Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Impact of Clitoria ternatea (butterfly pea) flower on in vitro starch digestibility, texture and sensory attributes of cooked rice using domestic cooking methods Charoonsri Chusak a , Jowynn Ang Yu Ying b , Joseph Lim Zhien b , Porntip Pasukamonset c , Christiani Jeyakumar Henry b,d , Sathaporn Ngamukote a , Sirichai Adisakwattana a, ⁎ a Department of Nutrition and Dietetics, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand b Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR), Singapore c Department of Home Economics, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand d Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore ARTICLE INFO Keywords: Clitoria ternatea Cooked rice In vitro starch digestibility ABSTRACT The effect of Clitoria ternatea flower (CTE) incorporated into cooked rice using domestic cooking methods on starch digestibility was determined. The incorporation of 1.25% and 2.5% (w/v) CTE caused a reduction in the starch digestibility of cooked rice using an electric rice cooker. In addition, there was significant alteration on the starch digestibility of cooked rice incorporated with 2.5% CTE using a microwave oven. Moreover, CTE sig- nificantly reduced the level of rapidly digestible starch and increased the level of undigested starch in cooked rice using an electric rice cooker. In the textural characteristics, the hardness of cooked rice with CTE remained unchanged, whereas a reduction in stickiness of cooked rice with CTE was observed. The sensory evaluation of cooked rice with CTE given by panelists demonstrated a good overall acceptability. Overall, the results show that CTE is a useful ingredient to incorporate with cooked rice for reduction of starch digestibility. 1. Introduction Carbohydrates, the primary energy source, account for 40–80% of the total caloric intake in foods. However, a high carbohydrate diet is regularly considered harmful with respect to energy imbalance because of the specific properties associated with postprandial metabolisms (Aller, Abete, Astrup, Martinez, & Baak, 2011). The glycemic index (GI) is an instrument to classify carbohydrate foods as an index of the acute postprandial glycemic response to a fixed amount of available carbo- hydrates from test food compared to the same amount of available carbohydrate from a standard food (Jenkins et al., 1981). The con- sumption of food having a high GI induces a rapid increase in plasma glucose and insulin secretion (Jenkins et al., 1981). In contrast, an in- take of low GI foods causes a slower rate of carbohydrate digestion and absorption than high GI foods, resulting in attenuated postprandial glucose. Interestingly, consumption of low GI foods (GI < 55) has been scientifically proven to lower postprandial blood glucose and insulin in diabetic patients (Brand-Miller, McMillan-Price, Steinbeck, & Caterson, 2009). With an increasing number of people diagnosed with diabetes, it is expected to products will be developed in answer to the growing consumer demand for starchy foods with low GI. The substitution or replacement of carbohydrate foods with other ingredients such as fruits, vegetables and edible plants has been indicated as an alternative ap- proach for reducing high-GI foods through inhibition of pancreatic α- amylase and intestinal α-glucosidases (Dewettinck et al., 2008; Fujiwara, Hall, & Jenkins, 2017). Edible plants containing bioactive polyphenols have been recently shown inhibitory activity against pancreatic α-amylase and intestinal α-glucosidases (Adisakwattana, Ruengsamran, Kampa, & Sompong, 2012). Rice (Oryza sativa L.) is a staple food consumed around the world. Several studies have reported that rice is considered to be a high-GI food (GI > 70) (Jenkins et al., 1981). In traditional cooking, rice is generally cooked and mixed with natural ingredients such as biryani, turmeric, pepper and garlic (Karizaki, 2016). It has been discovered that natural ingredients can attenuate postprandial blood glucose levels when consumed with carbohydrate-rich food. For example, rice con- taining the polyphenols from cinnamon bark powder, bay and pandan leaves reduced blood sugar level and improved insulin sensitivity in https://doi.org/10.1016/j.foodchem.2019.05.157 Received 10 January 2019; Received in revised form 13 May 2019; Accepted 23 May 2019 ⁎ Corresponding author at: Department of Nutrition and Dietetics, Faculty of Allied Health Sciences, Chulalongkorn University, 154 Rama 1 Rd., Wangmai, Pathumwan, Bangkok, Thailand. E-mail address: Sirichai.a@chula.ac.th (S. Adisakwattana). Food Chemistry 295 (2019) 646–652 Available online 24 May 2019 0308-8146/ © 2019 Elsevier Ltd. All rights reserved. T