The shelf life of chocolate depends on a variety of factors such as the type of chocolate (dark, milk or white), the type of packaging and the storage conditions. Key factors to take into account are taste, texture and appearance.
In chocolate, the water activity (the amount of free water in a product which promotes microbial growth in the food) is low and ranges between 0.3 and 0.4. Consequently, the risk of microbiological growth in chocolate is very low. Only Salmonella can pose a risk in cocoa ingredients and in milk powders, which is why every delivery at Puratos is carefully checked before being used in production.
Real dark chocolate, made with cocoa butter, has a very long shelf life; when stored in dry, cool conditions away from heat and sunlight, it can last for many years. Cocoa butter is a very stable fat and once chocolate is fully crystallised, it can resist bloom fairly well. Furthermore, the flavonoids in cocoa mass help to prevent oxidation. However, if fat bloom appears, dark chocolate becomes less visually attractive. This change in appearance often occurs together with a hardening in texture and a slower melting, which is caused by changes in the fat crystallisation. Note that even though fat bloom appears unattractive, the chocolate can still be used in recipes or melted down and re-tempered. Stored in the right conditions dark chocolate has a shelf life of 2 years.
Real milk chocolate, which also contains milk solids and milk fat, will not last as long as real dark chocolate. However, it still has a long shelf life when stored under proper (cool, dry) conditions. The main reason milk chocolate has a shorter shelf life is because milk fat oxidizes and goes rancid faster than cocoa butter. Shelf life is 1 year in this case.
White chocolate consists of sugar, milk solids, milk fat and cocoa butter. Because of its lack of cocoa mass and therefore natural antioxidants, white chocolate oxidizes and goes rancid comparatively easily, especially when exposed to light. This type of chocolate has the lowest shelf life in comparison with dark and milk chocolate. Shelf life being 6 months.
Because light and air cause chocolate to oxidise, good packaging is key to preventing light, air and moisture exposure.
It is best to store chocolate in a clean environment away from any foreign odours at temperatures of max 20°C and at a low relative humidity (max 60% relative humidity). Excessively high temperatures can result in fat bloom, while excessive humidity can cause sugar bloom.