Extraction of polyphenols during red winemaking is fundamental to obtain high quality red wines. Polyphenols are responsible for the colour, taste and aging properties of wine and contribute to the health effects attributed to moderate consumption. Pulsed electric field (PEF) is a low-energetic and environmental-friendly way to improve the extraction of polyphenols during vinification.
During traditional red winemaking, fermentation of the grape juice occurs together with the grape skins. In this step called maceration-fermentation step, yeasts convert the sugars of the juice into ethanol while polyphenolic compounds are extracted from the grape skin. This polyphenolic extraction has a big influence on red winemaking process and the wine quality.
Traditionally, there are two ways to obtain wines with a high phenolic content. One is to extend the maceration time for 2-3 weeks, instead of 1-2 weeks that are needed for fermentation. Another way is to increase the fermentation temperature, which speeds up the process of polyphenolic extraction.
However, some problems have been identified when these enological practices are used. Longer maceration time reduces the production capacity of the wineries or requires more fermentation tanks. Fermentation at higher temperature may cause loss of flavour, requires high energy and water consumption and there is a risk the fermentation process stops.
Winemaking with PEF
PEF technology permits to obtain the same objective with very low energy requirements and processing cost. PEF is a physical non-thermal method that induces the formation of pores in the cell envelopes of plant tissues. These pores accelerate and increase the extraction of phenolic compounds during maceration-fermentation.
Within the FieldFOOD project, PEF technology has been demonstrated and validated in a winery, producing wine from Grenache grapes treated by PEF with 3 days of maceration. At the end of the fermentation step, the PEF wine had the same colour and content of polyphenols as the control wine that was obtained after 6 days of maceration in a traditional process. After 6 months aging of the wines in bottles or oak barrels, the colour and polyphenol content remained, while the concentration of molecules related with fruity flavour notes was higher in the PEF wine.
PEF treatment can be applied in continuous operability and the implementation of the process in the processing lines of the wineries is very easy. The pulse power systems that has been developed recently for the food industry covers processing requirements ranging from a small winery (10 tn/h) to a big winery (50 tn/h) and the total costs, including both treatment and investment, are estimated between 0.03-0.005 €/L of wine respectively.
Other PEF applications
PEF minimizes quality deterioration of food compounds. Between other effects, PEF enhances different operations of the food industry such as the extraction of compounds located inside the cells. Currently, PEF has become an industrial reality for preservation of fruit juices or potato processing, but it is expected that new applications will emerge in the near future as consequence of the potential benefits that this technology has in the processing of many different foods.
Within the FieldFOOD project, PEF technology was tested and validated for five applications: olive oil, fruit juices, tomato peeling, cider and red wine. Benefits derived from the introduction of the PEF technology depended strongly on the specific application. Modular, portable, low cost PEF modulators developed during the project allow companies to evaluate this technology in the above-mentioned sectors or for new applications. For more information visit the FielFOOD website or contact the project coordinator Javier Raso.
FieldFOOD an EU funded initiative
FieldFOOD stands for: Innovative food processing technologies.
For whom: Food processors of plant based food such as Wineries, Olive oil companies, Tomato products companies, Fruit juices companies and Cidery.
Objective: Provide innovative solutions to overcome existing bottlenecks that prevent the implementation of Pulsed Electric Fields (PEF) in the food industry.
Reason: Effects deriving from PEF processing are very attractive to the food industry in order to improve food quality and process efficiency, reduce energy inputs and enhance eco-friendly processes.
How: By conducting a systematic process analysis of the processing lines of the different companies for a successful integration of the PEF technology in order to replace or complement the existing processing and by designing modular portable low-cost pulse generators to be install in the processing plant of the companies involved in the project.
Areas of interest: Food processing, Equipment manufacturing, Food safety, food quality, sustainability.
When: From April 2015 to April 2018.
Funded by: European Commission (635632-FieldFOOD-H2020).
Partners: Research institutions with well-established expertise in PEF technology: University of Zaragoza (Spain), Technical University of Berlin (Germany) ProdAl scarl (Italy), University college of Dublin (Ireland). Manufacturer of PEF generator: Energy Pulse Systems (Portugal). , End-users of the technology: Bodegas Aragonesas (Spain), Agrinarsa (Spain), F.D.D-Industria conserve Alimentari (Italy), Diesdorfer (Germany) , The Apple farm (Ireland). Promoters of technological transfer: EFFOST (Netherlands). Expert on evaluation of food process sustainability: CIRCE (Spain).
Coordination: Javier Raso. University of Zaragoza (Spain).