International Journal of Modern Science and Technology Vol. 01, Issue 01: April 2016. Page 1-4. http://www.ijmst.co/ ISSN: 2456-0235 Mini Review Article Role of extrusion technology in food processing and its effect on nutritional values G. Baskar*, R. Aiswarya Department of Biotechnology, St. Joseph’s College of Engineering, Chennai – 600 119. India. *Corresponding author: Email id: [email protected] Abstract Extrusion cooking is a multi-functional thermal/mechanical process, which has drawn wide attention in agro-food processing industries. This process has various beneficial effects like destruction of antinutritional factors, gelatinization of starch, increased soluble dietary fiber and reduced lipid oxidation. On the other hand, Maillard reaction also influence in the nutritional value of the food by the interaction between protein and sugars. The raw material and their composition along with the process condition also influence the nutritional value of the food. The extrusion cooking is widely applied for cereal and protein processing such that the mild extrusion condition (low temperature, low residence time and high moisture) improves the nutritional quality of food largely. In case of high extrusion condition such as high temperature <200ºC, low moisture content (<15%) with the presence of high reactive sugars adversely affects the nutritional quality of food. In order to obtain a nutritionally balanced food control of process parameters along with the physico-chemical changes should be monitored properly at timely basis. This review also suggests the recent development in food industries regarding the extrusion technology. Keywords: Extrusion cooking; Maillard reaction; Nutritional value; Temperature. Introduction and significant nutrient retention. This process Proper nutrition involves intake of involves high temperature and short time as food carbohydrates, fats and proteins at an appropriate materials are cooked in a tube by the level for balancing the body with fiber, vitamins, combination of pressure, moisture and minerals and energy. As generation changes, mechanical shear resulting in molecular globalization increases with consumption of fast transformation (Shivendra et al., 2007). This food including high calorie food styles. This has high temperature short time process is known as brought a drastic change in day-to-day lifestyle extrusion technology, reduces microbial with lot behavioral changes towards foods. contamination, inactivates the enzymes as it is Change in process technology and methods of one of the methods which supports in the agriculture from organic to scientific have prevention of both cold and hot extruded brought changes in nutritional values. Due to products with the water activity of 0.1 to 0.4 changes and non-consumption of nutritious food, (Bordoloi and Ganguly, 2014). The role of shear, people are prone to non-communicable diseases, temperature, moisture and feed composition are including obesity, diabetes and cancer (Allal et significant in the process of transformation of al., 2014). Health and nutrition play a vital role starch by extrusion. in the society and it also remains as one of the Characteristics of Extrusion Technology challenging field in this era. It is always a The extrusion technology has become an necessary fact to monitor the nutritional quality important technique in food processing of the food as it directly affects the health of an industries as it one of the cost effective method. individual. The variability of the product and high quality, Processing of food at high temperature productivity of the new foods are the added remains a challenge in food processing industries advantage of this technology (Chakraborty et al., as it leads to deterioration of nutritive values in 2009). This process tends to break the covalent food. In order to avoid this, extrusion cooking is bonds in biopolymers along with certain adopted as it has unique features when compared modification such as texturizing the food to the other heat process. Extrusion cooking is ingredients. This process also denatures the mostly preferred, as it owes high productivity undesirable enzymes and other antinutritional ©International Journal of Modern Science and Technology. All rights reserved. 1 Baskar and Aiswarya, 2016. Extrusion technology in food processing factors, by retaining the original colors and Lysine appears to the most reactive amino flavors of foods. Nutrition has reached the acid as it has two amino groups and it was highest level of concerns, especially for dietetic reported that the availability of this amino acid foods and meat replacers using extrusion (Ulrich are in range of 32 to 40% at 170ºC, 10-14% feed et al., 1994). moisture and 60 rpm screw speed. The The extrusion process finds its application in availability of lysine is maintained by avoiding the preparation of salty, sweet snacks, textured the extrusion temperature above 180ºC at a water meat materials, ready to eat cereals and content below 15%. The amount of reducing nutritious precooked food mixtures for infant sugars is also reduced during the extrusion feeding. Though, extrusion cooking has been process as they influence on the loss of lysine. applied with great commercial success for the As the extrusion process involves higher production of shaped products and other temperature, toxic compound known as breakfast cereals, the application of extrusion acrylamide a probable carcinogenic agent is technology is gaining attention, especially on formed. The compounds are formed when the using vegetable proteins for the production of food substance is exposed to higher temperature textured product. In recent times, changes at the <180ºC(Studer et al., 2004).The extrusion molecular level are noted within the shear field cooking also influences the total dietary fiber as of the extruders as the proteinaceous materials changes in dietary profile is primarily due to the denatures and melts in the extruders itself. In shift from insoluble dietary fiber to soluble order to understand the chemical changes in the dietary fiber. The mild extrusion temperature extruders, it is necessary to know about the solubilizes some fiber components and in severe temperature, pressure and shear such that condition, the content increases owing to its intermediate-mositure environment condition are increases in soluble dietary fiber and enzyme to be noted as it affects the quality of the product resistant starch fractions(Vasanthan et al., 2002). (Ledward et al., 1994). The nutritional values are The presence of vitamins is also influenced explained below. by the extrusion process where minimizing Nutritional changes in food temperature and shear within the extruders tends The nutritional value in vegetable protein is to protect the nature of vitamins present in the usually enhanced by mild extrusion cooking food ingredients. Various precaution are done for conditions such that it increases the digestibility controlling the loss of vitamins during extrusion due to protein denaturation and inactivation of such that post extrusion application are carried enzyme inhibitors present in raw foods. The out (Camire., 1998). The three main parameters, process variables such as temperature, feed ratio, which influences on the consumption of food are screw speed and length to diameter ratio plays a product, nutritional and microbial quality. The significant role in protein digestibility. The products are subjected to high temperature that antinutritional factors such as trypsin inhibitors confers the crunchy nature of the product such and tannis are destructed during extrusion that the texture and color are significant in terms cooking. The destruction of trypsin inhibitors of product quality. It is essential for the increases with increase in extrusion temperature specialized nutritional foods such as infant and and moisture content. It was reported that for weaning foods to possess high starch protein such as casein, the temperature at 153ºC, digestibility as it has reduced calorie during the 20% moisture and 2 min resisdence time resulted process of extrusion. The mild extrusion with 89% reduction in trypsin inhibitors. Higher conditions tend to form nutritive foods as they extrusion temperatures, lower feed moisture, provide high digestibility product. One of the longer residence time are key variables for the most important criteria in terms of consumers’ destruction of trypsin inhibitors(Bjorck & Asp, requirement is the microbial quality of the food. 1983).In addition, the Maillard reaction plays a This process was found to be efficient as it vital role during the processing of foods. The involves higher temperature where the vegetative reaction involving an amino group of protein and organisms are destroyed during the extrusion carbonyl group of reducing sugars results in process (Dehghan et al., 2010). browning and flavor production. This reaction Functional properties significantly decreases the availability of amino The type of extrusion depends mainly on the acids involved in protein digestibility(Fukuiet type and amount of the starch used in the al., 1993, Jaeger et al., 2010). process. Under high extrusion conditions, the ©International Journal of Modern Science and Technology. All rights reserved. 2 Baskar and Aiswarya, 2016. Extrusion technology in food processing sensory and nutritional quality of the product is extrusion and use of less reactive sugars may changed. Even the functional properties create a new line of research objectives.