Pomace (pronounced /PUHM-is/) is the solid remains of grapes, olives, or other fruit after pressing for juice or oil. It contains the skins, pulp, seeds, and stems of the fruit.
Grape pomace has traditionally been used to produce pomace brandy (such as grappa) and grapeseed oil. Today, it is most mostly used as fodder or fertilizer.
Oenocyanin, a natural red dye and food coloring agent, is produced from grape pomace. Some companies also recover tartrates (cream of tartar) and grape polyphenols from grape pomace.
“Pomace” is derived from the Latin
“pomum” (apple). The English
were the first to use the term “pomace” to refer to the byproduct of cider
In the Middle Ages, pomace wines with a low alcohol content of three or four percent were widely available. These faux wines were made by adding water to pomace and then fermenting it. Generally, medieval wines were not fermented to dryness; consequently the pomace would retain a small amount of fermentable sugar.
The Ancient Greeks
would use pomace to create a wine later known as piquette
. This was a low-end wine that was normally given to slaves
and common workers. After the wine grapes were pressed twice, the pomace was soaked in water for a day and pressed for a third time. The resulting liquid was mixed with more water to produce a thin, tepid wine that was not very appealing.
Wines & brandies
Apple pomace is often used to produce pectin
, or can be used to make Ciderkin
, a weak cider. While grape pomace is used to produce pomace wine and pomace brandy
, such as grappa
(in Italy), marc
(in France), zivania
(in Cyprus), lozovača
(in Croatia), Raki
(in Turkey and Albania), Orujo
(in Spain), Tsikoudia
(in Crete), Tsipouro
in northern Greece or bagaço
(in Portugal). There are many other local names and variants such as the English "press cake
". Essentially all wine producing cultures started making some form of pomace brandy once the principles of distillation
The components of pomace in winemaking
differs on whether white or red wine is being produced. In red wine production, pomace is produced after the free run juice (the juice created before pressing by the weight of gravity
) is poured off, leaving behind dark blackish-red debris consisting of grape skins, stems, as well as dead yeast
cells. The color of red wine is derived from skin contact during the maceration
period which can sometime include partial fermentation. The resulting pomace is more alcoholic and tannic
than pomace produced from white wine production. In white wine production, the grapes are quickly pressed after crushing in order to avoid skin contact with pomace being a by product of the pressing. The resulting debris is a pale, greenish-brown color and contains more residual sugars
than tannins & alcohol. This is the pomace normally used in brandy production.
Pomace is produced in large qualities in wine production with the issue of disposal being an important environmental consideration. Some wineries will reuse the material as fertilizer while others are exploring options of selling the used pomace to biogas
companies to be used in the creation of renewable energy
. As envisioned, pomace would be introduced into anaerobic digesters
that contain microorganisms
that aid in its decomposition
and produce methane
gas that can be combusted to generate power. However, to make this potential use commercially viable, more research is needed to find methods for improving the digestibility of pomace.
Studies have also shown that specific polyphenols in red wine pomace, may contain properties beneficial for dental hygiene. The study conducted at the Eastman Dental Center found that these polyphenols interferes with Streptococcus mutans, the bacteria in the mouth which causes tooth decay. Professor Hyun Koo, the lead researcher of the study, hopes to isolate these polyphenols to produce new mouthwashes that will help protect against cavities.
A 2004 Turkish study conducted by Erciyes University found that pomace can also act as a natural food preservative that could interfere with Escherichia coli, Salmonella and Staphylococcus bacterias. Scientist used the dried pomace from the white Turkish wine grape Emir Karasi and red Kalecik Karasi to produce a powder that was mixed ethyl acetate, methanol or water and exposed to 14 different types of food bacteria. The results showed that all 14 bacterias were inhibited to some degree by the pomace-depending on the grape variety and the concentration of the extract. The red wine grape Kalecik Karasi was shown to be the most effective due to what the study researchers believe is the higher concentration of polyphenols in red wine grape skins.