Thermal Pasteurization Research Articles

Effectiveness of pulsed light treatments assisted by mild heat on Saccharomyces cerevisiae inactivation in verjuice and evaluation of its quality during storage

The effects of pulsed light (PL) processing parameters such as depth of juice layer (1, 3, 5 mm), distance from the lamp (5, 10 cm) and number of pulses (0–50 pulses) on the inactivation of Saccharomyces cerevisiae in verjuice, a clarified beverage obtained from freshly-squeezed unripe grapes, were investigated. A reduction of 0.96 ± 0.27 log CFU/mL was achieved by applying a dose of 34 J/cm2 (1-mm layer depth, 5-cm distance, 50 pulses). PL was combined with mild heating (MH) at 43, 45 and 47 °C to increase its inactivation efficacy. Pasteurization was achieved by applying 17 J/cm2 at 45 °C (PLMH45–3) and 6.12 J/cm2 at 47 °C (PLMH47–3) to a 3-mm juice layer with S. cerevisiae reductions of 5.10 ± 0.24 and 5.06 ± 0.08 log CFU/mL, respectively. Quality properties of PLMH47–3-pasteurized verjuice were monitored during 6 weeks of storage at refrigerated (5 °C) and room temperature (25 °C), The results were compared to those of untreated and thermally pasteurized (72 °C/18 s) samples. Untreated juice spoiled within 2 weeks at 25 °C. No growth was detected in other conditions for 6 weeks. Among quality characteristics, only optical properties changed slightly during storage. It was concluded that mild MH-assisted pulsed light treatments have potential for verjuice pasteurization compared to conventional thermal pasteurization due to the better preservation of its fresh-like characteristics.

Review on Changes in Bioactive Composition of Fruits during Juice Processing

Fruits and vegetables are consumed at all times, and due to their convenient size; they are an excellent between-meal snack. Fruit juices are naturally rich in bioactive compositions like phenolic compounds. However, in some other cases heat processing may partially destroy them or significantly reduce their bioavailability, thus reducing beneficial health effects. Modern processing, packaging, ingredient technology and distribution systems are taken as a system that assure safe, stable and appealing fruit juice products in a convenient, economical form far from the raw material source or season. Fruits may contain different bioactive compounds, many of which may have antioxidant capacity. Many complex biochemical reactions are involved during the ripening process, such as the hydrolysis of starch and the synthesis of carotenoids, anthocyanins, and phenolic compounds in addition to the formation of various volatile compounds. The processing such as thermal pasteurization and sterilization, pulsed electric fields, high pressure, ultrasound, microwave treatment, and microfiltration aimed to preserve fruit juices due to their ability to inactivate a wide range of microorganism’s and spoilage enzymes may have another effect on bioactive compounds. So that avoiding over processing to save bioactive nutrients and following the best juice processing methods, adopting high energy transfer processing method such as high temperature short time pasteurization to reduce the treatment time, improving temperature and time combination in processing is recommended.

Changes in Quality Characteristics of Strawberry Juice After Equivalent High Pressure, Ultrasound, and Pulsed Electric Fields Processes

Understanding the efficacy of viable emerging technologies in preserving overall quality attributes and antioxidant characteristics of fruit juices is of great interest. This study aimed to evaluate the effect of high pressure (HP), ultrasound (US), and pulsed electric fields (PEF) processes on natural microbiota inactivation, as well as changes in physicochemical attributes and phytochemical content of strawberry juice (SJ). HP at 300 MPa (1 min), US at 55 °C (3 min) and 517.1 mW/mL acoustic energy density, and PEF at 35 kV/cm (27 μs) using monopolar square pulses with 2 μs pulse width were applied, and then compared with a conventional thermal pasteurization treatment (72 °C, 15 s). The nonthermal processes were equivalent in terms of Escherichia coli (E. coli) inactivation since the selected processing conditions led to almost identical inactivation level (at least 5-log) of inoculated E. coli. The current study analyzes why these equivalent processes had different effect on SJ quality. All treatments significantly reduced the initial natural microbiota (i.e., total mesophilic aerobic bacteria and yeast-molds) below 2 log CFU/mL. No significant changes were observed on the total soluble solid content (7.83–8.00 °Brix), titratable acidity (0.79–0.84 g/100 mL), and pH (3.45–3.50; except in sonication) between SJ processed samples and the untreated ones (p > 0.05). HPP and PEF significantly promoted higher retention of total phenolic content (TPC) and radical scavenging activity (RSA) than thermal pasteurization, and significantly enhanced total anthocyanin content (TAC) compared with unprocessed SJ. HPP and PEF increased the TPC (4–5%), RSA (18–19%), and TAC (15–17%) in comparison with unprocessed SJ. Multivariate data analysis tools, i.e., principal component analysis (PCA) and hierarchical cluster analysis (HCA), were successfully applied for discrimination and classification of SJ samples based on the similarities or differences among physicochemical and phytochemical characteristics. PCA and HCA indicated that HPP- and PEF-treated samples had similar enhanced properties in terms of phytochemical content and were superior to sonicated, thermally pasteurized, and unprocessed samples. The multivariate data analysis methods were very useful to compare and classify SJ quality characteristics as a function of the processing technology. This study demonstrated that the application of the equivalent processing approach may reveal new opportunities to produce equivalent or even enhanced quality fruit juices.

Effect of high hydrostatic pressure processing on phytochemicals, antioxidant activity, and behavior ofBotrytis cinereain white grape juice concentrate

High hydrostatic pressure (HHP) was applied on a white grape juice concentrate (GJC) to evaluate its effectiveness and possible application as an alternative to thermal pasteurization. GJC was processed at pressure levels of 200, 300, and 400 MPa for 2 and 4 min at room temperature (20 ± 2°C) and changes in various quality parameters after HHP processing and after subsequent storage at 4°C for 35 days were examined. The effect of the HHP treatments on the conidial fungi Botrytis cinerea was determined after inoculating the GJC with a conidial suspension. The results shown a significant reduction of B. cinerea (ufc/ml) at 400 MPa/4 min, in day 0 and after 35 days of storage sample. The physicochemical analysis of GJC showed that the sugar contents increased after treatments but decreased during storage. The total antioxidant activity and total flavonoid content in HHP-treated samples were significant decreased. Practical applications HHP processing of concentrated grape juice has proved to be efficient to retain content of antioxidant compounds and activity as well as characteristic quality of the GJC that is widely used in blending of fruit juices or as a natural sweetener in various food products. The experimental results have shown that HHP process could be a valid alternative to thermal pasteurization of GJC.

Non-thermal Processing of Pineapple (Ananas comosus [L.] Merr.) Juice Using Continuous Pressure Change Technology (PCT): Effects on Physical Traits, Microbial Loads, Enzyme Activities, and Phytochemical Composition

A comprehensive study using continuous pressure change technology (PCT) for the non-thermal processing of fresh pineapple juice on pilot scale was conducted (1 L/min, 50 MPa, argon, 3 min, <35 °C). The immediate effects of a single and a twofold PCT treatment on the most important quality parameters were examined and compared with those of fresh and thermally pasteurised (90 °C) juices. In comparison to the fresh juice, both PCT-treated samples exhibited slightly brighter and less yellowish colour (CIE L*a*b*). A significant reduction in the mean particle size resulted in diminished centrifugable pulp contents and enhanced cloud stability. Moreover, a slightly improved microbial quality (−0.9 to −1.2 log10 CFU/mL) in terms of total aerobic and yeast and mould counts was attained. Noteworthy, PCT retained a high bromelain activity (−3 to −15% reduction) and efficiently inactivated polyphenol oxidase. Water-soluble vitamins, phenolic compounds, and all further constituents assessed were mostly preserved. However, the high residual peroxidase activity (−10 to −23%) and microbial loads are likely to affect juice quality during storage. In contrast, thermal pasteurisation ensured a complete reduction in both microbial counts (−4.4 to −4.5 log10 CFU/mL) and effective inactivation of peroxidase. However, bromelain activity was strongly affected (−83%) by heat treatment, and colour was darkened and even less yellowish. Overall, this study highlighted the potential of PCT for the production of fresh-like pineapple juices; however, its current limitations were revealed as well.

Effects of radio frequency on physicochemical properties of powdered infant formula milk as compared with conventional thermal treatment

Radio frequency (RF) has been proved effective in inactivating Cronobacter sakazakii in powdered infant formula milk (PIFM). For successful industrial application, the quality of PIFM after combined RF and hot air treatment (RF-HA) were further investigated based on 5-log inactivation of Cronobacter sakazakii as compared with hot water treatment (HW). Severer color deterioration was observed on HW treated samples. No significant difference existed on solubility (>99%) and crude protein content (about 13 g/100 g) after both treatments. Protein denaturation temperature obtained from the differential scanning calorimetry curves increased with decreasing moisture content of PIFM and RF-HA resulted in more stable protein structures. Fourier transform infrared spectrum further confirmed the development of Maillard reaction, which was weaker in RF-HA. Microstructure by scanning electron microscopy revealed more obvious particle agglomeration behavior induced by RF. Overall, higher water activity, 0.4 as the upper limit, was not good for maintenance of nutritional attributes, though conducive to sterilization. This study could provide useful information for PIFM quality evaluation and optimization of thermal pasteurization methods.

Impact of UV-C treatment and thermal pasteurization of grape must on sensory characteristics and volatiles of must and resulting wines

UV-C treatment is a commonly known technique to inactivate microorganisms. The objective of this work was to investigate the impact of UV-C treatment of grape must on the sensory characteristics of the resulting wine and on the profile of volatile compounds of grape must and wine. Different UV-C doses were applied to Riesling must and compared with thermal pasteurization. The sensory off-flavor “ATA” and a content of 0.5 µg/L 2-aminoacetophenone were determined in the grape must and in the resulting wine after UV-C treatment with a high dose of 21 kJ/L. Sensory off-flavors did neither occur after thermal pasteurization nor after UV-C treatment with a dose of 2 kJ/L, which is sufficient for the inactivation of microorganisms. Minor changes in the volatiles’ profiles of grape must and wine, involving e.g. terpenes and C13-norisoprenoids, occurred in musts treated with thermal pasteurization as well as with a UV-C dose of 2 kJ/L.

Performance evaluation of biobased/biodegradable films for in-package thermal pasteurization

This study examined the feasibility of biobased/biodegradable films for in-package thermal pasteurization. Salmon in sauce and beet mixed mashed potato were vacuum packed in polylactic acid (PLA), and polybutylene adipate terephthalate (PBAT)-based pouches (oxygen transmission rate (OTR): 330–619 cm3 m−2 day−1 and water vapor transmission rate: 38–49 g m−2 day−1), pasteurized targeting 6-log reduction of L.monocytogenes (P70°C7.5°C = 3 min), and stored at 4 °C for 10 days. The gas barrier properties of all films decreased significantly (P < 0.05) after processing, and some haziness developed in PLA films. Although the OTR increased, the microbial, physical, and chemical qualities were maintained at the end of storage. The lipid oxidation, based on TBARS, was within the acceptable limit in salmon in sauce. However, the vitamin C in mashed potato packed in biobased/biodegradable films demonstrated losses 2–3 times higher than in the control (polyethylene) film. Overall findings indicate that selected PLA and PBAT-based films are suitable for in-package pasteurization and can replace polyethylene for ≤10 days of shelf life at 4 °C. Industrial significanceIncreasing consumer awareness about plastic waste disposal and demand for sustainable products has prompted food and polymer companies to develop sustainable solutions for food packaging. The use of biobased and biodegradable packaging could be one solution to address this challenge. However, current applications of biobased/biodegradable films are limited to fresh produce, meat, yogurt, some beverages, and dry products. Our findings extend the application of these films to in-package thermal pasteurization of high-moisture products, such as ready-to-eat meals.

Retention of Ascorbic Acid, Retinol, β-Carotene, and α-Tocopherol in Milk Subjected to Pressure-Assisted Thermal Processing (PATP)

Thermal treatments can cause undesirable sensory quality and nutritional changes in food, whereas high-quality retention has been widely reported for high-pressure processing (HPP). The aim of this study was to assess the retention of whole-fat milk vitamins after pressure-assisted thermal processing (PATP). The retention of ascorbic acid (AA), retinol, β-carotene, and α-tocopherol was determined by HPLC after 0.5 to 10 min treatments at 46 to 75 °C and 95 to 705 MPa. AA content was particularly sensitive to PATP treatments, particularly at 705 MPa and 75 °C for 5 min, reaching a loss of 55.1 ± 0.9%. Liposoluble vitamin losses were much lower than those observed for AA. For all treatments, retinol loss remained below 10.2 ± 1.7% and it was independent of the processing times tested (0.5, 5, and 10 min) for treatments at 400 MPa and 75 °C with losses of 6.3 ± 1.3, 6.1 ± 1.5, and 8.1 ± 3.2%, respectively. For PATP treatments at 75 °C, 5 min, and 95–705 MPa, α-tocopherol losses were minor and ranging from 5.0 ± 2.1 to 6.4 ± 0.6%. These values were similar to those observed after conventional thermal pasteurization. Low β-carotene losses were also observed at 75 °C for all PATP treatments with losses of −0.6 ± 2.9 to 4.4 ± 0.5% for 95–705 MPa/5 min and 2.4 ± 0.3 to 4.9 ± 2.1% for 400 MPa/0.5–10 min treatments. This study showed that in whole-fat milk subjected to PATP treatments, AA is significantly more sensitive than retinol, β-carotene, and α-tocopherol.

High-Pressure Carbon Dioxide Used for Pasteurization in Food Industry

The demand for safe, high-quality food has greatly increased, in recent times. As traditional thermal pasteurization can significantly impact the nutritional value and the color of fresh food, an increasing number of nonthermal pasteurization technologies have attracted attention. The bactericidal effect of high-pressure carbon dioxide has been known for many years, and its effect on food-related enzymes has been studied. This novel technology has many merits, owing to its use of relatively low pressures and temperatures, which make it a potentially valuable future method for nonthermal pasteurization. For example, the inactivation of polyphenol oxidase can be achieved with relatively low temperature and pressure, and this can contribute to food quality and better preserve nutrients, such as vitamin C. However, this novel technology has yet to be developed on an industrial scale due to insufficient test data. In order to support the further development of this application, on an industrial scale, we have reviewed the existing information on high-pressure carbon dioxide pasteurization technology. We include its bactericidal effects and its influence on food quality. We also pave the way for future studies, by highlighting key areas.

The impact of thermal pasteurization on viral load and detectable live viruses in human milk and other matrices: a rapid review.

Holder pasteurization (62.5°C, 30min) of human milk is thought to reduce the risk of transmitting viruses to an infant. Some viruses may be secreted into milk - others may be contaminants. The effect of thermal pasteurization on viruses in human milk has yet to be rigorously reviewed. The objective of this study is to characterize the effect of common pasteurization techniques on viruses in human milk and non-human milk matrices. Databases (MEDLINE, Embase, Web of Science) were searched from inception to April 20th, 2020, for primary research articles assessing the impact of pasteurization on viral load or detection of live virus. Reviews were excluded, as were studies lacking quantitative measurements or those assessing pasteurization as a component of a larger process. Overall, of 65 131 reports identified, 109 studies were included. Pasteurization of human milk at a minimum temperature of 56-60°C is effective at reducing detectable live virus. In cell culture media or plasma, coronaviruses (e.g., SARS-CoV, SARS-CoV-2, MERS-CoV) are highly susceptible to heating at ≥56°C. Although pasteurization parameters and matrices reported vary, all viruses studied, except parvoviruses, were susceptible to thermal killing. Future research important for the study of novel viruses should standardize pasteurization protocols and should test inactivation in human milk. Novelty In all matrices, including human milk, pasteurization at 62.5°C was generally sufficient to reduce surviving viral load by several logs or to below the limit of detection. Holder pasteurization (62.5°C, 30 min) of human milk should be sufficient to inactivate nonheat resistant viruses, including coronaviruses, if present.

The investigation and optimization of two combined pasteurization methods of ultrasonic‐pulse electric field and hydrodynamic‐pulse electric field on sour cherry juice using RSM‐TOPSIS

In this research, sour cherry juice (SCJ) was treated using a combination of the Ultrasound-Pulsed electric field (UP) wave and Hydrodynamic-Pulsed electric field (HP) systems. The main objective of this study was to investigate the effect of the combination of the pulsed electric field, ultrasonic wave, and hydrodynamic as new non-thermal technologies on the inactivation of microorganisms, energy changes in one cycle of E. coli inactivation, and the quality of SCJ. The range of experimental conditions was as follows: electrical field intensity: 5–10 kV/cm, electric field time: 5–35 s, ultrasound power: 100–200 W, ultrasonic exposure time: 3–5 min, and hydrodynamic exposure time: 3–9 min. The results of the treatments indicated that the combination methods maintained the total phenolic content, anthocyanins, and vitamin C compared to the conventional method. By TOPSIS, a comparison between two combination methods showed that the pasteurization with UP performed better than the HP method. Practical applications One of the most effective ways for the utilization of nutritional benefits of fruits is to use their extracts or juices. Also, to kill any harmful bacteria, most juices thermally are pasteurized. Where such treatments often lead to a substantial decrease in their quality (vitamins, phenolics, anthocyanins, etc.). For this goal, researchers are following up on new methods to dispel the adverse effects of thermal pasteurization. The present research aimed to assay the simultaneous effect of the ultrasonic-AC electric field and hydrodynamic-AC electric field to eliminate microorganisms and preserve the quality of SCJ. The current research recommends a novel and combined method for SCJ pasteurization and this method can benefit the food industry.

Comparison of the effects of novel processing technologies and conventional thermal pasteurisation on the nutritional quality and aroma of Mandarin (Citrus unshiu) juice

Conventional thermal pasteurisation (90 °C and 30 s), high pressure processing (HPP: 600 MPa, 4 °C and 300 s), ultrasound processing (US: 50 °C, 750 W and 36 min) and microwave processing (MW: 800 W, 80 °C and 70 s) were evaluated by examining their effects on the sensory and nutritional qualities of mandarin juice. The treated samples had <2 log CFU/mL total aerobic bacteria, which is equivalent to microorganism inactivation. Sugar and acid components were almost constant for all the treated mandarin juices, and no differences between treatments were perceptible. However, the mandarin juice treated with novel technologies maintained better colour (L*, a* and b*), nutritional value (ascorbic acid, total phenolic, total carotenoid content and phenolic components) and aroma than the thermally pasteurised one. This study showed that US, MW and HPP are good novel processing techniques to inactivate microorganisms and maintain the sensory and nutritional quality of mandarin juice.

Practical Elimination of Raw Meat Microbiological Risk using Thermal Pasteurization, a Novel Meat-Safety-Driven Technology

Although the safety of raw meat products has improved in recent decades, raw meat is still associated with a considerable incidence of foodborne illnesses and death. Standard raw meat antimicrobial interventions such as chemical sprays can reduce meat quality, and their effectiveness has plateaued. However, a new thermal pasteurization technology implementing direct steam injection into ground meat and subsequent chilling of the meat by expansion under vacuum has the potential to nearly eliminate pathogens in raw ground meat products while preserving the proteins in the raw state. An inoculation (Escherichia coli surrogates) study of a full-scale pilot pasteurization system demonstrated the effectiveness of pasteurization to significantly reduce illness-causing pathogens in raw ground beef. High-level (log 6.3 colony-forming units per gram [cfu/g]) inoculations were used to validate the minimum temperature required to achieve a 5 log microorganism reduction, and low-level (log 3.8 cfu/g) inoculations were used to validate the minimum temperature required to achieve a 3 log microorganism reduction. At both levels of inoculation, pasteurization achieved the targeted reduction in inoculated microorganism populations (mean ± SEM log microorganism reductions for high-level = log 5.8 ± 0.04 cfu/g, low-level = log 3.3 ± 0.03 cfu/g). Ground beef protein profile and color were studied to determine functional effects of the thermal pasteurization technology. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry revealed no significant changes in the protein profile (<i>P</i> &gt; 0.05). Colorimetric measurements revealed minor changes that were visually insignificant in the color profile of processed versus unprocessed ground beef. A consumer acceptance study found similar preferences for pasteurized ground beef products compared with retail-available ground beef products.

Optimization of the supercritical CO2 pasteurization process for the preservation of high nutritional value of pomegranate juice

This work aims to develop a high-pressure pasteurization process for pomegranate juice by supercritical CO2 (SC-CO2). The process was optimized in a mutibatch-system through Design of Experiment (DoE) and Response Surface Methodology. The optimized SC- CO2 process (12.7 MPa, 45 °C, 40 min) was compared with conventional thermal pasteurization (90 °C, 1 min) and High Hydrostatic Pressure process (600 MPa, 3 min) for the microbiological inactivation and the change in quality parameters of total phenols content (TPC), antioxidant activity (AAt) and colour, up to 28 days of storage at 4 °C. SC-CO2 treated juice was microbiological stable during the entire shelf life as well as colour and TPC. The antioxidant activity showed a significant (p < 0.05) decrease during the storage period, however this evidence was observed also for the thermal and high hydrostatic processed samples. Overall, SC-CO2 process is a promising technology for the development of innovative pasteurization technologies for high nutritional juice.

Effect of water activity on the thermal inactivation kinetics of Salmonella in milk powders

Persistence of Salmonella in milk powders has caused several foodborne outbreaks. The determination of proper pasteurization processing conditions requires an understanding of the thermal inactivation kinetics of Salmonella in milk powders. However, there is a lack of knowledge related to the effects of water activity (aw) and fat content on Salmonella inactivation in milk powder during thermal processing. Two types of milk powders, nonfat dry milk and whole milk powder, with different fat contents (0.62 and 29.46% wt/wt, respectively) were inoculated with a 5-strain cocktail of Salmonella and equilibrated to 3 aw levels (0.10, 0.20, and 0.30) for isothermal treatments at 75, 80, and 85°C to obtain D-values (the time required to achieve a 10-fold reduction of the bacteria at the isothermal treatment temperature) and z-values (the increase in temperature required to achieve a 90% reduction of the decimal reduction time D). Stability tests showed that the inoculation method used in this study provided a high and stable population of Salmonella for thermal inactivation studies. A moisture sorption isotherm was measured to understand the relationship between aw and moisture content of milk powders. The thermal resistance of Salmonella was found to significantly increase as aw decreased, which suggested that a higher temperature or longer processing time would be required at low aw to achieve the desired inactivation of Salmonella. The microbial inactivation kinetics were not significantly different for the 2 milk powders; therefore, data were combined to develop a universal model. A response surface model was compared with a modified Bigelow model. The modified Bigelow model performed well to predict D-values [root mean square error (RMSE) = 1.47 min] and log reductions (RMSE = 0.48 log cfu/g). The modified Bigelow model developed here could be used to estimate D-value as a function of water activity and temperature to design a thermal pasteurization system for milk powders.

Effect of Pulsed Light Treatment on Natural Microbiota, Enzyme Activity, and Phytochemical Composition of Pineapple (Ananas comosus [L.] Merr.) juice

The effect of pulsed light (PL) on numerous important quality characteristics of pineapple juice was studied and compared with untreated and thermally pasteurised samples. The laboratory scale PL batch system used was operated with each three different voltages (1.8, 2.1, and 2.4 kV) and numbers of pulses (47, 94, and 187). Treatments with 2.4 kV and either 94 or 187 pulses (757/1479 J·cm−2) resulted in a 5-log reduction in aerobic mesophiles and the yeast and mould counts. Peroxidase was more resistant to PL than polyphenol oxidase, whereas the bromelain activity was completely retained in all PL-treated juices. Colour and antioxidant capacity were minimally affected, while vitamin C, genuine pineapple furanones, and phenolic compounds declined. In contrast, thermal pasteurisation was more detrimental to colour, antioxidant capacity, and vitamin C content, but resulted in a superior inactivation of microorganisms and enzymes and retention of phenolic compounds. Principal component analysis (PCA) permitted the differentiation of fresh, thermally pasteurised, and all PL-treated juices. PCA on the basis of the individual juice constituents additionally arranged the latter juices according to the number of pulses and voltage levels applied, particularly promoted by the oxidation of ascorbic to dehydroascorbic acid. In conclusion, PL treatment represents a promising new alternative to conventional thermal preservation techniques, whereby the inactivation of deteriorative enzymes may be further optimised.

Impact of high-pressure and microwave-assisted thermal pasteurization on inactivation of Listeria innocua and quality attributes of green beans

In response to the increasing consumer demand for high-quality, minimally processed ready-to-eat (RTE) meals, the food industry has shown strong interests in exploring new processing technologies for production of safe RTE meals with an adequate shelf life in cold distribution chains. The purpose of this research was to understand the effect of high-pressure processing (HPP) and microwave-assisted thermal pasteurization on the quality attributes of green beans.The pasteurization conditions were selected as 600 MPa at 25 °C for 10 min for HPP and 70 °C for 2 min for processing with microwave-assisted pasteurization system (MAPS). Survival of L.innocua ATCC 51742 in green bean brine solution was analyzed right after the pasteurization processes. The quality attributes of the green beans, such as color, chlorophyll content, texture, vitamin C content, and pH, were further determined during storage at 2 °C for 36 days and 10 °C for 20 days.High-pressure treatment resulted in a 3.7-log CFU/g reduction in L. innocua ATCC 51742, whereas MAPS processing showed a 9.0-log CFU/g reduction. Both pasteurization processes provided significantly better green color retention when the beans were stored at 2 °C than when they were stored at 10 °C. Regardless of the pasteurization methods, the change in the greenness (a*) value of the beans followed similar trends during storage. Both methods caused an increase in the total color difference (ΔE) and a decrease in hue angle (yellowness) during storage (p < 0.05), but they had no significant effect on firmness, total chlorophyll content, and pH of the green beans. After the pasteurization processes, the vitamin C content of the HPP-treated green beans decreased significantly in comparison with the MAPS-treated beans (p < 0.05). This work reveals that both pasteurization treatments have a similar impact on quality attributes of green beans and that MAPS processing is more efficient in inactivating L. innocua ATCC 51742.

Non-thermal pasteurization of lipid emulsions by combined supercritical carbon dioxide and high-power ultrasound treatment.

Supercritical carbon dioxide (SC-CO2) is a novel method for food pasteurization, but there is still room for improvement in terms of the process shortening and its use in products with high oil content. This study addressed the effect of high power ultrasound (HPU) on the intensification of the SC-CO2 inactivation of E. coli and B. diminuta in soybean oil-in-water emulsions. Inactivation kinetics were obtained at different pressures (100 and 350bar), temperatures (35 and 50°C) and oil contents (0, 10, 20 and 30%) and were satisfactorily described using the Weibull model. The experimental results showed that for SC-CO2 treatments, the higher the pressure or the temperature, the higher the level of inactivation. Ultrasound greatly intensified the inactivation capacity of SC-CO2, shortening the process time by approximately 1 order of magnitude (from 50 to 90min to 5-10min depending on the microorganism and process conditions). Pressure and temperature also had a significant (p<0.05) effect on SC-CO2+HPU inactivation for both bacteria, although the effect was less intense than in the SC-CO2 treatments. E. coli was found to be more resistant than B. diminuta in SC-CO2 treatments, while no differences were found when HPU was applied. HPU decreased the protective effect of oil in the inactivation and similar microbial reductions were obtained regardless of the oil content in the emulsion. Therefore, HPU intensification of SC-CO2 treatments is a promising alternative to the thermal pasteurization of lipid emulsions with heat sensitive compounds.

Pasteurization of carrot juice by combining UV-C and mild heat: Impact on shelf-life and quality compared to conventional thermal treatment

The combination of UV-C radiation and mild heat (UV-H) treatment is a promising strategy for synergistically increasing microbial inactivation in low UV-transmitting juices. In this research, we explored the suitability of UV-H treatment in carrot juice pasteurization and its impact on juice quality during shelf-life compared to that of thermal pasteurization. UV-H treatment at 60 °C (3.92 J/mL, 3.6 min) enabled reductions of over 5 log10 cycles in the reference pathogens and a significant reduction in spoilage yeasts, bacteria, and bacterial spores. The activity of pectin methylesterase and polyphenol oxidase was reduced by UV-H treatment to levels close to those of low-temperature pasteurization (60 °C/18.1 min). The native population of total aerobic bacteria, lactic acid bacteria, and yeasts and molds of UV-H-treated juice remained undetectable during 29 days of cold storage. Furthermore, viscosity, cloud stability, and the color of fresh juice were better preserved by UV-H treatment than by thermal pasteurization throughout storage.Industrial relevanceThis study demonstrates that UV-H treatment is a beneficial alternative to conventional thermal processing in carrot juice pasteurization, since appropriate inactivation levels of pathogenic and spoilage microorganisms can be reached while better preserving the quality attributes of fresh juice throughout its shelf-life.