~ 2736 ~ International Journal of Chemical Studies 2020; 8(1): 2736-2740 P-ISSN: 2349–8528 E-ISSN: 2321–4902 www.chemijournal.com IJCS 2020; 8(1): 2736-2740 © 2020 IJCS Received: 04-11-2019 Accepted: 06-12-2019 Chaudhari Bhoomiben Bharatbhai Amul Dairy, KDCMPU Ltd., Anand, Gujarat, India Patel Amitkumar Manojbhai SMC College of Dairy Science, AAU, Anand, Gujarat, India Smitha Balakrishnan SMC College of Dairy Science, AAU, Anand, Gujarat, India Corresponding Author: Patel Amitkumar Manojbhai SMC College of Dairy Science, AAU, Anand, Gujarat, India Sensory, physico-chemical, microbial and textural changes in whey protein concentrate based extruded snack food during storage Chaudhari Bhoomiben Bharatbhai, Patel Amitkumar Manojbhai and Smitha Balakrishnan DOI: https://doi.org/10.22271/chemi.2020.v8.i1ap.8684 Abstract Extruded snacks are gaining recognition as well as appreciation these days due to their ready-to-eat nature, delicious taste and appealing look. Combination of lysine rich whey protein concentrate with lysine deficient cereal protein has synergistic effect that imparts a high nutritional value to the mixed protein in the product. The milk solids based extruded snack food and control sample were stored at room temperature (37±2 °C) after packaging in MET PET material. The whey protein concentrate based extruded snack food samples and control sample were analyzed for changes in sensory characteristics, physico-chemical properties and textural properties as well as for microbiological quality at 15 days interval. Sensory scores, fracturability for experimental sample and control decreased while moisture, water activity and hardness increased during entire storage period. The Standard plate count decreased while coliform count and yeast and mold count were found absent till 180 days of storage. Keywords: Whey protein concentrate, extruded snack food, extrusion cooking, twin screw extruder Introduction Snacks are a category of foods which are consumed during the meals to satiate the hunger. Snack foods are the first commercial extruded products and today, food manufacturers produce many foods and consumption of the extruded foods has been increasing. Owing to its convenience and low cost, snack foods consumption by all age groups, including adolescents and children has increased during the last twenty-five years (Sebastian et al., 2008) [15] . Snack food industry has been facing pressure from regulatory agencies to deliver healthier snack products. The snack market in India is quite large and diverse consisting of more than 1000 variants and about 300 types of savouries (Conti-Silva et al., 2012; Brennan et al., 2013) [8, 3] . Extrusion cooking is used for various food products such as snack food, baby food, breakfast cereals etc. (Huber, 2001) [9] . It is a low cost, energy efficient, versatile process which produces a high-quality product continuously without creating effluents. Whole grains, for instance corn and rice are often used to formulate healthy snack products using extrusion due to its relatively high starch content, bland taste and hypoallergenicity (Chaiyakul et al., 2009) [6] . Entire or partial incorporation of legume flour into ready-to-eat snack product have been proven to be desirable. However, several studies have indicated that partial substitution of cereal flour with high fibre and protein ingredients, for instance legume flour, can negatively affect the texture, expansion and overall acceptability of ready-to-eat snack products (Anton et al., 2009; Pastor-Cavada et al., 2011) [2, 12] . Whey protein concentrate (WPC) represents a protein source with considerable potential for blending with varieties of food products to improve their nutritional value and functional properties. Extrusion cooking is a modern high-temperature short-time (HTST) processing technology using high pressure, large shear forces and intensive mixing (Zheng &Wang, 1994). Under these conditions, the raw materials are subject to protein denaturation, starch gluten formation and plasticization of the complete volume. The evolved plasticized volume expands through the die due to rapid fall in pressure, to form an extrudate with characteristic properties (Cai et al., 1995) [5] . In extrusion cooking, not only feed ingredients, but also extrusion parameters for instance feed moisture, screw speed, barrel temperature, and feed ratio are responsible for end