Effects of NaCl and CaCl 2 on physicochemical properties of pregelatinized and granular cold-water swelling corn starches Sara Hedayati a , Mahsa Majzoobi b,e , Fakhri Shahidi a,⇑ , Arash Koocheki a , Asgar Farahnaky b,c,d a Department of Food Science and Technology, Ferdowsi University of Mashhad (FUM), Mashhad, Iran b Department of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz, Iran c ARC Industrial Transformation Training Centre for Functional Grains, Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, New South Wales 2650, Australia d School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, New South Wales 2650, Australia e NSW Department of Primary Industries, PMB Pine Gully Road, Wagga Wagga, 2650, Australia article info Article history: Received 11 February 2016 Received in revised form 13 May 2016 Accepted 5 July 2016 Available online 5 July 2016 Keywords: Corn starch Granular cold-water-swelling starch Drum-dried pregelatinized starch Sodium chloride Calcium chloride abstract The physicochemical properties of drum dried pregelatinized (PG) and granular cold-water-swelling (GCWS) corn starch pastes were determined in the presence of NaCl and CaCl 2 (0, 50, 100, 150 and 200 mM). Light micrographs revealed that NaCl roughened the surface of PG starch particles while CaCl 2 did not bring about obvious changes on their morphology. In the case of GCWS starch, there were some wrinkles on the surface of starch granules. NaCl increased the wrinkles but CaCl 2 softened the sur- face of granules. GCWS starch had higher water absorption, cold paste viscosity and textural parameters than PG starch and these parameters were enhanced with addition of CaCl 2 while NaCl exhibited an opposite trend for all of these factors. The Freeze-thaw (F-T) stability and turbidity of GCWS were also higher than PG starch. In presence of salts F-T stability and turbidity of both modified starches improved and CaCl 2 caused more evident changes. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Starch is the most important energy reserve of plants which is stored in semi-crystalline granules varying in composition, size and shape based on their botanical sources. It is composed of D-glucose molecules in two forms of amylose and amylopectin. Amylose is a linear molecule in which the glucose units are linked together by a (1?4) linkage. Amylopectin has the same basic structure but about 5% of the glucose units are joined together by a (1?6) linkage (Jobling, 2004). Native starch granules are water insoluble at room temperature due to their complex semi- crystalline structure thus cannot play their role as thickener, gelling agent and water binder. Cold water swelling starches are usually used to overcome these problems in food products that are processed at low temperatures (Eastman, 1987; Majzoobi, Kaveh, Blanchard, & Farahnaky, 2015). Drum drying of starch slurries is a traditional and one of the most common methods in producing these starches but they don’t provide a smooth texture and are susceptible to acidic conditions and shear due to the lack of granular structure (Anastasiades, Thanou, Loulis, Stapatoris, & Karapantsios, 2002; Majzoobi, Kaveh, Blanchard, et al., 2015). Thus several methods have been suggested for producing granular cold-water swelling (GCWS) starches. These modified starches provide higher viscosity, smoother texture and are more resistant to processing conditions. GCWS starches are produced by treat- ments such as aqueous alcohol treatment at high temperature and elevated (Jane, Craig, Seib, & Hoseney, 1986) or atmospheric pressure (Dries, Gomand, Goderis, & Delcour, 2014) polyhydric alcohol treatment at high temperature and atmospheric pressure (Rajaoopalan & Seib, 1992) and alcoholic-alkaline treatment (Chen & Jane, 1994a, 1994b; Li et al., 2014; Majzoobi, Kaveh, Blanchard, et al., 2015). Alcoholic-alkaline treatment is one of the best methods in producing GCWS starches due to its being effec- tive for a variety of starches high efficiency and manufacturing at ambient temperature. In this method sodium hydroxide breaks the intermolecular hydrogen bonds of starch granules, while ethanol inhibits the swelling of granules and maintains their integrity. When ethanol is evaporated, a cavity is formed in the hilum of starch granule and brings about a metastable starch granule with excellent cold water swellability (Han & Lim, 2004; Xin, Wang, & Liu, 2012). PG and GCWS can be used in a wide range http://dx.doi.org/10.1016/j.foodchem.2016.07.027 0308-8146/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: sara_hedayatiii@yahoo.com (S. Hedayati), majzoobi@shirazu. ac.ir, mahsa.majzoobi@dpi.nsw.gov.au (M. Majzoobi), fshahidi@um.ac.ir (F. Shahidi), koocheki@um.ac.ir (A. Koocheki), afarahnaky@csu.edu.au (A. Farahnaky). Food Chemistry 213 (2016) 602–608 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem