Anthocyanin degradation has been proposed as one of the primary causes for reduced colour and quality in red wine grapes grown in a warm climate. To study anthocyanin degradation we infused berries with l-phenyl-13C6-alanine and then tracked the fate of the anthocyanins comparing normal (25°C) and warm (45°C) temperature conditions. An untargeted metabolomics approach was aided by filtering the MS data using software algorithms to extract all M and M+6 isotopic peak pairs, allowing the analysis to focus solely on the metabolites of phenylalanine. A paired-comparison t-test was performed over the 8 biological replicates revealing 13 metabolites that were statistically different between 25°C and 45°C treatments. Most of these features had lower abundances in 45°C samples, confirming that 45°C treatment caused anthocyanin degradation. In addition, resveratrol was significantly reduced following heat treatment. However, 5 metabolites increased following the 45°C treatment. These unidentified metabolites are therefore suspects for anthocyanin degradation products.