Abstract:
In order to investigate the effects of different processing methods on the rheological properties and flavor components of Laiyang pear paste, this study analyzed the fluid types and compared the volatile substances of three homemade pastes (freeze-drying concentration, vacuum concentration, and atmospheric boiling) and seven commercially sampled pastes by employing a rheometer and gas chromatography-ion mobility spectroscopy (GC-IMS). The results showed that all pear paste samples exhibited pseudoplastic fluid behaviors with shear-thinning characteristics. The relationship between shear rate and shear stress conformed to the Power Law model, demonstrating an excellent fit (
R2>0.99). Among the ten samples, the paste prepared by freeze-drying concentration revealed the optimal rheological properties, showing neither excessive thinness nor thickness. Furthermore, GC-IMS identified different flavor compounds in 10 kinds of pear pastes and qualitatively detected the common flavor compounds, including 15 aldehydes, 14 esters, 13 ketones, 9 alcohols, 5 terpenes, 1 carboxylic acid, and 4 other compounds qualitatively. According to orthogonal partial least squares-discriminant analysis (OPLS-DA) and relative odor activity value (ROAV) screening, the key odor markers were identified as 2-methylbutanal, 2-methylpropanal, ethyl hexanoate, and ethyl butyrate. The flavor compounds of aldehydes and esters were typically associated with fruity aromas. Meanwhile, compared to pastes produced by atmospheric boiling and vacuum concentration, the paste prepared by freeze-drying concentration contained the highest level of ethyl butyrate, which contributed to a distinct fruity aroma. It indicated that the use of this method to produce Laiyang pear paste could maximize the preservation of the fruity aroma. In conclusion, findings of this study provide valuable insights for the processing and multi-dimensional quality evaluation of pear paste products.