Starch: Modified Starches
Native starch is a good texture stabilizer and regulator in food systems, but limitations, such as low shear resistance, thermal resistance, and high tendency toward retrogradation, limit its use in some food applications. These shortcomings can be overcome by starch modification, which is achieved through chemical (derivatization) or physical (heat moisture and high pressure) treatments, acid or enzymatic hydrolysis, or genetic modification. Chemical modification involves the introduction of functional groups into the starch molecule, resulting in markedly altered functional properties, and is generally achieved through derivatization such as etherification, esterification, cross linking, and grafting of starch. The distinguishing factors that affect the efficiency of modification are the starch source, amylose to amylopectin ratio, granule morphology, and type and concentration of the modifying reagent. The physical state of the ingested starch has a major impact on its digestibility and postprandial glycemic response. The methods commonly used to modify starches for food applications are discussed in detail in the present article.