RESEARCH ARTICLE Effects of hydrocolloids on acorn starch physical properties Mohammed Saleh 1 , Radwan Ajo 2 , Khalid Al-Ismail 1 and George Ondier 3 1 Department of Nutrition and Food Technology, The University of Jordan, Amman, Jordan 2 Department of Applied Science, Al-Huson University College, Al-Balqa Applied University, Jordan 3 Taylor Laboratories, Inc., Houston, TX, USA The effect of hydrocolloids (arabic gum, carrageenan, carboxymethyl cellulose, and xanthan gum) on the physical properties of acorn starch was investigated. First order mixture response surface model was used and the effects of 1% hydrocolloids on acorn starch water holding capacity, starch solution viscosity, gel strength, freeze–thaw stability, and pasting properties were evaluated. Contributions of each hydrocolloid on determining acorn starch functionality were also calculated. Hydrocolloid combinations significantly (p < 0.05) decrease acorn starch water holding capacity held at 23.3°C from 213.6% of 100% starch to less than 208.3% with minor exceptions. The increase in holding temperature, however, increased water holding capacity (WHC) irrespective of the hydrocolloids set used. The flow behavior indices of treatments ranged from 0.43 to 0.99 and were significantly (p < 0.05) greater than that of pure acorn starch (i.e., 0.66) for most treatments. The consistency coefficient of treatments were significantly (p < 0.05) greater than that of the control and were best fit for the shear-thickening model. Significant (p < 0.05) improvement in gel strength and decrease in freeze–thaw stability of treatments compared to the control was also reported. The pasting properties of treatments increased with the use of hydrocolloids, thus showing the significant role of hydrocolloids in dictating the pasting characteristics of the acorn–hydrocolloids interaction. Received: November 8, 2015 Revised: January 4, 2016 Accepted: January 13, 2016 Keywords: Acorn starch / Hydrocolloids / Physical properties 1 Introduction The use of oak (Quercus calliprinos, commonly referred to as acorn) milled flour; acorn for human consumption has increased due to its unique nutritional value. Acorn contains more than 55% of starch, 2.75–8.44% proteins, 0.7–7.4% fat, and significant amounts of minerals such as calcium, phosphorus, potassium, and niacin [1, 2]. Acorn also contains flavonoids and polyphenols such as tannins [1]. Flavanoids and polyphenols from acorn have recently been linked to cancer prevention [3–7]. Rakic et al. [8] showed that ethanolic extracts from thermally treated acorn can mini- mize lipids deposition, thereby limiting obese weight gain and the development of diabetic complications. Saffarzadeh et al. [9], reported a more nutritious amino acid composition in acorn protein than in pecans. Acorns have been a part of the European, North American, and Asians diets as coffee substitutes as well as additives to porridge dough, astringent and antidiarrhoeal agent, bread cake, and dark bread [2, 8, 10]. Food products rich in hydrocolloids would the potential of playing a significant role in the food industry, especially in the design and process of systems such as pumps, pipes, and heat exchangers [11]. For instance, hydrocolloids reportedly aid in imparting viscosity and thickness to aqueous solutions and dispersions; they have also been tested as fat replacers in many food applications [12]. The concentration to which hydrocolloids are used in product formulations depends on the type that is ideal for the target sensory properties as well as the acceptability of food Correspondence: Mohammed Saleh, Department of Nutrition and Food Technology, The University of Jordan, 11942 Amman, Jordan E-mail: misaleh@ju.edu.jo Fax: þ962 6 5300806 Abbreviations: ANOVA, analysis of variance; CMC, carboxymethyl cellulose; LSD, least significant differences; m, consistency coefficients; n, flow behavior index; Pasting T, pasting temperature; RVA, rapid viscosity analyzer; WHC, water holding capacity DOI 10.1002/star.201500304 Starch/Stärke 2016, 68,1–11 1 ß 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.starch-journal.com