Microwave and submerged cap maceration highlight cultivar-dependent responses in red wine phenolic composition and color

Abstract

Polyphenols play a central role in wine quality by contributing to color, astringency, and chemical stability. Their extraction during maceration depends on processing conditions and grape characteristics. This study evaluated cultivar-dependent effects of alternative maceration techniques on color and phenolic composition in red wines from Tannat, Marselan, and Arinarnoa (Vitis vinifera). Experimental vinifications were performed with grapes harvested in 2024. Four maceration techniques were tested in triplicate: traditional maceration (TM), microwave-assisted maceration (MW), short microwave-assisted maceration (SMW), and submerged cap maceration (SC). Macerations lasted 7 days, except SMW (3 days). Phenolic evolution during maceration and final wine composition were monitored by spectrophotometry and HPLC-DAD. Alternative maceration techniques modified phenolic composition relative to TM, but the effect depended on grape cultivar. Total HPLC pigments increased most in Tannat, with SC and SMW reaching roughly +33 % and +58 % vs TM, respectively. In Marselan and Arinarnoa, SMW produced the largest increases (+30 % and +39 %, respectively), whereas MW caused minor changes in Marselan, suggesting that pigment re adsorption during later maceration stages may be greater in this cultivar. Pigment profiles revealed cultivar treatment interactions. In Tannat, SMW wines showed lower relative malvidin derivatives than TM (about 85 % to 74 %) and higher delphinidin derivatives. In Marselan, SMW specifically increased acylated pigments, with p-coumaroylated anthocyanins rising from 15.3 to 30.0 mg/L. In all cultivars, alternative maceration increased color intensity more than total pigments relative to TM, consistent with stronger copigmentation. Consistently, flavonol contents also increased and were significantly higher in Marselan, whose grapes contained about threefold more flavonols than Tannat and Arinarnoa. Flavan-3-ol extraction kinetics also showed cultivar-specific patterns. In Marselan and Arinarnoa, the largest differences appeared within the first three days, mainly under MW and especially SMW (typically +10 to +60 % vs TM, and in some cases >80 % in Marselan), whereas in Tannat they became more evident at later stages (days 5 to 7), particularly under SC (+30 to +40 % vs TM). Sensory differences were clear, but alternative techniques were not always preferred. Statistically significant cultivar by treatment interactions (p < 0.05) were confirmed.