Evaluation of Nebraska hybrid hazelnuts: Nut/kernel characteristics, kernel proximate composition, and oil and protein properties

Recently, hybrid hazelnuts have emerged as a potential oilseed crop in Nebraska for food and value-added industrial applications. The quality of 20 hybrid hazelnuts genotypes harvested in 2007 and 2008 years were investigated, in terms of physical properties of nuts/kernels, kernels proximate composition, oil properties and amino acid profiles of the meal. Nebraska hybrid hazelnuts appeared to be smaller in size and lighter in weight compared to Turkish hazelnuts. Oil was the predominate component in the kernel with an overall average oil content of 58.2%, followed by 21.7% carbohydrate, and 17.1% protein. Genotype 10-50 was superior to the other genotypes and should be selected for further study, when combining large size and weight, kernel percentage, stable physical properties and oil contents over years. Oleic and linoleic acids were the major fatty acids in the oils and comprised more than 90% of the fatty acids. Oils had an average saponification number of 174.1 mg KOH/g oil, iodine value of 89.8 g I2/100 g oil and free fatty acid content of 0.45 mg KOH/g oil. Sixteen amino acids were identified. Seven essential amino acids were detected, and accounted for approximately 27% of the of total amino acid contents. The effect of harvest year on the quality of nuts was significant (p < 0.05). The average size and weight of the hazelnuts harvested in 2008 were significantly (p < 0.05) smaller and lighter than their counterparts in 2007. Nuts harvested in 2007 had marginally higher oil contents, palmitic, stearic, oleic and linolenic acids, saponification value, free fatty acid content, and lower protein, ash and carbohydrate contents than those harvested in 2008.