CHANGES IN OIL CONTENT, FATTY ACID, AND VITAMIN E COMPOSITION IN DEVELOPING HAZELNUT KERNELS.

Samples were collected from seven different hazelnutvarieties: Barcelona, Ennis, Daviana, Tonda Romana, Tonda Gentile delle Langhe, Tombul, and Tombul Ghiaghli. Hazelnuts exhibit a sigmoidal development pattern and there were two important periods in nut development. The period of growth and enlargement of the shell and the period of filling of the nut by the kernel which begins at the time of shell hardening.

Kernel oil content increased while moisture content decreased during development. Oil concentration was between 59.6% and 67%, at harvest and the major lipid class was triglycerides. The fatty acids comprising the triglycerides showed some interesting seasonal patterns. Oleic acid increased from 10% to become the most abundant fatty acid at harvest (74%). Linolenic acid content was high (up to 40%) at the beginning of growth but then decreased to about 1% by the end of the season. Linoleic increased from about 4% to around 30% early in the season but then decreased although it finally represented a high proportion of total fatty acids (between 19–22%).

Total vitamin E increased as oil content increased. -tocopherol was the major form of vitamin E and its concentration increased to around 400μg/g oil throughout the season and was almost 95% of total vitamin E. -tocopherol was high at the beginning and decreased until there was none. -tocopherol was only a minor constituent and decreased from the beginning to around 10–20 μg/gm of oil at the end. -tocopherol increased during the first stage of growth and then decreased during the second and third stages. The amount of -tocopherol differed among the cultivars. The pattern of -tocopherol synthesis implies progressive methylation during development.