Optimization of Color Protection Technology of Pear Paste Based on Z-score Evaluation Model

In order to optimize the color protection technology of ‘Yali’ pear paste, a Z-score (Z value) comprehensive evaluation model was established based on browning degree, total phenolics, total flavonoids content, and sensory score analysis and then the Z value was employed to optimize the color protection parameters for “Yali” pear paste through single factor tests and response surface methodolog (RSM). The flavour and taste of “Yali” pear paste prepared under optimized conditions and without color protection were tested with electronic nose and electronic tongue technology, respectively. Results showed that the optimum process conditions for “Yali” pear paste color protection were added amount of sodium ascorbate 0.02% (m/v), citric acid 0.05% (m/v) and potassium metabisulfite 0.02% (m/v). “Yali” pear paste prepared under the optimized conditions showed a semitransparent state with bright yellow color, special pear flavour, moderate sour and sweet feeling, its browning degree, total phenolics, total flavonoids content and the sensory score were 0.201, 59.80, 80.10 μg/mL and 9.38 respectively. Moreover, its Z-value for comprehensive evaluation method was 5.14, closing to the theoretical value of 5.03. The electronic nose technology made a perfect distinction on flavour between the optimized condition and without color protection of “Yali” pear paste. The electronic tongue analysis showed that “Yali” pear paste prepared under optimized conditions aroused stronger signals than paste without color protection in taste richness and sour sensors.