Value addition and quality evaluation of queensland arrowroot (Canna edulis L.)

Abstract

Tuber crops are known as poor man’s crop as it provides food of high calorific value and quality starch. Queensland arrowroot (Canna edulis L.) belonging to the family Cannaceae, is a perennial herb grown in many countries for its edible starchy rhizome. It is an outstandingly versatile and one of the underutilized crops of tropics. The present study entitled ‘Value addition and quality evaluation of Queensland arrowroot (Canna edulis L)’ was undertaken to evaluate the nutritional, antinutritional and organoleptic qualities of Queensland arrowroot rhizomes. The study also aimed to assess the quality aspects of the flour and starch powder prepared from the rhizomes. Organoleptic and shelf life qualities of the products developed with the flour and starch powder were also assessed. Nutritional and chemical constituents like moisture, protein, starch, total carbohydrate, fibre, calcium, iron, phosphorus, sodium, potassium, vitamin C, carotene, total phenols and oxalates were estimated. Fresh rhizome was rich in various nutrients especially carbohydrate, starch and mineral constituents. Total carbohydrate and starch content of fresh rhizome were 59.8 and 25.8 per cent respectively. Organoleptic qualities of cooked rhizomes obtained a mean score above 7.00 for all parameters. Flour and starch powder prepared from rhizomes were evaluated for various physical, microbial and sensory qualities initially and after three months of storage. The bulk density of rhizome flour and starch powder was found to be 0.74g per cc and 0.69g per cc respectively. Water absorption index (WAI) of rhizome flour and starch powder was 17.59 and 19.64 respectively. Oil absorption capacity (OAC) of rhizome flour was 0.84 g per g. In the case of starch powder it was 0.49 g per g. A decrease in the physical qualities was observed during storage for both flour and starch powder. A gradual increase in the microbial count was observed during storage. Insect infestation was not detected in both flour and starch powder throughout the storage period. High mean scores were obtained for sensory qualities like colour, flavour and texture of rhizome flour and starch powder. Two products namely vattal and murukku were prepared from rhizome flour and ready to use custard powder was standardized using rhizome starch. Vattal and murukku were prepared incorporating rhizome flour and rice flour in different proportions. Ready to use custard powder was also prepared using rhizome starch and corn flour in varying proportions. These products were evaluated organoleptically for different quality attributes using score card. Vattal prepared with 80 per cent rhizome flour and 20 per cent rice flour obtained higher mean scores for different quality attributes. The organoleptic scores obtained for all treatments were above 7 for murukku and the treatment with 30 per cent rhizome flour and 70 per cent rice flour obtained maximum scores for all quality attributes. Different treatments tried for custard powder also recorded high mean scores of above 8 for all quality parameters. Custard prepared exclusively with rhizome starch powder was selected as the most acceptable treatment. The selected products were packed and stored under ambient conditions for a period of three months. Decrease in mean scores of organoleptic parameters and gradual increase in the microbial count was observed during storage. Presence of insects and storage pests were not detected throughout the period of storage. The present study found that Canna rhizomes are rich in various nutrients especially starch, carbohydrate, and mineral constituents like sodium, phosphorus, calcium and potassium. Rhizome flour and starch powder were of good sensory qualities and can be used to prepare acceptable products like vattal, murukku and custard powder. The physiochemical properties of Canna tubers are very much suited for various food applications.