Dr. S. N. Moorthy - Research - Dr. S. N. Moorthy

Tropical Tuber Crops

The tropical tuber crops play a dual role in being a source of food as well as industrial raw material. However, they have not received enough importance due to various factors. The main factors are that the tubers are considered poor mans crop and there is little awareness of the variability available in the starch properties of these crops. Again the knowledge about the innumerable products, which can be produced from starch, has been scanty. So all these aspects needed to be addressed to enhance the importance of these crops and research projects covering food and industrial applications of these neglected crops were formulated and carried out. In addition, an ad-hoc project on minor tuber starches was undertaken in collaboration with RRL, Trivandrum.

Starch-lipid interactions of tuber starches

Lipids and surfactants can form strong complexes with starch and thereby modify the properties of the starches. Unlike cereal starches which contain considerable quantities of lipids present in them, the tuber starches are devoid of the lipids. A study was conducted to compare the types of starches using DSC. The starches were moistened with equal quantity of water in aluminum pans and the DSC run using a Seiko Calorimeter using indium as standard

Physicochemical and functional properties of Canna edulis starch

Apart from the major root crops like cassava, sweet potato, aroids and yams, many types of rhizomatous and tuberous root crops are grown in different countries including India. Queensland arrowroot (Canna edulis) is a perennial herb grown in many countries for its edible rhizome (Joseph and Peter, 1985) . According to Hermann (1994), the bakery products prepared from canna starch are much lighter, and crisper than those from wheat. This Institute has three accessions of Canna edulis classified from the leaf colour as green, purple and dark purple. Only the tubers of dark purple accession are consumed since the others are fibrous and contain large quantity of phenols. This paper describes the physicochemical and functional properties of starch isolated from these three accessions

Effect of Different Types of Surfactants on Cassava Starch Properties

The effect of anionic, neutral, and cationic surfactants in three different concentrations on cassava starch properties was studied. The iodine affinity of total amylose was reduced by 20 -40% by all surfactants, with highest reduction being observed for cetyltrimethylammonium bromide. The iodine affinity of soluble amylase was suppressed by all reagents except cetyltrimethylammonium bromide, which lowered the value to almost zero. There was no significant difference between the concentrations 0.04 and 0.06 mol of surfactant per 100 g of starch. Viscosity was stabilized by potassium stearate and potassium palmitate without greatly affecting the peak viscosity of 660 BU of pure starch, but sodium lauryl sulphate and cetyltrimethylammonium bromide increased the peak of viscosity to 900 and 780 BU respectively at 0.06-mol concentration and did not show stable viscocity during the holding period

Extraction of Starches from Tuber Crops Using Ammonia

Ammonia solution(0.03 M) was used to extract starch from various tuber crops by the conventional settling method. It was found that there was noticeable improvement in the yield of starch from Colocasia (6-16%), while it fell for sweet potato starch and remained almost the same for the other starches. The various properties of starch, thus extracted, were compared with those for starch obtained by water extraction. It was found that total amylose of all starches were unaffected while the ’soluble amylose’ was slightly suppressed for Colocasia starch extracted with ammonia solution. Peak viscosity was found to be increased to a large extent for Colocasia and Dioscorea esculenta starches by ammonia extraction, while it was lowered for sweet potato starch. The swelling volume of Colocasia starch extracted with ammonia was similarly enhanced by 25%, but the Dioscorea esculenta starch did not show such a tendency. Sweet Potato starch suffered a reduction in swelling a reduction in swelling volume, Phosphorous content was found to be independent of the extraction medium

A Regio-and Stereo-Specific Addition of Iodine Azide to C-9 and C-13 Cyclic Allenes

Iodine azide is known to undergo addition to alkenes and alkynes with a remarkable high degree of regio- and stereoselectivity¹. However, there are no reports of such additions of iodine azide to allenes. In this Communication a regio- and sterospecific addition of iodine azide to 1, 2-cyclodecadiene and 1, 2-cyclotridecadiene is described. The results are summarized in the Table.

The Physicochemical properties of starch of some accessions of amorphophallus paeoniifolius

Starch was extracted from the tubers of ten accessions of Amorphophallus paeoniifolius of the same maturity, with a yield varying from 7 to 14 % on a fresh weight basis. The starch was pure white in color. There was no significant difference in granule size between the different accessions. The starch granule size and viscosity values were lower in A. paeonifolius than in Dioscorea spp. And cassava, but the viscosity was higher than that of cereal starches. The viscosity stability was good, indicating suitability for many food applications

Studies on Dioscorea rotundata Starch Properties

Starch from six clonal selections of Dioscorea rotundata was isolated by standard procedure. The yield was between 20-24%. Various properties of these starches were compared. Granule size, 2% viscosity, peak viscosity, clarity, sol stability, total and soluble amylase contents were studied and only small variations were observed in the properties except paste viscosities among the clonal selections. The phosphorus content of Dioscorea starch was found to be three times as much as cassava starch, but low compared to potato starch. The higher gel strength of D, rotundata starch paste compared to cassava gel may be attributed to the phosphate linkages among the starch molecules in the granules

Physicochemical and Functional Properties of Tropical Tuber Starches: A Review

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