Measurement of antioxidants in distilled spirits by a silver nanoparticle assay

Ingestion of antioxidants from the diet is associated with improved health. Total antioxidant capacity as gallic acid equivalents (GAE) of distilled spirits was determined using a modified and validated silver nanoparticle (SNaP) assay utilizing silver nanoparticles pre‐capped with starch and microwave technology. GAE concentrations determined by the SNaP assay for the distilled spirits were validated by high‐performance liquid chromatography (HPLC) measurements of key antioxidant components including gallic acid, ellagic acid, caffeic acid, syringic acid, syringaldehyde and 2‐furaldehyde. SNaP assay and HPLC measurements of GAE were compared via statistical and graphical methods to demonstrate comparability. Application of the assay to 33 different distilled spirits demonstrated good agreement with published literature values, with the highest total antioxidant capacity values observed for bourbon samples followed by whisky, tequila and other types of liqueur. This study is novel for demonstrating the utility of a nanoparticle assay for determination of antioxidant capacity in distilled spirits with validation by HPLC. © 2018 The Institute of Brewing & Distilling