Soil Chemical Analysis

The tropical tuber crops contain starch as the major component and thus act as important source of starch. Except cassava and to a smaller extent sweet potato, starch from other tuber crops has not been exploited for industrial applications partly because of difficulty in the extraction of the pure starches and partly because of non-availability of information about the properties of these lesser known starches. This review attempts at collating data available on the physicochemical and functional characteristics of the tropical tuber starches, highlighting their unique properties and potential field of applications. The physicochemical properties like granule shape and size, X-ray diffraction (XRD) patterns, amylose content, or content of non-starchy components, show considerable variation among the tuber starches. In addition, factors like genetic origin, environmental conditions and age of the plant also influence the properties. The starch granules of Colocasia esculenta and Dioscorea esculenta tubers are very small whereas those of Canna edulis are very large. XRD patterns of yam starches are generally ‘B’, while the aroid starches possess ‘A’ patterns. DSC gelatinisation temperatures are low for cassava starch and high for the aroid starches. The functional characteristics like viscosity, swelling power and solubility also depend on a number of factors such as varietal variation, method of extraction, processing conditions and instruments used for analysis. Viscosity is high for cassava and C. edulis starches, but low for most aroid starches. Clarity is good for cassava and yam starches compared to the others. Digestibility also varies among the starches. The diversity available in the tuber starches shows that some of the starches can be used in place of chemically modified starches available on the market. The realisation of their importance can help in value addition of these neglected crops and also provide starch with special properties for specific applications.

Physicochemical and Functional Properties of Tropical Tuber Starches: A Review

Starch continues to be an important renewable biopolymer in both the food and non-food industries. Its properties, which vary depending on the plant source, stem directly from its structure. The recent substantial increase in knowledge of the molecular structure of starch components and the architecture of starch granules has contributed significantly to an enhanced understanding of the structural base of starch functionality. This resume provides an overview of the present views of the starch structure-function relationships with an emphasis on industrially important starch sources.

https://faculty.missouri.edu/~glaserr/3700s16/Starch_star201400188.pdf

Structure-function relationships of starch components

/pdf/eurasia-journal-of-mathematics-science-technology-education-xir8jfctxb.pdf

Eurasia Journal of Mathematics, Science & Technology Education

Experiments were performed on two varieties of apple tissue and one variety of potato tissue, in which cell turgor pressure was varied and the concomitant mechanical properties of the tissue were tested. Turgor pressure was controlled by immersion in solutions of various mannitol concentrations, and the degree of swelling or contraction of the tissue samples was measured. Under constant-strain-rate loading, mode of failure varied among the different commodities, and underwent a transition as the turgor pressure was varied. Rate of loading also caused a transition in failure mode. The stress and strain at failure and tissue stiffness were related to mode of failure, turgor pressure, and strain rate. From the osmotic swelling data, estimates were made of the cell wall stress-strain behavior and of the probability distribution for cell-wall strength in Ida Red apple tissue.

Rheology of apple and potato tissue as affected by cell turgor pressure

The properties of starch extracted from two species of Curcuma viz. Curcuma zedoaria and Curcuma malabarica were studied. The starch from C. malabarica tubers was white in color, while that from C. zedoaria was slightly yellowish due to the presence of the yellow pigment, curcumin. The granule size and shape, amylose content and solubility did not show noticeable difference between starches from the two species. Both the starches possess “B” type x‐ray diffraction pattern. Curcuma zedoaria starch showed a lower peak viscosity and swelling volume when compared to C. malabarica starch. The complete removal of curcumin from C. zedoaria starch by alcohol extraction, resulted in an increase in the swelling and viscosity values close to those of C. malabarica starch. The breakdown in viscosity was quite low for both the starches and setback was higher when compared to cassava and sweet potato starches. The experiments showed that Curcuma starch resembles Dioscorea starches in most of its properties. Di...

https://www.tandfonline.com/doi/pdf/10.1081/JFP-120016630

Physicochemical and Functional Properties of Starch from Two Species of Curcuma

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 a...

https://www.tandfonline.com/doi/pdf/10.1080/10942912.2010.509895

B. Vimala

Papers

Physicochemical and Functional Properties of Starch from Two Species of Curcuma

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