Thermal Pasteurization Research Articles

Comparative study on quality of whole milk processed by high hydrostatic pressure or thermal pasteurization treatment

Quality of whole milk pasteurized by high hydrostatic pressure processing (HPP: 600 MPa for 5 min) or HPP combined with microfiltration (MF + HPP) were compared with two conventional heat treatments, low temperature long time (LTLT: 63 °C for 30 min) and high temperature short time (HTST: 72 °C for 15 s). Inactivation of microorganisms, changes in volatiles, protein denaturation, gastric digestion, and sensory quality were evaluated after 8 days of storage at 5 °C. Total bacterial and E.coli counts were reduced to approximately the same level for both high pressure and heat treated milks. The denaturation of β-lactoglobulin was significantly higher for high-pressurized milks, while no significant differences were found in gastric in-vitro protein digestion compared with heat treated milks. The results of volatile compounds revealed that HTST and HPP-treated milks exhibited very similar aroma profiles, while LTLT-milks were characterized by higher levels of ketones. After 8 days storage, the sensory analysis showed that LTLT milk was the one that differed most from the other three milks with highest intensities of all the sensory attributes, while no tangible differences were found between HTST and any HPP and MF + HPP milk, except for Boiled Taste that was slightly but significantly lower for MF + HPP.

Effects of high-pressure processing and thermal pasteurization on quality and microbiological safety of jabuticaba (Myrciaria cauliflora) juice during cold storage.

The aims of this study were to investigate the effects of high-pressure processing (HPP) on jabuticaba juice characteristics including microbial levels, phenolic compounds, antioxidant activity, and physicochemical properties during 28days of storage at 4°C and to perform a sensory evaluation. Juice samples were pressurized at 200, 400, or 600MPa for 5min. During thermal processing, juice was treated in a water bath at 90°C for 60s. Elevated aerobic plate counts, coliforms, psychrotrophs and yeasts/molds, were not detected in the HPP-400, HPP-600, or thermal-processed (TP) juices and further cold storage showed at least a shelf life of 28days at 7°C. All HPP-treated juice had significantly higher antioxidant capacities, higher total phenolic, flavonoid, and monomeric anthocyanin content, and lower browning degrees, compared with the TP. The soluble solid content, titratable acidity and pH were not significantly different in the HPP-400, HPP-600, and TP after 28days. The ΔE values were significantly increased in all juice samples. Sensory analysis indicated that the HPP-treated juices had higher acceptance and lower bitter perception. In conclusion, HPP treatments above 400MPa were effective in ensuring microbiological safety, maintaining the overall quality parameters, extending the shelf life, and achieving consumer acceptance.

Nonthermal Plasma Induces the Viable-but-Nonculturable State in Staphylococcus aureus via Metabolic Suppression and the Oxidative Stress Response.

As a novel nonthermal technology, nonthermal plasma (NTP) has attracted a lot of attention. However, it could induce microorganisms into a viable but nonculturable (VBNC) state, posing a potential risk to food safety and public health. In this study, the molecular mechanisms of VBNC Staphylococcus aureus induced by NTP were investigated. With the use of a propidium monoazide quantitative PCR (PMA-qPCR) technique combined with a plate count method, we confirmed that 8.1 to 24.3 kJ NTP induced S. aureus into a VBNC state at a level of 7.4 to 7.6 log10 CFU/ml. The transcriptomic analysis was conducted and revealed that most energy-dependent physiological activities (e.g., metabolism) were arrested in VBNC S. aureus, while the oxidative stress response-related genes (katA, dps, msrB, msrA, and trxA) were significantly upregulated. In addition, this study showed that the ATP depletion by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) pretreatment could accelerate the formation of VBNC S. aureus The NTP-generated oxidative stress triggers the staphylococcal oxidative stress response, which consumes part of cellular energy (e.g., ATP). The energy allocation is therefore changed, and the energy assigned for other energy-dependent physiological activities (cell growth and division, etc.) is reduced, subsequently forcing S. aureus into a VBNC state. Therefore, the alterations of energy allocation should be some of the major contributors to the induction of VBNC S. aureus with NTP exposure. This study provides valuable knowledge for controlling the formation of VBNC S. aureus during NTP treatment.IMPORTANCE In recent years, nonthermal plasma (NTP) technology has received a lot of attention as a promising alternative to thermal pasteurization in the food industry. However, little is known about the microbial stress response toward NTP, which could be a potential risk to food safety and impede the development of NTP. A viable but nonculturable (VBNC) state is one of the most common survival strategies employed by microorganisms against external stress. This study investigated the mechanisms of the formation of VBNC Staphylococcus aureus by NTP in a more comprehensive and systematic aspect than had been done before. Our work confirmed that the NTP-generated oxidative stress induced changes in energy allocation as a driving force for the formation of VBNC S. aureus This study could provide better knowledge for controlling the occurrence of VBNC S. aureus induced by NTP, which could lead to more rational design and ensure the development of safe foods.

Non-thermal treatment for the stabilisation of liquid food using a tubular cellulose filter from corn stalks

Thermal pasteurisation is used for the microbial stabilisation of foods, but this process compromises quality food properties. This study proposes a novel cold preservation method with filtering materials obtained from agricultural by-products. Nano/micro-porous cellulose materials from native corn stalks (NCS), and the material obtained after delignification, were used as filtering materials for the microbial stabilisation of water and orange juice. The optimisation study of NCS and corn stalk tubular cellulose material (CSTC) to remove yeast Saccharomyces cerevisiae and Lactobacillus casei from water in accordance with processing variables was firstly conducted. Optimisation tests demonstrated the influence of cell concentration, filter size and flow rate on filter removal yields. Then the continuous filtration of commercial orange juice was performed for 20 days to remove S. cerevisiae. The results showed that delignified CSTC was an effective filtering material for removing S. cerevisiae and L. casei from water, and it successfully treated commercial contaminated orange juice. Despite juice colour diminishing when the process started and after filter regeneration cycles with hot water, almost initial parameter values were obtained as the process continued. Therefore, the proposed filtering material is a promising low-cost alternative to existing thermal pasteurisation technologies for liquid foods.

Microbial, nutritional, and organoleptic quality of pomegranate juice following high-pressure homogenization and low-temperature pasteurization.

This study investigated the effects of high-pressure homogenization (HPH) on microbial, nutritional, and organoleptic qualities of pomegranate juice. Juices subjected to HPH at 100 and 150MPa were compared to those subjected to thermal pasteurization at 55, 65, and 75 °C for 15 s, and to combined treatments. Physicochemical properties of pomegranate juices, such as color, pH, acidity, and total soluble solids, were marginally affected by either treatment. Significant microbial inactivation for the juices inoculated with Escherichia coli and yeast was achieved during 28 days of shelf life by HPH at 150MPa, followed by thermal treatment at 65 °C. There was no significant difference in ascorbic acid levels between the treated and fresh juice. Total polyphenol content and antioxidant activity were measured to be higher in case of both treatment methods. Analyzing treated HPH samples with electronic tongue and nose showed similar flavor profiles to the fresh juice. PRACTICAL APPLICATION: The work shows the benefits of using the advanced high-pressure homogenization (HPH) compared to common thermal treatment used today in fruit juice pasteurization. HPH is capable to provide sufficient reduction in microbial with better nutritional and organoleptic quality. In this manuscript, we showed the potential of HPH as alternative method for pasteurization on a highly healthy fruit like pomegranate. The work describes the advantages in HPH process through comprehensive analysis for nutritional, microbial, and sensorial quality.

Corona discharge development and its application to eliminate microorganism in raw milk

Raw cow’s milk or fresh milk is a natural food with a complete nutrients which provide many benefits for human health. Raw milk also provides almost ideal media for various microorganisms to grow rapidly that can harm human digestion, or make damages the milk itself. In attempt to investigate an appropriate processing technology as an alternative of thermal pasteurization, we developed non thermal corona discharge to eliminate total number of various microorganisms in milk. The generated corona discharge used 7 pins to plate surface configuration. With a distance 15 mm between the electrodes, the applied voltage of 6.48 kV by a homemade high voltage AC power supply yields in corona discharge that has temperature lower than 30°C after 8 minutes operation. The time dependent effects of the implementation of this discharge to raw milk were carried out at time interval 2, 4 and 8 minutes. It was found that there was three different types of bacteria colony morphology in the microorganism population of raw milk. The microorganism counts were decrease for 2 and 4 min corona treatments. However, when the corona treatment was done in 8 min, the total number of microorganism increased significantly. Although the corona discharge shows the potential benefits in milk decontamination processing at low temperature, more detailed study should be carried out to confirm the suitable in real application including the nutrient composition before and after treatment.

Effect of single and combined UV-C and ultra-high pressure homogenisation treatments on inactivation of Alicyclobacillus acidoterrestris spores in apple juice

Alicyclobacillus acidoterrestris is a spore-forming bacterium that can survive thermal pasteurization and acidic conditions. It produces changes in the odour and flavour of fruit juices leading to economical loses. A. acidoterrestris CECT 7094 spores were inoculated in clarified and cloudy apple juices (Golden delicious var.) in the range of 5–6 log10 spores/mL and submitted to different short-wave ultraviolet light (UV-C) doses (7.2–28.7 J/mL) and ultra-high pressure homogenisation (UHPH) treatments (100–300 MPa), including their combination. A. acidoterrestris could be inactivated in clarified apple juice at a level of 4.8 log10 CFU/mL by a 300 MPa-UHPH treatment when the inlet temperature was 80 °C. UV-C treatments showed to be more efficient achieving a lethality of 5.5 log10 CFU/mL with a dose of 21.5 J/mL at 20 °C. In cloudy apple juice (2357 NTU) UV-C treatments were less efficient with a maximum lethality of 4.07 CFU/mL after a dose of 28.7 J/mL. A previous application of UHPH contributed with UV-C to obtain higher reductions of A. acidoterrestris spores at the doses of 14.3 and 21.5 J/mL compared with UV-C single treatments. On the other hand, this previous treatment also changed the properties of particles in the matrix which apparently reduced the effectiveness of UV-C at 28.7 J/mL.

Evaluation of the economic and environmental sustainability of high pressure processing of foods

A comparative evaluation of the environmental/economic performance of High Pressure Processing (HPP) technology for food processing is made using Life Cycle Costing (LCC) and Life Cycle Assessment (LCA) methodologies. Thermal pasteurization (TP), in the form of indirect system (with energy recovery) and of retort process, and modified atmosphere packaging (MAP), are taken as benchmark during the evaluation, as traditional food processing technologies typically used to process orange juice (TP) and sliced Parma ham (MAP). Primary data on costs and consumption of HPP, TP and MAP plants were obtained from companies. Secondary data for LCA analysis was retrieved from the Ecoinvent 3.4 database and from available scientific literature.As a result of the assessment, HPP appears as more expensive than both TP processes, but turns out to have a lower environmental impact in almost all impact categories. Compared to MAP, HPP is less expensive and also has a lower impact in most of the impact categories, as MAP requires a significant amount of packaging materials and food gases. Industrial relevance: High pressure processing (HPP) is a well-known non-thermal technology, which since its introduction has had limited use, mainly due to the high cost of the electricity required for the process. Nowadays, however, new technologies in the food processing and new food product applications could make it more widely used. To correctly evaluate whether HPP technology is actually cost-effective and has low impact on the environment, detailed economic and environmental analyses have been carried out in this paper. Results are expected to enhance the use of HPP technology in industry.

Release of Electrode Materials and Changes in Organoleptic Profiles During the Processing of Liquid Foods Using Pulse Electric Field Treatment

Application of pulsed electric fields (PEFs) is an alternative treatment to thermal pasteurization of liquid foods, which inactivates microorganisms without degrading flavor, texture, and nutrients compared to other conventional technologies. This article scrutinizes the applicability of PEF processing of carbonated beer using a titanium electrode based sealed processing chamber that provides not only effective use of the highest electric field but also eliminates edge effects, and at the same time reduces turbulence by providing steady and uniform flow of the fluid under treatment. The release of metal ions during PEF processing is evaluated by using inductively coupled plasma atomic emission spectrometry (ICP-AES). As metal ions directly affect the organoleptic properties of beer, a sensory evaluation is conducted with the panelists comprised of brewing experts. It has been found that the released amounts of metal ions are lower than the detection levels of ICP-AES, and much lower than what is accepted in consumable foods (<2 parts per billion). Supporting the metal analysis data, the sensory panel also reported nonoff flavors in the PEF-processed beer. The treated and untreated beer samples are aged at 5 °C, 22 °C, and 34 °C for ten days. The shelf-life analysis is conducted for PEF-treated and untreated beer samples. The organoleptic property profile of the beer treated at 4 kV by PEF shows the potential of extending shelf life at least for 90 days. In addition, analytical indicators like the deterioration of trans-iso-α-acids confirm no chemical changes in beer before and after PEF treatment under the conditions studied.

Effects of high hydrostatic pressure on the microbial inactivation and extraction of bioactive compounds from açaí (Euterpe oleracea Martius) pulp.

The aim of this study was to investigate the effects of high hydrostatic pressure (HHP) on the inactivation of Lactobacillus fructivorans, on the inactivation of Alicyclobacillus acidoterrestris spores and on the extraction of anthocyanins and total phenolics from açaí pulp. The tested conditions comprised pressures of 400-600MPa, treatment times of 5-15min, and temperatures of 25°C and 65°C. Results were compared to those of conventional thermal treatments (85°C/1min). Regarding A. acidoterrestris spores, applying HHP for 13.5min, resulted in a value of four-decimal reduction. L. fructivorans presented considerable sensitivity to HHP treatment, achieving inactivation rates above 6.7 log cycles at process conditions at 600MPa and 65°C for 5min. All samples of açaí pulp processed showed absence of thermotolerant coliforms during the 28days of refrigerated storage (shelf life study). The açaí pulps processed by HHP (600MPa/5 min/25°C) had anthocyanin extraction increased by 37% on average. In contrast, conventional thermal treatment reduced anthocyanin content by 16.3%. For phenolic compounds, the process at 600MPa/5min/65°C increases extraction by 10.25%. A combination of HHP treatment and moderate heat (65°C) was shown to be an alternative to thermal pasteurization, leading to microbiologically safe products while preserving functional compounds.

High‐pressure processing, microwave, ohmic, and conventional thermal pasteurization: Quality aspects and energy economics

AbstractIn this work, we collect and compare product quality data (vitamin C and flavor compounds) for orange juice processed using conventional thermal and innovative (high pressure, microwave, and ohmic) technologies under commercially representative conditions. We also measure and compare their respective energy demands and associated costs. While significant efficiency gains are made due to electrification using the innovative technologies (especially the ohmic process), the high per‐unit costs of grid electricity results in poorer processing economics relative to conventional gas‐fired technologies. UK levelized cost of electricity (LCOE) data suggest that as the share of renewables in the electricity generation energy mix is increased, the innovative technologies will eventually become more economical, in addition to the significant greenhouse gas emission reductions per liter of product. No significant differences are observed in the quality attributes of the processed product across all the technologies. The innovative electricity‐driven technologies are thus promising alternatives to conventional thermal pasteurization.Practical applicationsBeverage processing by conventional thermal treatment is energy consuming and can adversely affect the sensory and nutritional quality attributes of the final product. Innovative, mild processing techniques such as high‐pressure processing, microwave, and ohmic heating are increasingly gaining industry attention due to their potentials to significantly address these challenges. Actual uptake is still relatively low due to factors including risk aversion, process validation issues, and economics. This work compares these technologies with conventional thermal treatment in terms of critical product quality attributes (vitamin C and flavor compounds) and process energy economics under commercially representative processing conditions. The results of this study will be useful as a guide to food processors for implementing the innovative technologies and could lead to new product development and process optimization.

Evaluation of thermal and nonthermal treatment of margarine: Pasteurization process efficiency, kinetics of microbial destruction, and changes in thermophysical characteristics

The objective of this study was the thermophysical characterization and microbial evaluation of the commercial margarine production process. Thermal destruction of Escherichia coli (K-12) was characterized between 60 and 70°C with a decimal reduction time (D value) between 4.44 and 0.22 min and a Z value of 7.72°C. Pulsed light treatment as a nonthermal alternative was used for comparison; however, the effectiveness was very weak with a 90% surface decontamination yield after 20 s of high-intensity pulsed light treatment. Rheological studies showed a two-stage flow behavior due to the melting phenomenon of margarine and the use of the Arrhenius model yielded an activation energy of 186.3 and 15.0 (kJ/mol) before and after a phase transition point at 36.6°C, respectively. The differential scanning calorimetric studies showed three main peaks related to the melting of unsaturated fats (−22.0°C), melting of brine phase (−6.1°C), and melting of saturated fats (31.3°C). The holding tube length was calculated based on the physical properties of margarine and different Reynolds numbers. Practical applications Margarine production is still a growing industry and nowadays many novel approaches are used for pasteurization purposes and hence the evaluation of process efficiency and product characterization is desirable. In this regard, the present work provides helpful data for te margarine production by adjusting a practical approach toward evaluating the thermal pasteurization efficiency. In addition, the evaluated thermophysical characterization of margarine presents a scientific basis for the research and development in terms of product formulation and thermal/nonthermal process adaptations.

Impact of ozone processing on microbiological, physicochemical, and bioactive characteristics of refrigerated stored Cantaloupe melon juice

The objective of this study was to evaluate the impact of ozone treatment on microbiological decontamination (intrinsic microflora and inoculated Listeria innocua) and some physicochemical characteristics and bioactive compounds of Cantaloupe melon juice, also during refrigerated storage. To determine adequate ozone exposure, the survival curve of L. innocua was previously assessed. A thermal treatment was also performed seeking comparison with ozone treatment impact. After ozone exposure, L. innocua was not detected in juice samples, while thermal pasteurization allowed a reduction of 5.2 ± 0.2 log cycles. Although ozone reduced the intrinsic microflora loads, this reduction was higher for heat‐treated samples. Vitamin C was highly retained in ozone‐treated juices (68%), when compared with the pasteurized ones (39%). After 13 days of storage, ozone allowed the retention of the most quality parameters analyzed and, therefore, it can be considered as a promising alternative to traditional pasteurization of Cantaloupe melon juice. PRACTICAL APPLICATIONS: The actual consumers' demand for high‐quality food standards has launched research to alternative and milder nonthermal processes, which have gained increasing attention and importance in the fruit juice industries. Ideally, preservation and/or processing of foods should involve technologies that prevent undesirable microbial survival and minimize quality attributes changes and nutrient losses. Thermal treatments are conventionally used to attain such targets; however, the content and the biological activity of the most health‐related compounds are dramatically reduced. In this context, and particularly in the beverages industries, ozone has been exploited due to its potential for inactivating spoilage and pathogenic microorganisms, while being effective in overall quality retention of the products.

Effects of ohmic heating on technological properties of whole egg

Abstract The aim of this work was to study the effects of different ohmic heating conditions on color, rheology, foaming, and gelling properties of whole egg. Industrial products treated by conventional heat pasteurization and the corresponding raw materials were also evaluated. Ohmic treatments accomplished in a static cell (65.5 °C × 3 min, 70 °C × 1 min, and 67 °C × 4.5 min) increased whole egg apparent viscosity (up to 190%), but also foam overrun (up to 28%) and gel hardness (up to 15%). The performance improvement was confirmed by treatments carried out in a continuous pilot plant (71 °C × 0.6 min, 68 °C × 1.4 min) and the products resulted stable during storage at 4 °C for 30 days. In conclusion, this study demonstrated that ohmic heating is a suitable alternative to conventional pasteurization. Low temperature treatments are preferable to avoid possible rheological issues due to protein denaturation. Industrial relevance Whole egg is a protein ingredient with multiple technological properties, used in many foods. Due to safety reasons, food manufacturers often use pasteurized liquid egg products, microbiologically safer and easier to handle with respect to shell eggs. In order to satisfy the required sanitary levels for liquid egg products, thermal pasteurization treatments are needed. However, since egg proteins are very sensitive to high temperatures, attention must be paid to avoid coagulation entailing deleterious effects against egg quality. In this study, different ohmic heating treatments were evaluated as milder alternatives to conventional pasteurization. The lab- and pilot-scale experiments and the subsequent statistical analyses of the obtained results contributed to assess the effects of the different ohmic treatments on technological features (e.g. color, rheology, foaming, and gelling properties) of liquid whole egg. This study demonstrated that ohmic heating is a suitable technology for whole egg treatment, paving the way for new opportunities in order to produce safe food ingredients with improved technological functionalities.

Identification of equivalent processing conditions for pasteurization of strawberry juice by high pressure, ultrasound, and pulsed electric fields processing

Abstract The objective of this study was to evaluate the effectiveness of high pressure processing (HPP), ultrasound (US) and pulsed electric fields (PEF) for the pasteurization of strawberry juice (SJ). Acid-adapted Escherichia coli was used to inoculate SJ prior to treatment with HPP, US, and PEF. HPP was applied at several pressures (200–400 MPa) up to 2 min while US (120 μm, 24 kHz) was conducted at 25, 40, and 55 °C up to 10 min in continuous pulsing mode. In order to avoid excessive use of SJ, PEF was performed using a model solution (MS) basically composed of citric acid (8 g/L), fructose (35 g/L), glucose (35 g/L), Na2HPO4 (0.2 M) and NaCl (5%) to simulate the SJ electrical conductivity, pH, and total soluble solid (TSS). A face-centered composite design was conducted for PEF processing at different electric field intensities (EFI) (25–35 kV/cm) and treatment times (5–27 μs). Processing conditions were selected that resulted in 5-log CFU/mL inactivation of E. coli. HPP at 300 MPa for 1 min, and US at 55 °C (thermosonication) for 3 min reduced E. coli in SJ by 5.75 ± 0.52 and 5.69 ± 0.61 log CFU/mL, respectively. PEF treatment at 35 kV/cm, 27 μs treatment time, 350 mL/min flow rate, and 2 μs pulse width in monopolar mode resulted in 5.53 ± 0.00 log reduction of E. coli in MS. Likewise, E. coli population in SJ was also reduced by 5.16 ± 0.15 log after applying the same PEF conditions to SJ. No E. coli was detected in SJ subjected to conventional thermal pasteurization at 72 °C for 15 s. All technologies reduced the natural microbiota below 2 log CFU/mL in terms of the total aerobic bacteria and yeast-mold counts. Thus, this study identified the equivalent conditions for the SJ pasteurization by three nonthermal processing technologies. Industrial relevance Consumers have an increasing interest towards fresh-like food products with desirable nutritional and sensorial attributes. High pressure, ultrasound and pulsed electric field are three relevant novel nonthermal technologies as alternatives to conventional thermal treatments. This study identified the processing conditions of these three nonthermal technologies for the pasteurization of strawberry juice based on equivalent inactivation of acid-adapted E. coli. From an industrial point of view, the established processing conditions are useful references for the development of novel berry juices. In addition to microbiological safety, this study on equivalent processing allows direct efficacy and quality comparisons of a given juice pasteurized by the three nonthermal technologies under consideration.

Overview of hygienization pretreatment for pasteurization and methane potential enhancement of biowaste: Challenges, state of the art and alternative technologies

Hygienization reduces the public health risks involved in the application of biowaste to agricultural land. Recent advances in the hygienization of treated biowaste have not been reviewed to date. In many countries, the process involves using low temperature thermal pasteurization. Thermal hygienization accounts for between 6% and 25% of primary energy production in European biogas plants. Hygienization pretreatment can also influence the production of biogas by the treated substrates (from a slight negative effect to a biogas yield surplus of 50% in most cases). Alternative athermal pasteurization technologies (including electro-technology, microwave, pressurization, ultrasound and chemical treatment) have been shown to be capable of considerably reducing the number of bacteria and increasing the methane yield. The performance of these alternatives varies greatly and depends on the type of biowaste, the operational parameters studied, energy input and the method of interpreting the experimental results. Analyses of energy and exergy efficiency, of environmental impacts and of economic feasibility show that thermal hygienization may be the most energy efficient and economical approach when it exploits the wasted heat recovered from other processes. The present study also revealed that the research focus has been confined to the sewage sludge. Studies on the other biowaste, including animal by-products, are needed.

Pasteurization of verjuice by UV‐C irradiation and mild heat treatment

AbstractVerjuice is a highly acidic juice and more prone to yeast spoilage. In this study, the efficacy of individual and combination processes of UV‐C irradiation (UV) and mild heat treatment (MH) for pasteurization of verjuice were assessed. Saccharomyces cerevisiae (NRRL Y‐139) was selected as the target microorganism and kinetic parameters for MH, UV, and combined UV + MH inactivation treatments were determined. The UV treatment alone at a UV dose of 0.57 J/cm2 (energy of 2.30 J/mL), provided only 0.54 ± 0.02 log CFU/mL reduction of S. cerevisiae. In contrast, the combined treatment (UV + MH2) substantially reduced the number of S. cerevisiae in verjuice, 5.16 ± 0.24 log CFU/mL reduction was achieved at 0.25 J/cm2 UV dose (energy of 1.01 J/mL) and 51.25 ± 1.47°C. The percentage of synergism for the UV + MH inactivation of S. cerevisiae in verjuice was maximized at 51.25°C (50.79% of synergistic effect). Inactivation kinetics of S. cerevisiae was best described by Weibull model with the smallest RMSE and AIC values. D value was decreased from 13.66 to 1.94 min when UV was combined with mild heating. The results showed that UV‐C light assisted by mild heat treatment can be a potential alternative to thermal pasteurization of verjuice.Practical applicationsFruit juices are prone to spoilage by yeasts, molds, and some acid‐tolerant bacteria. Saccharomyces cerevisiae is a heat resistant spoilage microorganism and found in some spoiled juices. Thermal pasteurization is widely used for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. This study illustrated that the combined UV‐C light assisted by mild heat treatment can deliver the required microbial reduction in verjuice. The synergistic effect of two processing methods is suggested for controlling the growth of spoilage microflora of fruit juices.

Effect of Voltage and Frequency in Pasteurization Pulsed Electric Field (PEF) Continous System of Pineapple (Ananas comosus [L.] Merr) Juice

Pineapple which is one of the perishable commodities with high water content about 90.73% in 100 gr of fresh material. Thermal pasteurization has a weakness that can degrade the quality of fruit juice products. In contrast, non thermal processes have expectations which is don’t make decreasing quality of the product. One of the non-thermal pasteurization type called Pulsed Electric Field (PEF). Nowadays, PEF system have two type batch and continous, which respectively used in this research is PEF continous system. This study uses research methods group random design (GRD) with two factorial that voltage (20, 30 and 40 kV) and frequency (10, 20, 30 and 40 kHz). Based on these studies it is known that the voltage and frequency is significantly different to the value of Total Plate Count (TPC), and absorbance. However there aren’t significantly different with the pH, vitamin C, viscosity, total dissolved solid (TDS), total sugar and color. The treatment based on the microbial test are at a voltage of 40 kV and a frequency of 40 kHz which can reduce bacteria significantly 1.01x103 cfu/mL or 0.94 by log cycle with the effectiveness of microbial death by 88.5%. The treatment based on the microbial test are at a voltage of 40 kV and a frequency of 30 kHz which The result indicates that physical and chemical characteristic of pineapple juice become 3.98 of pH, total dissolved solid (TDS) of 6.25 °brix, total sugar of 14.75 % viscosity of 3 cp, vitamin C of 7.6 mg/100ml, absorbance of 0.67, color on the brightness (L*) value of 24.05, redness (a*) of 6.35, and yellowish (b*) of 7.5. This result shows that PEF continuous respectively work system to pasteurize the pineapple juice.

Innovative Techniques of Processing Human Milk to Preserve Key Components.

Human milk not only contains all nutritional elements that an infant requires, but is also the source of components whose regulatory role was confirmed by demonstrating health-related deficiencies in formula-fed children. A human milk diet is especially important for premature babies in the neonatal intensive care unit (NICU). In cases where breastfeeding is not possible and the mother’s own milk is insufficient in volume, the most preferred food is pasteurized donor milk. The number of human milk banks has increased recently but their technical infrastructure is continuously developing. Heat treatment at a low temperature and long time, also known as holder pasteurization (62.5 °C, 30 min), is the most widespread method of human milk processing, whose effects on the quality of donor milk is well documented. Holder pasteurization destroys vegetative forms of bacteria and most viruses including human immunodeficiency virus (HIV) herpes and cytomegalovirus (CMV). The macronutrients remain relatively intact but various beneficial components are destroyed completely or compromised. Enzymes and immune cells are the most heat sensitive elements. The bactericidal capacity of heat-pasteurized milk is lower than that of untreated milk. The aim of the study was for a comprehensive comparison of currently tested methods of improving the preservation stage. Innovative techniques of milk processing should minimize the risk of milk-borne infections and preserve the bioactivity of this complex biological fluid better than the holder method. In the present paper, the most promising thermal pasteurization condition (72 °C–75 °C,) and a few non-thermal processes were discussed (high pressure processing, microwave irradiation). This narrative review presents an overview of methods of human milk preservation that have been explored to improve the safety and quality of donor milk.

Anthocyanins, non-anthocyanin phenolics, tocopherols and antioxidant capacity of açaí juice (Euterpe oleracea) as affected by high pressure processing and thermal pasteurization

Abstract We studied the effect of high pressure processing (HPP) (400, 450, 500, and 600 MPa/5 min/20 °C) and thermal pasteurization (85 °C/1 min) on anthocyanins, non-anthocyanin phenolic compounds, tocopherols and antioxidant capacity toward oxygen and nitrogen reactive species of acai juice. HPP was more effective for the preservation of anthocyanins than thermal pasteurization (up to 40%), probably due to its thermal-sensitivity. A significant increase was observed for the non-anthocyanin compounds' content at 500 MPa, possibly related to cell wall rupture due to the applied pressure. As a result, this sample showed greater antioxidant capacity (ORAC and total phenolic compounds). On the other hand, H2O2 scavenging capacity, tocopherols and vitamin E activity were not affected, whereas scavenging capacity against HOCl and NOC formation was not well correlated with bioactive compounds concentration. Nevertheless, these properties were effectively preserved in HPP treatments. These results indicate that HPP may provide acai juice with high functional quality. Industrial relevance Acai juice (AJ) has been increasingly valued worldwide due to its bioactive compounds and health-promoting effects, however, thermal pasteurization (TP), usually applied to AJ preservation, may cause degradation of these compounds and damage AJ bioactivities. Our results contribute to understanding how the main bioactive compounds and functional properties of AJ are affected by high pressure processing (HPP) and TP. In addition, they represent an important advance in the field of emerging preservation technologies as it indicates optimal high pressure conditions for AJ processing. Ultimately, given that HPP adds values to food products, our results may be used by the food industry to produce new acai-based formulations with high market value.