Three Phases of Malolactic Fermentation Bacteria

2017 was the first year that we had any reasonable amount of Chardonnay grapes for fermentation. The Chardonnay came in with approximately 10 g/L titratable acids so we wanted to convert some of the malic acid to lactic acid.
Oenococcus oeni is the lactic acid bacteria commonly used in malolactic fermentation (MLF). When grape sugars are available, O. oeni will ferment these sugars as their primary source of carbon for growth.
MLF is a survival mechanism that supplies energy to the bacteria when other nutrients become scarce. MLF converts naturally occurring malic acid to lactic acid, through the decarboxylation of L-malate to L-lactate.
Malolactic bacteria are present in low concentrations on grapes, approximately 100 cells/g, but then they increase to 10⁴ cells/mL after crush and 10⁷ cells/mL by the end of alcoholic fermentation when malolactic fermentation typically occurs. The metabolism of sugars and organic acids during malolactic fermentation can be divided into three phases:

• During the growth phase (Phase I), sugar catabolism occurs with little production of acetic and lactic acid; minimal citric and malic acid are metabolised in this phase
• As the bacterial cell numbers increase above 5 × 10⁶ cfu/mL during Phase II, the catabolism of sugar ceases and malic acid metabolism proceeds accompanied by production of lactic acid; citric acid remains untouched at this stage, and there is no acetic acid produced during malic acid degradation.
• Phase III is characterized by the metabolism of citric acid accompanied by an increase in acetic acid. The increase of lactic acid content in the wine results in a softer mouth-feel and the acetic acid contributes to the volatile acidity of the wine

When my husband added our packaged MBR31 for the MLF we expected some visible (by paper chromatography) results in two weeks. Given all that these bacterial helpers need to do for growth, maybe we need to be a little more patient.
References:
1. Scott Laboratories Malolactic Bacteria.
2. Swiegers, Jan, Bartowsky, Eveline, Henschke, P.A. & Pretorius, I.S., Microbial modulation of wine aroma and flavour, Australian Journal of Grape and Wine Research, 2005, 11. 139 - 173. 10.1111/j.1755-0238.2005.tb00285.x.
3. Whitney Lysbeth Beaman, Effect of Cell Density and Growth Phase on Malolactic Fermentation by Oenococcus oeni, May, 2011.
3. The Australian Wine Research Institute, Achieving Successful Malolactic Fermentation
Other related blogs:
Malolactic Fermentation
Diacetyl Formation

The Yin and Yang of Bacterial Fermentation

In December, 2017, I wrote about the lactic acid bacteria (LAB), Oenococcus oeni that we used to conduct Malolactic Fermentation. Oenococcus oeni is one of four genera of the lactic acid family that includes Lactobacillus, Leuconostoc and Pediococcus able to survive the unfavourable conditions (low pH, high ethanol concentration and low nutrients) present in wine. Oenococcus oeni is the most well adapted wine-associated species and is used almost exclusively for the induction of malolactic fermentation (MLF) in red, white and sparkling base wines
The only other family of bacteria commonly found in grape juice and wine is Acetobacter. While LAB is generally thought of as providing positive attributes, the members of Acetobacter are generally thought of as being spoilage organisms when found in wine, due to the formation of major oxidized products, such as acetaldehyde and acetic acid.

The modulation of wine flavour by bacteria

Organism	Compound	Aroma/Flavor Attribute
Acetobacter Gluconobacter oxydans, Acetobacter aceti, Acetobacter pasteurianus, Gluconacetobacter liquefaciens and Gluconacetobacter hansenii	Acetic Acid	Vinegar
Heterolactic bacteria	Mannitol spoilage	Sliminess and production of a vinegary-estery, slightly sweet taste
Oenococcus oeni and Lactobacillus	Acetaldehyde metabolism → acetic acid and ethanol
Oenococcus oeni	2,3-Butanedione (Diacetyl)	Buttery, butterscotch
Lactic acid bacteria and acetic acid bacteria	p-coumaric and ferulic acids → vinyl and ethyl phenols

In secondary fermentation with beneficial bacteria, oxygen is the enemy that encourages the growth of Acetobacter and vinegar flavors. Keeping the wine environment anaerobic encourages Lactic acid bacteria that will convert the harsher malic acid to lactic acid perhaps with an accompanying formation of diacetyl (aka buttery flavors). Take home message: top off all wines to keep the influence of oxygen and by extension, the growth of undesirable bacteria to a minimum.
References:
1. Scott Laboratories Malolactic Bacteria.
2. Swiegers, Jan, Bartowsky, Eveline, Henschke, P.A. & Pretorius, I.S., Microbial modulation of wine aroma and flavour, Australian Journal of Grape and Wine Research, 2005, 11. 139 - 173. 10.1111/j.1755-0238.2005.tb00285.x.

2006 Lopez de Heredia Viña Gravonia

Shocking to me how times flies. In 2011, I blogged about 2001 Lopez de Heredia Gravonia --- a Taste of Viura, so seven years later, I thought I would update tasting notes for this 2006 Lopez de Heredia Viña Gravonia.
We drank this wine in December, with two different food pairings over 2 nights. Not everyone appreciates a white wine made in an oxidized style and I was beginning to change my mind about this Viña Gravonia. Here is what I experienced: On the first evening, we paired the Gravonia with pear salad and I didn't quite appreciate the oxidized style of the wine. But on the second night, when we paired the wine with tortellini pesto, the rich mouthfeel, the honeyed flavor backed with acidity, was such a delicious pairing, I had to change my mind!
Today, I went to Wine Grapes, the Jancis Robinson et al. Bible and looked up "Viura". I was surprised NOT to find an entry. When I consulted the index, I found that Viura is another name for Macabeo! In Rioja, where this Lopez de Heredia Viña Gravonia comes from, the Macabeo grape is referred to as Macabeo/Viura. Wine Grapes describes the Viura as:
          Big, compact bunches of medium-sized, thick-skinned berries.           Late budding and late ripening. Cool, damp sites are unsuitable.           Very susceptible to botrytis bunch rot and vine bacterial necrosis,           less so to downy mildew. Responds well to low yields and relatively           early picking.¹ Other notes that I found online include: Viña Gravonia Blanco 2006 is 100% old-vine estate Viura fermented in old oak vats and matured in old oak for four years. Fined with egg whites but left unfiltered. The dry white Rioja is entering maturity now and will drink through 2022.²
Lopez de Heredia is still family owned and the wines are made in the traditional way, not bending to modern trends.
References:
1. J. Robinson, J. Harding and J. Vouillamoz, Wine Grapes - A complete guide to 1,368 vine varieties, including their origins and flavours, pg. 560-561.
2. 2006 R. López de Heredia Viña Gravonia.

In Search of Wine Quality: Soil and Water---Part 4

Following up on my last posting of In Search of Wine Quality: Soil and Water---Part 3 which was about Soil Drainage, today's post is about Tiling.
Prior to installing tiling in our vineyard, I looked online for a video that would show us how to do it. I found one made by Hans Walter-Peterson of the Finger Lakes Grape Program and blogged about here:
How to Put Drain Tile in the Field.
Part 4. Tiling
Tiling is a soil management technique that seeks to improve the soil water content which directly impacts root health and function. All vineyards can benefit from the installation of subsurface tile drainage, to improve wet soil conditions.
We put in our drainage tiling with the help of Barry, Geoff, and Bill from December 14, 2012 into January 11, 2013.

Why did we go through all of this during a particularly cold winter, you might ask? The answer to that question is that we sought to prepare our land so that the young vines would find a hospitable place to set down their roots. Tiling a vineyard addresses the question of vine root health, the part of the grape vine that we can't see.^*
Attributes of a healthy root system:

• Large and actively growing
• Creates active root tips for exploration and water/mineral uptake
• Large structural root system provides a good supply of carbohydrates and amino acids for overwintering and spring remobilization
• The site of cytokinin and gibberellin production, critical to many metabolic functions within the whole vine

Conversely, the effects of standing water on the root system:

• Contributes to low oxygen near the root zone, drastically impeding water uptake
• Will eventually initiate rotting of flooded tissues

In putting tilng in our vineyard, we tried to do what we could to promote good vine health, in our quest to make quality wines. Next up in this series
In Search of Wine Quality: Soil and Water---Part 4 Irrigation.
References:
1. K.H. Fisher, Drain Tile Systems for Vineyards, University of Guelph, Vineland Station, Ontario, February 22, 2013.
2. Previous blogs in this series:
In Search of Wine Quality: Vineyard Location
In Search of Wine Quality: Soil and Water---Part 2 Water Holding Capacity
In Search of Wine Quality: Soil and Water---Part 3 Soil Drainage
^*Note: The appropriate rootstock selection can mitigate some of the existing soil conditions. In a future blog, I hope to get to the selection of the appropriate rootstock for a particular soil type.

A Question of Taste

While surfing the Internet, I found this beautiful chart jam packed with wine tasting factoids from Visually. It's pretty cool so I think you will enjoy it, too.

by adolfux.

References:
From Visually.

Determining Genetic Relationships Between Auxerrois and Chardonnay

Over the Christmas holidays, my husband and I were seeing a lot of commercials touting DNA kits as Christmas gifts. We also watched Henry Louis Gates, Jr. show Finding Your Roots on PBS. Knowing your genetic background is pretty cool.
Knowing a grape variety's genetic background, for me, is pretty cool, too. My husband and I have known that the Auxerrois that we planted and the Chardonnay are offspring of Gouais Blanc and Pinot Noir. This knowledge came from a Science article that came out in 1999, when thoughts of having a vineyard and winery were just dreams.
I blogged about it in 2013, in a blogpost I called 1999 DNA Typing Article Gives Clues. I was unhappy with the photo I took to put on the blog and have been looking for the article (where in the world did I put it?) ever since. Found it! Here is my new (better camera) and slightly modified (better photo editing) attempt at the genetic relationship illustration:

The above illustration seems to suggest that all of the varieties represented on the left hand side are equally related. However, in an earlier paper authored by G. N. Ye, et al., using Random Amplification of Polymorphic DNA (RAPD), a form of genetic analysis, showed that Chardonnay and Auxerrois are much more closely related.
The RAPD technique makes use of PCR amplified fragments separated on agarose gels. In this study, the authors used 53 10-mer primers to generate a total of 464 bands from the genomic DNA of 16 genotypes. The pairwise percentage similarity between genotypes was calculated by the number of bands (amplification products were resolved by electrophoresis on 1.5% agarose gels) shared by both cultivars divided by the total number of bands analyzed.

The results obtained above showed that the similarity between Chardonnay and Auxerrois was 86.7%. Close relationships can also be depicted as a dendrogram:

These references show that the similarity that exists between Chardonnay and Auxerrois is because they are the offspring of Pinot Noir and Gouais Blanc. One consequence of this relationship is that when making blends, Chardonnay and Auxerrois tastes like a seamless blend, whereas Chenin Blanc and Auxerrois in our hands was not quite as seamless.
References:
1. Bowers, J., Boursiquot, J.M., This, P., Chu, K., Johansson, H., & Meredith, C, 1999, Historical Genetics: The Parentage of Chardonnay, Gamay, and Other Wine Grapes of Northeastern France, Science: 285, pp 1562 - 1565.
2. G. N. Ye, G. Soylemezoglu, G. Soylemezoglu, N. F. Weeden, N. F. Weeden, W. F. Lamboy, W. F. Lamboy, R. M. Pool, R. M. Pool, B. I. Reisch, Analysis ofthe relationship between grapevine cultivars, sports and clones via DNA fingerprinting , Vitis, 1998, Vol.37, No.1 pp. 33-38.

2012 Vajra Freisa Kyè

We drank this wine on New Year's Eve when our son and daughter-in-law were visiting from Seattle. My husband made slow cooked beef short ribs. The color of the wine was clear garnet and there was a nice aroma of red raspberries and dark cherries. There was a good deal of fruit flavor backed with a nice acidity, which was a perfect foil for the slightly fatty short ribs.
We have had several other wines made by Vajra, 2012 Vajra Riesling, 2009 G.D. Vajra Barbera d'Alba, and 2009 Vajra Barolo, all of which we enjoyed.
The Freisa grape is grown in the Langhe region of the Piedmonte. In reading Wine Grapes, by Robinson, et al., I learned that the Freisa grape is related to Nebbiolo.
I learned more about the 2012 Vajra Freisa Kyè on Liberty Wines. Here are the vinification notes:
The destemming and elimination of the most acidic parts along with the greenest tannins, is an essential practice for this variety. Fermentation lasted approximately two weeks, at temperatures no higher than 28-30ºC, allowing the tannins to become well integrated. For this rather wild variety, malolactic fermentation is equally important. The wine was aged for 12-18 months in Slavonian oak barrels and barriques, giving necessary balance to the wine. This wine contains 6.5 g/L acidity and 3.1 g/L residual sugar.
References:
1. J. Robinson, J. Harding and J. Vouillamoz, Wine Grapes - A complete guide to 1,368 vine varieties, including their origins and flavours, pg 367-368, Allen Lane 2012 ISBN 978-1-846-14446-2.

In Search of Wine Quality: Soil and Water---Part 3

I'm back to blogging about Wine Quality. Winter is the time for recapitulation---reviewing the first things I learned in the U.C. Davis online course. I started in December, 2017 with the following two blogposts:
In Search of Wine Quality: Vineyard Location
Following by:
In Search of Wine Quality: Soil and Water---Part 2
Today's blog is about:
Part 3. Soil Drainage
Another way to think about the water holding capacity of the soil is to look at the drainage of the different soil textures. The following chart shows soil drainage as it relates to the type of soil texture. Soil Drainage is expressed in the NRCS soil databases as: "Natural drainage class refers to the frequency and duration of wet periods under conditions similar to those under which the soil developed."

The Cornell Site also provides the following descriptions of soil drainage. I reversed the order of the drainage types to be consistent with the color coded chart above beginning with the clays and silty clays that are very poorly drained and not suitable for growing grapes.

Description	Relevance to Grapes
Very poorly drained. Water is removed from the soil so slowly that free water remains at or very near the ground surface during much of the growing season. The occurrence of internal free water is very shallow and persistent or permanent.	Not acceptable for grapes
Poorly drained. Water is removed so slowly that the soil is wet at shallow depths periodically during the growing season or remains wet for long periods. The occurrence of internal free water is shallow or very shallow and common or persistent. Free water is commonly at or near the surface long enough during the growing season so that most mesophytic crops cannot be grown, unless the soil is artificially drained. Not acceptable for grapes except possibly with extensive tile drainage, but not recommended.	Not acceptable for grapes
Somewhat poorly drained. Water is removed slowly so that the soil is wet at a shallow depth for significant periods during the growing season. The occurrence of internal free water commonly is shallow to moderately deep and transitory to permanent. Wetness markedly restricts the growth of mesophytic crops, unless artificial drainage is provided.	Not recommended except with tile drainage at close spacing. Not recommended due to general soil limitations and cost of drainage.
Moderately well drained. Water is removed from the soil somewhat slowly during some periods of the year. Internal free water occurrence commonly is moderately deep and transitory through permanent. The soils are wet for only a short time within the rooting depth during the growing season.	Generally acceptable, but may have poor soil aeration during wet periods. Tile drainage is likely needed.
Well drained. Water is removed from the soil readily but not rapidly. Internal free water occurrence commonly is deep or very deep. Water is available to plants throughout most of the growing season in humid regions. Wetness does not inhibit growth of roots for significant periods during most growing seasons.	Good soil for grapes as it has a good balance of drainage for good aeration for root growth with adequate water and nutrient-holding capacity. Due to water holding capacity they provide plenty of water and tend to be better for white varieties.
Somewhat excessively drained. Water is removed from the soil rapidly. Internal free water occurrence commonly is very rare or very deep. The soils are commonly coarse-textured and have high saturated hydraulic conductivity or are very shallow.	Generally excellent for grapes although may be droughty and/or low in nutrients. Excellent, if irrigation is available. Such soils tend to be preferred for red varieties that do best with some water stress.
Excessively drained. Water is removed very rapidly. The occurrence of internal free water commonly is very rare or very deep. The soils are commonly coarse-textured and have very high hydraulic conductivity or are very shallow.	Excellent soil aeration for root growth. If too light, such soil may hold too little water unless the soil is very deep. Irrigation may be needed. The course texture (gravel or sand) soils may also have low fertility.

Our soil texture is sandy loam so our soil falls into the "well drained, somewhat excessively drained to excessively drained" categories. Nevertheless, we chose to put tiling to ensure that we have good drainage in the vineyard. Next up, how to tile a vineyard.
References:
1. Alan N. Lakso and Tim E. Martinson , The Basics of Vineyard Site Evaluation and Selection, Department of Horticulture, Cornell-Geneva.
2. Terry Pritchard, Winegrape Irrigation Scheduling Using Deficit Irrigation Techniques.

Post-Bomb Cyclone Blog

Phew! We were so fortunate to make it through the bomb cyclone pretty much unscathe. Yes, there is snow and yes, there was a brief 5 minute interval where we lost power, but all in all, Mother Nature spared us. So, to honor this event, I thought I would go au naturel with this blog:

No, this isn't our vineyard crew (at least not that I know of). The above photo came from Naturists harvest French vineyard grapes entirely nude, that my husband said is a literal take on "natural" wine. The harvest crew in a vineyard in the commune of Crest consisted of seven men and one woman.
Hoping this blog puts a smile on your face! More technical blogs to follow in the coming days.

Vintage 2018: Winter East Coast Bomb Cyclone

The New Year has brought some brutally cold temperatures, beginning with New Year's Eve with temperatures in the teens. New York City rang in 2018 in 9-degree weather, the coldest midnight temperature since 1907. My husband went to the vineyard yesterday where he took the following picture.

This week's forecast brings news of a bomb cyclone, characterized by a weather system that drops at least 24 millibars over 24 hours, in a process called bombogenesis. Winds could kick up to 55 mph just off the coast of New England, with hurricane force winds that could result in near blizzard conditions. How ominous does this look:

Crossing our fingers that the bombogenesis will fizzle before hitting us sometime later this evening.
References:
1. The East Coast Is About To Get Hit by a “Bomb Cyclone”.

Happy 2018!