Effects of Pre-Fermentative Treatments with Non-Synthetic Ternary Component Fining Agents Based on Pea Protein on the Volatile Profiles of Aromatic Wines of Tămâioasă Românească

Abstract

To remove oxidizable polyphenolic compounds from wines, fining treatments with products of various origins are applied before or after fermentation. Seeking alternatives to the treatments with animal proteins or synthetic materials such as polyvinylpolypyrrolidone (PVPP), vegetal and mineral products are tested. One of these alternative agents is pea protein (P), which can be combined with chitosan (K), yeast cell walls (Y), active carbon (C), and/or Ca-bentonite (B). Aside from the proven polyphenol removal effect, these products can also have an impact on aroma. This research evaluates the effect of P and ternary combinations with P on the volatile compounds of aromatic wines from the Tămâioasă românească variety. Several variants of treatments with P and with ternary mixtures involving P were prepared in triplicate with a total dose of 20 g/hL of fining agent applied during the pre-fermentative phase. Volatile profiles were determined using a flash gas chromatograph with two short columns of different polarities. The chromatographic peak areas for the identified ethylic esters, acetates and terpenes were used to compare the fining treatment effects. To test the significant differences between experimental variants, the Analysis of Similarity (ANOSIM) was used. The influences of P used alone and PVPP used alone were both significantly different compared to control (untreated), but based on the dissimilarity index R, PVPP affected the volatile profile about twice as much as P, showing that pea protein is a good alternative for PVPP. The ethyl esters were especially reduced by PVPP, while P especially reduced the terpenes. From all the tested pea protein ternary agents, those containing bentonite (PCB and PYB) showed a significant reducing effect on all classes of compounds and therefore are not recommended. The combinations containing yeast cell walls, PCY and PKY, are the most interesting alternatives to both PVPP and P used independently, PCY being the least aggressive of all treatments on overall aroma, preserving well the aroma compounds of all determined classes, including terpenes.