Cryoextraction techniques for better tasting wine?

Studies have reported that for white grapes, namely Muscat of Alexandria, the contact between grape juice and skin enhances the aromas of the variety and the resulting wines are notable for their aroma. 

 

Freezing grapes is a winemaking technique known as cryoextraction. The changes that take place in the frozen grapes facilitate the transfer of certain compounds from the grape skins into the musts. 

 

A recent Spanish study has tested the effect of two cryogenic techniques on Muscat of Alexandria grapes, a variety of white grape with specific compounds of interest in their skin. The experimentation compared three different vinification procedures. The first wine was the reference, made by crushing the grapes at room temperature (20°C) and then pressing them. The second wine was made using “ultra-fast mechanical freezing”. The grapes were deep-frozen in a highly powerful freezing chamber that brought the grapes down to −28°C in 15 minutes. For the third wine, the grapes were frozen at  −196°C for less than 1 minute using liquid nitrogen. For both cryoextraction techniques, the grapes were stored in the same chamber at −18°C for 2 hours, then allowed to thaw at room temperature for 3 hours. The semi-thawed grapes were then crushed and pressed. Afterwards, the three different wines were tasted by a panel of experts in a normalized tasting room and a sensory analysis was performed. 

 

The authors found that freezing procedures reduced acidity, increased alcoholic strength and, most importantly, produced wines that were more aromatic than the reference wine, since they contain greater amounts of the components that are more closely associated with the specific characteristics of Muscat grape wine. When comparing the wines produced by the two freezing techniques applied in this study, liquid nitrogen freezing produced the wines with the most intense aromas and were the best valued by the tasting panel.  

 

The complete article is available for download in FRIDOC.

 

Sources 

Ruiz-Rodríguez, A.; Durán-Guerrero, E.; Natera, R.; Palma, M.; Barroso, C.G. Influence of Two Different Cryoextraction Procedures on the Quality of Wine Produced from Muscat Grapes. Foods 2020, 9, 1529. https://doi.org/10.3390/foods9111529