Studies on development and quality evaluation of rice bran incorporated breakfast foods

STUDIES ON DEVELOPMENT AND QUALITY EVALUATION OF RICE BRAN INCORPORATED BREAKFAST FOODS By A. VIJAYAKUMAR Degree : DOCTOR OF PHILOSOPHY IN FOOD SCIENCE AND NUTRITION Chairman : Dr.T. PADMINI, Ph.D., Professor and Head, Dept. of Apparel Designing and Fashion Technology, Home Science College and Research Institute, Madurai – 625 104. 2012 The rice bran varieties viz., ADT 39 (Culture ponni), ASD 16 (Peruvattu), ADT 43 (Chella ponni) and ADT 45 (Delux ponni) were selected and sieved through mesh no. 80 BS sieve to get same particle size and to remove the unwanted foreign material. The suitability of the rice bran variety for processing, chemical and nutrient composition and antioxidant contents were studied. Rice bran was stabilized by keeping in an air tight container and pressure cooked for 15 minutes. Excess moisture was dried in a cabinet drier at 60 o C for 2 hr to final moisture content of 5 per cent. The dried bran was packed in polyethylene bag and kept in ambient condition. The physicochemical characteristics of stabilized rice bran such as moisture, protein, fat, crude fibre, ash, insoluble ash, nitrogen solubility, , antioxidant activity, water absorption and oil absorption was studied. Among the rice bran samples selected, the physico – chemical characteristics showed that the ADT 43 had higher protein, antioxidant activity and water absorption whereas the fat, crude fibre and ash content were more or less similar in all the varieties. Finally, ADT 43 (Chella ponni) was found to be highly suitable for incorporation of rice bran incorporated breakfast foods. The selected ADT 43 rice bran was used for the preparation of the rice bran incorporated breakfast foods such as rice bran milk beverages, rice bran incorporated spiced idli, sweet pittu, savoury pittu, sweet idiappam, savoury idiappam. The freshly prepared breakfast foods were evaluated for the quality based on physico chemical characteristics and sensory evaluation. Freshly prepared convenience foods like spaghetti, instant idiappam, pittu and idiappam mixes were prepared and the organoleptic characteristics were evaluated in cooked form and physico-chemical quality were evaluated in uncooked form. Also the keeping quality of convenience foods packed in polyethylene bag without vacuum (P1) and with vacuum (P2) and and milk beverages packed in glass bottles were studied at a regular interval of 30 days and 7days respectively. Rice bran milk beverages were prepared with different flavours such as vanilla and badam essence and chocolate powder. The organoleptic evaluation of chocolate flavour milk beverage showed an excellent flavour and delicious taste in chocolate flavoured milk beverages . The physic chemical characteristics like protein, fat, TSS and total antioxidant activity were comparatively higher among the three different rice bran beverages.The beverages were stored under refrigeration condition for 21 days. Rice bran incorporated spiced idli was prepared by incorporating 1, 3 and 5 per cent levels of rice bran. The results of sensory evaluation of spiced idlis prepared with 3 per cent rice bran incorporation showed that the idlis were soft and non sticky and highly acceptable taste. All the physico chemical characteristics such as bulk density, protein, fat, crude fibre and total antioxidant of spiced idli were increased as the increase in the percentage of incorporation of rice bran. Rice bran incorporated sweet and savoury pittu and pittu mix were also prepared by incorporating rice bran at different level viz., 6, 8 and 10 per cent with rice flour. The taste and overall acceptability of rice bran incorporated (8 %) sweet pittu was pleasant aroma and sweet taste with highest sensory mean scores. The addition of rice bran enhanced the nutritive value of the pittu and pittu mixes and darkened when the level of incorporation increased. Rice bran incorporated sweet and savoury idiappam and idiappam mix were prepared by incorporating rice bran with rice flour at different levels as 8, 10 and 12 per cent. They were also analyzed for protein, fat, ash, crude fibre and antioxidants and found to be increased with their content in appreciable level when addition of rice bran increased. The colour intensity were found to be decreased in L* value and increased in a* and b* value with the level of increase in the incorporation of rice bran . The same trend of changes were also noted for the idiappam mix. Rice bran incorporated extruded products like spaghetti and instant idiappam were prepared from wheat semolina and rice flour respectively with the incorporation level of 8, 10 and 12 per cent rice bran. The sensory scores for the freshly prepared spaghetti and instant idiappam showed best response in terms of flavour and taste was obtained with 10 per cent rice bran incorporation. The texture of these products was also coarser and firmer. The bulk density of cooked and uncooked spaghetti and instant idiappam were decreased when the level of rice bran increased and expansion ratio of rice bran incorporated uncooked spaghetti were also found to be decreased with the addition of rice bran. The cooking losses of cooked spaghetti and instant idiappam were also high at this level. The strands of instant idiappam and spaghetti were broken during extrusion when the level of incorporation of bran exceeds 12 per cent. The chemical constituents such as moisture, protein, fat, ash content, crude fibre and total antioxidant activity of rice bran incorporated cooked and uncooked spaghetti and instant idiappam were increased in appreciable quantity of making the product and more valuable for health. Levels up to 8 – 10 per cent were found to be highly acceptable in these breakfast foods. Storage behaviour of rice bran milk beverages and rice bran incorporated convenience foods such as spaghetti, instant idiappam, pittu and idiappam mixes were studied based on physico chemical, sensory evaluation and microbiological qualities at a regular interval of 7 days for rice bran milk beverages and 30 days for convenience foods for 21 and 180 days respectively. During storage study, there was no change in the sensory character up to 21 days of storage in all the flavoured milk beverages. The colour and appearance, taste, consistency and overall acceptability of chocolate flavoured drink was found to be highly acceptable initially and maintained without any changes up to end of the storage period. During storage study bacterial count of rice bran milk beverage was none detected in rice bran milk beverages up to two weeks and after 3 rd weeks, it was found to be increased to 2.0 x 10 2 cfu/ g in all the beverages. The storage behavior of the rice bran incorporated convenience foods (spaghetti, instant idiappam, pittu mix and idiappam mix) were studied based on changes in physico chemical characteristics, sensory evaluation and microbial qualities. Moisture, free fatty acid and microbial count were increased gradually in all the rice bran incorporated convenience foods. The packed convenience foods (without vacuum and with vacuum) did not reveal any apparent deterioration based on physico chemical and microbial count throughout the storage period for six months. However, significant changes were observed in the moisture uptake and free fatty acid content and microbial count during storage. The products packed in polythene bags without vacuum stored at ambient temperature had significantly higher moisture and free fatty acid content than in vacuum packaging. The mean scores of sensory evaluation of stored convenience foods were decreased gradually during storage period. Due to changes in fat, flavor and taste of these products turned less acceptable after 2 3 months of storage. The scores had slightly higher in P2 than P1. Products packed under vacuum did not appear to influence the attributes like flavour and taste. There was no appreciable change in colour and texture during storage. The freshly processed convenience foods showed minimum bacteria, fungi and yeast count in all the treated and control samples. A slight increase in that microbial count were observed in both control and rice bran incorporated convenience foods irrespective of packaging conditions at the end of storage period. Convenience foods packed in vacuum packaging showed least microbial counts at the end of 180 days of storage. These observations indicated that addition of 8 to 10 per cent of rice bran can be recommended for traditional convenience foods.