Starch legume

Guar gum [9000-30-0] derived from the seed of a legume (11,16), is used as a flocculant in the filtration of mineral pulps leached with acid or cyanide for the recovery of uranium and gold (16). It is also used as a retention aid, usually in a chemically modified form (14,17). Starch and guar gum are subject to biological degradation in solution, so they are usually sold as dry powders that are dissolved immediately before use. Starch requires heating in most cases to be fully dissolved. 

THORNE M J, THOMPSON L u, JENKINS D J (1983) Factors affecting starch digestibility and the glycemic response with special reference to legumes. Am J Clin Nutr. 38 481-8. 

The predominant polysaccharide in dehulled field pea flour is starch (49.7-59.8%) and the major soluble sugars are a-galactosides (4.78%) and sucrose (1.85-2.2%) (8,23,24). Verbascose is the major a-galactoside present in field pea flour (23,24). The a-galactosides are the main contributors to the flatulence caused by ingestion of legume flours. 

Composition and Functionality of Protein, Starch, and Fiber from Wet and Dry Processing of Grain Legumes... 

Grain legumes have also been processed into refined starch (10,11) and protein isolates (12,13,14) by procedures derived from the traditional corn starch and soybean protein industries (15). However, comparative data on product yields, composition and losses have not been published. A commercial plant for the wet processing of field pea into refined starch, protein isolate and refined fiber has been established in Western Canada. Little is known about the characteristics of the protein isolate or refined fiber product. Water-washed starch prepared from the air-classified starch fractions of field pea (16,17) and fababean (6) have been investigated for certain physico-chemical and pasting properties. Reichert (18) isolated the cell wall material from soaked field pea cotyledons and determined its fiber composition and water absorption capacity. In addition, the effects of drying techniques on the characteristics of pea protein Isolates have been determined (14). 

On the basis of proteinate yields (Table II) and their protein contents (Table I), the recoveries of protein during wet processing were about 73% for both legumes, which was only slightly below the efficiency of the dry process. However, the losses of starch in the whey and wash solids were substantial, and starch recoveries averaged 77.5%. The yields of refined fiber were about 8% of the raw materials. Almost 30% of the dry matter from wet processing would have to be recovered from whey and wash extracts to make the process economical. 

Functional Properties. The pH s of the flours and products obtained by air classification varied between 6.5-6.7 (Table III), which was typical of legume flours (1.3). The proteinates were near oH 7 because of the neutralization orocedure after isoelectric orecioita-tion while the refined starch and fiber were still alkaline in pH despite several washings with distilled water. In a previous study, adjustment of the pH of lupine flour was shown to have a significant influence on functional properties (1) but pH was not adjusted in the present investigation. 

Like NSI, the oil absorption capacities of the legume flours were decreased by pin milling, and the protein fractions were more functional in this parameter than were the starch fractions... 

The proportion of the legume flours which gelled when heated in a closed container increased from about 60 to 80% as a result of pin milling (Table IV). Also, most of the protein and starch fractions from field pea gelled under these conditions but a portion of fababean fractions remained as a pourable slurry. The proteinate and refined starch gave very firm gels. 

Product Colours. Both legume flours showed creamy-yellow colours under the Hunter Color Difference Meter but fababean flour was also slightly greenish (Table V). Pin milling improved the lightness of the flour and this colour was retained by the protein and starch fractions at the expense of the yellow values. The proteinates were light brown in appearance whereas the refined starches were essentially white. The refined fiber retained only a light shade of yellow as compared to the other products. 

Gemat, C., Radosta, S., Damaschun, G., and Schierbaum, F. (1990). Supramolecular structure of legume starches revealed by X-ray scattering. Starch/Starke 42,175-178. 

Wheat grain, legumes Colon cancer Contains digestion-resistant starch and other non-digestible carbohydrates which increase fermentation in colon and hence production of volatile fatty acids... 

Wehmeyer et al. (1969), Bower et al. (1988), and Amarteifio and Moholo (1998) reported the content of carbohydrate to be 23%, 24%, and 19%, respectively. These values have been obtained indirectly as the difference between 100% and the content of proteins, lipids, and minerals. Holse et al. (2010) found that the content of carbohydrate was dominated by total dietary fiber as it varied between 18.7% and 26.8% dm (Table 5.2). The majority of the dietary fiber is insoluble as only about 4% of the dietary fibers are soluble. Comparing the content of total dietary fiber of morama bean with the content of peanut (9% dm) and soybean (10% dm) (U.S. Department of Agriculture, 2007), it appears that the morama bean has a considerably higher level of indigestible carbohydrates. Holse et al. (2010) also reported a very low starch content, which is in contrast to other legumes, in which starch is usually the most abundant carbohydrate... 

Hoover, R. and Sosulski, E. W. (1991). Composition, structure, functionality, and chemical modification of legume starches— A review. Can. ]. Physiol. Pharmacol. 69, 79-92. 

Longland, A. ., M. K. Theodorou, R. Sanderson, S. J. Lister, C. J. Powell, and P. Morris. 1995. Non-starch polysaccharide composition and in vitro fermentability of tropical forage legumes varying in phenolic content. Anim. Feed Sci. Technol. 55 ... 

---