In this post, we would like to present the article of the second place awarded in the HPP Research Awards, Berta Torrents, from the Institute of Agri-Food Research and Technology (IRTA). In it she presents a summary of her study entitled “Meta-analysis of the microbial inactivation in high pressure treated fruit and vegetable juices and purees”.
From Hiperbaric we are proud that with this kind of initiatives we can give more visibility to studies as interesting as this one and we thank all the participants for their effort and dedication.
Without further ado, we leave you with Berta’s fascinating study. We hope you find it as interesting as we do.
Meta-analysis of the microbial inactivation in high pressure treated fruit and vegetable juices and purees
High pressure processing (HPP) is a non-thermal technology alternative to thermal pasteurization, preserving the nutritional and sensory qualities of fruit and vegetable juices and purees. This study collected and meta-analyzed available literature data on HPP’s inactivation of Listeria spp. and Escherichia coli in fruits and vegetables. From selected articles, pressure level and pH category were identified as significant factors. A predictive model was developed and integrated into a hazard control decision support system (HC-DSS) to help the food industry validate HPP parameters, ensuring safety and compliance with food safety regulations.
High pressure processing (HPP) is a non-thermal preservation technology alternative to thermal pasteurization for fruit and vegetable juices and purees showing an increasing market trend thanks to its minimal effect on nutritional and organoleptic characteristics. The current food legislation requires the food business operators to have a preventive food safety management system (i.e. pre-requisite programs and Hazard Analysis and Critical Control Points, HACCP) requiring the application of control measures to reduce or eliminate hazards and HPP plays a relevant role in this respect. In this context, validation of any technology applied as a control measure acquires a paramount importance and needs to be performed during the design of the processing treatment, before its rutinary implementation for the commercial production. Mathematical models about the behavior of microbial hazards during food processing and preservation are tools to provide scientific evidence in a validation study.
The purpose of this study was to collect and meta-analyze available data on HPP inactivation of Listeria spp. and Escherichia coli in fruits and vegetables products.
From an extensive literature search, articles providing HPP inactivation data were selected. To estimate the DP, as the HPP time to obtain a decimal reduction under different pressure levels for different matrixes. The time to achieve 5-log reduction (D5) as the target performance criterion was also calculated accounting for the inactivation during pressure come-up and shoulder. Principal Component Analysis (PCA) and Generalized Linear Mixed models (GLMM) were used to identify significant factors impacting on kinetic parameters (DP and D5), including pressure level, pH category (high acid (pH<4), acid (4≤pH≤4.5), low acid (pH>4.5)) and microorganism as fixed effects, and strain (nested to microorganism) and study as random effects. Secondary Bigelow models considering pH category and/or microorganism were fitted to the entire data set. Pressure level and pH category explained more than 90% of the data variability and the mixed models confirmed the statistical significance of these factors, together with the microorganism and a global model was obtained for each pH category. When predicted inactivation values were compared with the data collected from the literature (those not used to build the model), most of the predictions provided by the LogDP model were within the acceptable simulation zone (±1 log) or fail-safe.
The study incorporated the predictive model to a hazard control decision support system (HC-DSS) prototype, particularly focusing on setting and validating HPP conditions for fruits and vegetables. The HC-DSS comprises two modules:
- The first module evaluates HPP efficacy in inactivating pathogens in fruit and vegetable purees for infants. Users select the pH category of the product. Subsequently, users enter the HPP parameters, specifically the pressure (within the range of 300 to 600 MPa) and time (up to 10 minutes). The obtained output is the estimated inactivation and a plot displaying log reduction over time.
- The second module determines HPP conditions (time and pressure) needed to meet specified performance criteria for pathogen inactivation. Users define the pH category of the product, the target performance criteria (number of log10 reductions) and pressure level. The output is the estimated time to achieve the target performance criteria for the selected pH category and pressure conditions.
The HC-DSS is a useful tool for the food industry to validate HPP processing conditions, ensuring food safety in the production of fruit and vegetable products, complying with regulatory requirements and maintaining public health standards.
If you are interested in learning more about Berta’s study, feel free to watch her full presentation at the HPP Innovation Week 2024 session below.
