This tasting was all about kosher wines, and in particular Mevushal Wines. Here is a brief synopsis of what I talked about at the tasting.
In short, for wine to be considered Kosher the entire winemaking process from crushing to bottling must be handled by Sabbath-observant Jews and no non-kosher finings or additives may be included.
Wine needs to be made with only Kosher ingredients. Grapes, of course, are always Kosher in their natural state, but as with all Kosher law, production is complicated and any finings or additives must be Kosher.
In Kosher winemaking, ruling out complicated agents of isinglass, gelatin, and casein, the most commonly-used agent is bentonite, though egg whites may be used in smaller productions outside the U.S.
Wine that is described as “kosher for Passover” must have been kept free from contact with chametz and kitnios. This would include grain, bread, and dough as well as legumes and corn derivatives.
Picking up a bottle of kosher wine, you might notice the term “mevushal,” or “non-mevushal” branded next to the kosher symbol. Translated literally, mevushal means “cooked.” In reality, and in most situations, this now means that the wine undergoes flash-pasteurization or flash détente, whereby the grape must is heated for a short period of time to a high temperature.
When kosher wine is mevushal it thereby becomes unfit for idolatrous use and will keep the status of kosher wine even if subsequently touched by an idolater.
The mevushal process allows the wine to be handled by anyone. Otherwise, from when the grapes are first crushed, until when the wine is bottled and sealed, non-mevushal wine may only be touched by Sabbath-observant Jews to be considered kosher. Separately, but equally, a bottle of non-mevushal wine may only be opened and poured by a Sabbath-observant Jew, as well. The mevushal process allows the wine to be handled freely by anyone, a condition that greatly simplifies wine usage commercially. Thus, the need for mevushal wine in America is prevalent.
Link to Google Slides https://docs.google.com/presentation/d/1kk6gFHAVkO0ky0CKLdwlXXoSrzJVv4eKhuOjv4RwwG8/edit?usp=sharing
Great Article Discussing Kosher wines and Mevushal Wine in greater detail: https://www.chabad.org/library/article_cdo/aid/4283691/jewish/Mevushal-Keeping-Kosher-Wine-Kosher.htm