The Effect of Kernel Size on Bioactive Compounds in Kalınkara Hazelnut Cultivar

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Objective: This study was carried out to determine the effect of kernel size on the change of bioactive compounds in Kalınkara hazelnut cultivar. Materials and Methods: This study was conducted on the Kalınkara hazelnut cultivar grown in a producer's orchard in Ulubey (Ordu) district. The study was designed according to the randomized plot design with three replications and three ocak in each replication. Harvested nuts were classified according to kernel size as “small”, “medium” and “large”. Then, total phenolics, total flavonoids, and antioxidant activity were determined. In addition, correlation coefficients were calculated, and principal component analyses were performed to determine the relationships between the examined features. Results: In the study, it was observed that kernel size was effective on bioactive compounds in Kalınkara hazelnut cultivar. According to the research findings, the total phenolics was determined between 759 mg 100 g-1 (medium) and 819 mg 100 g-1 (large), the total flavonoids was determined between 8.2 mg 100 g-1 (medium) and 8.7 mg 100 g-1 (small), and total antioxidant activity was determined between 0.46 mmol 100 g-1 (medium) and 0.60 mmol 100 g-1 (large) according to the FRAP assay, while it was determined between 1.83 mmol 100 g-1 (medium) and 1.92 mmol 100 g-1 (small) according to the DPPH assay. In addition, a positive correlation was determined between the total phenolics and antioxidant activity. Accordingly, while the correlation coefficient between total phenolics and DPPH assay was r=0.921***, it was r=0.982*** with FRAP assay. Conclusion: As a result of the research, it was determined that the total flavonoids, and antioxidant activity according to the DPPH test were higher in small kernels. In comparison, total phenolics, and antioxidant activity according to the FRAP assay were higher in large kernels.