Effects of different roasting conditions on physical-chemical properties of Polish hazelnuts (Corylus avellana L. var. Katalonski)

The influence of different roasting conditions on the physical-chemical (water activity, moisture, colour, volatile compounds, tocopherols, phenolic content) properties of Polish hazelnuts (cv. Katalonski) was determined. Nuts were roasted at specific temperature/time conditions: 130\ub0C/40\ua0min, 130\ub0C/50\ua0min, 130\ub0C/60\ua0min, 160\ub0C/20\ua0min, 160\ub0C/25\ua0min, 160\ub0C/30\ua0min. Hazelnuts roasted at 160\ub0C showed a darker colour and a lower water activity and moisture than samples roasted at 130\ub0C. Compared to raw hazelnuts, the phenolic content increased in all roasted samples, although with a more concentration in nuts roasted at 160\ub0C (2998.84\ua0mg/100\ua0g, 3429.52\ua0mg/100\ua0g and 2927.81\ua0mg/100\ua0g after 20, 25 and 30\ua0min, respectively). The different roasting conditions led to several aroma modifications, in fact in raw hazelnuts were identified just only 22 compounds, whereas in samples roasted at 130\ub0C and 160\ub0C were found 79 and 102 volatile compounds, respectively

Changes of the lipid fraction during fruit development in hazelnuts (Corylus avellana L.) grown in Poland

Detailed changes in composition of fatty acids, as well as alterations in the content of triacylglycerols and tocopherols during the maturation of Katalo\u144ski hazelnuts grown in Jankowice, Poland were studied. Samples with different maturity levels were collected at weekly intervals between August and September 2013. Nineteen different fatty acids were identified. The amount of oleic acid (n9) was the greatest in all samples, the amount of linoleic acid (n6) acid was second greatest, while the amount of palmitic acid was third greatest in all samples, except during the very first stage of maturation. A decreasing trend in the amount of polyunsaturated fatty acids (PUFA) was observed from early developed to completely maturated hazelnuts (from 30.09 to 10.28g 100g-1 of oil). On the other hand, the amount of monounsaturated fatty acids (MUFA) in hazelnuts increased from early to harvest stage (from 22.03 to 79.17g 100g-1 of oil). Linoleic acid and oleic acid were the most abundant fatty acids located in sn-2 position of triacylglycerols. Different distributions of both acids were reported during maturation. Oleic acid reported a constant distribution in an internal position, whereas linoleic acid content in sn-2 position increased during maturation. Finally, the tocopherol content increased from early to harvest stage and the amount of \u3b1-tocopherol was observed to be the highest among tocols