Potato chemical structures

Fig. 9.3 Chemical structures of the selective phytotoxins 9 and 10 produced by canola virulent isolates of Leptosphaeria maculans. Phytotoxins 9 and 10 are produced in potato dextrose medium...

Odake, K. et al.. Chemical structures of two anthocyanins from purple sweet potato, Ipomoea batatas. Phytochemistry, 31, 2127, 1992. 

Fractionation of various starches. A wide variety of starches should be separated by Pentasol precipitation, to determine the distribution of the fractions. Comparison of the physical properties of the purified fractions from typical starches (especially corn, wheat, rice, potato, tapioca, canna, lily and arrowroot) should clarify specific differences in chemical structure. 

Nicotine (NIK-uh-teen) is a thick, colorless to yellow, oily liquid with a hitter taste that turns brown when exposed to air. It occurs in high concentrations in the leaves of tobacco plants and in lower concentrations in tomatoes, potatoes, eggplants, and green peppers. Nicotine gets its name from the tobacco plant, Nicotiana tabacum, which, in turn, was named in honor of the French diplomat and scholar Jean Nicot (1530-1600), who introduced the use of tobacco to Paris. Nicotine s correct chemical structure was determined in 1843 by the Belgian chemist and physicist Louise Melsens (1814-1886) and the compound was first synthesized by the research team of A. Pictet and A. Rotschy in 1904. 

Use of MALDI-TOF-MS allows relatively straightforward separation and identification of oligosaccharides with DPs up to 30. This feature makes it possible to identify products from enzymatic debranching of amylopectin. Richardsson et al. employed MALDI-TOF-MS and ESI-MS for enzyme-aided structure analysis of cationic potato amylopectin. " By MALDI-TOF-MS, identification of the oligosaccharides with DP 6-20 obtained from hydrolysis with pullulanase could be performed. Use of ESI-MS", on the other hand, provided detailed information on the chemical structure of oligosaccharides with DP <5. However, the lack of suitable standards prevented quantification by MALDI-TOF-MS and ESI-MS. 

Apart from the rather expensive and inferior methyl rubber produced in Germany during World War I, the first industrial production of synthetic rubbers took place in 1932, with polybutadiene being produced in the USSR, from alcohol derived from the fermentation of potatoes, and neoprene (polychloroprene) being produced in the USA from acetylene derived from coal. In 1934 the first American car tyre produced from a synthetic rubber was made from neoprene. In 1937 butyl rubber, based on polyisobutylene, was discovered in the USA. This material has a lower resilience than that of natural rubber but far surpasses it in chemical resistance and in having a low permeability to gases. The chemical structures of these materials are shown in fig. 6.10. 

Starch is another widely available natural polymeric biomaterial, which is generally isolated from corn, wheat, potato, tapioca, rice, etc. The major carbohydrate reserve in the plants is in the form of starch. It mainly consists of two glucosidic macromolecules 20%-30% of linear molecule amylase and 70%-80% of branched molecule amylopectin. The chemical structure of starch is given in Figure 53.2. 

The starch component of the Fantesk starch-oil composite can vary in its chemi-cal/structural properties (amylose, amylopectin, waxy) as well as in the type of crop source (corn, potato, rice, etc). Likewise, the oil component of the Fantesk starch-oil composite can have a variety of chemical/structural properties, compositions, and end uses. Over the years, Fantesk starch-oil composites of various combinations of starch and oil have been prepared and investigated for a variety of food and nonfood applications, including cosmetics, pharmaceuticals, polymers, coatings, and lubricants [4, 30-33]. 

Fig. 5 Chemical structures of simplest fructose-containing oligosaccharides present in GM potatoes in which the 1-SST gene or both 1-SST and 1-FFT genes were expressed...

Fig. 7 Chemical structure of N,N -bisdihydrocaffeoylspermine (kukoamine A), one member of a family of compounds revealed to be present in potato for the first time by LC/MS metabolite profiling...

Table III shows the results of chemical analyses of amylose samples compared, where possible, with values of Mn. These indicate the presence of more than one nonreducing, terminal group in some of the amylose samples. In the case of potato starch, this result is thought to be attributable to the presence of contaminating amylopectin rather than to inherent branching in the molecule.106 Other methods of examining the fine structure of amylose, and the question of branching, will be dealt with later (see p. 381).

NMR is an incredibly versatile tool that can be used for a wide array of applications, including determination of molecular structure, monitoring of molecular dynamics, chemical analysis, and imaging. NMR has found broad application in the food science and food processing areas (Belton et al., 1993, 1995, 1999 Colquhoun and Goodfellow, 1994 Eads, 1999 Gil et al., 1996 Hills, 1998 O Brien, 1992 Schmidt et al., 1996 Webb et al., 1995, 2001). The ability of NMR to quantify food properties and their spatiotemporal variation in a nondestructive, noninvasive manner is especially useful. In turn, these properties can then be related to the safety, stability, and quality of a food (Eads, 1999). Because food materials are transparent to the radio frequency electromagnetic radiation required in an NMR experiment, NMR can be used to probe virtually any type of food sample, from liquids, such as beverages, oils, and broth, to semisolids, such as cheese, mayonnaise, and bread, to solids, such as flour, powdered drink mixes, and potato chips. 

If amylases are to be used as tools for the detailed study of the breakdown and structure of their substrates it is obviously important to separate them from other enzymes and from other naturally associated constituents which may influence the results. It is then equally important to study the properties of the purified amylase and to supply it with the chemical environment necessary to protect it from inactivation and to enable it to act efficiently. With beta amylases this ideal has often been approached. Beta amylases from several sources have been prepared by selective inactivation of other enzymes that accompany them in nature23 and highly active products have been obtained by extensive purification.20 24-26 Balls and his associates have recently reported the crystallization of beta amylase from sweet potato.27... 

High-resolution 13C NMR studies have been conducted on intact cuticles from limes, suberized cell walls from potatoes, and insoluble residues that remain after chemical depolymerization treatments of these materials. Identification and quantitation of the major functional moieties in cutin and suberin have been accomplished with cross-polarization magic-angle spinning as well as direct polarization methods. Evidence for polyester crosslinks and details of the interactions among polyester, wax, and cell-wall components have come from a variety of spin-relaxation measurements. Structural models for these protective plant biopolymers have been evaluated in light of the NMR results. 

Jarvis, M. C., Hall, M. A., Threlfall, D. R., Friend, J. (1981a). The polysaccharide structure of potato cell walls chemical fractionation. Planta, 152, 93-100. 

Jane, J. L., Shen, J. J. (1993). Internal structure of the potato starch granule revealed by chemical gelatinization. Carbohydr. Res., 247,279-290. 

Modification, which involves the alteration of the physical and chemical characteristics of the native potato starch to improve its fimctional characteristics, can be used to tailor it to specific food applications. The rate and efficacy of any starch modification process depend on the botanical origin of the starch and on the size and structure of its granules. This also includes the surface structure of the granules, which encompasses the outer and iimer surface depending on the pores and channels, which cause the development of the so-called specific surface (Juszczak, 2003). Potato starch modification can be achieved in three different ways physical, conversion, and chemical (derivatization) (Table 10.6). 

---