Multi variate approach to define the quality of rice

Abstract

A study on “ a multi variate approach to define the quality of rice” was carried out assets the major quality parameters such as physical characteristics, cooking characteristics, organoleptic qualities and nutritional composition. Sixty rice varieties (thirty hybrid derivatives, twenty eight traditional / local varieties and two other improved / market varieties ) were selected.

The programme envisaged not only a detailed study on different quality parameters like physical characteristics, cooking characteristics, organoleptic qualities but also the suitability of the varieties to rice based preparations. Importance was paid to nutritional quality of the varieties. All the above indicators were tested both for raw as well as for parboiled rice.

Among the various indicators studied under physical characteristics, in general, thousand grain weight was found to be higher in hybrid derivatives of rice while head rice yield and moisture content in traditional varieties. Process of parboiling was found to increase the thousand grain weight and head rice yield.

Less cooking time, less gruel loss, lower viscosity , higher elongation index and elongation ratio were noticed in other improved varieties while higher water uptake and volume of expansion after cooking a desirable trait were noticed in hybrid derivates of rice. As a result of parboiling, optimum cooking time, elongation index and gelatinization temperature were found to increase and there was a decrease in gruel loss, volume expansion and water uptake due to parboiling.

Rice based preparations using different cooking methods such as boiling, fermenting and steaming , fermenting and shallow frying, powdering, roasting and steaming, powdering , roasting and boiling and baking attempted. The overall acceptability of the quality attributes revealed the market varieties were found to obtain highest score, followed by traditional and hybrid derivatives.

Cluster analysis was carried out to group/cluster the various rice varieties based on their multiple characters. The D2 analysis based on organoleptic qualities revealed that thirty five varieties were found to be homogeneous with respect to the above qualities for the preparation of cooked rice using raw and parboiled rice.

Seventeen varieties were selected for nutrient composition on the basis of D2 analysis using physical and cooking characteristics of rice varieties. Parboiling had a positive influence on calorific value, ash and mineral content while negative effect on starch, amylase and protein in all the selected rice varieties.

Discriminant function approach was used to discriminate the various varieties of rice based on multiple characters relating to the quality parameters and individual indices were developed for quality parameters and also for various rice based preparations.

A comprehensive index was also developed based on physical , cooking , organoleptic and nutritional composition of selected rice varieties. Hybrid derivatives like Vyttila -3, Hraswa and remya were found to obtain high index scores among the seventeen varieties. Apart from these, traditional varieties like Veluthari Thavalakannan, Kutticheradi and Chuvannari Tavalakannan were also found to obtain high index scores. Hybrid derivatives such as bhadra, Nila, Jayanthi, Asha and traditional variety Kavungin Poothala were found to be least acceptable on the basis of index scores optained.