Effect of High-Pressure Processing and Thermal Treatment on Quality Attributes and Nutritional Compounds of Songold Plum Puree

The application of hydrostatic high pressure on a Songold plum puree was assessed in comparison with heat pasteurization. To simulate industrial conditions, one-half of the total puree was manufactured with a pretreatment of thermal blanching (TB) and the other half without it (nonthermally blanched, NTB). Changes after thermal treatment and high-pressure processing (HPP: 400, 600 MPa) and after 20 d of refrigerated storage were evaluated. HPP maintained the microbial stability of the purees until the end of the storage period. Polyphenol oxidase activity was lower in TB purees than NTB purees. No treatment was completely effective to stop the enzyme activity, although a significant reduction was reached. Thermally treated purees showed more intense color changes after processing and storage than HP-treated purees. After processing, high-pressure (HP) purees treated at 600 MPa (TB and NTB) increased the extractability of carotenoids compared with initial untreated puree. Nevertheless, at the end of the storage, the highest carotenoid content was found in the TB puree treated at 400 MPa. After processing, total polyphenol levels were similar in all purees. TB and 600 MPa processing was more effective in the maintenance of the polyphenols than the other purees. TB increased the level of antioxidants after storage, compared to NTB purees. A previous TB step is necessary to inactivate browning enzymes before HPP to maintain the levels of bioactive compounds. HPP of plum puree could be a suitable alternative to traditional thermal processing, but more studies are necessary to ensure a major inactivation of polyphenol oxidase. Practical Application: High-pressure processing is one of the most successful technologies to obtain high-quality fruit purees without appreciable losses in taste, flavor, color, and nutritive value. However, for the introduction of a new technology, some advantages compared to the traditional thermal treatment need to be emphasized. The application of this technology could be reduced due to resistance of certain enzymes to pressurization. For this reason, in some cases the application of a previous thermal blanching can be necessary at industrial level. However, this can reduce the advantages of HPP application. This paper provides interesting information about the storage stability of plum purees after high-pressure treatments and assesses the need for applying heat pretreatments.