Rancidity and Shelf Life

While there is much to recommend the use of nuts in confectionery, they are not without their challenges. Expense is a consideration for any professional, and nuts are among the most expensive ingredients a confectioner uses. Nuts also present shelf-life concerns, not through moisture content or water activity but through the instability of the fats they contain. Nut oils are susceptible to rancidity from a variety of causes, so handling, storage, and freshness are prime concerns when dealing with products that contain nuts. Factors contributing to rancidity include enzymatic action and exposure to heat, oxygen, light, and the metals used in processing. Nuts placed on the surface of a confection are more susceptible to rancidity than those that are enrobed. This is due to their exposure to oxygen. For the same reason, the more finely nuts are chopped or ground, the more likely it is they will become rancid. Further, toasted nuts will always become rancid more readily than unroasted ones, due to the breakdown of fatty acids during roasting. Nuts should be purchased in small quantities that allow for quick product turnover and should be stored tightly sealed in a cool, dry environment to retard the onset of rancidity. All nut products should be tasted prior to use to ensure their freshness and should be rejected if rancid flavors are detected. Toast nuts close to the time they are to be used in order to avoid the off flavors brought on by rancidity.