Effect of heat treatment on antioxidant capacity and flavor volatiles of mead

The objective of this study was to evaluate the effects of heat processing on the antioxidant capacity of mead (honey wine). Soy and buckwheat honey musts were subjected to 2 heat treatments and fermented into wine. Total phenolic concentration was determined. High-performance liquid chromatography (HPLC) phenolic profiling was performed on the methanol fraction of Amberlite extraction. Antioxidant capacity was evaluated using the oxygen radical absorbance capacity (ORAC) assay. Changes in volatile components were evaluated by headspace-solid phase microextraction/gas chromatography-mass spectrometry (H-SPME/GC-MS). ORAC values of experimental meads (3.62 mM Trolox equivalent) were comparable to those of commercial white wine (3.66 mM Trolox equivalent). No significant difference in antioxidant capacity due to heat treatment or honey type was observed. There was no difference in total phenolics between heat treatments in buckwheat mead; however, soy mead made from high-heated must had significantly greater phenolic concentration than the gently heated mead (α = 0.05). Linear regression analysis indicated a strong positive correlation between total phenolic concentration and antioxidant capacity by ORAC (r = 0.9077; P < 0.0001). HPLC analysis of phenolic profiles in the methanol fractions of Amberlite extraction of the meads indicated significantly higher levels of certain phenolics as a result of the high-heat process in buckwheat mead, but not in soy mead. Differences in volatile components that potentially impact flavor were noted between high and low heat treatments. Results of this study suggest dramatic heat treatments that are often avoided because their flavor impact in mead production have the potential to alter the antioxidant capacity of mead by changing phenolic profiles.