisting of a glans (g) and cupule (cm). 

The cotyledons the first leaflike structures. Note these may... 

Heat treatment involved in the chemical analysis of isoflavones may affect their structure. Kudou et al. (1991) separated the soybean into three fractions (seed coat, hypocotyl and the cotyledons) and extracted isoflavones using 70% aqueous ethanol at room temperature for 24 h or at 80°C for 15 h. Total isoflavone concentration in hypocotyl was 5.5 to 6 times higher than that in the cotyledon. Glycitin and its derivatives occurred only in the hypocotyl fraction. Most of the malonyl isoflavones were converted to respective glucosides after extraction at 80°C for 15 h. 

Mature soybeans are oval shaped and their sizes are variety-dependent. The seed consists of three major parts seed coat or hull, cotyledon, and germ or hypocotyls. These structural components have the approximate composition shown in Table 2.1. 

At the surface of the placenta, the two arteries and the vein divide into numerous branches supplying the different chorionic trees. The chorionic tree (Figure 2) is the most important structure inside the placenta. The treelike configuration of each fetal cotyledon is duplicated by the vascular system within the tree (25). In each cotyledon there is one chorionic tree, constituted of villi of a different order, in which the fetal vessels run. 

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