Effect of High-Pressure Processing Combined with Propolis Extract on the Quality and Microbiological Safety of Apple Puree

The aim of this study was to evaluate the influence of high-pressure processing (HPP) combined with natural extract on physical–chemical (Total soluble solids (TSS), moisture, pH, water activity (aW), color parameters) and microbiological characteristics (Total mesophilic aerobic microorganisms count at 30 °C, molds and yeast count at 37 ºC) of apple puree, during 90 days under refrigerated conditions. Three processes were applied: HPP (600 MPa, 3 min) with and without the addition of propolis extract (2.5% w/w); and conventional pasteurization (75 ºC, 10 min), as a reference method in the industry. The results showed that immediately after the application of the three processes, the load of aerobic microorganisms decreased from 3.40 to < 1 Log CFU/g. At the end of the shelf-life study, in all treatments, the count of aerobic microorganisms and of molds and yeasts was less than 2 and 1 Log CFU/g, respectively. Likewise, in the evaluation of TSS, moisture and aW no significant differences were found between processes. In the color analysis, HPP increased the stability over the shelf-life but promoted a higher initial change. The addition of extract enhanced color and pH stability, being the only treatment in which the product’s color did not change significantly during shelf-life. In conclusion, HPP is a good alternative to conventional pasteurization in the production of apple puree. The addition of propolis enhances the quality of puree while providing differentiation to the product.