Development of an Objective Index for Evaluating New Fining Agents Used in Winemaking: A Case Study of the Cell Wall Material from Red Grape Skin.

This study aimed to establish a fining index based on objective criteria to evaluate and compare the effects of various commercial fining agents on red wine. The agents included pea and potato protein isolates, porcine gelatine, and bentonite. The phenolic composition of Syrah wine was analysed to assess the impact of clarification on anthocyanins, flavanols, flavonols, and overall turbidity. Results showed significant variability among agents, with gelatine causing the highest phenolic reduction (%) and fining efficiency, reducing flavanols by 33.80%. In contrast, bentonite showed minimal impact on phenolic content, with a reduction of only 0.02% in flavanols. A fining index was proposed, allowing for the classification and prediction of untested fining agents' effects based on similarity to known agents. This index could facilitate more precise selection of fining agents, optimizing wine quality while addressing allergenicity and fining concerns. Moreover, its application could help manufacturers reduce production costs by selecting the most efficient fining alternatives. Furthermore, a case study of the cell wall material from red grape skin was evaluated using samples from three different physiological states.