Potato starch content

Komiyama, S., Kato, J., Honda, H., Matsushima, K. (2007). Development of sorting system based on potato starch content using visible and near-infrared spectroscopy. J. Japan Soc. Food Sci. TechnoL, 54, 304-309. 

Starch-based polymers can be based on crops such as com (maize), wheat, or potatoes. Starch content may range from 10% to >90%, but significant material breakdown occurs above 60%. As the starch content increases, the polymer compos-... 

Fruits and vegetables Potato, carrot Edible, proteins stable in storage tissues Must be cooked before consumption (potato), high starch content (potato)... 

The oxidation of starch in aqueous suspension with H202 in the presence of iron phthalocyanine gives both carboxylic and carbonyl groups (Table 3.1). The best yields were obtained with a molar ratio 12900/1 (0.0078 mol%), but the oxidation was still quite efficient with 0.0039 mol% of catalyst [25800 per anhydroglucose unit (AGU)/catalyst ratio]. The oxidized starch had almost the same final Fe-content as the initial potato starch. Still, the efficiency of this method in view of scaling up was limited by comparatively low activity and product isolation problems. 

FIGURE 5.9 DSC profiles of potato starch at different water contents (volume fraction of water indicated next to each profile). Heating rate=10 °C/min. Donovan (1979), Phase transitions of starch-water system. Biopolymers, 18, 263-275. Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission. 

Starch, a reserve polysaccharide widely distributed in plants, is the most important carbohydrate in the human diet. In plants, starch is present in the chloroplasts in leaves, as well as in fruits, seeds, and tubers. The starch content is especially high in cereal grains (up to 75% of the dry weight), potato tubers (approximately 65%), and in other plant storage organs. 

The phenotype of a potato plant is very plastic (environmentally variable) with regard to many traits of interest for potato breeders. The effect of production environment on traits such as yield, tuber number, tuber size, specific gravity, and processing quality presents a challenge that is difficult to overcome. It requires the testing of clones in multiple years and locations. For example, quantitative trait loci have been detected for tuber starch content, but few were stable across environments (Schafer-Pregl et al., 1998). Similarly, environment has a laige impact on... 

Schafer-Pregl, R., Ritter, E., Concilio, L., Hesselbach, J., Lovatti, L., Walkemeier, B., Thelen, Ft., Salamini, F., Gebhardt, C. (1998). Analysis of quantitative trait loci (QTLs) and quantitative trait alleles (QTAs) for potato tuber yield and starch content. Theoretical and Applied Genetics, 97, 834-846. 

The bulk of potato tubers is made up of parenchyma cells that have thin, non-lignified, primary cell walls (Reeve et al., 1971 Bush et al, 1999, 2001 Parker et al., 2001). Unless stated to the contrary, potato cell walls refers to parenchyma cell walls. These walls and their component polysaccharides are important for a number of reasons they form part of the total intake of dietary fiber, influence the texture of cooked potato tubers and form much of the waste pulp that is produced in large amounts by the potato starch industry when starch is isolated. The pulp is usually used as cattle feed, but potentially could be processed in a variety of ways to increase its value (Mayer, 1998). For example, the whole cell-wall residues could be used as afood ingredient to alter food texture and to increase its dietary-fiber content, or cell-wall polysaccharides could be extracted and used in a similar way or for various industrial applications (Turquois et al., 1999 Dufresne et al, 2000 Harris and Smith, 2006 Kaack et al., 2006). 

Micronutrients do also affect potato quality and yield applications of B, Mn, and Zn increase the starch grain size, while applications of iodine or ammonium molybdate increase the dry matter and starch content. 

Starch content of potato dry matter is calculated as follows ... 

In recent years, a new research method was developed to determine total starch content of potato dry matter by comparing the gelatinization enthalpy of potato dry matter and standard starch using differential scanning calorimetry (DSC) (Liu et al., 2005). 

Most potato starches are composed of a mixture of two polysaccharides, a linear fraction, amylose, and a highly branched fraction, amylopectin. The content of amylose is between 15 and 25% for most starches. The ratio of amylose to amylopectin varies from one starch to another. The two polysaccharides are homoglucans with only two types of chain linkage, a-(l 4) in the main chain and a-(l 6)-linked branch chains. Physicochemical properties of potato and its starch are believed to be influenced by amylose and amylopectin content, molecular weight, and molecular weight distribution, chain length and its distribution, and phosphorus content (Jane and Chen, 1992). 

Figure 8.4 The gelatinization of native potato starch at 30% solid content by DSC.

Liu, Q., Lu, X., Yada, R. (2005). The effect of various potato cultivars at different times during growth on starch content determined by differential scanning calorimetry. Journal of Thermal Analysis and Calorimetry, 79(1), 13-18. 

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