Non-thermal Food Processing Technology Research Articles

Sono-physical and sono-chemical effects of ultrasound: Primary applications in extraction and freezing operations and influence on food components.

Ultrasound is an advanced non-thermal food-processing technology that has received increasing amounts of interest as an alternative to, or an adjuvant method for, conventional processing techniques. This review explores the sono-physical and sono-chemical effects of ultrasound on food processing as it reviews two typical food-processing applications that are predominantly driven by sono-physical effects, namely ultrasound-assisted extraction (UAE) and ultrasound-assisted freezing (UAF), and the components modifications to food matrices that can be triggered by sono-chemical effects. Efficiency enhancements and quality improvements in products (and extracts) using ultrasound are discussed in terms of mechanism and principles for a range of food-matrix categories, while efforts to improve existing ultrasound-assist patterns was also seen. Furthermore, the progress of experimental ultrasonic equipments for UAE and UAF as food-processing technologies, the core of the development in food-processing techniques is considered. Moreover, sono-chemical reactions that are usually overlooked, such as degradation, oxidation and other particular chemical modifications that occur in common food components under specific conditions, and the influence on bioactivity, which was also affected by food processing to varying degrees, are also summarised. Further trends as well as some challenges for, and limitations of, ultrasound technology for food processing, with UAE and UAF used as examples herein, are also taken into consideration and possible future recommendations were made.

The effects of atmospheric cold plasma on inactivation of Listeria monocytogenes and Staphylococcus aureus and some quality characteristics of pastırma—A dry-cured beef product

In this study the effectiveness of cold atmospheric plasma (CAP) in inactivating two bacterial pathogens on inoculated pastırma was investigated. In addition, the effect of this treatment on the total mesophilic aerobic bacteria (TMAB) and yeast–mold counts was also observed. Pastırma samples were inoculated with Staphylococcus aureus and Listeria monocytogenes and subjected to CAP applications using oxygen (100%), argon (100%) and two oxygen/argon mixtures (25%O 2 /75%Ar and 50%O 2 /50%Ar) for 180 and 300 s. Maximum reduction of 0.85 log CFU/cm 2 for S. aureus counts and 0.83 log CFU/cm 2 for L . monocytogenes counts were found from starting level of 5.78 and 5.71 log CFU/cm 2 , respectively. However, it was determined that the TMAB and yeast–mold counts were reduced by 1.41 log CFU/cm 2 and 1.66 log CFU/cm 2 , respectively. It was found that pastırma samples had a 7.34% decrease in moisture content as a result of CAP application due to evaporated water from the sample's surface. In the light of these results, this study showed that cold atmospheric plasma can be used to lower levels of S. aureus and L . monocytogenes in pastırma. Thermal treatments can cause sensory and nutrient changes in meat products. Non-thermal food processing technologies are innovative applications that continue to attract attention. Cold plasma, which is one of the non-thermal technologies, is environmentally friendly and causes minimal changes to treated products. In this study, cold atmospheric plasma treatment was effective against S. aureus and L . monocytogenes inoculated on pastırma and reduced their counts. Moreover, it also succeeded in reducing counts of TMAB and yeast–mold in the pastırma. • CAP reduced numbers of S. aureus by maximum 0.85 log from starting level of 5.78 log CFU/cm 2 • CAP decreased numbers of L. monocytogenes by maximum 0.83 log from starting level of 5.71 log CFU/cm 2 • Inoculation levels 4.70 log CFU/cm 2 of yeast-mold count decreased by 1.66 log with CAP application

Inactivation of Potato Polyphenol Oxidase Using Microwave Cold Plasma Treatment.

This study was conducted to examine the effects of microwave cold plasma (CP) treatment on inactivation of polyphenol oxidase (PPO) of potato. The PPO activity and treatment variables were fit to first-order kinetics, the Weibull model, and the second-order model. The optimum CP-generation power and treatment time for inactivating PPO in the PPO extract were found to be 900 W and 40 min, respectively, which resulted in the highest inactivation of PPO (49.5%). PPO activity after CP treatment of potato slices decreased from 72.4% to 59.0% as the sample surface-to-volume ratio increased from 7.1 to 9.0. CP treatment delayed the browning of potato slices. Microwave CP treatment effectively inactivated PPO in potatoes, demonstrating the potential of CP treatment for controlling PPO activity in foods. PRACTICAL APPLICATION: This study demonstrated that microwave CP treatment, a nonthermal food processing technology, inactivates PPO activity in potatoes. The results showed that the inactivation effect of CP treatment on PPO corresponded to the surface-to-volume ratio of potato slices. Furthermore, this study proposed an enzyme inactivation model that is suitable for predicting the inactivation of PPO activity and confirmed that CP treatment delayed browning in potatoes.

Anti-Inflammatory Effects of High Hydrostatic Pressure Extract of Mulberry (Morus alba) Fruit on LPS-Stimulated RAW264.7 Cells.

Mulberry fruit (Morus alba L.) contains abundant bioactive compounds, including anthocyanins and flavonols, and has been reported to possess potent beneficial properties including anticancer, antidiabetic, and anti-oxidant effects. High hydrostatic pressure (HHP) processing, a nonthermal food processing technology, is suitable for the extraction of bioactive compounds from plants. Nevertheless, the anti-inflammatory effects of HHP extract of mulberry fruit (HM) in RAW264.7 cells remain unclear. The present study aimed to investigate the anti-inflammatory effects of HM on lipopolysaccharide (LPS)-induced inflammation in vitro. RAW264.7 cells were treated with various concentrations (0.1–1 μg/mL) of HM in the presence or absence of LPS. HM inhibited the inflammatory mediator, nitric oxide (NO) release, and mRNA expression of nitric oxide synthase 2 (NOS2) in LPS-induced RAW264.7 cells. In addition, HM suppressed both mRNA and protein expressions of prostaglandin-endoperoxide synthase 2 (PTGS2). Moreover, it reduced the LPS-induced secretion of proinflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α. These results revealed that HM exerts anti-inflammatory effects by inhibiting several mediators and cytokines involved in the inflammatory process.

Microwave-dried or air-dried? Consumers' stated preferences and attitudes for organic dried strawberries. A multi-country investigation in Europe

Non-thermal food processing technologies are becoming more important in the organic food sector because, beyond preserving the organic feature, they could offer organic products with additional benefits in terms of enhanced nutritional content and healthiness as well as better sensory properties that could satisfy the more complex demands of organic consumers. Berries have a well-known health benefits and show increasing market shares in European markets while dehydration can increase the food convenience in terms of extended shelf-life. This study investigates for the first time organic consumers' stated preferences, attitudes and individual differences for a non-thermal organic processing technology. Specifically, we investigated consumers' preferences for organic dried strawberries varying in drying technology used, such as the most conventional (i.e. thermal) air drying and the most innovative (i.e. non-thermal) microwave drying, origin, price levels, and nutrient contents in three European countries: Norway, Romania and Turkey. Data from a total of 614 consumers were collected through an online choice experiment. Results show that on average consumers prefer organic dried strawberries produced with air drying technology that have national origin, with natural nutrient content and at low price, but country and individual differences are identified. Consumers who showed least rejection for microwave dried products are young, mostly from Norway and have higher positive attitudes towards new food technologies. Consumers who showed most rejection for microwave dried products are older, mostly from Turkey and have higher positive attitudes for organic, natural and ecological products. Organic producers who adopt microwave drying might better inform consumers about the characteristics, the process and highlight the nutritional benefits of such technology. Finally, this research informs policy makers about the need to define and regulate more clearly microwave drying as an organic technology, as well as to regulate labelling to ensure that consumers are not misled and correctly informed about the new technology.

Effect of cold plasma on storage toxigenic fungi - Aspergillus flavus : Poster

Cold plasma is a novel non-thermal food processing technology that uses energetic, reactive gases to inactivate contaminating microorganisms such as fungi and bacteria. This flexible sanitizing method uses electricity and a carrier gas (air, oxygen, nitrogen, or helium) antimicrobial chemical agents are not required. The primary modes of action are due to UV light and reactive chemical products of the cold plasma ionization process. Aspergillus flavus is the predominant species responsible for fungal contamination and subsequent production of aflatoxins mainly in grains during postharvest operations and storage. Due to their relatively high contamination risk, decontamination methods for fungi are of great interest for economic and environmental reasons, as well as in public health. Improved post-harvest processing followed by further prevention of fungal growth is an effective way to restrict aflatoxin contamination and would have major impact on reducing health related risks and on production economics. Thus, the objective is to evaluate the inactivation of A. flavus by cold plasma. The experiment was conducted with 3 mm sample A. flavus in PDA culture medium. Plasma was applied at different durations (2, 5, 10, 12, 15 and 20 min). After application, the Petri dishes with treated samples were stored at 25°C for 6 days. There was fungal growth after 2 days in the treatments with2 and 5 min durations, 4 days with the treatments with 10 and 12 min durations and there was no fungal growth with the treatments of 15 and 20 min after 6 days. The durationof 15 and 20 min with the plasma parameters tested, were efficient for the inactivation of A. flavus. Cold plasma may be a promising green method to be applied in this microorganisms present in grains and other products during storage.

Ultraviolet-C resistance of selected spoilage yeasts in orange juice

This study determined the ultraviolet-C (UV-C) dose necessary to reduce 90% population (DUV-C) of 17 spoilage yeasts and their composited inoculum in orange juice (pH 3.71, 11.60 °Brix, 0.55% citric acid, 2.46% w/v insoluble solids). Growth parameters of all test yeasts were first established to standardize the growth stage of the cells prior to harvesting and eventual UV-C challenge studies. Approximately 4–5 log CFU/ml cells in the mid-stationary growth phase (30.3 t0 39.9 h, 25 °C) were suspended in 4 ml turbulent flowing juice and subjected to UV-C irradiation at an incident surface irradiance of 3.64–4.97 mW/cm2. The inactivation rates of each yeast and their composited inoculum were determined using 2 methods namely, the linear regression and Baranyi and Roberts (1994) model-fitting. Results showed that the yeasts exhibited either log-linear or biphasic inactivation behavior with downward concavity or inactivation lag. Regardless of the method of determination, Cryptococcus albidus (LJY1) exhibited the significantly greatest (p < 0.05) UV-C resistance with DUV-C values of 1924.31 and 2174.63 mJ/cm2. On the other hand, Candida parapsilosis was determined to be least resistant with a DUV-C values of 245.83 and 357.88 mJ/cm2. Majority of the DUV-C values determined from the model-fitting were greater than those calculated from linear regression. However, only those determined for the composited inoculum were significantly different. The results of this study address knowledge gaps pertinent to the UV-C resistance of less studied spoilage yeast, and help in better understanding the utility of this non-thermal food processing technology.

Predictive modeling for 5‐hydroxymethylfurfural formation by some application conditions of high hydrostatic pressure, namely glucose concentration and application temperature, in high glucose containing model beverages

AbstractHigh hydrostatic pressure (HHP) is a nonthermal food processing technology. Many studies have shown that HHP may be used as a process to increase the shelf life of beverages, which are inherently containing glucose or subsequently glucose added. Depending on food processing technologies and storage conditions 5‐hydroxymethylfurfural (5‐HMF) formation from glucose in foods occurs. There are some limitations about the amount of the 5‐HMF present in foods based on World Health Organization and various International Standards, such as European Commission Directive 2007/196/EC. The aim of this study is to present the effect of glucose concentration and HHP in 5‐HMF formation in model beverages with different glucose concentrations (10, 40, and 70 g/200 mL). A strong positive correlation was observed between 5‐HMF formation and glucose concentration (R = 0.6055) and application temperature (R = 0.6774). Also a predictive analysis model was fitted to the 5‐HMF formation response by response surface model (RSM).Practical applicationsThe equation obtained as a model in this study can be used to calculate the formation of 5‐HMF for a glucose containing beverages processed by HHP as a response of glucose concentration and application temperature within the conditions of the study. The model was calibrated and validated on glucose containing model beverages, which are representatives of some high glucose containing beverages. HMF content is an important parameter and should be included as one of the quality parameters for commercial beverages. Because of that, this equation has an importance especially for the beverage producers, who process their product by HHP, to predict 5‐HMF formation by controlling glucose concentration and HHP treatment conditions. Moreover, developed model can easily be adapted to the standard procedures of academic and industrial applications.

Current status of emerging food processing technologies in Latin America: Novel non-thermal processing

Non-thermal emerging technologies in the sector of food processing have often been cited by researchers as an alternative to conventionally heat treatments for food processing in order to develop safe foods with minimal damage to nutritional and sensory properties. Non-thermal emerging technologies for foods processing have been widely developed in Europe and U.S.A. However, the interest in these technologies and commercialisation opportunities started catching up in Latin America. Thus, this review describes the basic principles and main effect of this technologies in the food and the recent scientific reports on its applications and potential advantages of the so-called non-thermal emerging technologies like ultrasound, high hydrostatic pressure, pulsed electric field, ionising radiation and atmospheric cold plasma, as alternative food preservation process. This review focuses on the current status in Latin America of novel non-thermal food processing technologies, highlighting the limits for scaling up to industrial level in order to be commercially successful.

Nonthermal Processes for Shelf‐Life Extension of Seafoods: A Revisit

For the past two decades, consumer demand for minimally processed seafoods with good sensory acceptability and nutritive properties has been increasing. Nonthermal food processing and preservation technologies have drawn the attention of food scientists and manufacturers because nutritional and sensory properties of such treated foods are minimally affected. More importantly, shelf-life is extended as nonthermal treatments are capable of inhibiting or killing both spoilage and pathogenic organisms. They are also considered to be more energy-efficient and to yield better quality when compared with conventional thermal processes. This review provides insight into the nonthermal processing technologies currently used for shelf-life extension of seafoods. Both pretreatments such as acidic electrolyte water and ozonification and processing technologies, including high hydrostatic pressurization, ionizing radiation, cold plasma, ultraviolet light, and pulsed electric fields, as well as packaging technology, particularly modified atmosphere packaging, have been implemented to lower the microbial load in seafood. Thus, those technologies may be the ideal approach for the seafood industry, in which prime quality is maintained and safety is assured for consumers.

Chemical Modifications of Lipids and Proteins by Nonthermal Food Processing Technologies.

A range of nonthermal techniques have demonstrated process efficacy in ensuring product safety, extension of shelf life, and in general a retention of key quality attributes. However, various physical, chemical and biochemical effects of nonthermal techniques on macro and micro nutrients are evident, leading to both desirable and undesirable changes in food products. The objective of this review is to outline the effects of nonthermal techniques on food chemistry and the associated degradation mechanisms with the treatment of foods. Oxidation is one of the key mechanisms responsible for undesirable effects induced by nonthermal techniques. Degradation of key macromolecules largely depends on the processing conditions employed. Various extrinsic and intrinsic control parameters of high-pressure processing, pulsed electric field, ultrasound processing, and cold atmospheric plasma on chemistry of processed food are outlined. Proposed mechanisms and associated degradation of macromolecules, i.e., proteins, lipids, and bioactive molecules resulting in food quality changes are also discussed.

Effects of High Pressure Processing on Bioavaliability of Food Components

Today’s consumers are more aware of benefits and health-related effects of food and food compounds, and would like to get benefit of health promoting effects from the food consumed. It is well known that food can be deteriorated by microbiological, chemical and physical factors that their health-promoting effect of food as well as their bioavailability are diminished or lost. Food are processed to extend the shelf-life with elimination of the detrimental effects, but most common food processing technologies cause denaturation of health-promoting compounds resulting in a decrease in food bioavailability. Thus, alternative technologies preserving nutritional and health-promoting effect of food and food compounds come forward. High pressure processing (HPP) as one of the leading nonthermal food processing technologies provides safety of food with fresh-like properties with minimal lost on nutritional and sensory properties; however, limited number of studies involve bioavailability of these compounds.

Modification of starch using low pressure radio frequency air plasma

Cold plasma is one of the emerging nonthermal food processing technologies recently drawn interest as a chemical-free biopolymer modification method. In the present study, two starches (corn and tapioca) were exposed to low pressure radio frequency plasma at 40 W and 60 W for 10 and 20 min. The effect of air plasma treatment on the starch properties was determined by measuring amylose content, swelling power, powder flowability properties, gelatinization temperatures and pasting properties. The amylose content of corn and tapioca starches was observed to decreased and increased respectively. Increase in water binding capacity and swelling power of both starches. The results of pH showed partial oxidation of starches as evident from the decrease in pH. Rapid visco analyzer showed an increase in final viscosities after the plasma treatment. The increase in viscosities is the result of higher amounts of leach out of particles from the starch granules. Plasma treated corn starches exhibited lower peak temperatures and enthalpies whereas it increased in tapioca starches. X-ray diffractogram revealed an A-type pattern of both starches and plasma treatment did not show any significant effect on the crystallanity pattern. Cold plasma offers a unique route for starch modification without affecting its bulk properties.

Color change of orange and carrot juice blend treated by non‐thermal atmospheric plasma

Dielectric barrier discharge (DBD) atmospheric plasma treatment is an innovative non-thermal food processing technology. There is an abundant body of research on the effectiveness in inactivation of foodborne pathogens on fresh fruit and vegetable produce with atmospheric air DBD plasma. However, studies that disclose plasma interactions with fruit or vegetable juices are scarce in number to the knowledge of the author. Color changes of orange and carrot juice blend due to atmospheric air DBD plasma treatment have been examined to estimate the extent of juice changes after treatments at varying durations of 5 s,15 s, and 30 s. Results indicate potentiality of cloud loss reduction, while treatments can cause minor degradation of color attributes. However, browning of treated samples was not observed. The influence of this new non-thermal treatment on measured properties of orange and carrot juice blend shows promising results which need to be further confirmed and established. Practical applications The work described in this research offers an innovative treatment of orange and carrot juice blend with atmospheric air DBD plasma. This article assesses the suitability of atmospheric air DBD plasma to be used in orange and carrot juice blend, and its effects on color attributes. The results indicate the potential of treatment as a browning inhibitor in orange and carrot juice blend during processing which could be of practical industrial relevance.

Application of innovative technologies, moderate-intensity pulsed electric fields and high-pressure thermal treatment, to preserve and/or improve the bioactive compounds content of pumpkin

Abstract The application of novel technologies such as moderate-intensity pulsed electric fields (MIPEF) and/or high pressure thermal (HPT) treatments improved the quality of processed pumpkin. MIPEF was applied to whole pumpkin in order to increase the bioactive compounds content, in contrast, HPT treatment was applied in order to preserve the purees. Traditional thermal treatment (TT) of pasteurization and sterilization was compared with equivalent HPT treatments. The effect of processing (TT vs. HPT) in purees made from pumpkin pretreated with MIPEF was evaluated. Microbiological counts, enzyme inactivation (polyphenol oxidase, PPO) and bioactive compounds content (carotenoids, phenolic compounds and antioxidant activity) were analyzed in all processed purees. Regarding the pretreatment of the pumpkin, the application of MIPEF increased the content of some bioactive compounds of interest, such as carotenoids. The HPT treatment equivalent to sterilization preserved high levels of carotene compounds and antioxidant activity of pumpkin puree although this treatment importantly modified the original color of puree. However, the HPT treatment equivalent to pasteurization did not inactivate PPO enzyme in contrast to the effect reached by the equivalent TT. The bioactive compounds levels in HPT treated puree were similar or lower than those treated by TT. Industrial relevance Pulsed electric fields and high pressure thermal processing are emerging non-thermal food processing technologies. Moderate-intensity pulsed electric fields (MIPEF) were applied to increase the generation of bioactive compounds in vegetables. This treatment enhanced the carotenoids content in pumpkin. High pressure thermal treatment (applied at conditions equivalent to sterilization) was the method that best preserved pumpkin purees. The application of MIPEF to pumpkin and HPT treatment to the resulting purees could be proposed as a strategy for producing and preserving vegetable products with high bioactive compounds content.

Active packaging using an olive leaf extract and high pressure processing for the preservation of sliced dry-cured shoulders from Iberian pigs

Abstract The effect of an active packaging (AP) based on olive leaf extract and/or high pressure processing (HPP) was evaluated for the preservation of sliced Iberian dry-cured shoulders during storage. Shoulders came from Iberian pigs (100%) reared outdoors in the Dehesa and fed with acorns and pasture. Dry-cured shoulders were sliced and vacuum packaged in an active packaging with olive leaf extract. HPP at 600 MPa for 7 min was applied to packages and microbiological, color, oxidative and sensory changes were evaluated during 150 days of refrigerated storage. High reductions of microbial counts were found after HPP and the subsequent storage. Instrumental color parameters of dry-cured shoulder were similar in control and AP and/or HPP, and values were stable during storage. Neither AP and/nor HPP modified lipid oxidation values; and during refrigerated storage similar increases of TBA-RS were found in all treatments. Protein oxidation did not show significant differences among treatments, however, protein oxidation was not modified during storage. Most sensory parameters (appearance, taste, flavor and texture) did not show significant differences due to AP and/or HPP. Therefore, AP with olive leaf extract was not effective to preserve sliced dry-cured shoulder alone or combined with HPP. HPP was effective to decrease microbial counts, also, oxidative, color and sensory parameters were not affected after processing and after 150 days of refrigerated storage. Likely oxidative characteristics of shoulders from pigs reared outdoors would be partly responsible of the high stability of this product during processing and storage. Industrial relevance The demand of sliced dry-cured Iberian ham has importantly increased in the last years. During the slicing and packaging, the shelf-life and the safety of the hamcan be reduced. Industrial sector demands new methods to prolong the shelf-life and maintain the original quality of sliced ham during storage. The utilization of an active packaging with antioxidant and antimicrobial properties could increase the shelf-life of this product. Hydrostatic high pressure processing is a non-thermal food processing technology which allows the inactivation of pathogens. The combined effect of both methods (processing and packaging) could improve the antimicrobial effect while preserve the quality after processing to enhance the shelf-life of the product.

Color development, physiochemical properties, and microbiological safety of pork jerky processed with atmospheric pressure plasma

Abstract We investigated the applicability of atmospheric pressure plasma (APP) as an alternative to sodium nitrite in pork jerky manufacturing. Pork slices were marinated in brine with no sodium nitrite at 4 °C for 16 h and treated by APP for 0, 20, 40, and 60 min, respectively. The sample marinated in the brine with sodium nitrite (100 ppm) was also prepared. Then, all samples were dried. As APP treatment time increased, the a⁎ value (redness), nitrosoheme pigment content, and residual nitrite content increased, while lipid oxidation decreased (all P Industrial relevance The global interest in sodium nitrite substitute for meat products manufacturing has considerably grown for years because consumer's demand of foods labeled “natural” and “chemical-free” has been increasing. In general, APP is recognized as a novel non-thermal food processing technology that uses energetic, reactive species to inactivate microbes on various foods. Recently, meat curing system involving direct APP treatment was proposed. The present study tried to apply APP to manufacturing pork jerky without using sodium nitrite. As a result, similar quality properties, particularly color, were observed in jerky applied by APP compared to jerky made with sodium nitrite. Application of APP also improved the microbiological safety of pork jerky. Therefore, APP can be applied for manufacturing potentially safer pork jerky by inactivation of heat-resistant pathogens without added sodium nitrite.

Effects of High Pressure on Bacillus licheniformis Spore Germination and Inactivation.

Bacillus and Clostridium species form spores, which pose a challenge to the food industry due to their ubiquitous nature and extreme resistance. Pressurization at <300 MPa triggers spore germination by activating germination receptors (GRs), while pressurization at >300 MPa likely triggers germination by opening dipicolinic acid (DPA) channels present in the inner membrane of the spores. In this work, we expose spores of Bacillus licheniformis, a species associated with food spoilage and occasionally with food poisoning, to high pressure (HP) for holding times of up to 2 h. By using mutant spores lacking one or several GRs, we dissect the roles of the GerA, Ynd, and GerK GRs in moderately HP (mHP; 150 MPa)-induced spore germination. We show that Ynd alone is sufficient for efficient mHP-induced spore germination. GerK also triggers germination with mHP, although at a reduced germination rate compared to that of Ynd. GerA stimulates mHP-induced germination but only in the presence of either the intact GerK or Ynd GR. These results suggests that the effectiveness of the individual GRs in mHP-induced germination differs from their effectiveness in nutrient-induced germination, where GerA plays an essential role. In contrast to Bacillus subtilis spores, treatment with very HP (vHP) of 550 MPa at 37°C did not promote effective germination of B. licheniformis spores. However, treatment with vHP in combination with elevated temperatures (60°C) gave a synergistic effect on spore germination and inactivation. Together, these results provide novel insights into how HP affects B. licheniformis spore germination and inactivation and the role of individual GRs in this process.IMPORTANCE Bacterial spores are inherently resistant to food-processing regimes, such as high-temperature short-time pasteurization, and may therefore compromise food durability and safety. The induction of spore germination facilitates subsequent inactivation by gentler processing conditions that maintain the sensory and nutritional qualities of the food. High-pressure (HP) processing is a nonthermal food-processing technology used to eliminate microbes from food. The application of this technology for spore eradication in the food industry requires a better understanding of how HP affects the spores of different bacterial species. The present study provides novel insights into how HP affects Bacillus licheniformis spores, a species associated with food spoilage and occasionally food poisoning. We describe the roles of different germination receptors in HP-induced germination and the effects of two different pressure levels on the germination and inactivation of spores. This study will potentially contribute to the effort to implement HP technology for spore inactivation in the food industry.

Nutrient Profiles and Volatile Odorous Compounds of Raw Milk After Exposure to Electron Beam Pasteurizing Doses.

Raw milk is known to contain relatively high numbers of microorganisms, some of which include microbial pathogens. Electron beam (eBeam) processing is a nonthermal pasteurization food processing technology. The underlying hypothesis was that eBeam processing will not negatively influence the composition, nutrient content, and aroma profile of raw milk. Raw milk samples were exposed to eBeam doses of 1 and 2 kGy, since our studies had shown that 2 kGy is suitable for raw milk pasteurization. The untreated and eBeam-treated raw milk samples were analyzed to detect changes in lactose, vitamin B2 , vitamin B12 , and calcium concentrations. The possible breakdown of casein and whey proteins and lipid oxidation were investigated along with the formation of volatile aroma compounds. Even though vitamin B2 showed a 31.6% decrease in concentration, the B2 content in eBeam-pasteurized raw milk met all USDA nutritional guidelines. Even though there were no indications of lipid oxidation after the 2.0-kGy eBeam treatment, there was lipid oxidation (58%) after 7 d of refrigerated storage. However, based on the GC-olfactory analysis, the lipid oxidation did not necessarily result in the development of a wide variety of off-odors.

Numerical and experimental studies on a novel Steinmetz treatment chamber for inactivation of Escherichia coli by radio frequency electric fields

Abstract Radio frequency electric field (RFEF) is an emerging non-thermal food processing technology that is alternative to pulsed electric fields (PEF). A novel Steinmetz treatment chamber design, that increases homogeneity of the electric field distribution, has been proposed and constructed. The design was performed and evaluated via Multiphysics modelling. The model was validated by comparison with experimental measurements of outlet temperature, power consumption and current. Inactivation studies showed the influence of electric field intensity, temperature, and treatment time on the inactivation of Escherichia coli in saline water with electrical conductivities between 0.02 and 0.1 S m− 1. A maximum inactivation of 3.6 log CFU mL− 1 was obtained at 26.5 kV cm− 1, 45 °C and 900 μs treatment time. An energy demand of 63 kJ kg− 1 is required for 1 log reduction, when processing at 25 °C, for foods having 0.1 S m− 1 conductivity at 20 °C, but energy consumption increases with the electrical conductivity.