depends on the food. Light can speed up the break down process of some organic compounds

For many foods light deteriorates as can air, oxygen, moisture, microbial growth, and temperature. Light and temperature damage food through discoloration and oxidation, the development of foul smells and changes in taste. Light is one of the major factors responsible for the deterioration of fresh and dehydrated produce. The exposure of foods to light can result in their photodegradation (or spoilage).. If their exposure to light and heat are controlled nutrient loss can be prevented. And it can also affect things such as pigments, fats, proteins, and vitamins and results in discoloration, off-flavor development, and vitamin losses. It can affect meat stored in light at the store, and even liquids can change when exposed to light.

yes and no...it can help and it can be harmful. depends on the food, the packaging etc

Did you ever wonder if the light effect how fast food will spoil? Almost all foods are exposed to light from natural or artificial sources during processing, packaging, storage, shipping, and marketing. Exposure of foods to light can result in its deterioration (also known as photodegration). Photodegration usually occurs in specific food constituents. Foods are exposed to several sources of light in their production display. Some common lights sources are sunlight outdoors, incandescent lamps, and fluorescent lamps. Incandescent lamps (regular light bulbs) have a metal filament that is heated to a glowing point. Fluorescent lights give off light when ultraviolet rays strike certain materials called phosors. These substances then give off visible light. Foods are also exposed to other sources of light, such as: germicidal lamps used to reduce bacterial and mold counts, and black lights used to detect contamination in foods. When light strikes a package of food, several things happen. The light is: reflected off the surface of the package, absorbed by the packaging material, scattered and absorbed by the food, and transmitted through the food. The light is absorbed by the food that can cause deterioration. In most of the solid foods, light only penetrates the outer layer and so deterioration occurs in this surface layer resulting in discoloration on the surface layer of the food source. In liquid foods, light penetration can be greater and with the mixing of food due to agitation, larger portions of food constituents may become deteriorated. Light induced changes in food usually begin in one of two ways: 1) light is absorbed by component in the product that will directly undergo chemical reaction or 2) one component in a food causes some other component to undergo reaction because of light. A large variety of foods can undergo changes in their color, flavor, and nutrient composition when exposed to light. The extent of these changes depends on many factors including the composition of the food and the light source. Not all types of natural or artificial light are equally absorbed or equally destructive. The effects.