26-4 |
Application of liquid full scraped surface heat exchanger for production of kheer |
D. V. BANGALORE, Food & Agricultural Products Research & Technology Center, Oklahoma State University, Stillwater, OK 74078-6055 and K. Rajkumar, Dairy Engineering Div., National Dairy Research Institute, Karnal, 132001, India. Kheer, a rice-based dessert is a popular traditional dairy product of India. However, lack of appropriate process technology has been a major handicap in its commercial production. Application of Liquid full scraped surface heat exchanger [LFSSHE] for kheer processing was considered because of its ideal plug flow characteristics and our assumption of maximum particle retention. The objectives were to develop a process prototype incorporating LFSSHE for continuous kheer processing; study the effect of process variables on flow, power, rheological and sensory characteristics in LFSSHE and finally comparing it with batch processed product. Experimental prototype incorporating horizontal LFSSHE, holding tube (~ 3minutes) and driving assembly with suitable instrumentation was developed. Buffalo milk (fat: 5%, SNF: 9.7%), sugar (@10% of milk), and pre-soaked and dried Basmati rice (@ 5% of milk) were the raw materials used. LFSSHE was evaluated at a range of process conditions, including mass flow rates of 50-100lph, rotor speed of 75-150rpm and temperature of 105-1150C. Properties measured included flow behavior (based on radial temperature difference [DTr]), rheological properties (using Rheomat 108 E/R viscometer), power consumption (on energy meter),particle retention (using glass plates) and sensory characteristics (using 10-point hedonic scale). System incorporating LFSSHE for continuous kheer production was developed. DTr for our conditions ranged from 2.5-280C supported with Rer/Rerc values of 0.22-0.81 indicating laminar flow. Power consumption increased with rotor speed but decreased with temperatures. Kheer exhibited pseudoplastic and thixotrophic property with m and n values ranging from 0.3 to 0.56 and 0.35 to 8.4 respectively. Kheer processed at 50lph, 100rpm and 1150C had minimum DTr, 50-60% particle retention, sensory scores (22.8/27. vs. 24.6/27) and rheological values (m: 0.41.vs. 0.47 and n: 0.85. vs. 0.36) in comparison to batch product. The developed prototype with LFSSHE produced Kheer similar to conventional process offering a practical process option for dairy industry.
Session 26, Dairy Foods: General developments in dairy technology
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