Concord and Niagara grapes, American hybrids, are more perishable than the Europen-type grapes sold through grocery stores year round. Concord and Niagara grape skins are much softer. They need to be handled with care to keep skins from splitting. We do our best during harvest to pick and handle the grapes with care. They are moved to cold storage here on the farm as soon as they are picked. It is important that they be refrigerated if planning to keep them for a while. We’ve found that placing them in a sealed container in the refrigerator keeps them fresh longer than simply putting them in a bowl. They keep well for several weeks.
We advise using the grapes fairly quickly after purchase. If one plans to work them up for jam, juice, wine, or to be eaten in a day or two, they can be kept safely in a cool dry area un-refrigerated; but, refrigeration is best.
The Concord and the Niagara varieties of grapes are both North American in origin, as opposed to the Europen varieties of grapes typically sold year-round in grocery stores. Concords are blue in color, and do not have a reddish glow in the sunlight when ripe. Niagaras are “white grapes” and are more light green-yellow in color. It is a bit more difficult to tell when a Niagara berry is ripe. The berries actually turn from a green shade to a somewhat yellow color when ripe. The amount of sugar in the Concord and Niagara berries continues to rise over the month of September. Both varieties are very delicious to eat, great for making juice, jams, and jellies, and for making wine. Each variety has a unique flavor of its own. It’s all a matter of taste as to which variety is your favorite.
Concord and Niagara grapes have what is called a slip skin, and offer a unique eating experience totally independent of Europen-type grocery store grapes. The usual way of eating this type of grape is to hold a single berry with your fingers, squeeze the berry firmly into your mouth to get all the juice, and swallow the pulp whole, including the seeds, and then throw away the skin. The pulp and skins are more acidic if chewed, however the skins are rich in antioxidants and very nutritious if eaten. Alternatively, chew the whole grape, including the skin, and sieve out the seeds with the teeth and tongue. Or for every last bit of nutrition and fiber, crunch the seeds to get the grape seed oils. Whatever your favorite method, be sure to introduce a friend to this eating experience!
The answer is simply “No.” Once the bunch is picked from the vine, the grapes do not continue to ripen.