Managing high-density commercial scale wine fermentations.
OBJECTIVE
To investigate the effects of grape juice dilution and different temperature/nitrogen addition regimes on commercial-scale, high-density Shiraz and Chardonnay fermentations.


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.


CONCLUSIONS
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.
Chaney
D
D
Department of Viticulture and Enology, California State University-Fresno, USA.
Rodriguez
S
S
Fugelsang
K
K
Thornton
R
R
D003132:Commerce; D005260:Female; D005285:Fermentation / Q000502:physiology; D005434:Flow Cytometry / Q000379:methods; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D006801:Humans; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000302:isolation & purification; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013649:Taste; D013696:Temperature; D014920:Wine / Q000382:microbiology
D009584:Nitrogen