RESEARCH ARTICLE Pasting, swelling, and solubility characteristics of rice batter prepared from different wet grinding systems Pankaj Sharma 1,y , Vasudeva Singh 2 and Rangaswamy Subramanian 1 1 Department of Food Engineering, Central Food Technological Research Institute, CSIR, Mysore, Karnataka, India 2 Department of Grain Science and Technology, Central Food Technological Research Institute, CSIR, Mysore, Karnataka, India Pasting behavior of raw and parboiled rice (IR-64) batter prepared from different wet grinding systems (stone grinder, mixer grinder, and colloid mill) with average particle size (620 mm) similar to the market sample was studied after 14–16 h fermentation. Gelatinization tempera- ture (GT) for raw and parboiled rice varied from 70 to 758C and 77 to 798C, respectively. Peak viscosity (PV) was highest in the batter prepared from stone grinder which could be due to the predominant compressive forces involved in wet grinding. PV of parboiled rice batter was 40– 45% less than the raw rice which was attributed to the presence of pre-gelatinized starch. In parboiled rice batter, breakdown (BD) reduced drastically and the relative breakdown (BD r ) was also low compared to the raw rice batter. Swelling power and solubility when studied at various temperatures 50–1008C were lower in the batter prepared from stone grinder compared to the shear imparting mixer grinder and colloid mill indicating the probable role of grinding forces involved. Received: June 14, 2012 Revised: September 6, 2012 Accepted: September 12, 2012 Keywords: Batter / Grinding / Solubility / Swelling / Viscosity 1 Introduction Rice being a staple cereal for Asian countries, has been used in wet ground form along with a specific legume, black gram (Phaseolus mungo) to produce traditional snack foods such as idli and dosa. The main constituent of rice is starch, which is made of two major polymers, namely, linear amylose and branched amylopectin. Amylose is the key determinant of cooking and eating quality of rice [1]. Previously, authors have described the fine structure of amylopectin in rice starch and related this to the texture of cooked rice [2]. In wet grinding of cereals, the protein matrix holding the starch granules is destroyed, releasing the starch granules from the protein network [3]. Wet grinding is a critical step in the preparation of batter based snack foods. Desikachar et al. [4] conducted a classical study for elimination of the wet grinding and concluded that the flour pre-soaking method could be an alternative to the conventional process. However, wet grinding still remains as the practical method of batter preparation for idli as well as dosa. Processes known as gelatinization, pasting, and retro- gradation typically affect starch cooking characteristics [5]. These characteristics are a function of starch concen- tration, temperature, and pH [6]. The transformation of a batter to a solid structure in cereal products has been attributed to gelatinization of starch to set the structure of a baked product [7]. Factors influencing paste viscosity or consistency include the volume fraction occupied by y Current address: Department of Food Science, University of Otago, Dunedin, New Zealand Correspondence: Dr. Vasudeva Singh, Head of the Department, Grain Science and Technology, Central Food Technological Research Institute, Mysore 570 020, Karnataka, India E-mail: singhva2003@yahoo.co.in Fax: þ91-821-251-7233 Abbreviations: BD, breakdown; BD r , relative breakdown; BU, Brabender units; BWT, boiling water temperature; CPV, cold paste viscosity; GT, gelatinization temperature; HPV, hot paste viscosity; PV, peak viscosity; RPM, revolutions per minute; RTC, ready-to-cook; SB, setback; SB t , total setback DOI 10.1002/star.201200126 374 Starch/Sta ¨ rke 2013, 65, 374–381 ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.starch-journal.com