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New World Wine Maker Blog - MLF

Bacteria in winemaking – it’s all about timing

Cheese

“The early bird gets the worm, but the second mouse gets the cheese.”
Willie Nelson

Being early is not always a guarantee of success, especially if you’re a mouse. Evidently, timing is critical. An example of this is gossiping about a colleague when he or she walks in (I never do this) or adding lysozyme to your must before co-inoculating with yeast and bacteria. As far as the latter example of bad timing is concerned, I know of a winemaker that did this. Suffice it to say, no MLF took place.

Timing is usually critically important in any winery, especially when it comes to the tiny microbes in your fermenting must and wine. The presence or absence of yeast and bacteria at certain stages of the winemaking process will ultimately determine the quality of your wine. For instance, a beer brewer phoned me a while ago and complained about bacterial spoilage of his artisan beers by lactic acid bacteria. I recommended Delvozyme® (a lysozyme preparation that Anchor sells locally) and have not heard from him since. No news is good news, right?

Another case comes to mind. A winemaker told me that he’s been involved in a long-standing feud with ubiquitous LAB that perennially invade his barrels of premium Chardonnay. The winemaker has since made a compromise, as a certain percentage of barrels are allowed to be annexed by the marauding LAB and the remainder of the barrels are treated with lysozyme. All the wine is eventually blended and the combination of wine with diacetyl notes versus more fruit driven wine has proven to be quite enchanting.

As a parting shot, I read about an Australian winemaker that was told by a consultant that he could use less sulphur in his wine if he used lysozyme during stabilisation. The end result; an oxidised, microbiologically stable wine and a well-timed kick to the consultant’s backside!

Bernard Mocke is a technical consultant for Oenobrands

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Lactobacillus – the good, the bad and the ugly

My husband is obsessed with this movie and the theme song. It was his cell phone ring-tone for a while – a long while actually – drove me bonkers. I guess that is why it was the first title that popped into my head when I thought of how to describe Lactobacillus in winemaking. It used to be the bad and in many cases the ugly. If you look at articles on stuck fermentations and wine spoilage from a few years ago, Lactobacillus almost always features somewhere in the article as one of the main culprits. So it is not surprising then that sales attempts to sell Lactobacillus starter cultures for malolactic fermentation are often greeted with GREAT resistance, aggression, jaw dropping, gawking or a call for Security.

Well folks you can pick up your jaws because it seems that there are “good” guys amongst the bad and ugly ones. The two companies that are taking the lead on commercializing some good guys are Oenobrands and Lallemand. The Lallemand culture V22 is a pure Lactobacillus plantarum culture from European origin and can be used for both co-inoculation during alcoholic fermentation as well as sequential inoculation after alcoholic fermentation. The Oenobrands product, marketed under the Anchor brand and called Anchor NT 202 Co-Inoculant, is a blend of selected Oenococcus oeni and Lactobacillus plantarum strains. These strains are South African isolates.

Okay, I know what your minds are screaming…VA! Indeed something to scream about. But not in this case. These two commercial Lactobacillus plantarum cultures are homofermentative. That means they can utilize only malic acid as a carbon source to form mainly lactic acid. Other Lactobacillus strains (often present in spontaneous MLF’s) as well as Oenococcus strains  are heterofermentative, meaning they can also utilize grape sugars and citric acid and as a result form acetic acid. However, reputable commercialized Oenococcus oeni MLF starter cultures, although heterofermentative, strongly prefers malic acid as carbon source (they have been selected because of this), even during co-inoculation where grape sugars and citric acid are present in high concentrations. Not all starter cultures are suitable for co-inoculation though.

Okay so why Lactobacillus? In the case of Anchor NT 202 Co-Inoculant the Lactobacillus plantarum in this mixed culture brings aroma and roundness to the party. The Oenococcus is the workhorse bringing, security and speed to the party. The application of NT 202 Co-inoculant is also rather simplistic. You add equal amounts of sachets of bacteria and packets of NT 202 wine yeast to the juice, at the same time, before the onset of fermentation. No waiting for 24 hours. No extra calculations. Scientific research has shown this Lactobacillus plantarum strain to have a very different enzyme profile to Oenococcus oeni in general and as a result the typical varietal character of red grapes, specifically monoterpenes and norisoprenoids, are released from their non-aromatic precursors, thereby increasing wine aroma and thus quality.

So while you still need to do your best to keep the “bads” and the “uglies” out of your wines, experimenting with the “good guys” might just give you that kick @$$ competitive edge you strive to achieve in your wines…

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A malolactic starter BLEND? Huh?

Yes yes, it has arrived. The first commercial bacterial blend has seen the shelves so to speak. It has been commercialised by Anchor Wine Yeast and is a blend of Oenococcus and Lactobacillus. This product is also to be used in co-inoculation with the wine yeast only and not for inoculation after alcoholic fermentation.  Anchor takes it even a step further and recommends it with a specific yeast only. Okay so every man and his dog already have MLF cultures. Why should one even consider this product?

The Oenoccoccus and Lactobacillus cultures are South African isolates and the research was done by the Institute for Wine Biotechnology in Stellenbosch, South Africa. They were isolated from high alcohol high pH wines that underwent successful natural MLF. Why? These are often conditions associated with new world red winemaking; therefore making this bacterial blend very suitable for conditions such as these in other parts of the world. But I’m a European / New Zealand winemaker, I don’t have high alcohol, high pH conditions so what would I bother? Well I guess for the same reason that not everyone in the USA where the speed limit is 65 miles per hour drives a Ford Ka. Some people actually do drive faster, better performing cars in slow conditions. It’s about the ride they say – so much more comfortable in a Mercedes CLK. When you ferment a must with a potential alcohol of 14% its comforting to know that the yeast you use is actually resistant to 16%. The same goes for using this bacterial culture blend.

Okay moving along to the next argument as to why it’s a good idea – Lacotobacillus has a higher pH optimum (3.5 – 4) than Oenococcus (3.2 – 3.5). That means in higher pH conditions, faster onset of MLF since the Lactobacillus will kick off first. And no – the Lactobacillus is homofermentative meaning it only converts malic acid to lactic acid and not sugar to acetic acid. By the time alcoholic fermentation is finished MLF is either completed or down to 1 g/l or less of malic acid. MLF is then completed a few days later. Meaning much faster processing and protection of the wine against Brett for instance.

Not convinced yet? The Lactobacillus also smells and taste good. Trials done comparing the Oenococcus on its own and the blend shows increased aromatic complexity in the favour of the blend. The blend also shows increased aromatic complexity when compared to other commercial MLF starter cultures.

Another differential is that the culture is inoculated with the yeast at the same time. No need to wait 24 hours as long as sulphur addition at crushing does not exceed 50 ppm. That should not be a problem for most people. Anchor also recommends the bacterial blend, known as NT 202 Co-Inoculant,  with the wine yeast NT 202 seeing the this yeast is very stimulatory for MLF, amongst various other positive attributes. The whole idea is to have completely trouble free MLF’s. We will just have to wait and see – this might just end up being the Holy Grail of MLF. Exciting times!

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A case for co-inoculation of malolactic bacteria and wine yeast

This morning I was looking at some results from MLF trials done in Italy during the 2009 harvest season and once again the benefit was overwhelmingly on the side of co-inoculation of the bacteria with the fermenting yeast. Over the past few years I have seen various research reports, published articles and powerpoint presentations at conferences on the topic of co-inoculation. Every time the co-inoculated MLF result is better than inoculation after alcoholic fermentation and certainly streets ahead of the spontaneous fermentation results. Why is everybody not doing it? Well the answer to that question in my humble opinion is two-fold:
 
1. "Fear” because people think that inoculating for MLF before alcoholic fermentation is completed, can have the bacteria grow on sugar instead of malic acid, and as a result form volatile acidity. This is after all what happens in the case of a stuck fermentation. So the fear is justified, but in the case of stuck fermentations it is the natural lactic acid bacteria present on the grapes that cause the havoc. The specific commercial bacteria trialled and tested in the case of co-inoculation do not produce VA. There exists enough evidence for this now.
 
“2. "Cost” because MLF can happen automatically and it won’t cost you a sent. In these economic times many winemakers go for this option. Some people buy a small amount of commercial cultures and then “mother tank” them. However, to ensure a successful MLF, just like a successful alcoholic fermentation, one needs to inoculate a certain population size. By inoculating less, you could run into a stuck MLF which will cost you more to resolve than what inoculating adequate amounts of the starter culture would have cost you in the first place.  There are various other advantages of using specific bacterial starter cultures versus spontaneous – biogenic amines and sensory attributes to name but two.
 
Inoculating after alcoholic fermentation means you inoculate bacteria into very harsh conditions of high alcohol concentrations and possible non-optimal temperatures, since red wine production is towards the end of summer / autumn and cellar temperatures can drop quite substantially. So, you take your chances with a low inoculum due to “mother tanking” into harsh conditions and you expect it to work perfectly every time? These types of practices make me very nervous. I like things to work. My personal view on this is that if you are into quality winemaking you should not be taking any unnecessary chances. Companies selling bacterial starter cultures can only guarantee a successful outcome to some extend if you follow their instructions and use the bacteria under the conditions they are suitable for.
 
Personally I would go for co-inoculation. Why? Well you inoculate the bacteria into juice with no or very little alcohol. How nice is that for the bacteria??? The temperature is also very optimal for the bacteria since yeast produces a significant amount of heat during fermentation. The only thing is that one should ideally keep the temperature in the mid 20’s (degrees Celsius) since that is what will be optimal for the yeast / bacterial combination. It is anyway a good idea in the case of the yeast as well, since high fermentation temperatures increase ethanol toxicity. In most of the trial results I have seen, MLF is completed when AF is completed. The time saving and energy saving (no heating up of tanks) can have a profound effect on your bottom line. Generally one has to inoculate the bacteria 24 hours after the yeast inoculation. The reason for this is to give the SO2 that was added at crushing time to bind since free SO2 can have an inhibitory effect on lactic acid bacteria. With co-inoculation there are no short cuts. You have to use the inoculum size specified by the supplier as well as use only bacteria proven suitable for co-inoculation. Suppliers also specify the yeasts that are best suited for the co-inoculation.
 
So, it will cost you, but you will get what you pay for: a more predictable and reliable outcome and latest research shows there is a sensory advantage as well!!! Sounds like a good deal to me. The company that I am forced to work for since I did not marry into money employs an American marketing consultant who would have ended off this blog with the following words:
 
Can you afford NOT to be part of this REVOLUTION???!!!
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