Starch native

Native starches, obtained by the various wet-milling processes described in Chapter 8, are industrially transformed by physicochemical and enzymatic processes into modified or functional starches or an array of syrups with different degrees of sweetness. Approximately 285 million bushels of native and modified starches were produced in the United States in the year 2006 (U.S. Department of Agriculture, Economic Research Service 2009). Modified starches acquire specific functional properties for special applications in the food industry. They are widely used as thickeners in the canning industry, as base for batters and breadings (Chapter 10), as emulsifiers, and as adhesives or glues in non-food-related industries. 

The main industrial use of starch is as a basic raw material for the production of syrups, glucose and fructose being the most widely produced sweeteners. In the United States, approximately 764 million bushels of sweeteners were produced in the year 2006. About 70% of these sweeteners were high-fructose maize syrups (U.S. Department of Agriculture, Economic Research Service 2009). The biotransformation of starch into syrups consists of the hydrolysis of amylose and amylopectin chains by specific amylolytic enzymes (BeMiller and Whistler 2009, Whistler et al. 1984). The glucose isomerase enzyme is used to convert glucose into the sweeter fructose, present in fructose syrups, which are in high production and demand. 

Starch is the most important food ingredient for mankind. The industrial use of refined starch has increased during the last decades due to the increasing demand for sweeteners, alcohol, and pseudoplastic packaging films. In the United States, 26 million metric tons of maize are converted into starch by the wet-milling industry (Chapter 8). Of these, approximately 20 million metric tons of maize are further converted into sweeteners (Johnson and May 2003, Hobbs 2003). 

All cereals store amylose and amylopectin molecules in simple or compound granules (Chapter 4). Starch grauules from a single cereal differ from one another in size, shape, and other characteristics. The different granules possess different melting and swelling properties and respond differently to enzymatic hydrolysis. A 

---

Fats contribute to the rheological properties in flowable and pastry foods. By combining with starches to form a clathrate, a product different from the native starch is formed, eg, shortening in baked goods. The highly developed shortness of pies baked in eadier times resulted from the use of high levels of lard. The use of less fat in pie cmsts is evident, ie, the cmsts are harder and readily become soggy. 

Low DS starch acetates ate manufactured by treatment of native starch with acetic acid or acetic anhydride, either alone or in pyridine or aqueous alkaline solution. Dimethyl sulfoxide may be used as a cosolvent with acetic anhydride to make low DS starch acetates ketene or vinyl acetate have also been employed. Commercially, acetic anhydride-aqueous alkaU is employed at pH 7—11 and room temperature to give a DS of 0.5. High DS starch acetates ate prepared by the methods previously detailed for low DS acetates, but with longer reaction time. 

Compared to native starches, monophosphate esters have a decreased gelatinization temperature range and swell in cold water at a DS of 0.07. Starch phosphates have increased paste viscosity and clarity and decreased retrogradation. Their properties are in many ways similar to those of potato starch, which naturally contains phosphate groups. 

Dextran gels have been utilized since the late 1950s (1) for the separation of biopolymers. First attempts on Sephadex (2-5) and Sephadex/Sepharose (6-8) systems are documented for hydrolyzed and native starch glucans. Up until now, particularly for the preparative and semipreparative separation of polysaccharides, a range of efficient and mechanically stable Sephacryl gels (9-14) have been developped. 

FIGURE 16.7 Native starch ( ) and fractions of native starch differing in their branching characteristics (nb/lcb amylose -type fraction scb amylopectin -t/pe fraction ) separated on semipreparative... 

Agarose gels have been used for more than two decades to separate polysaccharides (17-22). In particular, Sepharose CL 2B is widely used (6-8) to separate native starch, but continuously improved mechanical and chemical stability made all of the Sepharose CL gels perfect systems for the analysis of high molecular and broad distributed polysaccharides (23-28). 

FIGURE 16.19 Degree of polymerization distribution (m dpD d) of wild-type potatoe starch ( ), a nb/lcb fraction ( amylose -type A)- s b fraction ( amylopectin"-type ) of the native starch ... 

A related class of gels are those formed by extensive hydrogen bonding. An example is the polyethylene oxide)-poly(methacrylic acid) complex [18]. Spontaneously gelling natural polymer solutions are frequently of this type, including gelatin and native starch. 

Tang, H.R., Godward, J., and Hills, B. 2000. The distribution of water in native starch granules A multinuclear NMR study. Carbohydr. Polym. 43, 375-387. 

Figure 7.12 Retention of cationic and native starches during handsheet formation using fibres refined for 0, 30 and 60 minutes.

Instead, native starch has been oxidized with H202 in the presence of soluble organometallic complexes to meet specific hydrophilic/hydrophobic properties needed for end-products to be used in paper, paint and cosmetic industries [79-... 

Starch is obtained from a variety of plant sources. Corn, cassava, sweet potato, wheat, and potato are the major sources of food starch while sorghum, barley, rice, sago, arrowroot, etc. serve as minor sources of starch in different localized regions of the world (Gaillard, 1987 Ratnayake and Jackson, 2003). Raw starch granules do not disperse in cold water. This limits the use of raw native starches for food as well as industrial applications, and therefore starch is often cooked during product-manufacturing... 

FIGURE 5.7 X-ray diffraction profiles of native (ungelatinized), partially gelatinized, and completely gelatinized (amorphous) tapioca starch. Reprinted from Carbohydrate Polymers, Vol. 67, Ratnayake and Jackson (2007), A new insight into the gelatinization process of native starches. Pages 511-529, 2007, with permission from Elsevier. 

Matveev, Y. I., Elankin, N. Y., Kalistrova, E. N., Danilenko, A. N., Niemann, C., and Yuryev, V. P. (1998). Estimation of contributions of hydration and glass transition to heat capacity changes during melting of native starches in excess water. Starch/Starke 50, 141-147. 

Sahai, D. and Jackson, D. S. (1999). Enthalpic transition in native starch granules. Cereal Chem. 76, 444-448. 

Understanding the Crystalline Polymorphism in Native Starch. From this study, it is clear that the A and B forms have in common not only a double-helix but a... 

Before weaving, the warp is covered with a layer of polymer to withstand the mechanical stress (abrasion, tension) during weaving. These polymer coatings are so-called sizes. Normally native starch, modified starch like carboxymethyl-starch (CMS), carboxymethyl-cellulose (CMC), polyvinylalcohols (PVA), polyacrylates, and proteins can be used. The amount of added polymer for staple yarns like Co is between 8 and 20% of the weight of the warp. As a result, in many cases the final amount of polymer to be removed in the desizing step is approximately 5-10% of the weight of the fabric. 

Starch, either in the presence of amylose alone or combined in native starch, which is more difficult to redisperse. Rapid cooling of starch allows some inter- and intrachain hydrogen bonding, but also allows water molecules to be captured within the precipitating starch allowing it to be more easily redispersed (Figure 9.2). 

Starch is an inexpensive and abundant renewable raw material. Native starch occurs in plants as discrete particles (starch granules) and serves as food reserve and energy source of the plant. 

Fig. 23 Viscosity profiles of (a) native starch, (b) Native starch heated up at 50°C for 24 h. (c) Telomerized starch with DS = 0.055. (d) Telomerized starch with DS = 0.1. Dotted line. temperature profile...

When a thermal treatment was applied to starch before the analysis, a very different behavior (Fig. 23b) was obtained. After such a treatment, no maximum was observed for the viscosity which increased slowly up to 82°C. In the case of starch modified with octadienyl chains (DS 0.055 (Fig. 23c) and DS 0.1 (Fig. 23d)), the viscosities were much lower than for native starch (b) in both cases. The presence of hydrophobic chains at the surface of the material could prevent the interaction of water molecules with the macromolecules after the splitting, thus avoiding the formation of a gel. 

Most native starch types are slightly phosphorylated with phosphate groups monoesterified to the glucose residues (Blennow et ak, 2002). The presence of phosphate esters in starch has been known for more than a century (Fembach, 1904). The content of phosphate esters in starch... 

Blennow, A., Bay-Smidt, A. M., Leonhardt, R, Bandsholm, O., Madsen, H. M. (2003). Starch paste stickiness is a relevant native starch selection criterion for wet-end paper manufacturing. Starch, 55,381-389. 

Blennow, A., Bay-Smidt, A. M., Olsen, C. A., Mailer, B. L. (2000). The distribution of covalently bound starch-phosphate in native starch granules. Int. J. Biol Macromol, 27, 211-218. 

Blennow, A., Sjbland, K. A., Andersson, R, Kristiansson, P. (2005a). The distribution of elements in the native starch granule as studied by particle-induced X-ray emission and complementary methods. Anal. Biochem., 347, 327-329. 

---