Smooth peas

Pea starch granules are oval, sometimes fissured, with a diameter of 20-40 ym (13). Molecular and structural characteristics of the two main components of field pea starch—amylose and amylopectin—are important in determining functional properties (25,26). Smooth field pea starch concentrate contains 97.2% starch of which 30.3-37.8% is amylose (9,23,25-27), and wrinkled pea starch concentrate contains 94.8% starch, which is 64% amylose (26). The gelatinization temperature of smooth pea starch is between 64 to 69 C, and that of wrinkled pea starch is greater than 99 C to 115 C. Gelatinization temperature depends on maturity of field pea seed and amylose content (26,27). 

Native starch granules exhibit three main types of X-ray diffractogram. The A type is characteristic of most starches of cereal origin the B t5q)e of potato (Figure 8.3), other root and tuber starches, and amylomaize starches and retrograded starch the C type of smooth pea and various bean starches. 

Colonna, R, Mercier, C. (1984). Macromolecular structure of wrinkled- and smooth-pea starch components. Carbohydrate Research, 126,233-247. 

Figure 5.9 Distribution of the crystalline domains in pea starch (a) optical micrograph of a typical sample of smooth pea starch after a 7 im step irradiation with an x-ray beam of 2p,m diameter, each step consisting of a 1 6s exposure (b) set of microfocus x-ray diffraction patterns recorded on a smooth pea starch granule. Each diagram corresponds to a diffraction area of " 3 xm2 steps of 7pm separate the diagrams. (Reproduced with permission from reference 41)...

Figure 6.12 Proposed cluster model of smooth pea amylopectin (a) the mode of interconnection of small structural units to build up dextrin b1. Arrows trace the sub-pieces (included in boxes) of the larger dextrins (b) the fine structure of the dextrins showing how the clusters of short chains (—) are interconnected by long B-chains.261...

Doublier, J. L. 1987. A rheological comparison of wheat, maize, feba bean and smooth pea starches. J. Cereal Sci. 5 247-262. 

High amylose (ca. 60-85% amylose) pea starch (HAP) was obtained from Stauderer (Germany) with a composition of starch 80% and protein ca. 1%. Normal yellow smooth pea starch (ca. 35% amylose STL) was purchased from Pelmolen (The Netherlands). The composition was starch 84% and protein ca. 5%. Water (W) and glycerol (G) were used as plasticizers. Waxy com (Amioca, WCN) and potato starch (Farina, PN) were obtained from National Starch and Avebe, respectively. 

Protein Composition of Peas (Reduced Data Set) (a) 1 = Smooth Pea Cultivars 2 = Wrinkled Pea Cultivars (b) LaurelPs Technique (c) Ultracentrifugation... 

This structure is an almost perfectly left-handed sixfold one. Depending on the starch genotype, three different crystal native forms can be detected A (cereal starches), B (mber starches and cereal starches rich in amylose), and C (smooth pea and various beans) [6]. The difference between A and B type is due to how the double helices are packed and how many water molecules are incorporated in the crystal cell. 

In nature, starch is found as crystalline beads of about 15-100 /u.m in diameter, in three crystalline modifications designated A (cereal), B (tuber), and C (smooth pea and various beans), all characterized by double helices almost perfect left-handed, six-fold structures, as elucidated by X-ray diffraction experiments (18,20,21). Starch beads may also show V crystallinity, characterized by a single helix when starch is in presence of fatty acids (22). 

Fig. 2. Typical DSC curves for pea and maize starch. Water volume fractions (Vi) wrinkled pea (A), Vi = 0.35 smooth pea (B) Vi = 0.29 high amylose maize (C), Vi = 0.20 and normal maize (D), Vi = 0.55. Reprinted from Ref 72, copjrright 1985, with kind permission from Elsevier Science.

Fig. 6.3. (A) Changes in the levels of starch and dextrin ( ), dextrin (o), free sugars (a) and extracted protein (v) in the cotyledons of the smooth pea (cv. Alaska). Time of radicle elongation was not reported in these studies. (B) Changes in starch phosphorylase (o) and amylase ( ) enzymes in cv. Early Alaska. After Juliano and Varner, 1969 [79]...

Syn. Smooth Pea Starch Wrinkled Pea Starch G. Erbsenstarken E amidons de pois... 

P. are starch granules that are deposited in the cotyledons of different pea species as reserve polysaccharide, together with oligosaccharides and proteins. Industrial or pilot-plant products, obtained by ->wet milling and raffination from either Pisum sativum convar. sativum L. (smooth pea) or Pisum sativum convar. medullae ALEE (wrinkled pea). The first one contains 47-54% starch, 5-7% oligosaccharides, 21-34% protein and fiber, the second contains 30-37% starch, 25-36% protein, oligosaccharides and fiber. 

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