Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt Exploring epigallocatechin gallate impregnation to inhibit 5- hydroxymethylfurfural formation and the effect on antioxidant ability of black garlic Chieh-Hsiu Lee a , Yu-Ting Chen a , Hsin-Jung Hsieh a , Kai-Ting Chen a , Yi-An Chen b , Jung-Tsung Wu b , Ming-Shiun Tsai c , Jer-An Lin d , Chang-Wei Hsieh a,e,∗ a Department of Food Science and Biotechnology, National Chung Hsing University, 145 Xingda Rd, South Dist, Taichung, 402, Taiwan b College of Biotechnology and Bioresources, Da-Yeh University, 168 University Rd, Dacun, Chang-Hua, 515, Taiwan c Department of Food Science and Biotechnology, Da-Yeh University, 168 University Rd, Dacun, Chang-Hua, 515, Taiwan d Graduate Institute of Food Safety, National Chung Hsing University, 145 Xingda Rd, South Dist, Taichung, 402, Taiwan e Department of Medical Research, China Medical University Hospital, No. 2, Yude Road, North Dist, Taichung, 404, Taiwan ARTICLE INFO Keywords: Black garlic 5-Hydroxymethylfurfural Maillard reaction Epigallocatechin gallate Kinetic analysis ABSTRACT 5-hydroxymethylfurfural (5-HMF) is regarded as a neo-formed contaminant (NFC) that may negatively affect human health. Among the foods undergoing thermal processing, the 5-HMF content of black garlic is relatively high. However, many researches have shown that 5-HMF has antioxidant ability; therefore, in this study, we aimed to explore the use of epigallocatechin gallate (EGCG) to reduce 5-HMF whether would also affect the antioxidant ability of black garlic. Hence, mitigating the 5-HMF formation in black garlic and increasing the safety of black garlic consumption were the purposes in this study. At the 30th day of aging, the 5-HMF content of garlic with EGCG impregnation for 12 h was 2.37 ± 0.11 mg/g dry weight, which mitigated the formation of 5-HMF by approximately 50% compared with the control. It indicated that EGCG could be adducted with 5-HMF to reduce the formation of 5-HMF during the production of black garlic. Moreover, it also found that as the impregnation time increased, the antioxidant ability of black garlic was higher. EGCG impregnation is a useful method for mitigating 5-HMF formation in black garlic without affecting the bioactivity of black garlic, such as its antioxidant ability. 1. Introduction 5-hydroxymethylfurfural (5-HMF) is the furanic compound that has aldehyde and hydroxymethyl functional groups (Shapla, Solayman, Alam, Khalil, & Gan, 2018). 5-HMF is mainly formed through Maillard reaction and dehydration of sugars under acidic conditions (Capuano & Fogliano, 2011). Factors affecting 5-HMF formation include pH, type of sugars, temperature, cations, water activity, etc (Grainger, Owens, Manley-Harris, Lane, & Field, 2017; Kowalski, Lukasiewicz, Duda- Chodak, & Zięć, 2013; Shapla et al., 2018; Zhang, Li, Lu, Liu, & Qiao, 2016). 5-HMF is present in foods which have undergone thermal pro- cessing, such as baked food, coffee, juice and malt (Authority, 2005; Capuano & Fogliano, 2011). Recently, 5-HMF is regarded as a neo- formed contaminant (NFC) that may cause cancer in humans. The current researches indicate that 5-HMF is an indirect mutagen because it is metabolized to the sulfuric acid ester 5-sulfo-oxymethylfurfural (5- SMF) in vivo, which has been reported to exhibit liver and kid toxicity, DNA damage and neoplastic transformation and other negative effects (Pastoriza de la Cueva et al., 2017; Shapla et al., 2018; Zhao et al., 2018). On the other hand, 5-HMF is also used as a standard indicator for determining food quality in the food industry. For example, 5-HMF concentration is recognized as a parameter for the freshness and safety of honey. The European Codex Alimentarius Commission has set the maximum limit for 5-HMF in honey at 40 mg/kg to ensure that it has not undergone excessive heating (Rizelio et al., 2012; Shapla et al., 2018; Zhang et al., 2016). Vrzal, Štěrba, Jurková, and Olšovská (2019) also used 5-HMF as a standard for determining the sensory quality of beer; a rapid, cheap and objective method has been developed to monitor the change of beer flavor during the storage. Black garlic is a processed garlic products which has received much attention in recent years. Black garlic is a processed product made from fresh garlic under conditions with high temperature and humidity. In https://doi.org/10.1016/j.lwt.2019.108628 Received 30 May 2019; Received in revised form 10 September 2019; Accepted 13 September 2019 ∗ Corresponding author. Department of Food Science and Biotechnology, National Chung Hsing University, 145 Xingda Rd, South Dist, Taichung, 402, Taiwan. E-mail address: welson@nchu.edu.tw (C.-W. Hsieh). LWT - Food Science and Technology 117 (2020) 108628 Available online 14 September 2019 0023-6438/ © 2019 Elsevier Ltd. All rights reserved. T