The four primary characteristics of hazelnuts are flavor, fatty acids, moisture, and water activity. Understanding these four factors will help you get the most out of your hazelnuts.
The typical mild flavor of hazelnuts is found in the carbohydrate fraction, rather than in the kernel fat. As a result, the flavor is more easily extracted and concentrated. Volatile flavors are developed upon roasting, chopping or grinding. Hazelnuts are very compatible with a wide variety of foods and flavors.
Hazelnuts are very low in saturated fats (7% of the total fat). Mono-unsaturated fats, such as oleic acid, make up about 82% of the total fat content. The remainder is polyunsaturated fat, such as linoleic acid.
Moisture and Water Activity
Raw hazelnuts contain between 4 and 6% moisture, while roasted or baked contain about 2-3%. While moisture absorption in finished products is small, the crisp texture can be maintained by coating with sugar, chocolate, fat or edible shellacs and waxes. Hazelnuts have a water activity (aw) of about .46 to .49 at sale point.
The Food and Drug Administration has established 0.70 at 25C as a safe water activity level. Low moisture and high vitamin E levels contribute resistance to oxidation and development of off flavors.
Low water activity and low moisture promote bacteriological and texture stability.