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Barcelona, Daviana, and Ennis varieties of hazelnuts were sampled in commercial orchards between Cotvallis and Portland for incidence of kernel white mold. What was thought to be storage mold actually occurred on the trees even when the nuts were in early development. There were significant differences between the three years. Mold incidence was highest in 1986, and lower in 1987 and 1988. There were some differences in mold percent between the samples from tree and ground. Ramularia was the only species of fungus that was identified in all samples and was found at high percentages. No incidence of any Aspergillus species were found. Temperatures for drying and storage had no effect on mold percentage nor did number of nuts per cluster.
Kernels in the shell were compared to bare kernels with pellicles, half nuts, blanched nuts, finely chopped nuts, and roasted nuts. Whole nuts and whole kernels were stable for up to two years of storage provided they had not been exposed to high temperatures. Nuts stored at low temperatures (0 and 5°C) did not lose significant amounts of vitamin E. Increasing surface area by dividing nuts or finely chopping them, increased the loss of vitamin E. Samples that had lower surface areas did not lose much vitamin E and peroxide value was low. Higher roasting temperatures caused losses in vitamin E and increased peroxide values at the beginning and during storage, even when stored at 0°C. Intact nuts and low storage temperatures did not show changes in fatty acid composition. High temperature treatments changed fatty acid composition, mainly decreasing linoleic initially and finally oleic acids.