Impact of fiber mixture on dough and chapatti quality using D-optimal response surface methodology

Shalini S. Arya, Sachin K. Sonawane
2016 Journal of Microbiology, Biotechnology and Food Sciences  
Keywords: Chapatti, fiber, response surface methodology INTRODUCTION Cereal fiber, which have a great proportion of insoluble fiber, have physiological advantages such as the chewing mechanism, stimulation of intestine function and influence on intestine transit period (Bollinger, 2000) . Health authorities, worldwide, recommend a decrease in the consumption of animal fats and proteins and an increase of cereal intake, which is an important source of dietary fiber, and, in most European
more » ... st European countries, cereals constitute a major source of dietary fiber. In addition to these physiological properties, cereal fiber consisting mainly of cellulose have advantageous technological properties such as a high water and fat binding capacity and they are optimal ingredients for achieving high yields and reduced cost. One to three percent fiber in certain foods can also reduce lipid retention when these foods are fried (Ang, 1993; Thebaudin et al. 1997) . A wide variety of fiber from plant sources have been developed for use in various foods to provide more fiber, to improve the texture, color and aroma with a reduced energy of the final product (Jeltema et al. 1983; Morrison et al. 2008; Sánchez -Alonso et al. 2007; Yanniotis et al. 2007). Lemon and apple fiber have been reported to have relatively high water holding capacity and therefore used in cakes, breads and similar cereal products to improve the softness and the product yield with a reduced energy value of the product (Chen et al. 1988).The development of safer and healthier low-calorie products with acceptable functional and sensory characteristics, by employing the conventional processing equipment is of major industrial concern to fulfill consumers' expectations. The latest functional significance is of major interest in the performance of lowcalorie staple foods, particularly chapatti. There are very few reports on effect of fiber addition on chapatti quality. Flour tortillas (soft tacos and tortillas, wraps, flat breads) with improved texture and nutritional characteristics were made using flour milled from specific barley cultivars with waxy starch characteristics and high levels of fiber (Ames et al. 2003). Therefore, to meet this requirement for dietary fiber, the development of enriched chapatti with a higher dietary fiber content could be a potential option. Chapatti can be enriched with dietary fiber, including wheat bran (Ranhotra et al. 1990; Sidhu et al. 1999), soy fiber, gums, such as guar gum and modified cellulose (Pomeranz et al. 1977), β-glucans (Knuckles et al. 1997). Both the expansion and structure of these products depend on starch gelatinization, which is affected by processing conditions and raw material composition. Increasing fiber content in the form of bran resulted in premature rupture of gas cells, which reduced overall expansion of bread in one study by Mendonca et al. (2000) and Moore et al. (1990). The common experimental approach in most of the studies has been to investigate the effect of variables one at a time. However, the examination of several variables individually is laborious and time consuming. It results in large quantities of data that are difficult to interpret and, in addition, it fails to measure interaction effects. To overcome the limitations of this experimental approach, a process optimization technique that involves factorial designs and multiple regression techniques, called response surface methodology (RSM), can be used. The advantages of an RSM approach are that it examines variables simultaneously, it is less time consuming and more cost effective, and it explains any synergies between variables. Furthermore, the results may be illustrated graphically in easy to understand 2-D contour and 3-D response surface plots. When the mixture components are subject to the constraint that they must sum to one, there are standard mixture designs for fitting standard models, such as simplex-lattice designs and simplex-centroid designs. When mixture components are subject to additional constraints, such as a maximum and/or minimum value for each component, designs other than the standard mixture designs, referred to as constrained mixture designs or extreme-vertices designs, are appropriate. In mixture experiments, the measured response is assumed to depend only on the relative proportions of the ingredients or components in the mixture and not on the amount of the mixture. The amount of the mixture could also be studied as an additional factor in the experiment; however, this would be an example of mixture and process variables being treated together. Proportions of each variable must sum to 1. The main distinction between mixture experiments and independent variable experiments is that with the former, the input variables or components are non-negative proportionate amounts of the mixture, and if expressed as fractions of the mixture, they must sum to one. If for some reason, the sum of the component proportions is less than one, the variable proportions can be rewritten as scaled fractions so that the scaled fractions sum to one. 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. Threedimensional 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. ARTICLE INFO
doi:10.15414/jmbfs.2016.5.5.424-433 fatcat:luy6baulenajbhw7yhjlbsa24q