Contents lists available at ScienceDirect Radiation Physics and Chemistry journal homepage: www.elsevier.com/locate/radphyschem Physicochemical and functional properties of gamma irradiated buckwheat and potato starch Ruchi Verma a , Shumaila Jan b , Savita Rani c , Kulsum Jan d , Tanya L. Swer e , Kumar S. Prakash c , M.Z. Dar a , Khalid Bashir c, ⁎ a Gautam Bhudha University, Greater Noida, India b Sant Longowol Institute of Engineering and Technology, Sangrur, India c National Institute of Food Technology Entrepreneurship and Management, India d Shaheed Rajguru College of Applied Sciences for Women, India e Bhaskaracharya College of Applied Sciences, New Delhi, India ARTICLE INFO Keywords: Buckwheat starch Potato starch Swelling Transmittance ABSTRACT Starches isolated from buckwheat and potato were subject to different doses of irradiation at 0, 5, 10, 15 and 20 kGy. Native and irradiated starch samples were evaluated for their physicochemical and functional properties to assess the effect of gamma irradiation. Apparent amylose content decreased significantly from 26.84% to 22.12% and 27.01 to 16.11% for buckwheat and potato starch respectively as the dose increased. A significant decrease was observed in pH, swelling power and syneresis as the dose increased for both buckwheat and potato starch. pH decreased from 5.20 to 3.81 and 5.81 to 3.95 for buckwheat and potato starch, respectively. Carboxyl content, freeze thaw stability, water and oil absorption capacity and transmittance showed increasing trend with increasing irradiation dose. Carboxyl content increased from 0% to 0.23% and 0–0.22% for buckwheat and potato starch, respectively. 1. Introduction From the past decade gamma irradiation has been continuously explored to study its effects on the various properties of starch. Starch has certain limitations in its natural (native) form like tendency towards retrogradation, high viscosity values even at low concentrations, poor freeze-thaw stability etc., that preclude its use in food industries. In order to overcome these problems starch granules are modified prior to their final use as food or food ingredient (Shi and BeMiller, 2000; Tester et al., 2004; Bashir and Aggarwal, 2016a). The modified starch has gained attention in food business because of its ability to be used as dietary fat replacer. Also the consumption of starch within adequate limits has been linked with the prevention of cancer, diverticulitis, coronary heart diseases (Asp and Bjorck, 1992; Lopez et al., 2001). Although, several starch modifications are available including, enzy- matic and chemical methods. The enzymatic methods being complex and time consuming have limited applications in the food industry and related sectors. The chemical methods although being faster, pose risks because of leaving certain chemical residues into the final product. Physical modification using gamma irradiation is a fast, low cost and environmentally friendly technique requiring minimal sample preparation, no catalysts requirement as well as no pollutant agents or no penetration of toxic substances into the treated products are in- volved. The physicochemical properties of macro-components in foods are modified by gamma irradiation via free radical mechanism which hydrolyzes the chemical bonds, thus cleaving large molecules of starch into smaller fragments of dextrins, organic acids and sugars. These changes affect the physicochemical properties of the irradiated foods, causing increased solubility as well decreased swelling power and viscosity of starch (Kaur et al., 2012; Wani et al., 2014; Bashir and Aggarwal, 2016b; Bashir et al., 2017a). Extensive research has been done on the modification of starches from various sources. However, there is very limited literature available on the modification of buck- wheat and potato starch particularly by gamma irradiation. Several researchers have established that gamma irradiation de- creases the gelatinization temperature, gelatinization enthalpy, visc- osity (specific and intrinsic), iodine affinity absolute density and swelling capacity whereas increasing the formic acid, solubility and reducing sugars content of rice starch (Wu et al., 2002a, b; Bao et al., 2005; Lee et al., 2008). Likewise, Rombo et al. (2001), Liu et al. (2012a,b), AOAC (2012), Lee et al. (2013) and Bettaïeb et al. (2014) demonstrated that gamma irradiation of maize starch resulted in https://doi.org/10.1016/j.radphyschem.2017.11.009 Received 18 July 2017; Received in revised form 13 November 2017; Accepted 15 November 2017 ⁎ Corresponding author. E-mail address: kbnaik25@gmail.com (K. Bashir). Radiation Physics and Chemistry 144 (2018) 37–42 Available online 16 November 2017 0969-806X/ © 2017 Elsevier Ltd. All rights reserved. T