Hi George,

You don't even have to do the juicing right now if you don't want to.
I've actually frozen the grapes whole and then later juiced them and
made them into jelly. It worked beautifully. I've done the same with
the wild mustang grapes--same result. Here is an abstract from an
article that further explains that freezing the grapes whole for use
later actually increases yield of juice and color:

Juice Quality from Whole Muscadine Grapes Held in Frozen Storage
L. F. Flora 1

1 Department of Food Science, University of Georgia College of
Agriculture Experiment Stations, Georgia Station, Experiment, Georgia
30212.

"Juices were pressed from heated and unheated whole black (`Hunt') and
bronze muscadine grapes that had been held at -28 C for 9 months.
Quality factors of the juices were measured, and the juices were
submitted to panelists for acceptance ratings. Freezing apparently
increases juice yield and pigment content of the juices. The flavor
and color of the juices from frozen stored grapes were acceptable,
with no indications of off-flavors or excessive browning. Results
indicate that whole muscadines may be frozen for later processing into
juice, jelly, preserves, wine, and other products."

Accepted on March 11, 1976

I didn't download the entire article--it is a pay-to-play site but,
the above is enough for me to confirm my own findings.

Hope this helps.

: - )