Winery cleaning and sanitization, monitoring methodology and efficacy of cleaning and sanitization chemistries

This project analyzed the ability of cleaners and sanitizers frequently used in the wine industry to inactivate microbial populations in solution (planktonic) and stationary (biofilm) physiologies. A screening of 20 different cleaner and sanitizer chemistries was conducted using 96-well plates and the crystal violet method. Next, biofilms were grown on 304 stainless steel coupons by incubating the coupons in an inoculated grape juice medium. These coupons were treated with chemicals at varying concentrations and contact times and then swabbed with ATP luminescence swabs and traditional plate count swabs to determine the microbial load and soil after treatment. Further trials were then conducted in the UC Davis teaching winery facility at the 200 L and 2000 L scale. For the 200 L fermentations, a custom device was constructed to prove 110 replicate soiled coupons that could be used for further treatment in the laboratory setting. These trials allowed for the development of an optimized protocol that could be tested against other similar treatments at the 2000 L-scale. For these larger scale trials, a five-step cleaning and sanitizing framework was employed, and again ATP and traditional plate count data were collected. The results of these experiments show that the vulnerable areas of tanks (gaskets and areas in the shadow of spray arms) have consistent microbial contamination, regardless of the cleaning protocol or contact time. These need to be areas of focus in any cleaning and sanitation protocol, and winemakers must be prudent to develop a system that exceeds the typical visual inspection protocol often employed in the winery environment.