Must (from the Latin vinum mustum, “young wine”) is freshly pressed fruit juice (usually grape juice) that contains the skins, seeds, and stems of the fruit. The solid portion of the must is called pomace; it typically makes up 7%–23% of the total weight of the must. Making must is the first step in winemaking. Because of its high glucose content, typically between 10 and 15%, must is also used as a sweetener in a variety of cuisines. Unlike commercially sold grape juice, which is filtered and pasteurized, must is thick with particulate matter, opaque, and comes in various shades of brown and/or purple.
The length of time that the pomace stays in the juice is critical for the final character of the wine. When the winemaker judges the time to be right, the juice is drained off the pomace, which is then pressed to extract the juice retained by the matrix. Yeast is added to the juice to begin the fermentation, while the pomace is often returned to the vineyard or orchard to be used as fertilizer. A portion of selected unfermented must may be kept as Süssreserve, to be added prior to bottling as a sweetening component. Some winemakers create a second batch of wine from the used pomace by adding a quantity of water equivalent to the juice removed, letting the mixture sit for 24 hours, and draining off the liquid. This wine may be used as a drink for the employees of the winemaker or as a basis for some pomace brandies. Grappa, however, by law, must be produced only from the pomace solids, with no water added.
For mead production 
In cookery 
Must was commonly used as a cooking ingredient in ancient Rome. It was boiled down in lead or bronze kettles into a milder concentrate called defrutum or a stronger concentrate called saba. It was often used as a souring agent and preservative, especially in fruit dishes. Reduced must is used in Balkan and Middle Eastern cookery, either as a syrup known as pekmez or dibis or as the basis for confections where it is thickened with flour: moustalevria, soutzoukos, churchkhela. Moustokoúloura ("must cookies") is a popular Greek variety of soda cookies or biscuits whose sweet dough is made by kneading flour, olive oil, and must. They are made in various shapes and sizes, and they are dark brown in color because of the must.
Roman lead poisoning theory 
Geochemist Jerome Nriagu published an article in the New England Journal of Medicine in 1983 hypothesizing that defrutum and saba may have contained enough lead acetate to be of danger to those who consumed them regularly. This theory has been thoroughly criticized by, among others, pharmacologist John Scarborough.
In Christian liturgy 
In Roman Catholic Eucharistic liturgy, must may be substituted for sacramental wine, on condition that the ordinary has granted permission for the benefit of a priest or lay person who should not, usually because of alcoholism, ingest wine; but in normal circumstances it may not be used in place of wine.
Official Roman Catholic documents define must (mustum in Latin) precisely as "grape juice that is either fresh or preserved by methods that suspend its fermentation without altering its nature (for example, freezing)," and it excludes pasteurized grape juice.
This teaching goes back at least to Pope Julius I (337–352), who is quoted in Thomas Aquinas's Summa Theologica as having declared that in case of necessity, but only then, juice pressed from a grape could be used. Aquinas himself declared that it is forbidden to offer fresh must in the chalice, because this is unbecoming owing to the impurity of the must; but he added that in case of necessity it may be done.
Aquinas himself declared:
- Must has already the species of wine, for its sweetness ["Aut dulcis musti Vulcano decoquit humorem"; Virgil, Georg. i, 295] indicates fermentation, which is "the result of its natural heat" (Meteor. iv); consequently this sacrament can be made from must. ... It is forbidden to offer must in the chalice, as soon as it has been squeezed from the grape, since this is unbecoming owing to the impurity of the must. But in case of necessity it may be done: for it is said by the same Pope Julius, in the passage quoted in the argument: "If necessary, let the grape be pressed into the chalice."
Liturgical norms 
- The Ordinary is competent to give permission for an individual priest or layperson to use mustum for the celebration of the Eucharist. Permission can be granted habitually, for as long as the situation that occasioned the granting of permission continues (e.g., the priest is an alcoholic).
- When the principal celebrant at a concelebration has permission to use mustum, a chalice of normal wine is to be prepared for the concelebrants.
- Given the centrality of the celebration of the Eucharist in the life of a priest, one must proceed with great caution before admitting to Holy Orders those candidates unable to ingest alcohol without serious harm.
- Attention should be paid to medical advances in the area of alcoholism and encouragement given to the production of unaltered mustum.
See also 
- Grout, James. "Lead Poisoning and Rome". University of Chicago. Archived from the original on July 22, 2011. Retrieved July 22, 2011.
- "Gluten Allergies/Alcohol Intolerance and the Bread and Wine used at Mass", circular letter Prot. 89/78-174 98 of 24 July 2003, Congregation for the Doctrine of the Faith, to Presidents of Episcopal Conferences.
- "The Use of Mustum and Low-Gluten Hosts at Mass". United States Conference of Catholic Bishops. November 2003. Retrieved 2008-08-05.
- Summa Theologica, III, q. 74, art. 5, reply to objection 3.
- Summa Theologica, III, q. 74, art. 5, reply to objection 3
Further reading 
- Baldy, Marian W. The University Wine Course: A Wine Appreciation Text & Self Tutorial, 2nd Edition. San Francisco, Calif.: The Wine Appreciation Guild, 1995. ISBN 0-932664-69-5.
- Gozzini Giacosa, Ilaria. A Taste of Ancient Rome. Chicago: University of Chicago Press, 1994. ISBN 0-226-29032-8.
- Herbst, Ron, and Sharon Tyler Herbst. Wine Lover's Companion. Hauppauge, N.Y.: Barron's, 1995. ISBN 0-8120-1479-0.
- Nriagu, Jerome O. "Saturnine Gout Among Roman Aristocrats: Did Lead Poisoning Contribute to the Fall of the Empire?" New England Journal of Medicine 11, no. 308 (17 March 1983): 660–3.
- Whittaker, John. Winemaking Made Easy. Edmonton: Lone Pine Publishing, 1993. ISBN 1-55105-030-7.
- Further information from the USCCB's Committee on Divine Worship
- Further information from the Liturgy Office of the Catholic Bishops' Conference of England and Wales