The first question that needs to be answered is whether our wines are made
differently from our non-kosher counterparts? The answer is absolutely
not. Our basic ingredient, grapes, are the same the world over. Basic
practices in both kosher and non-kosher wineries are the same, the
grapes need to be harvested, crushed, fermented, aged, filtered and
bottled. Kosher wines use kosher products for these processes whereas
non-kosher wines do not necessarily.

Wine is made from grape juice to which yeast has been added and allowed
to ferment. The resulting wine is cloudy and would be quickly rejected
by the average consumer if it was not treated any further. The
winemaker has a number of tools for dealing with this, including the
use of filtration and the use of additional fining agents.

Fining agents are compounds that are used to help improve the clarity
of the wine and also to remove overt bitterness. Commonly used fining
agents are a clay-like substance called bentonite, a polymer called
PVPP and egg whites (often used in red wines). Some winemakers may use
compounds such as isinglass (a fish derivative), casein (a dairy
compound) or gelatin (an animal byproduct). These latter two products
will severely compromise the kashrut of the wine. Dalton uses only
strictly supervised kosher products and certainly no diary products. By
the way, kosher wines are not necessarily suitable for vegetarians and
vegans.

Secondly, the production of kosher wine must be carried out in a
Halachically correct manner (ie. in accordance with Jewish laws): This
is more of an issue for wines from Israel as there are many laws
pertaining to the upkeep of vineyards such as orla and the sabbatical
year (shmitta) and the giving of tithes (maaserot and trumot), which
must be respected. For example a vineyard belonging to a Jew in Israel
may not be harvested in its first three years (orla), the fruit may
only be taken from the fourth year.

Finally and probably the most complex issue is as follows: there is the
fear that wine bound for sanctification in a Jewish ceremony will have
been used in some non-Jewish rite or ritual beforehand. To this end the
Rabbis specify that only observant Jews may be involved in the
production of kosher wine thus ensuring the religious integrity of the
wine for its use in Jewish ritual.

To further ensure this religious integrity, many wines undergo the
mevushal (cooking) process where the wines are flash pasteurised to
around 90º C or 200º F. Contrary to popular opinion, you can not make a
non-kosher wine kosher by pasteurising it and a kosher wine does not
become more kosher after pastuerisation. However, it does make the wine
unfit for non-Jewish ritual, and as a result the rabbis permit its use
in environments where non-Jews come into contact with kosher wines,
such as restaurants and catering halls. Mevushal wines will usually be
marked as such.

I will address the question as to whether there is a difference in
quality between mevushal and non-mevushal wines in a different post.

For the sake of good order, the supervising Rabbis for Dalton are
Rabbi Almishali of Merom Hagalil (our local Rabbi) Rabbi Machpud of the
Badatz Yoreh Deyah (He is from Bnei Brak and has been with us since the
winery was established), the Union of Orthodox Congregations (OU) we
took them because at the time no one in the US knew who Rabbi Machpud
was, they do now, and finally Rabbi Mordechai Ungar, he is a really
nice Rabbi from New Square New York who brings us added credibility
with the ultra orthodox communities, a segment of the market for whom
the supervising rabbi is often more important than the contents of the
bottle.