Abstract
This study aimed to investigate effects of thermal treatments on major phenolics and their antioxidant contributions in Acer truncatum leaves and flowers (ATL and ATF, respectively). With ultra performance liquid chromatography-diode array detector-quadrupole time-of-flight-mass spectrometer/mass spectrometer, phenolic compositions of ATF were first characterized and compared with those of ATL. An optimized high performance liquid chromatography fingerprint was then established, and 10 major phenolics existing in both ATL and ATF were quantified. Gallic acid derivatives and flavonol-3-O-glycosides were found to be their dominant phenolic constituents, with the former being key constituents which was affected by thermal treatments and further influencing the variations of total phenols. Moreover, the mechanism underlining the changes of phenolics in ATL and ATF by the treatments was characterized as a thermolhydrolysis process. During thermal treatments, polymerized gallotannins were hydrolysed to 1,2,3,4,6-pentakis-O-galloyl-β-d-glucose, ethyl gallate and gallic acid, resulting in more than fivefold and twofold increase of their contents in ATL and ATF, respectively. By contrast, contents and antioxidant contributions of flavonol-3-O-glycosides gradually decreased during the process.\\absbreak Overall, this is, to our knowledge, the first report on the effects of thermal treatments on phenolics and their antioxidant contributions in ATL and ATF, and the three gallic acid derivatives with potentially higher bioactivity could be efficiently achieved by thermal treatments.
Highlights
In order to maintain health benefits, compounds of interest in food products need to withstand processing, to be released from the food matrix and to be bio-accessible in the gastrointestinal tract [1]
We aimed to address the impact of thermal treatment on changes of total phenols, overall antioxidant abilities, individual phenolic profiles and their antioxidant contributions in A. truncatum leaves (ATL) and A. truncatum flowers (ATF)
All authentic standards for high performance liquid chromatography (HPLC) analyses were purchased from National Institutes for Food and Drug Control (Beijing, China) except tannic acid, which was from Sigma Chemical Company (St Louis, MO, USA)
Summary
In order to maintain health benefits, compounds of interest in food products need to withstand processing, to be released from the food matrix and to be bio-accessible in the gastrointestinal tract [1]. Changes undertaken in food processing profoundly affect health benefits of target compounds. Thermal treatment is a major process to convert food to edible form and extend its shelf life [2], and can break down covalent bonds in insoluble bound phenolics and liberate natural antioxidants from plants [3]. Studies have been conducted on how thermal treatment affected phenolic compositions in blueberry [4], elderberry [5] and clove [6], but conflicting results exist regarding its effects in these materials. Other than its ornamental function and ability to yield superior vegetable oil, A. truncatum leaves (ATL) have long been used as folk medicine and a healthy drink to treat coronary arteriosclerosis, cerebrovascular diseases and angina pectoris in China [8]. Several individual phenolics in ATL were subsequently determined, and 1,2,3,4,6-penta-O-galloyl-β-D-glucose and quercetin 3-Orhamnoside were identified as its important antioxidant contributors [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
