Assessing mannoprotein dosage effects on physicochemical stability and organoleptic characteristics of red wine

Considering the need of the winemaking industry to utilize commercially available yeast mannoprotein concentrates in a knowledgeable and secure manner, just prior to bottling, it is imperative to comprehend the physicochemical characteristics of these compounds and their interaction with the wine matrix in order to guide their selection and dosage. The present study aims to enhance our knowledge of the technological and organoleptic implications of mannoprotein use in winemaking, specifically with respect to color stability, mouthfeel sensations and aromas, ultimately improving the overall quality of the red wine. In the first part of this work, five specific mannoproteins, recommended for addition prior to bottling, along with a control (untreated), were tested in two commercial qualities of Cabernet Sauvignon wine from Chile, namely "Blend" and "Premium". Prior to testing, the concentration of mannose and glucose were analyzed by enzymatic method, along with the total polysaccharide concentration, protein concentration, and filterability of the mannoproteins. Normalized doses of mannose were then defined for all the mannoproteins based on the average mannose content provided in the recommended doses by the producers. The wines were evaluated using the RATA (Rate-all-that-apply) methodology for sensory analysis. Simultaneously, the monosaccharide content and molecular weight distribution of these five mannoproteins were characterized using size exclusion chromatography with refractive index detector (HPSEC-RID) and gas chromatography with mass detector (GC-MS). The commercial mannoprotein that was selected was found to be significantly different for both wine qualities, reducing the "alcoholic burning" descriptor and increasing the descriptors of "smooth" and "sweet". This manoprotein presents a single peak of medium molecular weight, while the others contained a mixture of different molecular weights or did not show significant differences in sensory terms for both wine qualities. In the second part of this study, the selected commercial manoprotein is being used, and the effects of the dosage of mannoprotein, wine quality, and aging time of bottled wine are being studied. For this, the physicochemical properties have been analyzed, including color indices (IC and hue), stable color (copigmented color and stable color against bleaching by bisulfite), concentration of phenolic compounds, volatile compunds, total mannose, and distribution of molecular weights of polysaccharides, along with sensory analysis of the samples. The objective is to determine the impact of mannoprotein dosage on the physicochemical stability and sensory characteristics of wine for two commercial qualities (Blend and Premium) and two different bottle aging periods (3 and 6 months). This study will determine if an optimal dose of mannoprotein exists that can improve both the physicochemical and sensory properties of wine, considering the base wine matrix. These findings will be useful for producers seeking to improve the quality and physicochemical stability of their wines.