Comparison of high-hydrostatic pressure and frozen treatments on raw freshwater clam marinated in soy sauce: Impact on microbiological and organoleptic qualities

Abstract

The purpose of this study was to compare how the two different methods of food processing, high pressure processing (HPP) under 300–500 MPa for 3 min and freezing, affect the microbiological, chemical, and organoleptic qualities of soy sauce-marinated freshwater clams (Corbicula fluminea) during refrigeration. The aerobic plate count (APC), psychotropic bacteria count (PBC), Salmonella spp., and coliform of high pressure processed soy sauce-marinated clams (HPP marinated-clams) were obviously lower than conventionally frozen soy sauce-marinated clams (frozen marinated-clams), or were not detected. In addition, after all samples’ 15-day refrigeration period, HPP was found to significantly inhibit the growth of APC, PBC, Salmonella spp., and coliform, while the microbial counts of frozen marinated-clams increased gradually with time. However, the surface areas, moisture contents, and salt contents of all samples of both HPP marinated-clams and frozen marinated-clams slightly increased during refrigeration. Furthermore, the results of organoleptic analyses exhibited that the storage life of marinated clams can be increased from 9 days under freezing treatment to 15 days under HPP (300 MPa and 500 MPa). Using high-throughput sequencing, HPP treatment significantly changed the microbiota of marinated clam and delayed the spoilage process. Therefore, the study suggests using HPP at least 300 MPa for 3 min to effectively inhibit the microbial growth and significantly extend the storage life of the samples during the refrigeration period. This is a first study to use HPP technology to replace the traditional freezing technology in the application of raw soy sauce-marinated freshwater clam products, and at the same time, HTS was used to evaluate the changes of microbiota during refrigeration.