Issue link: http://read.dmtmag.com/i/402796
w w w. v w m m e d i a . c o m N o v - D e c 2 014 | V I N E YA R D & W I N E RY M A N A G E M E N T 3 5 hile wine filtration can prevent micro- bial activity and spoilage in the bottle, there is a perception with some in the wine industry that it has the potential to remove positive attributes as well. Moreover, many winemakers prefer for their wine to evolve with minimal manipulation, to reflect the grapes and vineyard and not the hand of the winemaker. Yet the decision to filter a wine should be based on the potential for wine spoilage post-bottling, and this will depend on wine style, chemistry and microbial content. There are many protocols that should be part of a winery's sanitation program to pre- vent microbial contamination. They begin in the vineyard, by cultivating healthy clusters without damage or disease, and harvest- ing clusters in a fashion that preserves berry integrity. Maintaining sanitized processing equipment during sorting, destemming and delivery to tank, and in reality, throughout the entire elevage of the wine, is imperative. If the grape must is already contaminated with mold or mildew from the vineyard, or if the initial sugar content is very high, this can negatively affect primary fermentation. If the yeast struggles, there is an opportunity for the growth of spoilage organisms. It is always a good idea to encourage a healthy fermenta- tion, and it may be wise to choose a strong fermenting yeast strain to avoid a stuck or sluggish fermentation. Keep an eye on nutri- ent content, as nutrient additions can help yeast complete a healthy fermentation, and utilize sulfur dioxide additions to select for intended strains of Sacchromyces yeast. Once the fermentation is complete, leaving the wine in a vessel that exposes the wine to oxygen, for example, by not gassing tanks with inert gas or topping barrels frequently, can also lead to spoilage. It is a good precaution to check topping wine for microbial content before using it to top other lots. In wineries with sanitation or contamination issues, or even as an extra-cautious protocol, microbial analysis can be done on individual lots or combined lots to check for the presence of spoilage organisms at various stag- es of wine maturation. SCORPIONS DETECTS SPOILAGE ORGANISMS ETS Laboratories (ETS), based in Napa Valley, was the first inde- pendent lab to offer genetic detec- tion of wine-spoilage organisms. By using molecular techniques, the lab can determine in just two days if a spoilage organ- ism is present in a wine. These assays, Scorpions, are much m o r e c o m p r e h e n- sive and sensitive than standard micro- s c o p i c e x a m i n a - tions, and are much quicker than con- ventional plating. Scorpions analy- s i s i s c a p a b l e o f detecting the total viable population of a target organism, including the "viable but non-culturable" (VNC) cells, which are not detected by s t a n d a r d p l a t i n g . Despite their inabili- ty to grow on plating media, these VNC c e l l s c a n r e m a i n active in wine for + The decision to filter a wine should be based on the potential for wine spoilage post-bottling. + Wine style, chemistry and microbial content are considerations in deciding whether or not to filter. + Harvesting healthy grape clusters and sanitizing processing equipment are imperative in minimizing spoilage potential. + Technology has reduced, or nearly eliminated, any obvi- ous sensory impact to the wine that has been filtered. AT A GLANCE Get it Right Before it Goes in the Bottle Filtration is the final defense against wine spoilage SOIL & CELLAR REMI COHEN