Summary
The effects of three pre-fermentative techniques (standard procedure, cold soak pre-fermentation and cryomaceration), temperature (20 or 30°C) and saignée (with/without) on the extraction of ...total anthocyanins were investigated during maceration of must obtained from Sangiovese grapes. A Bayesian hierarchical model was developed to estimate time-dependent contrasts while addressing the peculiar features displayed by the experimental units (wine tanks): substantial heterogeneity among replicates, departure from low-order `textbook' kinetics and the occasional presence of very low observations. Prior distributions of critical model parameters were elicited with the help of wine{making experts and by considering the results of previous experiments. The posterior distribution of model parameters was approximated by Markov Chain Monte Carlo simulation using JAGS software. Among the main findings, it is to be highlighted that temperature and saignée increased the total anthocyanin concentration in all the techniques, although at different times during maceration. In all the procedures the total anthocyanin gain decreased as the maceration came to an end.
The oenological potential of native strains of Metschnikowia pulcherrima B-5 and Candida famata WB-1, isolated from blackberries, was investigated in pure and sequential fermentation of Chardonnay ...grape with commercial Saccharomyces cerevisiae QA23. The effect of pre-fermentative cold maceration was also analysed. The fermentations were performed in the pilot-scale trials and the profile of volatile compounds and their sensory characteristics were determined. The application of C. famata WB-1 and M. pulcherrima B-5 reduced the volatile acidity and increased total polyphenols of the wines, compared to the control samples. Higher alcohols and esters were dominant, while fatty acids and aldehydes and ketones were also detected. Esters had the greatest contribution to sensory characteristics, especially the development of floral and fruity aromas. Most esters were present in lower concentrations in sequential fermentations compared to the pure fermentations with M. pulcherrima B-5 or C. famata WB-1. Pre-fermentative maceration positively affected both the aroma and the sensory profile. The best sensory score was determined for wines produced using C. famata WB-1 in the fermentations without pre-fermentative maceration, and the sequential fermentation of M. pulcherrima B-5 with maceration. Native strains of M. pulcherrima B-5 and C. famata WB-1 have shown great potential for the enhancement of the aromatic and sensory profile of Chardonnay wine.
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