Standardisation and quality evaluation of rice based fermented dairy products

Abstract

Summary, etc. The present study was undertaken to standardise rice based fermented dairy products and to enrich the standardised products with bits and pulp of fruits. The study also envisaged to evaluate the physical, chemical, nutritional, organoleptic and keeping qualities of the standardised products. Rice based fermented dairy products (RBFDP) were prepared using rice slurry made out of roasted and unroasted rice flour of raw rice, parboiled rice and germinated rice in different proportions with or without milk. With a view to find out the most appropriate combination for the preparation of RBFDP, the 18 treatments were evaluated for various organoleptic qualities like appearance, colour, flavour, odour, texture, taste, after taste and overall acceptability and compared with the characteristics of plain yoghurt (control). In different treatments tried for the preparation of RBFDP, the mean scores for different quality attributes showed a decreasing trend with increase in the quantity of rice slurry. The products prepared with milk and rice slurry made out of unroasted flour of raw, parboiled and germinated rice in 50:50 proportions were selected as the most acceptable treatments for the preparation ofRBFDP. The selected RBFDP was enriched with bits and pulp of pineapple and mango separately @ five per cent. Based on the organoleptic scores, RBFDP prepared out of unroasted flour of germinated rice enriched with bits of pineapple and RBFDP prepared from unroasted flour of raw rice enriched with pulp of mango were selected as the most acceptable ones. The selected RBFDP and fruit enriched RBFDP along with control were stored for 14 days under refrigerated condition (4°C) and evaluated for nutritional qualities initially and at the end of 14th day of storage. The physical, chemical and

microbial qualities of the selected products were evaluated initially and at weekly intervals. A significant decrease was noticed in protein, fat and starch content of RBFDP and fruit enriched RBFDP during storage. Enrichment with fruits improved the fibre p-carotene and vitamin C content of RBFDP. The products were found to be a fair source of thiamine and riboflavin. The products had appreciable amounts of calcium and phosphorus which decreased significantly during storage A decrease in the curd tension and a subsequent increase in viscosity of the RBFDP and fruit enriched RBFDP was recorded in seven days of storage. By 14th day of storage the curd tension increased and the later remained unchanged. Syneresis was noticed only during the initial evaluation. The moisture content and pH of RBFDP and fruit enriched RBFDP decreased during storage with an increase in the titrable acidity thereby influencing the organoleptic qualities of the products. An increase in the total soluble solids CTSS) of RBFDP and fruit enriched RBFDP was noticed during storage whereas a decrease was observed in plain yoghurt (control) Presence of contaminating bacteria was not detected in any of the samples during storage. Mold and yeast were not' detected in the products till 7th day of storage. But in fruit enriched RBFDP presence of mold and yeast were detected during final evaluation. Viable count of Lactobacillus delbrueckii ssp bulgaricus and Streptococcus salivarius ssp thermophilus decreased in 14 days of storage. The viable count of cultures noticed in RBFDP made out of germinated rice was comparable with control. Cost of production of RBFDP and fruit enriched RBFDP was found to be lower than the cost of plain yogurt and fruit enriched yogurt available in the market.