Abstract:

The time-course of lipid oxidation determined by peroxide value and acid value, and the sensory quality of walnut (Carya cathayensis Sarg.) stored at different temperatures (2, 12, 22, 32 ℃) were evaluated, and the separate kinetic models of peroxide value and acid value with respect to storage time at different storage temperatures were established based on Arrhenius equation, so as to predict and control the quality of walnut during storage. Results indicated that peroxide value and acid value increased with prolonged storage time and increasing storage temperature resulted in a prompt increase in both the values. The sensory quality of walnut decreased with prolonged storage time and dropped promptly with increasing storage temperature. Changes in the peroxide value and acid value of walnut perfectly followed first order reaction model and Arrhenius equation (R2 ＞0.9). The predicted storage life had a relative error within ±10% when compared with the experimental results. In conclusion, the storage-life of walnut stored at temperatures ranging from 2 to 32 ℃ can be predicted according to its peroxides value and acid value.

Key words: walnut, kinetic models, oxidative rancidity, sensory evaluation, storage period