Technological and Nutritional Evaluation of Sel-Roti
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TECHNOLOGICAL AND NUTRITIONAL EVALUATION OF SEL-ROTI Dissertation Submitted to the Central Department of Food Technology, Institute of Science and Technology, Tribhuvan University, Nepal for the Award of Doctor of Philosophy (PhD) Degree in Food Technology. BY: SURENDRA BAHADUR KATAWAL Central Campus of Technology, Hattisar, Dharan, Sunsari, Nepal 20 May, 2013 i Recommendation This is to certify that Mr. Surendra Bahadur Katawal has completed dissertation entitled Technological and Nutritional Evaluation of Sel-roti for the award of Doctor of Philosophy in Food Technology under my supervision. To my knowledge this work has not been submitted for any other degree. Date: 16th April.2012. …………………. Prof. Dr. Dilip Subba Supervisor ii Declaration I hereby declare that the work presented in this dissertation has been done by myself and has not been submitted for the award of any degree. All the sources of information have been acknowledged by reference to the authors or institution. …………………. SURENDRA BAHADUR KATAWAL Central Campus of Technology, Hattisar, Dharan, Sunsari, Nepal 16th April, 2012 iii Acknowledgements I express my deepest gratitude to my guide Prof. Dr. Dilip Subba, Central Campus of Technology, Dharan, Nepal for his excellence guidance, encouragement, and valuable suggestions during this research work. I would like to express my sincere gratitude to Head of the Department and other staffs of Central Department of Food Technology, Dharan and Assistant Dean and laboratory and library staffs of Central Campus of Technology, Dharan for timely help and encouragement throughout the work. I would like to thank to Dean and the staffs of research section therein, of Institute of Science and Technology, T.U., Kirtipur, Kathmandu, Nepal for giving me the chance to do this research work. I would like to express my sincere thanks to the respondents of the survey who co- operated me to give valuable information which were the basis for the experimental work and documentation. Similarly, I would like to express many many thanks to sensory panelists who assisted me in evaluating the product i.e., Sel-roti for long period of time with immense patience. Furthermore, I would also like to express my thank to SEAM-N, Dharan and its laboratory in-charge and staffs at Biratnagar for their valuable help in analyzing the proximate composition, minerals and characteristics of fat of the rice and Sel-roti sample. Similarly, I would like to thank the chief and staffs of Eastern Regional Laboratory of DFTQC, Biratnagar for assisting me in analysis of fat/oil of Sel-roti. I would like to thanks to all my seniors, my colleagues inside and outside of this campus for encouraging me during the work and M.Tech Students especially Santosh Dahal for helping me in analysis. Last but not least I would like to express my deepest and sincere thank to my sons Ishwor and Kishor; on top of all to my beloved wife Mrs. Kamala Katawal without her encourage, and patience & fatigueless assistance this work would not be completed. Surendra Bahadur Katawal Central Campus of Technology, T.U., Dharan, Nepal iv Abstract Sel-roti is a popular and delicious rice-based, sweet, puffed, spongy, deep-fat fried, ring- shaped doughnut like Nepalese indigenous food product prepared from the batter of rice flour, ghee and sugar. Sel-roti making technology is an indigenous technology of Nepal. A survey study of 126 respondents comprising different casts, ethnicity, religion, age, sex from different district of Eastern and Central Development Regions of Nepal was conducted to gather the information on ingredients, recipe, equipments and processing methods of Sel-roti by using questionnaires. The factors affecting quality, storage and shelf life and also production, marketing, socioeconomic and cultural aspects were gathered and documented. It showed that the variety and age of rice, type of ingredients, method of preparation, and storage condition influence the quality and self-life of Sel-roti. To study the effect of particle size of rice flour on the physical properties, sensory quality and textural attributes of Sel-roti, the soaked rice was ground into flour with the help of iron mortar and pestle, analyzed for particle size distribution by using standard sieves and separated into three particle size categories i.e. coarse (>890 µm), medium (450-225 µm) and fine (<120 µm). They were mixed in different proportions; analyzed their distribution and calculated mean particle diameter; prepared Sel-roti, and analyzed for bulk density & fat uptake; and sensory and texture attributes were evaluated by trained panelists. The experiments were conducted in triplicate. The results obtained showed good positive correlation between mean particle size and the bulk density (r = 0.97, p≤ 0.05) and a good negative correlation between mean particle size and fat-uptake (r = -0.90, p≤ 0.05). Also, good correlations of mean particle size with sensory texture attributes like smoothness (r = -0.97, p≤ 0.05), hardness (r = 0.99, p≤ 0.05), fracturability (r = 0.96, p ≤ 0.05), cohesiveness (r = -0.92, p ≤ 0.05), Stickiness (r = -0.76, p≤ 0.05) and oily mouth feel (r = -0.85, p≤ 0.05), but fair relation with chewiness (r = 0.65, p> 0.05) were found. The ANOVA and LSD of panel scores for each sensory attribute like appearance, taste, texture, flavor and overall acceptance showed significantly difference (p≤0.05) among treatments. From the same experiment the optimum particle size of flour i.e., 520±6µm was selected for good Sel-roti preparation. v Processing parameters like soaking of rice, kneading of ingredients, ageing of batter, consistency of batter, frying temperature and time had significant effect (p≤0.05) on some physical properties and sensory quality of Sel-roti. From the same study the optimum processing parameters investigated were 2h(minimum) soaking time of rice; 10mim kneading time of ingredients for 250 g flour; 1.935DS/L corresponding velocity flow rate, 2.302cm/s or 25 ml water per 100g fresh flour; minimum 1h ageing time of batter; and 210°C(initial) frying temperature and 33S frying time. The frying medium had also effect on the quality of Sel-roti. Among the used ghee and oils refined soybean oil was selected. The result of the study of the effect of age of rice and ‘daun ‘ on the quality of Sel-roti revealed that daun is must for good Sel-roti preparation whereas age of rice had not significant effect(p>0.05). There were significant effect (p≤0.05) of ageing temperature and ageing time of batter on the biochemical parameters such as pH, acidity, reducing sugar and total sugar. On the comparision Sel-roti prepared from optimized process and recipe were found to be superior to Sel-roti prepared from traditional process. The physical properties of Sel-roti determined were 542kg/m3, 10.78±0.55cm, and 1.93±0.16cm for bulk density, ring diameter and cross section diameter of Sel-roti respectively. The sensory properties of Sel-roti were ringed shape, light to reddish brown colour and grainy surface, moderate sweet taste, soft and little crunchy texture and sweetish and burnt sugar flavor characteristics to Sel-roti; and the proximate composition of Sel-roti were found to be as 4.68±0.10, 26.46±1.35, 0.30±.01, 0.16±0.02 and 68.41±1.44 on dry weight basis for crude protein, crude fat, ash, crude fibre and carbohydrate respectively and calorific value of Sel-roti was found to be 533kcal on dry weight basis. The texture attributes of Sel-roti were found to be 8.20±1.6, 6.01±1.4, 8.53±1.6, 7.33±1.5, 5.70±1.5, 9.47±1.6 and 15.00±3.0 for smoothness , hardness, fracturability, cohesiveness , stickiness, oily mouth feel and chewiness respectively. Key words: Sel-roti, indigenous, texture, sensory, quality vi Abbreviations AAS = Atomoc Absorption Spectrometer ANOVA = Analysis of Variance AOAC = Association of official Analytical Chemists AV = Acid Value CLA = Conjugated linoleic fatty acid DFTQC = Department of Food Technology and Quality Control DG = Diglyceride FFA = Free fatty acid HDL = High density lipoprotein HPLC = High Performance Liquid Chromatography LDL = Low density lipoprotein LSD = Least Square Difference MG = Monoglyceride PC = Polar compound RDS = Rapidly digestible starch RI = Refractive Index RM = Reichert Messel RS = Resistance starch SDS = Slowly digestible starch SV = Saponification value TG = Triglyceride vii Table of Content Recommendation ................................................................................................................ ii Declaration ......................................................................................................................... iii Acknowledgements ............................................................................................................ iv Abstract v Abbreviations .................................................................................................................... vii Table of Content .............................................................................................................. viii 1. Introduction ......................................................................................................................1 1.1 General introduction ...................................................................................................1 1.2 Justification ................................................................................................................3 2. Objective of the study ......................................................................................................5