Starch root tuber

Starches oj tubers, roots, stems, etc. The more important of these aie ... 

Reserve starch is usually formed in amyloplasts, although it is occasionally formed in chloroamyloplasts. These are chloroplasts that have lost their lamellar structure and subsequently start producing fairly large reserve starch granules.17 Chloroamyloplasts form starch independent of photosynthesis. They have been described in tobacco (Nicotiana tabacum L.) leaves, Aloe leaves and flowers, central pith of potato (Solanum tuberosum L.) fruit, Pellionia and Dieffenbachia stems, and other tissues.17,18 Such sources of reserve starch are insignificant, however, when compared to the reserve starch formed in roots, tubers and seeds. 

Paste properties of native starches from different botanical origins have been reviewed.92,133 Relevant to practical usage of starch, the most important paste properties are viscosity, texture, paste transparency, resistance to shear and tendency to retrograde. In terms of texture, the translucent potato starch pastes can be described as cohesive, long-bodied, stringy and rubbery. Other root, tuber and waxy starches give pastes of similar texture to that of potato starch, but are generally less cohesive. On the other hand, pastes from common cereal starches are opaque and can be described as noncohesive and short- and heavy-bodied. These and other properties of several native starches are summarized in Table 8.1. 

Extraction of flour or starch from tubers, roots, or fruits Patent number GB1146854 (1969)... 

Starch is one of the most abundant polysaccharides occurring in nature. All organs of higher plants contain starch. Starch granules can be found in pollen, leaves, stems, woody tissues, roots, tubers, fruits, flowers, bulbs, and seeds. Starch can also be found in mosses, ferns, algae, and bacteria. 

Starch occurs as microscopic granules in the roots, tubers, and seeds of plants. Corn, potatoes, wheat, and rice are important commercial sources of starch. Heating starch with water causes the granules to swell and produce a colloidal suspension from which two major components can be isolated. One fraction is called amylose and the other amylopectin. Most starches yield 10—20% amylose and 80—90% amylopectin. 

Starch, as is it known, is the most widespread material of plants. Starch is formed in leaves of plants as a result of photosynthesis and is postponed in roots, tubers and seeds as grains. In industrial conditions starch is received from potato and com. Starch of wheat, rice, sorghum and other plants has less industrial value. The production technology of starch depends on the kind of raw material and the purposes for which the starch is made. 

First, cassava (also known as manioc, tapioca, and yuca but only Manihot escu-lanta Crantz) is a human food crop. The plant is a short-lived shrub that produces root tubers (resembling potatoes), which are harvested as a starch source in much of the tropical world. Global production in 1990 was estimated in excess of 100 million tons. The toxicity of incorrectly processed (insufficiently leached with water) tubers has been known for at least 400years. The major toxic constituents are reported to be the two cyanogenic glycosides, linemarin, and lotaustralin, whose structures are shown below. 

Plants store polysaccharides as food reserve in all types of cell but primarily in special storage cells or organs such as parenchymous cells or roots, tubers, and pith. The most important of these food reserves are starches, fructans, mannans, and galactomannans. The mannans are sometimes food reserves and sometimes structural material in the plant cell wall. In animals the chief reserve polysaccharide is glycogen, which in chemical structure is much like one of the components of starch (see Part II of this chapter.). 

Natural Starch. Very little of the available carbohydrate occurring naturally in foods occurs as the dissaccharides sucrose, lactose, or maltose or as the monosaccharides glucose or fructose. Cereal grains, roots, tubers, legumes, nuts, and some fruits and vegetables provide carbohydrate to the diet mainly as starch. The major sources of starch are the seeds of corn, rice, rye, sorghum, and wheat. Potatoes, which... 

Worldwide, natural starch is an important energy food. The staple food of a country provides the primary source of starch for example, corn in Mexico roots, tubers, and sorghum in parts of Africa and rice in India, China and Indonesia. Starch is an economical food hence, it contributes a large portion to the diets where income is low. As income increases, the amount of starch in the diet decreases while consumption of fat, animal protein, and sugar increase. 

Starch is a semi-crystalline biopolymer used for a number of applications. It is a branched homopolymer of glucose, with a-(1 4] linear links and ce-(l 6] branched links (Sweedman et al., 2013]. It serves as a carbohydrate reserve in roots, tubers, seeds, fruits, plants, and cereals (Zavareze and Dias, 2011]. Depending on the original source of starch, the starch granule has been found to vary in size, shape, structure, and chemical composition. Amylose and amylopectin macromolecules are the prime constituents of starch. Figure 1.12 shows the schematic and chemical composition of amylose and amylopectin (Sweedman et al., 2013]. 

Amylose is one component of starch, which is the most abundant carbohydrate storage reserve in plants. Carbohydrates such as starch function as a reservoir of energy for later metabolic use. It is found in many different plant organs, including seeds, fruits, tubers, and roots, where it is used as a source of energy during periods of dormancy and regrowth. 

Hoover, R. (2001). Composition, molecular structure, and physicochemical properties of tuber and root starches a review. Carbohydr. Polym., 45, 253-267. 

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. 

---