Native waxy maize starch

The major starch sources are corn, potato, waxy maize, wheat and tapioca. Refined starches are supplied in powder form or as slightly aggregated pearl starch.16 Unmodified (native) starch is rarely used in the paper industry, except as a binder for laminates and in the corrugating process. Most starches for use in papermaking are specialty products that have been modified by controlled hydrolysis, oxidation or derivatization.17... 

Surimi is fish paste from deboned fish used to make simulated crab legs and other seafood. For preservation the paste is blended with cryoprotectants, such as sucrose, sorbitol and phosphates, and frozen. To make the final product, the frozen paste is thawed, blended with starch and extruded as a film onto a belt. The belt takes the film into an oven that heat-denatures the fish protein and cooks the starch. The film is then rolled to form striations, shaped, colored and cut. Depending on the required distribution, the product is frozen or refrigerated. Potato and tapioca starch were used in surimi products 400 years ago, since they provided a cohesive, elastic matrix consistent with seafood. Frozen distribution has made the use of highly-stabilized, moderately crosslinked tapioca starch popular, alone or with native tapioca starch. Modified waxy maize products are used, as is unmodified com starch, for increased cuttability. Kim188 reported that the gel strengthening ability of starch correlates with starch paste viscosity. 

Native starches contain approximately 25% amylose, yet there are some mutant varieties of com that contain 85% amylose (high-amylose com) or no amylose (waxy maize) (Whistler and Daniel, 1985). Amylose leaches from starch granules during... 

PREPARATIVE TECHNIQUES Fractionation of starches. Native starches usually contain about 70-80% amylopectin. Genetic modification can result in starches having virtually no amylose content, such as waxy maize. 

Starch PoIy(ethyIene-vinylalcohol) copolymer, 56% VA waxy maize, native com and high-amylose starches extrusion-blended x-ray, DSC, SEM, TEM Phase separated starch domains. Oriented droplets, 0.05-5 jm in length (waxy maize), 0.05-1.2 pm domains (native com), <0.25 pm (high amylose) (81)... 

Figure 4 Brabender viscosity profiles of native starches (8%, wAr, dispersions) 1, potato 2, waxy maize 3, regular maize.

Besides plasticizer features, properties of the starch itself such as the amylose/ amylopectin ratio, also have an influence on the final material. As mentioned above, amylose and amylopectin recrystallize in different ways. Amylose will form the more crystaUine part of a thermoplastic and amylopectin the amorphous component the opposite behavior is found in the native starch granule, in which amylopectin is predominantly the crystalHne part. The source of the starch determines the ratio and the molar mass distribution of amylose and amylopectin, and consequently the properties of the thermoplastics made out of it [7]. In this chapter the effects of and relations between the plasticizer, the amylose/amylopectin ratio, and the mechanical properties of four starches from different sources-potato, pea, wheat, and waxy maize-are described and discussed. Besides an overview of the properties, this should finally lead to better insight into the behavior of starch materials during processing. 

---