I have a 2011 Chardonnay from California fermented out to dryness. I added malolactic culture during alcoholic fermentation but it did not complete. The pH shift was from 3.38 to 3.52 after eight weeks. I then racked it and added sulfites. I did a chromatography test and it showed that there was still some malic acid present. I have heard about using lysozyme to stop any restarting of malolactic fermentation. What do you suggest?
In my day job in Napa, California (as Winemaker for Garnet Vineyards as well as other consulting projects) I bottle plenty of “partial ML” Chardonnay every year and love the style. In fact, my Garnet Vineyards Sonoma Coast Chardonnay is about two-thirds malolactic complete, depending on the natural acidity of the year (lower acid years may only be 50% complete) and none of my Chardonnays, even Russian River or Santa Barbara Chardonnays, are ML complete. Not having tasted your wine or knowing any other numbers like Total Acidity (TA) or alcohol, it seems to me that a bottling pH of 3.52 is a perfectly reasonable balance point between crispness and roundness.
It seems like you are willing to bottle a partial-ML Chardonnay and kudos to you. So many of we winemakers in California and elsewhere are doing so that I think we are seeing a nationwide paradigm shift in Chardonnay making. We are collectively tossing aside the fat, greasy and over-oaked concoctions of the past for a style where the satisfaction in the tipple comes from the balance of inherent elements and the fresh charm of the Chardonnay fruit itself.
As such, if you are planning to bottle soon, I advise you to not bother with the lysozyme but make sure your free SO2 is around 30 ppm, use a sterile filter (0.45 micron nominal) and use obsessively-clean sanitation before and during bottling. If a filter like one of the small models suited to home winemakers (like the Buon Vino, www.buonvino.com) is an expensive proposition for you (they run about $300 and up) see if you can rent one from your closest home winemaking or homebrewing supply store, or borrow one from a local winemaking club. Excluding bacteria that can eat malic acid and turn it into lactic acid is the only way to make sure you don’t get re-fermentation in the bottle.
Sometimes sold under brand names “Lysovin” “Lysoeasy” and “Lactizyme,” lysozyme is a naturally-occurring enzyme isolated from egg whites and has been used for decades in the dairy and pharmaceutical industries worldwide. It is a protein (as all enzymes are) that suppresses the activity of gram-positive bacteria. In real-cellar terms, this means that it’s effective against most strains of lactic acid bacteria (AKA “LAB,” Oenococci, Pediococci and Lactobacilli species are the most well-known), but not yeast or other winemaker bugaboos like acetobacter. Available in liquid or powdered form, it is usually dosed into wines at 100–500 ppm level and can be used at any point in the winemaking process. It is deployed for specific reasons, usually to enable primary fermentation in must infected with rot (allows the yeast to better compete), to delay MLF in red wines undergoing microoxygenation (high CO2 levels from MLF reduces micro-ox’s effectiveness) or to halt an unwanted spoilage LAB infection in ML-complete or partial-ML wines during aging. See Tim Patterson’s 2002 article, “It’s Lysozyme Time” at www.winemakermag.com/component/resource/article/407 for an expanded viewpoint of what lysozyme can — and most importantly — can’t do for your wines during all stages of winemaking.
With regards to lysozyme cautions as regards bottle-ready wine, first let me say that it is not a magic bullet. If lysozyme kills lactic acid bacteria then can it be a complete substitute for SO2 and sterile filtration in managing lactic acid bacteria refermentation post-bottling? In a short answer, no. First of all, lysozyme is not an antioxidant so will provide none of the protection against browning that SO2 does. This is especially important in white wines as you want to make sure your wines age gracefully. Secondly, lysozyme’s activity is not persistent, meaning that it wears off over time, usually about two weeks, depending on the number of microbes present and the amount added to the wine. This means that unless you add lysozyme very close to bottling, the activity will be diminishing as you go to bottle and some microbes might get through. Adding lysozyme close to bottling can be fraught with difficulty, however, because as a protein it can flocculate and cause a white wine to become heat-instable. Because it’s a protein it can also strip color from red wines so is usually counter-indicated in light-color varietals like Pinot Noir. Additionally, some strains of LAB are resistant to lysozyme so its use is no guarantee.
That being said, if you have absolutely no access to a sterile filter setup, a little lysozyme treatment is better than nothing. Try dosing in lysozyme at a rate of 400 ppm and rack after two weeks. If having a heat-stable (no protein precipitation) white wine is very important to you, fine with bentonite afterwards (about two weeks apart as bentonite and lysozyme can work against each other) at a higher rate than you normally would for bottle-prepping. Adjust your free SO2 to 50 ppm like usual, maintain the strictest of sanitation regimens as you go to bottle, and cross your fingers. Be sure to let 24 hours elapse between any lysozyme and SO2 additions; their activity can cancel each other out.