Effects of gamma irradiation on chemical and sensory characteristics of natural hazelnut kernels

• Published in: Postharvest biology and technology Vol. 123; pp. 12 - 21
• Main Authors: Koç Güler, Saadet, Bostan, Saim Zeki, Çon, Ahmet Hilmi
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2017; Elsevier BV
• Subjects: Cellulose; Chemical characteristics; Fatty acids; Food; Food safety; Gamma irradiation; Gamma rays; Hazelnut; Hazelnuts; Humidity; Hydrogen peroxide; Irradiation; Kernels; Moisture content; Nuts; Peroxide; Relative humidity; Sensory characteristics; Sensory evaluation; Sensory properties; Storage; Studies; Tocopherol; Vitamin E; Water activity; Gamma irradiation; Storage; Sensory characteristics; Hazelnut; Chemical characteristics
• ISSN: 0925-5214; 1873-2356
• DOI: 10.1016/j.postharvbio.2016.08.007

•Hazelnut kernels were treated with 0, 0.5, 1 and 1.5kGy of gamma irradiation.•Examine chemical and sensory changes in irradiated hazelnuts.•Contribute to broaden the use of this technology in food stuff.•Optimal irradiation dose of 0.5kGy for hazelnut kernel was obtained. In present study, natural hazelnut kernels were treated with, 0.5, 1 and 1.5kGy of gamma irradiation. The irradiated and untreated hazelnuts were stored at 20±0.5°C and 55–60% relative humidity for 18m. After irradiation, 0.5, 1 and 1.5kGy doses of gamma irradiation significantly increased the total fat values (p<0.05) and this value decreased during the storage. After treatment, free fatty acid values were similar in untreated and treated hazelnuts. After 6m of storage, irradiated and untreated hazelnuts had less than 1% free fatty acid values. However, control and 1.5kGy yielded higher than 1% free fatty acid after 9m of storage. After irradiation, peroxide values increased proportionally to the dose but the increase was not significant. Peroxide values increased during the storage period (p<0.05). Control and 0.5kGy-treated hazelnuts had maximum peroxide values after 9m of storage, while 1kGy and 1.5kGy-treated hazelnuts had maximum levels after 12m of storage. Applied doses did not cause any significant changes in crude protein, water activity (aw), crude cellulose and moisture content of hazelnuts (p>0.05). Storage period significantly affected the water activity and crude cellulose (p<0.05). Irradiation doses didn’t affect the L*, a* and b* values (p>0.05), but storage period significantly affected the color values (p<0.05). At the end of storage period, L* and vitamin E values decreased proportionally to the dose. The 0.5kGy-treated hazelnuts had the lowest free fatty acid and peroxide values and such a case also reflected in sensory analyses. Furthermore, these hazelnuts had the highest vitamin E value after the control group. Application of 0.5kGy gamma irradiation seems to be acceptable for natural hazelnut kernels, but food safety issues have to be evaluated in order to recommend its application as a useful conservation alternative.