Managing high-density commercial scale wine fermentations

Abstract

Aims: To investigate the effects of grape juice dilution and different temperature/nitrogen addition regimes on commercial‐scale, high‐density Shiraz and Chardonnay fermentations. Methods and Results: Duplicated fermentations (30 hl) were conducted at two temperatures for Shiraz and for Chardonnay. Two additional tanks of Chardonnay and Shiraz were diluted. Nitrogen was added once at inoculation or in aliquots over several days. Yeast concentration and viability was determined by flow cytometry. Fermentation chemistry was monitored by Fourier transform infrared spectroscopy. Fermentations arrested in both of the undiluted, higher temperature duplicate tanks of Shiraz. Different fermentation temperature resulted in sensorially different Shiraz, but not Chardonnay, wines made from undiluted musts. The converse was observed for wines made from diluted musts. Conclusions: High‐density musts can be fermented completely using reduced fermentation temperature coupled with incremental nitrogen addition. Significance and Impact of the Study: This is the first study in duplicated, commercial‐scale, high‐density grape juice fermentations to address temperature, nitrogen addition, and juice dilution effects on stuck fermentation potential and wine sensory properties.

Effects of Extended Grape Ripening With or Without Must and Wine Alcohol Manipulations on Cabernet Sauvignon Wine Sensory Characteristics

“…This implies that there were few developmental changes in fruit composition of sensory importance late in maturation. These results are in agreement with those of Chaney et al (2006) in relation to Chardonnay, but not in relation to Shiraz.…”

“…This result suggests that, while increasing final alcohol concentration, sugar additions are less effective than expected in mimicking fruit maturity, perhaps due to the sensory effects of adding alcohol besides the direct effect on the increase in alcohol concentration. It might be that alcohol interacts with fruit-or yeast-derived compounds in a sensorially significant way and thus our results differ from those of Gawel and co-workers (2007), while they are similar to the Shiraz results of Chaney et al (2006), but not to their Chardonnay results.…”

“…However, neither of these two studies conducted any sensory evaluation on the resulting wines. Chaney et al (2006) harvested Chardonnay and Shiraz at about 26 °Brix and 30 °Brix respectively, and then diluted some of the musts back to 24 °Brix and 22 °Brix respectively. After fermentation, the wines were equalised in alcohol concentration by the addition of deodorised ethanol.…”

Transcriptional response of Saccharomyces cerevisiae to low temperature during wine fermentation

“…A possible factor contributing to this difference could be an earlier induction of the stress response at 12.5°C compared to 25°C, since a subset of stress genes was up-regulated at exp at 12.5°C compared to 25°C; thus subsequent up-regulation for the transition to stat at 12.5°C was lower. As suggested by Beltran et al (2006) and Chaney et al (2006), these early changes could allow cold-fermented cells to maintain higher viability during fermentation. Other studies that show higher yeast cell viability during fermentation at low temperatures suggest that increased survival is due to enhanced ethanol resistance from increased sterol production (Chaney et al 2006;Torija et al 2003).…”

Understanding Problem Fermentations – A Review

“…In recent years, flow cytometry (Bruetschy et al, 1994;Bouix and Leveau, 2001;Malacrino et al, 2001Malacrino et al, , 2005Thornton et al, 2002;Boyd et al, 2003) has been used to monitor live and dead yeast cell concentrations during fermentation (Chaney et al, 2006). This technique allows the counting, examining, and sorting of microscopic particles suspended in a stream of fluid.…”