Abstract:

Stir-frying in which oil-stirring procedure is of great importance is one of the most specific Chinese cooking techniques. Traditionally, oil-stirring procedure is accomplished manually. Empirical manual operation, however, cannot accurately control oil temperature, materials/oil ratio and dispersion degree of materials. Automatic stirrer was adopted instead of manual operation in the present study. In order to score the highest comprehensive sensory evaluation, four processing parameters [i.e., oil temperature, material (shredded pork fillet)/oil ratio, stirring frequency and stirring duration] were optimized using orthogonal array design. Three sensory indexes including tenderness, dispersion degree and color were weighed by paired comparison method and sensory evaluation scores were analyzed statistically by fuzzy math method. Range analysis for the comprehensive sensory score with various processing parameters indicated that their influences decreased in the following order: stirring duration > oil temperature > material/oil ratio = stirring frequency. Stirring duration and oil temperature were further optimized using quadratic orthogonal regression design. The best processing parameters were as follows: oil temperature 122.2 ℃, stirring duration 15.02 s, material/oil ratio 1:5 and stirring frequency 50 r/s; meanwhile water analysis indicated that the moisture loss was minimized when oil temperature and stirring duration were 125 ℃ and 14 s, respectively.

Key words: automatic oil stirring, oil temperature, stirring duration, moisture measurement