Signs of Bad Quality in Grapes

Color

• When grapes are ripe and of good quality, they should be either blue, red or very light green. If the grapes are still dark green, they are not yet ripe. The variety consumers recognize as "green" grapes are categorized as white grapes. These grapes are ripe when they turn a light chartreuse (a subtle yellow-green). If a grape is brown or turning brown, it is either going bad or did not get the required nutrients while it was growing. Look for a uniform color across the grapes on the vine. If colors vary, then the grapes are getting an uneven amount of nutrients, which will lead to lower quality grapes.

Size

• There is no standard grape size. Size depends on grape variety, including whether it is seedless or not. However, size can be a good indicator of grape quality. Look for a standard size across all the grapes on the vine. If the grapes on the vine are vastly different sizes, the grapes are not getting an even amount of nutrients and will be a lower quality grape.

Firmness

• When grapes are growing, they are very firm. Look for grapes that are firm but give and spring back when touched. Check their quality by giving several grapes a very gentle squeeze. If the grapes are soft or have soft spots, then they are going bad. If grapes are still on the vine and getting soft, then they were not picked soon enough or they did not receive the proper amount of nutrients.

Taste

• At times, the color, taste and firmness can all indicate that a grape is good. In these cases, the only thing left to do is taste it. Even if grapes give all indications that they are good, the taste may prove otherwise. At times, grapes grow properly but do not come out sweet. When this happens, try letting the grapes ripen longer, but if they doesn't get sweeter, they didn't get all the required nutrients. When tasting, be sure to try a single grape. If possible, do not remove a bunch from the vine, because once grapes are removed from the vine, they cannot ripen any further.