Abstract In this study, effect of heat treatments (liquefaction at 55 °C for 12 h and pasteurisation at 90 °C 15 sec) on total phenolic content, antioxidant activity and phenolic compounds of astragalus and sunflower-cornflower honeys was investigated. Total phenol content and antioxidant activity of honeys were assessed by Folin-Ciocalteu and ABTS methods, respectively. Phenolic profile was determined by HPLC-DAD system. Only pasteurisation process had a significant impact on sunflower-cornflower honey with regard to total phenolic content and antioxidant activity. Protocatechuic, 4-hydroxybenzoic, caffeic, p-coumaric, and ferulic acids, rutin, kaempferol were detected in astragalus honey, while 2,5-dihydroxybenzoic, chlorogenic, caffeic, p-coumaric, and ferulic acids, apigenin, rutin, kaempferol-3-glucoside, isorhamnetin-3-glucoside, quercetin, luteolin, kaempferol were detected in sunflower-cornflower honey. Pasteurisation significantly decreased caffeic acid in astragalus honey and other detected phenolics showed no significant difference after heat treatments. The impact of liquefaction process is lower than the pasteurisation process in terms of quantitatively phenolic compounds changes.

Abstract The aim of this study was to investigate the impact of removing sugar and/or amino groups by applying one ion exchange (Dowex 50Wx8) and two adsorbent (Activated Carbon and Amberlite XAD-16) resins to grape juice in the control of Maillard reaction. Grape juices, a control sample and separately applied with each resin, were concentrated up to 50, 60 and 70 °Bx and stored at three temperatures (50, 65 and 75 °C) for 10 days. HMF accumulation was lower in the grape juices which were treated with Amberlite or activated carbon throughout the boiling. Rate constant, activation energy and Q10 values indicated that activated carbon application has a decelerating effect on HMF formation in molasses, particularly molasses with 50 οBx. Dowex was more effective than Amberlite in controlling of brown pigment formation. Analysing the results of HMF and brown pigment, activated carbon was the best resin to control the Maillard reaction.