MVSc

The study on “Formulating extruded foods based on dioscorea and taro” was undertaken to utilize dioscorea and taro for the development of the extruded products to ascertain their acceptability, nutritional and shelf-life qualities.
The nutritional and chemical qualities of four tuber flour i.e., Sree Priya, Sree Dhanya, Sree Rashmi and Thamarakkannan were evaluated. Sree Priya had the highest protein, starch and crude fibre content. Thamarakkannan (T2) exhibited the highest total ash content while moisture content was higher in D2 (Sree Dhanya). Acidity was found to be higher in dioscorea variety. In dioscorea, Sree Priya (D1) was found to be the superior in protein, starch, crude fibre and total ash than Sree Dhanya. In taro, Thamarakkanan (T2) was found to be superior in the above characters when compared to Sree Rashmi (T1).
Yield ratio was higher in Thamarakkannan and lower in Sree Dhanya while processing loss was much less in Thamarakkannan. Yield ratio of taro was significantly higher than that of dioscorea. Processing loss was significantly higher in dioscorea.
The storage study of the flour revealed that there was a steady increase in moisture content of the flour. Sree Priya (D1) and Thamarakkannan (T2¬) had highest shelf life than Sree Dhanya (T2) and Sree Rashmi (T1). There was no change in acidity throughout the storage period of three months. There was no significant difference between varieties and containers. There was no insect infestation upto three months of storage period irrespective of containers and flours. Microbial quality of the stored flour was analysed and the data revealed that microbial count was less in flour stored in PET containers than polypropylene covers. Dioscorea flour had less microbial attack than taro flour.
Dioscorea and taro flours were the main ingredients for the formulation of the sev and vermicelli. To increase the protein content and the binding capacity maida, rice flour and soya flour were tried along with tuber flour. Sixteen combinations with above ingredients were tried for product development and the principle governing the selection of the suitable combinations were yield ratio, nutritional quality, extrusion behaviour, cost and overall acceptability.
The combination with maida, tuber flour and soya flour in proportion 50 : 40 : 10 got the maximum score and this combination was selected for the development of the products, ‘sev and vermicelli’.
The physical characteristics such as fineness, shape, uniformity of strands, packaging quality and tensile strength of the D1 and T2 products were found to be good. Dioscorea based products secured higher scores for all the parameters than taro based products. Though there was difference in the quality parameters, it was not statistically significant.
The cooking characteristics such as cooking time, water absorption index and bulk density was found to be good in D1 and T2 products. But the difference in these characters was not statistically significant .
Nutritional and chemical qualities of the product showed that protein and starch content was found to be higher in Sree Priya (D1) products while crude fibre and total ash content was higher in product with T2 (Thamarakkannan). Significant difference was present between tubers and between varieties. Minerals like phosphorus and iron content was higher in D1 products. Eventhough there was difference in mineral contents it was not statistically significant.
Organoleptic qualities such as appearance and texture was found to be higher in T2 products while other quality parameters were found to be higher in D1 products. Dioscorea based products secured higher scores than taro based products. Though there was difference in the organoleptic qualities, it was not statistically significant.
Shelf-life studies of the products revealed that there was steady increase in the moisture level of the products during the storage period. Products with dioscorea flour had higher moisture content than products with taro flour. While there was no change in acidity irrespective of the products, tubers and storage period. There was no insect infestation in stored products throughout the storage period. Microbial analysis of the products showed that products with D1 and T2 were more microbiologically safer than D2 and T1 products. Sev and vermicelli prepared with D1 and T2 had more shelf-life than D2 and T1 products with less moisture content and less microbial contamination.
Type tests administered to the developed products showed that all the values were below the values specified by the ISI.
Fifteen recipes with sev and vermicelli were formulated and standardised in the laboratory such as stuffed bread roll, burfi, sugar stick, sev halwa, coco stick, pakoda, patties, sweet stick, samosa, payasam, sev pak, coconut sev, burger, sev madhuri and sev toffee.
The acceptability of the fifteen recipes were assessed among technical experts, college students, working women and farm women. Majority of the recipes were scored positively by these groups. Stuffed bread roll and patties were preferred mostly by these groups.
From the above observations, it can be concluded that, it is possible to develop extruded food based on minor tubers dioscorea and taro with good nutritional, organoleptic and shelf-life qualities and thereby value addition could be done to these tubers. Novel recipes could also be standardised through these product.