Impact of high-pressure carbon dioxide on polyphenoloxidase activity and stability of fresh apple juice

Freshly-extracted apple juice was exposed to high pressure carbon dioxide (HP-CO2) treatment at 20, 35 and 45 °C at different pressure conditions (6.0, 12.0 and 18.0 MPa) for up to 30 min. Samples were analysed for residual enzymatic activity. The time needed for 90% enzyme inactivation (Dp) decreased when CO2 pressure increased, while the CO2 pressure sensitivity of the enzyme (zp) showed no variation with temperature. The HP-CO2 treatment at 12 MPa and 35 °C allowed the minimum residual enzyme activity (20%) to be reached in 10 min. Samples treated under these conditions showed lower polyphenoloxidase activity and higher microbial stability than untreated apple juice while presenting a sensory fresh-likelihood higher than thermally pasteurized apple juice. © 2016 Elsevier Lt

Training in tools to develop quantitative microbial risk assessment along the food chain of Spanish products

Food safety is a widespread challenge. Every year it is estimated that almost 1 in 10 people in the world fall ill after eating contaminated food resulting in over 400,000 deaths. The risk of outbreaks is higher when consuming ready-to-eat (RTE) products because they are eaten without a further cooking process that could inactivate pathogenic microorganisms. Hence, food processing is essential to increase the safety of RTE products. Microbiological risk assessment (MRA) integrates food science, microbiology and data science to provide a comprehensive understanding of the safety of the food system. MRA provides qualitative and/or quantitative information to decision makers, which might promote the adoption of better food practices. In this contest, this project aims to study and implement tools for quantitative microbial risk assessment (QMRA) of food products along the food chain. A common RTE product (cured ham) from Spain was used as a case study. Following, the exposure assessment model was implemented using mathematical models and statistical software to describe the microbial behaviour along the food chain. The study presents the possibility to identify the risk exposure in different scenarios (e.g. growth during different storage conditions, inactivation induced by traditional or innovative decontamination techniques), showing the flexibility of the predictive tools developed

Effect of hyperbaric stress on yeast morphology: Study by automated image analysis

The effects of hyperbaric stress on the morphology of Saccharomyces cerevisiae were studied in batch cultures under pressures between 0.1 MPa and 0.6 MPa and different gas compositions (air, oxygen, nitrogen or carbon dioxide), covering aerobic and anaerobic conditions. A method using automatic image analysis for classification of S. cerevisiae cells based on their morphology was developed and applied to experimental data. Information on cell size distribution and bud formation throughout the cell cycle is reported. The results show that the effect of pressure on cell activity strongly depends on the nature of the gas used for pressurization. While nitrogen and air to a maximum of 0.6 MPa of pressure were innocuous to yeast, oxygen and carbon dioxide pressure caused cell inactivation, which was confirmed by the reduction of bud cells with time. Moreover, a decrease in the average cell size was found for cells exposed for 7.5 h to 0.6 MPa CO2.CAPES and CNPq (Brazil). Fundação para a Ciência e Tecnologia (Portugal)

Supercritical CO2 Pasteurization of Solid Products: a Case Study on Fresh-cut Potatoes

During the last decades, supercritical carbon dioxide (scCO2) pasteurization has been intensively studied as a potential technology to increase the safety and shelf-life of fresh food. However, the high risk of post-process contamination still represents a barrier to its industrialization. This study reports a proof of concept study in order to demonstrate the applicability of a novel method that combines scCO2 and Modified Atmosphere Packaging (MAP) for fresh-cut potatoes. The process was investigated by a full-factorial design of experiment, studying the effect of temperature (35 - 45 °C), pressure (8 – 12 MPa), and treatment time (5 – 35 min) on the microbial inactivation of E. coli and the color of the processed product. The method was able to reduce up to 1.50 Log CFU/g the load of inoculated E. coli at 45°C, 8.0 MPa and 35 min, without excessively modifying the product color. Moreover, the color did not significantly change during storage at 4 °C for 7 days

Optimization of the appearance quality in CO2 processed ready-to-eat carrots through image analysis

A high-pressure CO2 process applied to ready-to-eat food products guarantees an increase of both their microbial safety and shelf-life. However, the treatment often produces unwanted changes in the visual appearance of products depending on the adopted process conditions. Accordingly, the alteration of the visual appearance influences consumers’ perception and acceptability. This study aims at identifying the optimal treatment conditions in terms of visual appearance by using an artificial vision system. The developed methodology was applied to fresh-cut carrots (Daucus carota) as the test product. The results showed that carrots packaged in 100% CO2 and subsequently treated at 6 MPa and 40◦C for 15 min maintained an appearance similar to the fresh product for up to 7 days of storage at 4◦C. Mild appearance changes were identified at 7 and 14 days of storage in the processed products. Microbiological analysis performed on the optimal treatment condition showed the microbiological stability of the samples up to 14 days of storage at 4◦C. The artificial vision system, successfully applied to the CO2 pasteurization process, can easily be applied to any food process involving changes in the appearance of any food product

Improving phylogeny reconstruction at the strain level using peptidome datasets

Typical bacterial strain differentiation methods are often challenged by high genetic similarity between strains. To address this problem, we introduce a novel in silico peptide fingerprinting method based on conventional wet-lab protocols that enables the identification of potential strain-specific peptides. These can be further investigated using in vitro approaches, laying a foundation for the development of biomarker detection and application-specific methods. This novel method aims at reducing large amounts of comparative peptide data to binary matrices while maintaining a high phylogenetic resolution. The underlying case study concerns the Bacillus cereus group, namely the differentiation of Bacillus thuringiensis, Bacillus anthracis and Bacillus cereus strains. Results show that trees based on cytoplasmic and extracellular peptidomes are only marginally in conflict with those based on whole proteomes, as inferred by the established Genome-BLAST Distance Phylogeny (GBDP) method. Hence, these results indicate that the two approaches can most likely be used complementarily even in other organismal groups. The obtained results confirm previous reports about the misclassification of many strains within the B. cereus group. Moreover, our method was able to separate the B. anthracis strains with high resolution, similarly to the GBDP results as benchmarked via Bayesian inference and both Maximum Likelihood and Maximum Parsimony. In addition to the presented phylogenomic applications, whole-peptide fingerprinting might also become a valuable complementary technique to digital DNA-DNA hybridization, notably for bacterial classification at the species and subspecies level in the future.This research was funded by Grant AGL2013-44039-R from the Spanish “Plan Estatal de I+D+I”, and by Grant EM2014/046 from the “Plan Galego de investigación, innovación e crecemento 2011-2015”. BS was recipient of a Ramón y Cajal postdoctoral contractfrom the Spanish Ministry of Economyand Competitiveness. This work was also partially funded by the [14VI05] Contract-Programme from the University of Vigo and the Agrupamento INBIOMED from DXPCTSUG-FEDER unha maneira de facer Europa (2012/273).The research leading to these results has also received funding from the European Union’s Seventh Framework Programme FP7/REGPOT-2012-2013.1 under grant agreement n˚ 316265, BIOCAPS. This document reflects only the authors’ views and the European Union is not liable for any use that may be made of the information contained herein. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Exploring Novel Supercritical CO2 Drying Combined with High Power Ultrasounds: a Case on Peas and Apples

The current global population stands at 8.1 billion people and is projected to reach 9 billion by 2037. The food sector will need to undergo significant transformations to ensure food security. In this context, drying plays an important role in enhancing global food security by facilitating the safe storage of agricultural products and food. In this study, we employed two innovative drying methods: supercritical carbon dioxide (scCO2) drying and its combination with high-power ultrasound (scCO2+HPU) to assess their performance in drying seeds and fruits such as peas and apples. Among drying methods, supercritical carbon dioxide is emerging as a promising technology in the food drying industry. So far, the use of scCO2 has yielded promising results in the drying of spices, meat, and vegetables, but further studies are needed. High-power ultrasound has shown substantial potential in enhancing water mass transfer and microbial inactivation when coupled with technology. The outcomes of our experimental implementation demonstrated a significantly greater reduction in weight, moisture content and a notably lower water activity level for scCO2+HPU compared to scCO2 alone. These findings validate the significant potential of this integrated technology, which warrants further exploration in diverse food matrices

Supercritical Carbon Dioxide Treatment Combined with Rosemary Essential Oil to Prolong the Shelf-Life of Chicken Breast Meat

Essential oils are well known for their antimicrobial properties, making them attractive for food preservation. However, when used alone, their effectiveness can be limited. Combining essential oils with other technologies shows promise for enhancing their efficacy.. The present work focuses on a laboratory-scale feasibility analysis investigating the potential synergism between supercritical carbon dioxide (scCO2) and rosemary essential oil (REO) to extend the shelf life of chicken breast meat, a product with a short storage time that contributes significantly to food waste. In this context, a novel method with supercritical carbon dioxide and modified atmosphere packaging (scCO2MAP) was used in combination with 1% REO. This method has a lower impact on product colour change with respect to traditional scCO2 processes while increasing food safety by reducing the number of viable microorganisms. Storage tests were conducted for up to 12 days at 4°C, measuring the load of the total mesophilic and psychrophilic microorganisms, water activity and pH. At day 0, the results showed a significant reduction in both mesophilic and psychrophilic microorganisms, respectively about 2.11 and 2.05 log CFU/g. During storage, the microorganism counts in the treated samples were lower compared to the untreated ones. The pH and water activity were not significantly different during the whole shelf life. This study shows promise for the development of a low-temperature treatment capable of enhancing the safety and of prolonging the shelf life of poultry meat

Financial sustainability and profitability of supercritical CO2 pasteurization of liquid products: A case study

This work presents an analysis of a supercritical CO2 (SC-CO2) pasteurization process, focusing on the financial and economic parameters that make the process sustainable at an industrial level. A small company processing 5,000,000 bottles of apple juice per year has been chosen as a case study. Investment and operating costs have been estimated based on data collected from the market and the relevant economic literature. The financial sustainability assessment was performed through the Discounted Cash Flow methodology, proving that SC-CO2 pasteurization is profitable on a 10-year horizon. The Net Present Value is strictly positive and the Internal Rate of Return higher than the cost of funding. The sensitivity analysis shows the robustness of this study to possible changes in the model parameters. Overall, this work demonstrates SC-CO2 pasteurization to be profitable and, considering the current growth of the high-nutritional value fruit juice market, it suggests positive financial returns for both incumbents and new entrants

SARS-CoV-2 inactivation by supercritical carbon dioxide coupled with hydrogen peroxide

The recent COVID-19 pandemic has underscored the need for innovative decontamination techniques capable of treating sensitive materials potentially contaminated. Combining supercritical carbon dioxide (scCO2) with sterilant agents has shown promise in this regard. This study aimed at testing scCO2 as a virus inactivation method for biomedical materials contaminated with the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2). The virus was inoculated on a stainless-steel carrier and treated at 45 °C and 8 MPa. No inactivation was detected when only scCO2 was used, even after long treatment times (60 min). The addition of 50 ppm of H2O2 to the process allowed the inactivation of more than 5 Log PFU (Plaque Forming Unit) of the virus by only pressurising and depressurising the vessel, while a 20-min process is needed by only using H2O2. Overall, the study demonstrates a synergistic effect when H2O2 is added to the scCO2 process for the inactivation of SARS-CoV-2