Alummoottil N. Jyothi

Textural and Gelatinization Characteristics of White, Cream, and Orange Fleshed Sweet Potato Tubers (Ipomoea Batatas L.)

Sweet potato is an important food crop having nutritive value in terms of starch, carotein, and minerals. The acceptability and overall quality of the products depend on their textural and rheological attributes. Cooking quality of the tubers could be related to the textural, pasting, and gelatinization properties, which vary depending on the flesh color of the tubers. Also, being a promising ingredient in many of the traditional and industrial products, the physico-chemical and functional properties of sweet potato flour are very much important for their selection for developing various value added products. The textural, gelatinization, and pasting characteristics of white, cream, and orange fleshed sweet potato tubers were analyzed and their thermal softening behavior was modeled by linear regression and fractional conversion techniques. Significant variations were observed in the properties among different varieties (p < 0.05). Kinetics of texture degradation on cooking were explained by first-order and dual-mechanism first-order models and the latter was found to be more suitable. The first three principal components explained about 85% of the total variation in texture profile parameters, gelatinization, and pasting properties. Though there was no similarity in the textural properties of the raw tubers among the varieties of same flesh color group, the quality of the cooked tubers and flours of different varieties in the same group are similar as revealed by the multivariate analysis.

Chitosan and Starch-Based Hydrogels Via Graft Copolymerization

Graft copolymerization is an attractive method for surface functionalization of natural polymers and can be initiated by chemical methods, radiation technique, and other systems. Polymer grafting onto polysaccharides is an effective method for the synthesis of superabsorbents. Depending upon the type of monomers and the conditions employed the properties of graft copolymers vary to a large extent. Chitosan is a nontoxic, biocompatible polysaccharide, and starch is a natural hydrophilic biopolymer. Both these are most abundant natural organic materials which are extensively investigated in the development of biodegradable and environment-friendly materials. Their hydrogels are of utmost importance for wide use in many fields including structural transplants, target drug delivery, tissue engineering, biosensors, adsorbents, etc. In this chapter, the various techniques used for the synthesis of chitosan/starch graft copolymers, their properties and possible applications are discussed in detail.

Effect of chemical modification with citric acid on the physicochemical properties and resistant starch formation in different starches

Potato, cassava, sweet potato, banana and lentil starches were modified with citric acid (CA) with the main objective of enhancing the resistant starch (RS) and slowly digestible starch (SDS) fractions and to compare starches of diverse botanical origins. The percentage CA substitution of modified starches ranged from 3.84 to 15.06 and showed similar type of XRD patterns, but with variation in intensity and percentage crystallinity. The peaks around 1705 cm-1 and 1150 cm-1 in FT-IR spectra of modified starches confirmed the presence of CA group. Scanning electron microscopy confirmed that there were no noticeable changes in granular structure and morphology. No peaks could be observed in RVA pasting profiles of modified starches, confirming cross-linking reaction. The SDS and RS were significantly higher in modified starches of all origins and consequently there was a lower estimated glyceamic index (EGI). Modified starches were associated with lower setback viscosity indicating their lower temperature stability.