Effect of γ-irradiation on the physicochemical and sensory properties of walnuts (Juglans regia L.)
2009
Mexis, Stamatios F. | Kontominas, Michael G.
The present study evaluated physicochemical and sensory quality parameters of walnuts as a function of irradiation dose in order to determine dose levels causing minimal undesirable changes to walnuts. Physicochemical parameters including peroxide value (PV), hexanal content, fatty acid composition, volatile compounds and sensory parameters including color, texture, odor and taste were determined for unirradiated and irradiated walnuts at radiation doses of 1.0, 1.5, 3.0, 5.0 and 7.0 kGy. PV increased from 1.1 to 3.0 meq O₂/kg walnut oil while the hexanal content increased from 3.80 to 34.3 mg/kg walnut after irradiation at a dose of 7.0 kGy. Of the fatty acids determined, stearic and palmitic acids concentration increased while oleic acid decreased with irradiation dose. Polyunsaturated fatty acids were unaffected by irradiation. Volatile compounds such as aldehydes, ketones, alcohols and hydrocarbons increased after irradiation indicating enhanced lipid oxidation. Color parameter L*, a* and b* remained unaffected by irradiation. Sensory analysis showed that taste was the most sensitive of all sensory attributes for the evaluation of walnut quality. Based on taste and odor scores, walnuts remained organoleptically acceptable at doses <=3.0 kGy.
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