IMPACT OF FIBER MIXTURE ON DOUGH AND CHAPATTI QUALITY USING D-OPTIMAL RESPONSE SURFACE METHODOLOGY

Abstract

Demand for health oriented products such as sugar-free, low calorie and high fiber products are increasing. One such recent trend is to increase the fiber content in food products to overcome health problems such as hypertension, diabetes, and colon cancer, among others. Chapatti is an important staple food consumed by majority of the population in the Indian subcontinent hence it can be a very good vehicle for fiber fortification. Fiber from natural sources such as wheat, soy fiber and type III resistant starch (RS) were used to study their impact on rheological characteristics of whole wheat flour dough and chapatti singly and in associated mixtures at different levels. D-optimal response surface methodology mixture design was applied to a mixture containing three ingredients: x1, wheat fiber, x2, soy fiber and x3, type III RS. The variation selected to each variable was based on values which were optimized on the basis of sensory properties and textural properties of chapatti, where x1, x2, x3 were changed from 2.5 to 5 g/100 g of whole wheat flour. For each of the response variables, model summarized F-tests and lack of fit tests which were then analyzed for linear or quadratic models. Three-dimensional response surface plots were generated for all quality parameter. Calculation of optimal processing conditions for optimum stickiness, strength, tear force and extensibility of dough and chapatti were performed using a multiple response method called desirability. Addition of wheat, soy fiber and type III RS in wheat flour mixture decreased dough stickiness and improved dough strength. Dough containing wheat fiber (2.5%), soy fiber (5.0%) and type III RS (2.5%) yielded highly acceptable chapattis in terms of textural properties such as low tear force values and high extensibility.