Sequential Inoculation with Pichia kluyveri and Agitation as an Enological Technique to Enhance Wine Quality
Andrew Nalle and Miguel Pedroza*
*California State University, Fresno, 2360 E Barstow Ave, Fresno,
CA, 93740 (miguelp@csufresno.edu)
Sequential inoculation techniques using non-Saccharomyces yeasts have become a valuable winemaking tool to diversify the aroma, taste, and mouthfeel attributes of wines. Within the commercially available yeasts for sequential inoculation, Pichia kluyveri is distinguished for its aerobic metabolism and film-forming qualities. Due to the recent commercial introduction of this yeast, there is a need to determine the fermentation conditions that maximize the impact of P. kluyveri on wine quality. This research aims at evaluating the effect of agitation as a strategy to enhance film formation of P. kluyveri, and its impact on the chemical composition and sensory attributes of white and rosé wines made with Sauvignon blanc and Zinfandel grapes, respectively. Three experimental conditions were studied: agitation, no agitation, and a control without sequential inoculation. The agitation treatment used a pump to recirculate the fermenting juice underneath the film layer for 10 min during the first three days of fermentation (total 30 mins). The no-agitation treatment allowed P. kluyveri to develop without recirculation following the manufacturer’s recommendations. Film formation monitored with digital images showed that agitation encouraged faster implantation of P. kluyveri and a thicker film than the non-agitated wines. Basic wine chemistry parameters showed that both sequential inoculation treatments (agitation and no-agitation) had significantly less ethanol and more glycerol than the control. A preliminary sensory evaluation with 15 consumers showed that the aroma intensity increased in wines with sequential inoculation, although no differences were found between agitation treatments. Ongoing analysis of the volatile composition by gas chromatography-mass spectrometry is expected to identify differences between the agitation treatments, particularly in fermentative esters and terpenes.
Funding Support: Gusmer Enterprises
