The Impact of Cold Soak vs Extended Maceration in Petit Verdot Wine (2017)

This study examines the impact of cold soaking vs extended maceration on Petit Verdot wine, with maceration time being equal between treatments. The goal was to have on treatment spend more time exposed to an aqueous phase, with the other treatment having more time exposed to an alcoholic phase. Petit Verdot grapes from the same vineyard block were harvested on the same day and destemmed into two separate T Bins. One T Bin underwent a 4 day cold soak prior to inoculation, whereas the other was immediately inoculated without cold soak. Both treatments underwent a 25 day maceration before being pressed off on the same day: thus, the cold soak received less time in contact with must in an alcoholic phase. All other treatments between wines were identical. Wine chemistry and ester profiles were not much different between treatments. The extended maceration treatment had higher levels of color, epicatechin, and tannin, but other phenolic compounds were not much different. The wines were not found to be significantly different via triangle testing. However, there was a strong trend for the cold soak wine to have higher Astringency than the extended maceration wine. There was a slight tendency for this wine to have increased Bitterness and lower Body as well. The total maceration time for these wines was long in both cases, and as such the differences seen here may be greater if smaller overall maceration times are used. In the future, this should be performed, and more microbial analysis should be performed as well.

Read Full Report (PDF)

Skin Contact vs Traditional Pressing of Petit Manseng (2016)

This study compares the effects of destemming and cold soaking Petit Manseng Grapes for 6 hours prior to pressing compared to directly pressing whole clusters. Juice produced with skin contact showed higher pH without much change in TA. The wine which underwent skin contact showed much lower TA and much higher pH. Skin contact also increased color intensity, catechin, tannin, caffeic acid, gallic acid, and astilbin. Caftaric acid was decreased by skin contact. This loss in caftaric acid and gain in caffeic acid could be due to equilibrium pressure. Sensory testing found the wines to be significantly different. Direct to Press wines had a slight tendency for higher Tropical Fruit aromatics, and a strong tendency for these wines to have higher Overall Aromatic Intensity. Skin-Contacted wines had strong tendencies towards increased Bitterness, and a slight tendency for higher Astringency. In general, people tended to prefer wines made from direct pressing. Studies of this kind, in conjunction with phenolic fining studies, should be performed in the future.

Read Full Report (PDF)

The Effect of Zymaflore Alpha Yeast (Laffort) during Cold Soak on Cabernet Franc Wine (2016)

This study examines the impact of adding Zymaflore Alpha (T. delbrueckii) (Laffort) yeast prior to a cold soak on the chemical and sensory characteristics of Cabernet Franc wine. Cabernet Franc from the same block was harvested on the same day and processed into two separate T Bins. All additions were identical, except that one T Bin received Zymaflore Alpha yeast and the other received no yeast. Both bins then underwent a 6 day cold soak at 50°F. After cold soak, both bins were inoculated with FX 10 yeast. All other treatments were identical. Wine was pressed around 3 weeks after processing. The Zymaflore treatment lowered titratable acidity and slightly lowered ethanol, but otherwise no major chemistry differences were apparent between wines. The Zymaflore treatment had increased acetaldehyde and propanol, but most other higher alcohols and fusel oils were lowered by the treatment. The Zymaflore treatment also slightly lowered color intensity. Triangle testing showed that, of 7 people who answered, 4 people chose the correct wine (57%), suggesting that the wines were not significantly different. However, the wines were almost significantly different. 3 out of 4 judges who answered correctly preferred the Zymaflore treatment to the control, and the other judge had no preference. The wine with Zymaflore was described as being slightly smoother, less harsh, or more balanced in terms of acidity. No major trends were discovered for the descriptors used in this study. There was a slight tendency for the Zymaflore wine to have lower Astringency and Overall Aromatic Intensity. The use of non-Saccharomyces yeast strains merits further work.

Read Full Report (PDF)

Different Maceration Techniques in Cabernet Franc (2015)

Cabernet Franc was fermented in three separate ways.  The control received no cold soak nor extended maceration.  One wine was fermented in the Maceration a Chaud du Marc style, where fermenting juice was racked into another tank where the temperature was kept around 20C (70F), the skin was left in the Tbin and temperature was brought up to 42C (107F) until the juice reached a specific gravity of 1.020 and was blended back with the skin.  The third wine received both a cold soak and extended maceration.  No chemical differences were observed between wines, except that the wine with cold soak and extended maceration had higher pH, lower TA, and lower ethanol.  Maceration a Chaud du Marc slightly increased polymeric pigment and color, and slightly decreased hue.  People tended to prefer the Maceration a Chaud du Marc, in spite of being described of having some typical Brettanomyces aromas.

Read Full Report (PDF)

Cold Soak vs. No Cold Soak with Merlot (2014)

Two different Merlot clones (181 and 343) were evaluated for chemical and sensory differences due to cold soaking.  Not much color difference was observed between wines that had undergone cold soak compared to controls.  However, significant sensory differences existed between wines, with most people preferring cold soaked wines.

Read Full Report (PDF)