Feeding Hamsters Grapes and raisins

Grapes and raisins are one and the same fruit; raisins are just simply dried grapes. Raisins are rich in nutrition and extremely high in calories and are a good source of iron and potassium. They also contain a large amount of vitamin A and some vitamin B. Sulphur dioxide is a colorless and toxic gas used as a preservative and in the drying process of most dried fruits. It is also used as a preservative in alcoholic drinks. Unless you have a hamster that regularly hit's the bottle you shouldn't have a problem with it. Sulphur dioxide is used in the drying process of apricots, sultanas, raisins and many other fruits. Although the drying process destroys most of the Vitamin C. This preservative is used to maintain the appearance of the fruit rather than to prevent it from decaying.

Raisins also have very high natural sugar content, the natural sugar being fructose, which is 60% by weight
Grapes and raisins are generally not considered to be harmful to hamsters. But here are a few points to consider before feeding this fruit to any of your pets as no one knows for sure yet if they are affected by them. Grape and raisin toxicity in dogs is already well documented, and is still as yet relatively new ground. The consumption of grapes and raisins are known to present a potential health threat to dogs. The toxicity of this fruit in dogs can cause the animal to develop acute renal failure, and as little as 7 grapes or raisins can damage the animal’s kidneys. No one knows for sure why this fruit is toxic to dogs, and if only certain breeds of dogs may be affected by them. It is still not known if this fruit poses a potential health hazard only to dogs or if other animals may be affected by them.

Grapes in their fresh or dry form are known to cause the animal to develop acute renal failure (Kidney failure) A problem that affects the kidneys ability to function adequately. It may be acute which is a sudden appearance, or chronic, meaning the symptoms can appear over a period of time.
Most animal centers now advise that grapes and raisins should not be fed to any animal until the toxic substance has been identified.
Mycotoxins are thought to be involved. Mycotoxins are toxic compounds produced by fungi that contaminate plants; mycotoxins are not destroyed by cooking, freezing or drying.