Journal of Ready to Eat Food | July-September, 2014 | Vol 1 | Issue 3 | Pages 85-99 © 2014 Jakraya Publications (P) Ltd JOURNAL OF READY TO EAT FOOD Journal homepage: www.jakraya.com/journal/jref ORIGINAL ARTICLE Optimization of Process Parameters for Hot Air Puffing of Wheat-Soy Based Ready-to-Eat (RTE) Snacks: A Response Surface Approach I. L. Pardeshi a* , P. K. Chattopadhyay b and R. V. Jaybhaye c a *Associate Professor, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra-444104, India, b Retired Professor, Department of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur, West Bangal-721 302, India. c Assistant Professor, Section of Agricultural Engineering, College of Agriculture, Latur, Maharashtra-413512, India. *Corresponding Author: I. L. Pardeshi Email: ilpardeshi@gmail.com Received: 10/08/2014 Revised: 31/08/2014 Accepted: 27/09/2014 Abstract The experiments were carried out to prepare wheat-soy snack food with maximum soy fortification up to 7.5 % in refined wheat flour. The cold extrudates prepared by adding 0.5384 kg/kg dm initial moisture content to wheat-soy composite flour could be optimally steamed at 70 kPa for 10.75 min and puffed in whirling bed hot air high temperature short time (HTST) puffing system at 215 °C for 30 s. The experiments were conducted using Central Composite Rotatable Design (CCRD) and the analysis for optimization of the process variables was carried out using Response Surface Methodology (RSM). The velocity of whirling bed hot air was fixed constant at 3.95 m/s. The wheat-based puffed snack food prepared at optimum process parameters was having minimum moisture content of 0.165 kg/kg dm, maximum expansion ratio of 1.99 R, maximum colour (L-value) of 60.56 and maximum crispness (+ve peaks) of 10.40 at hardness of 928.5 g. However, the higher moisture content of the puffed samples required further oven toasting at temperature of 113 °C for 27 min yielding wheat-soy ready-to-eat snack food having moisture content of 0.0457 kg/kg dry matter, colour (L-value) of 56.54, crispness of 18.00 and hardness of 930.20 g. The level/proportion of soy flour in the product was fixed by ensuring statistically non-significant variation in optimally developed snack food. Keywords: HTST, Puffing, RTE snack, Wheat, Soy, Cold extrudate, RSM, Optimization. Introduction The importance of breakfast cereal is gaining significance in an era of changing life-style, rapid urbanization, convenience and above all, a health- conscious society. The convenient and ready-to-eat (RTE) foods are also becoming popular among the people. However, the balanced and sufficient nutrition content of available ready-to-eat foods is major issue of verification. Though an analysis of the daily requirement and intake of calories and nutrients indicate large gaps among different populations; rice, wheat and pulses form the major items of the staple food of India. Therefore, these items may play significant role in preparation of RTE foods for Indian people (Bhole, 1992). Moreover the gelatinization, dextrinization and caramelization of the cereal starches imparting the crispiness and flavour changes are of great importance in preparation of RTE foods (Srivastava, 1993). Pulse proteins are deficient in sulphur containing amino acids, particularly in methionine, and in tryptophan. It is only in case of soybean that the tryptophan level is equal to the FAO provisional pattern. Overall most satisfying pulse protein from standpoint of the FAO provisional pattern is that of soybean (Manay and Shadaksharaswamy, 2004). The deficiency of lysine in cereals like rice and wheat is more than compensated for if pulses like soybean are blended with these cereals. Since, rice/ wheat and soybean are complementary to each other in nutrient terms; the weakness of one is the strength of other. The full fat and defatted soya flour have been used as ingredients in the preparation of high protein snacks.