Development of Dietary Fibre Rich Fish Snack Products Using Twin Screw Extrusion

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Table 3: Trial experiment flour composition 7

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INTRODUCTION

Extrusion cooking technology is the most used technique for the production of snack foods (White, 1994). Extrusion is a powerful processing operation, which utilizes high temperature, pressure, and shear force to produce highly expanded, low-density products with unique texture properties (i.e. crispiness, crunchiness). Extrusion of snack foods demands close control of many variables such as feed moisture, feed composition, feed particle size, feed rate, barrel temperature, screw speed, screw configuration, and die geometry. These material and process variables determine the extent of macromolecular transformations during extrusion, which in turn influence the rheological properties of the food melt in the extruder and, consequently, the product characteristics of extrudates. Physical characteristics such as expansion, density, and hardness are important parameters to evaluate the consumer acceptability of the final product (Patil, Berrios, Tang, & Swanson, 2007). Cereals, in turn, are the customary, traditional snack ingredient due to their high starch content (Perez-Navarrete et al., 2006).

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Background

Extrusion technology has many advantages, including its versatility, high productivity, low cost, and the ability to produce unique product shapes and high product quality (Singh and Smith, 1998; Singh et al., 1999; Koksel et al., 2004). Extrusion-cooking is a versatile and feasible alternative for manufacturing snacks and water reconstitutable foods, and it has been the object of studies to enhance the nutritional and functional properties of extrudates for the development of products (Sacchetti et al.., 2005; Shankar and Bandyopadhyay, 2005; Gonzalez-Soto et al., 2006; Hernandez-Diaz et al., 2007).

In modern days there is an ever increasing awareness about health foods and fish is gaining more acceptance because of its special nutritional and functional properties. Fish is an excellent source of high nutritional value protein and an excellent source of lipid that contains omega-3 fatty acids, especially, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Kris-Etherton et al., 2000; Kris-Etherton et al., 2002). Omega-3 fatty acids are essential for normal growth and development and may prevent or moderate coronary artery disease, hypertension, diabetes, arthriti

s, others inflammatory and autoimmune disorders as well as cancer (Simopoulos, 2000). Interestingly, fish is also a good source of various vitamins (A, D, B6, B12, etc.) and minerals (Iron, Zinc, Iodine, Selenium, Potassium, Sodium etc.).

Dietary fiber is the indigestible component of foods that includes cellulose, hemicellulose, lignins, pectins, gums, and mucilages (Goni, I., Díaz-Rubio, M.E., Pérez-Jiménez, J. & Saura-Calixto, F. 2009). Its beneficial effects on human health have received much attention. Lack of adequate dietary fiber in the diet is associated with constipation, diverticulosis, cardiovascular disease, and cancer (Trowell, H., Burkitt, D. & Heaton, K. eds. 1985.), and increased consumption of dietary fiber has been advocated. Dietary fiber-rich materials have gained popularity as food ingredients for health benefits in recent years. However, relatively little is known about the effects of processing conditions on structural and mechanical properties of fiber containing foods. The incorporation of dietary fibers into extruded products plays an important role on their structural characteristics. High levels of fiber have often resulted into a compact, tough, non-crisp and undesirable texture (Lue, S., Hsieh, F., Huff, H.E., 1991.). Many studies on the effects of extrusion cooking using different fiber sources, like corn bran, soy fiber and sugar beet fiber have been reported.

In extrusion cooking, important parameters for product quality include moisture content of the material, residence time, which is influenced by feeding rate, screw speed and configuration, die geometry, temperature and time (Gogoi and Yam, 1994; Obatolu et al., 2005). The results of extrusion are gelatinization of starch, denaturation of proteins, inactivation of many native enzymes and anti-nutritional factors, reduction of microbial counts, and improvement in digestibility and biological value of proteins (Martin-Cabrejas et al., 1999; Milan-Carrillo et al., 2002). The suitability of extruded foods for a particular application depends on their functional properties like water absorption and water solubility indexes, expansion index, bulk density and viscosity of the dough (Hernandez-Diaz et al., 2007).

Chickpeas are the third most important legume in the world after dry beans and dry peas (Singh, Subrahmanyam, & Kumar, 1991). Chickpeas have one of the highest nutritional compositions of any dry edible pulse and do not contain any specific major antinutritional

factors (Chavan & Salunkhe, 1986). Research has shown that chickpeas are an excellent source of protein (24.4%), dietary fiber (9.0%), complex carbohydrates (60.0%), folate, and trace minerals such as iron, molybdenum, manganese (Poltronieri, Areas, & Colli, 2000; Wang & Daun, 2004). In addition, chickpeas have been reported to reduce the levels of cholesterol and blood glucose (Singh & Singh, 1992). Hence, Chickpeas are increasingly being used in healthy diets to promote general well-being and to reduce the risk of cardiovascular diseases and diabetes (Pulse Canada, 2008).

Chickpeas have a high (40–50%) starch content (Huang et al., 2007; Wang & Daun, 2004), which may favor an extrusion process to produce directly expanded snack foods. Using chickpeas instead of cereals in extruded snacks would improve the nutrient density of these foods because chickpeas have more protein. Hence, development of chickpea-based snacks could provide an attractive outlet for chickpea utilization. However, processing of chickpeas into extruded snacks is limited. Few reports (Bhattacharya & Prakash, 1994; Shirani & Ganesharanee, 2009) indicated that incorporation of chickpeas into rice flour decreased product expansion. The extrudates exhibited increased density and breaking strength, indicating poor textural effects of chickpea flour inclusion. The above studies dealt with relatively simple raw material compositions. A more complex mixture, involving starch and protein fortification, may promote expansion and nutritional quality of a chickpea based snack.

The objective of