Non-thermal Processing Technique Research Articles

Effect of high hydrostatic pressure on physicochemical properties of quinoa flour

High hydrostatic pressure (HHP) has potential to modify physicochemical properties of food systems. Quinoa (Chenopodium quinoa) has attracted research focus for nutritional properties. Three different types of whole grain quinoa flour were processed using HHP up to 600 MPa. HHP of 500 and 600 MPa decreased the viscosity during pasting event (e.g., peak viscosity from 4.90 to 0.18 Pa⋅s), gel hardness (e.g., from 0.185 to 0.0343 N), enthalpy change (ΔH) of gelatinization (e.g., from 11.8 to 0 J/g), and in vitro starch digestibility of quinoa flour (e.g., from 954 to 862 g/kg), while increasing the water solubility (e.g., from 15.8 to 40.2% at 55 °C). The extents of these changes were seen to depend on the type of quinoa flour. Structural analysis showed that, to a large degree, the HHP induced changes in the physicochemical properties could be attributed to the gelatinization of the starch component, and to a smaller extent, to the changes in non-starch components. The physicochemical properties of the quinoa four were much less significantly affected by HHP of 200 and 400 MPa. HHP as a non-thermal processing technique has potential to modify grain flour properties.

The usage of high hydrostatic pressure (HHP) to control food-borne pathogens in hummus

ABSTRACTWith the increasing demand for fresher, higher quality, minimally processed and safer food, there is a strong necessity to develop non-thermal processing techniques. Also for hummus, which is popular all around the world. In this work, the effect of refrigerated storage on the survival of pathogens in hummus treated by high hydrostatic pressure (HHP) (500 MPa/10 min/room temperature) was evaluated. The cocktail of two Salmonella, four Listeria monocytogenes and two Escherichia coli strains was used in this study. All pathogen types were able to survive in hummus during 60 days of refrigerated storage. HHP-treated samples plated on day 0 successfully achieved a > 5 log cfu/g reduction for all pathogen types. No residual survivors were present after 30 and 60 days in any of the HHP-treated samples. These results demonstrate that HHP may be a useful technique for the inactivation of pathogens and therefore helpful in designing non-thermal HHP conditions for pressurization of hummus.

Induction of viable but putatively non-culturable Lactobacillus acetotolerans by thermosonication and its characteristics

This study aimed at investigating for the first time whether thermosonication (TS), a non-thermal processing technique, could induce the beer-spoilage bacterium, Lactobacillus acetotolerans CGMCC 7.150, into the viable but putatively non-culturable (VPNC) state. After determining culturable, viable and total cell counts, we found that L. acetotolerans in beer could enter the VPNC state by TS at a constant frequency of 24 kHz at 50 °C at three relatively low volumetric powers (0.6, 1.2 and 1.8 W/mL, but not 2.4 W/mL). Furthermore, with the increase of volumetric power, the time required for L. acetotolerans cells to enter the VPNC state shortened. The addition of Tween 80 at a concentration of 0.1% v/v into de Man Rogosa Sharpe agar enabled the VPNC cells to regain culturability with a recovery time of approximately 3 days. However, their recovery capability decreased with the increasing volumetric power. Scanning electron microscopy analysis showed that cells decreased in size and gradually changed morphology from short rods to coccoids upon entering the VPNC state. An insignificant difference in beer-spoilage ability was found between the exponential-phase and VPNC cells. The resistance of these VPNC cells to 0.025 M NaOH and 0.025 M KOH was enhanced compared with the exponential-phase cells.

Impact of high‐voltage electric discharge treatment on cocoa shell phenolic components and methylxanthines

AbstractCocoa shell is one of the by‐products obtained in chocolate industry which was considered as waste for a very long time. Recently, the presence of high‐valuable bioactive components in cocoa shell was recognized, and research on the pallet of food products enriched with cocoa shell is increasing. The most abundant bioactive components of untreated cocoa shell (UCS) are theobromine (3.906 ± 0.070 mg/g), caffeine (0.646 ± 0.055 mg/g), and (+)‐catechin (0.290 ± 0.005 mg/g), followed by gallic acid (0.147 ± 0.041 mg/g) and (−)‐epicatechin (0.165 ± 0.099 mg/g). Furthermore, the impact of concentration (1.5 and 3% of cocoa shell in water), high‐voltage electric discharge (HVED) treatment (40 and 80 Hz), and treatment time (15, 30, and 45 min, respectively) on bioactive compounds content was evaluated. Statistically significant differences between treatment conditions were obtained. Generally, water‐HVED treatment at 40 Hz has lower impact on bioactive components than water, and water‐HVED at 80 Hz, therefore, can have a significant effect on future treatments of materials rich in bioactive compounds.Practical applicationsHVED is an innovative nonthermal processing technique that has mechanical and electrical effect on the product resulting with lower costs and increase of functional properties. This study has shown that HVED causes lower decrease of phenolics and methylxanthines in cocoa shell which can have a significant effect on future treatments of materials rich in bioactive compounds. Because it is not recorded in scientific literature that HVED treatment was used on cocoa shell so far, it will help in future research and applications of cocoa shell in the food industry.

UV-C treatment of grape must: Microbial inactivation, toxicological considerations and influence on chemical and sensory properties of white wine

UV-C was investigated to inactivate microorganisms in grape must. The aim was to evaluate the effect of UV-C on wine-related yeasts under winery conditions, to investigate the toxicological potential and to analyze the effects on chemical and sensory wine properties. Metschnikowia pulcherrima showed the highest UV-C tolerance, Saccharomyces cerevisiae the lowest. With an initial cell count of 106 cfu/mL, M. pulcherrima required a UV-C dose of >1.2 kJ/L, S. cerevisiae <0.8 kJ/L for inactivation. Inactivation efficacy decreased with higher must turbidity (26.7–144.5 NTU), optical density and degree of microbial load (104–108 cfu/mL) suggesting a shadowing effect of individual microbes. UV-C treatment did not impact mutagenicity as tested by the Ames test. A decrease in dissolved oxygen and caftaric acid content indicated oxidative reactions. UV-C induced color bleaching (ΔE: 0–13) was also observed indicating a degradation of colored pigments. GC × GC–MS analysis revealed a decrease of β-damascenone and linalool content in wines made from UV-C treated must. Descriptive analysis by a trained sensory panel showed that off-flavors did not occur at doses that were relevant for microbial inactivation (between 1.0 and 3.0 kJ/L). UV-C treatment is a non-thermal processing technique for the preservation of food. In this study, the applicability of UV-C treatment for the inactivation of spoilage yeast in grape must was demonstrated in pilot scale. The treatment provided sufficient microbial inactivation without having toxicological impact as examined by the Ames test and without causing off-flavor formation in the wines using relevant doses.

Application of Ultrasound, Microwaves, and Magnetic Fields Techniques in the Germination of Cereals

Cereal germination involves a series of complex physiological and biochemical processes that are influenced by multiple internal and external factors. Previous studies have shown that certain non-thermal processing techniques can be used to effectively induce a range of physiological and biochemical changes in cereal seeds, thereby increasing the digestibility and bioavailability of cereals and enhancing the nutritional value, flavor, and quality of cereal sprouts. Here, we provide an overview of the principle of promoting cereal germination to enrich physiologically active components review the effects of treating cereal seeds with three new non-thermal processing technologies, namely, ultrasound, microwaves, and magnetic fields, on the contents of enzymes and various other seed components during germination. Finally, we summarize the advantages and disadvantages of applying the above techniques to cereal germination.

Perimetric Distributed UV Reactor and Its Validation and the Decontamination of Fresh Broccolis

The ultraviolet (UV) irradiation as a non-thermal processing technique for microbial decontamination of food (MDF) has been the gainer in many variations after the inclusion of UV light as an alternative for MDF by the US FDA. However the lasts years increase the application of the UV light in food, water and pharmaceutical utilization. In this report, we describe a new type of reactor, where the UV emitters are parametrically distributed for decontaminating fresh broccolis. We described the constructed reactor and its characterization with the validation of the system with controlled contaminated broccolis. The overall liquid was contamined with 105 UFC/mL E. coli operating with a flow rate of 80 L/min in 30 L and six lamps in the reactor and the collection of samples in intervals of 25 min. The E. coli used in this experiment was eliminated in 99,99% The intensity of UVC light distributed in the internal part of the reactor is practically homogeneous due to the developed geometry. The kinetics of microbial death presented no great influence on this variation. That is, any volume of water contained in the process can be decontaminated. A relation between UV and the flow rate was stablished. The system demonstrated its capacity in inactivating the microorganism.

Structure and functionalities changes in high-pressure homogenized clam protein isolate

High-pressure homogenization (HPH) under 0–100 MPa was performed to treat clam protein isolate (CPI) for three cycles. Results indicated that HPH treatment resulted in significant improvements of CPI functional properties. Absolute zeta potential, emulsifying activity index, and emulsion stability index significantly increased by 19.37 mV, 33.26 m2/g, and 14.00 min after HPH under 100 MPa. Solubility of CPI dramatically increased by 70.8% under 80 MPa. Foaming ability and foaming stability increased by 33.8% and 14.4% under 60 MPa. HPH resulted in significant decrease in percentage of both α-helix and β-turn, but percentage of β-sheet greatly improved as the pressure increased. Free sulfhydryl and surface hydrophobicity increased but fluorescence intensity decreased significantly after HPH treatment. Improvements of these functionalities were due to protein structure changes and particle size reduction. This study demonstrated that HPH has the potential to improve functional properties of shellfish protein through modifying protein structure. Practical applications A nonthermal processing technique using HPH can improve functional properties of CPI, including solubility, emulsifying properties, and foaming properties. Therefore, HPH can be potentially used to process shellfish proteins to improve their functional properties.

Effect of thermosonication and thermal treatments on phytochemical stability of barberry juice copigmented with ferulic acid and licorice extract

Abstract This study was designed to compare the effect of thermosonication and thermal treatment on color and anthocyanins stability of natural and copigmented barberry juice during processing and storage. Addition of copigments significantly induced the hyperchromic effect and increased the total phenolic and antioxidant activity of barberry juice. Copigmentation especially at 1:2 M ratio, markedly enhanced the color and anthocyanin stability of barberry juice during processing. Thermal treatment negatively affected the phytochemical compounds, whereas thermosonication especially at low amplitude showed no significant changes. A similar trend in the degradation of anthocyanins and color instability of samples was observed during storage. Copigmentation, especially with licorice extract, considerably increased the half-life of anthocyanins and well preserved pelargonidin 3-glucoside and the color parameters of the juice during storage. The results indicate that licorice extract can be a good alternative to synthetic copigments and the application of thermosonication maintains the effectiveness of copigmentation reaction. Industrial relevance Barberry (Berberis vulgaris) is one of the most important medicinal plants which is mainly cultivated in Iran. Barberry fruits are used in preparing sauces, jellies, candies, marmalades and especially juice drinks. Like other berry fruits, barberry contains high amounts of anthocyanins. Due to the highly instability of these pigments, the preservation of these nutrients during industrial processing and storage of barberry juice is very important. Intermolecular copigmentation of anthocyanins with phenolic compounds, especially with phenolic extract from various plant species, is an efficient method to stabilize these compounds. Moreover, because of the adverse effect of thermal treatment on the copigmentation reaction and the degradation of nutritive compounds of fruit juice, there is a need for non-thermal processing techniques like sonication or high pressure to preserve the nutritional and sensory properties of juices. Therefore, in this study, for the first time, the simultaneous use of thermosonication and copigmentation with ferulic acid and licorice extract on the stability of color and anthocyanins of barberry juice was evaluated. The results of our study revealed that licorice extract due to having various flavonoid compounds such as liquiritin and isoliquiritin can be a good alternative to synthetic copigments. Furthermore, the application of thermosonication in comparison with thermal treatment maintains the effectiveness of copigmentation reaction.

Effects of ultrasound on structure and functional properties of mussel (Mytilus edulis) protein isolates

The effects of ultrasound treatment on structure and functional properties of mussel protein isolates (MPI) were investigated. MPI were treated with ultrasound probe (20 kHz) at 200, 400, and 600 W for 18 and 36 min. Ultrasound treatment did not modify protein profiles of MPI, but caused changes in secondary, tertiary, and quaternary structure. Ultrasound treatment improved functional properties of MPI, including solubility, oil holding capacity, emulsifying properties, and foaming properties. Therefore, ultrasound technology can be potentially used to process MPI to improve its functional properties. Practical Applications A nonthermal processing technique using ultrasound can improve functional properties of mussel protein isolates, including solubility, oil holding capacity, emulsifying properties, and foaming properties. Therefore, ultrasound technology can be potentially used to process shellfish proteins to improve their functional properties.

Inactivation of Pichia rhodanensis in relation to membrane and intracellular compounds due to microchip pulsed electric field (MPEF) treatment.

The effect of microchip pulsed electric field (MPEF) treatment on lethal and sublethal injury of Pichia rhodanensis (P. rhodanensis) were employed under 100–500 V for 20–100 pulses and the underlying mechanism of MPEF treatment was investigated as well. A 6.48 log10 reduction of P. rhodanensis was achieved at 500V for 80 pulse. The fluorescent staining with Propidium Iodide (PI) verified that the rate of sublethal injury cells maximum up to 27.2% under 200 V. MPEF can cause the damage of cell morphology and ultrastructure, meanwhile causing a decrease in cellular enzymes, antioxidant enzyme activity and cell membrane fluidity. The leakage of intracellular compounds (protein, nucleic acid, K+, Mg2+) and Ca2+-ATPase gradually increased as the growth of voltage, especially the proportion of protein in the supernatants increased from 2.0% to 26.4%. Flow cytometry analysis showed that MPEF has significant effect on membrane potential, but no obvious influence on non-specific esterase. MPEF can cause the changing of the secondary structure of protein, at the same time, double helix structure of DNA became loose and unwinding. These results provide a theoretical guidance for the widespread using of MPEF technology in the application of a non-thermal processing technique for food.

UV-C Irradiation on the Quality of Green Tea: Effect on Catechins, Antioxidant Activity, and Cytotoxicity.

Short wavelength ultraviolet (UV-C) irradiation is a nonthermal processing technique that is a possible alternative to the heat pasteurization of tea beverages. This study investigated the effect of UV-C irradiation on the antioxidant concentration of green tea and analyzed cytotoxicity of irradiated a green tea beverage using a novel continuous flow-through UV system. The results demonstrated that the UV-C irradiation did not significantly deplete catechins or produce cytotoxic byproducts.

Effects of High Pressure Treatment on Physicochemical Quality of Pre- and Post-Rigor Palm Ruff (Seriolella Violacea) Fillets

ABSTRACTFish and fish products are characterized for having a short shelf life. Nonthermal processing techniques such as high hydrostatic pressure (HHP) have increasingly been employed to extend shelf life of food products. The aim of this study was to evaluate changes on flesh physicochemical spoilage parameters (pH, total volatile bases (TVB-N), trimethylamine (TMA), thiobarbituric acid (TBA), and color) of palm ruff (Seriolella violacea) fillets in pre- and post-rigor conditions, subjected to two different HHP conditions: 450 MPa and 550 MPa, for 3 and 4 min each. Unpressurized and pressurized fillets were kept in chilled storage (4 ± 1°C) for 26 days to assess the effect of HHP on shelf life. pH and TBA values increased after HHP treatment and with storage time for both unpressurized and pressurized samples. This is attributable to pressure-induced lipid oxidation. Lightness (L*) values increased with pressure, where fish fillets had a cooked appearance. TMA and TVB-N values decreased after HHP treatment compared to the unpressurized samples, showing that HHP treatment is an efficient method to maintain the quality of palm ruff fillets. There was no clear difference between pre- and post-rigor in the parameters evaluated.

Effect of pH and pulsed electric field process parameters on the aflatoxin reduction in model system using response surface methodology: Effect of pH and PEF on Aflatoxin Reduction.

The presence of aflatoxin, a carcinogenic and toxigenic secondary metabolite produced by Aspergillus species, in food matrix has been a major worldwide problem for years now. Food processing methods such as roasting, extrusion, etc. have been employed for effective destruction of aflatoxins, which are known for their thermo-stable nature. The high temperature treatment, adversely affects the nutritive and other quality attributes of the food, leading to the necessity of application of non-thermal processing techniques such as ultrasonication, gamma irradiation, high pressure processing, pulsed electric field (PEF), etc. The present study was focused on analysing the efficacy of the PEF process in the reduction of the toxin content, which was subsequently quantified using HPLC. The process parameters of different pH model system (potato dextrose agar) artificially spiked with aflatoxin mix standard was optimized using the response surface methodology. The optimization of PEF process effects on the responses aflatoxin B1 and total aflatoxin reduction (%) by pH (4-10), pulse width (10-26µs) and output voltage (20-65%), fitted 2FI model and quadratic model respectively. The response surface plots obtained for the processes were of saddle point type, with the absence of minimum or maximum response at the centre point. The implemented numerical optimization showed that the predicted and actual values were similar, proving the adequacy of the fitted models and also proved the possible application of PEF in toxin reduction.

Influence of non-thermal processing and storage conditions on the release of health-related compounds after in vitro gastrointestinal digestion of fiber-enriched strawberry juices

Strawberry juices enriched with inulin and oligofructose were treated using non-thermal processing techniques [ultrasound (7.5 min, 40 kHz, 180 W) combined or not with antimicrobials vanillin (1.25 mg/mL) or geraniol (0.225 µL/mL)] and stored for two weeks at 5 °C. The impact of the non-thermal processing and storage conditions on the release of health-related compounds (phenolic compounds, flavonoids and ascorbic acid), and on the total antioxidant capacity (determined by DDPH and TEAC assays) after in vitro gastrointestinal digestion was investigated. After gastric digestion, the release of most of bioactive compounds decreased in comparison with non-processed juices. Conversely, exposing the treated juices to simulated intestinal conditions enhanced the release of phenolic and flavonoid compounds and the total antioxidant capacity (determined by the TEAC assay). Storage conditions led to slight changes in bioactive compounds’ content. In conclusion, fiber-enriched strawberry juices preserved with non-thermal processing are an important source of nutritionally relevant compounds.

A High-Voltage Solid-State Switch Based on Series Connection of IGBTs for PEF Applications

Pulsed electric field (PEF) technology is a promising nonthermal processing techniques that can be utilized to inactivate microorganisms in liquid food with high-voltage PEF. Herein, a high-voltage solid-state switch consisting of 64 insulated gate bipolar transistors (IGBTs) connected in series was designed and developed for the PEF treatment. Regarding the unbalanced sharing of voltage in series-connected IGBTs, the resistor–capacitor–diode snubber circuit was specifically used and investigated in terms of model of parameters. Furthermore, using gate drivers and optic fiber, the driving circuit and protection circuit were designed and validated. A 50-kV isolation level power supply was built in order to provide 16 independent IGBT stacks with 24 V of power each. The results show that the developed switch works adequately a delay time of 380 ns with 35.8-kV voltage and 44.8-A current capacity. Moreover, the response time of the short-circuit protection is acceptable as well with a reaction time of under $7~\mu \text{s}$ . In conclusion, the switch designed for PEF treatment of liquid food performs within set parameters and is ready for pilot-scale processing capability.

Mitigation of Patulin in Fresh and Processed Foods and Beverages.

Patulin is a mycotoxin of food safety concern. It is produced by numerous species of fungi growing on fruits and vegetables. Exposure to the toxin is connected to issues neurological, immunological, and gastrointestinal in nature. Regulatory agencies worldwide have established maximum allowable levels of 50 µg/kg in foods. Despite regulations, surveys continue to find patulin in commercial food and beverage products, in some cases, to exceed the maximum limits. Patulin content in food can be mitigated throughout the food processing chain. Proper handling, storage, and transportation of food can limit fungal growth and patulin production. Common processing techniques including pasteurisation, filtration, and fermentation all have an effect on patulin content in food but individually are not sufficient safety measures. Novel methods to remove or detoxify patulin have been reviewed. Non-thermal processing techniques such as high hydrostatic pressure, UV radiation, enzymatic degradation, binding to microorganisms, and chemical degradation all have potential but have not been optimised. Until further refinement of these methods, the hurdle approach to processing should be used where food safety is concerned. Future development should focus on determining the nature and safety of chemicals produced from the breakdown of patulin in treatment techniques.

Inactivation of tobacco mosaic virus using gamma irradiation and its potential modes of action

Gamma irradiation is a non-thermal processing technique used to disinfect harmful microorganisms in agriculture. This technology has been shown to be an effective method to control bacterial and fungal plant pathogens. However, its effect on viral plant pathogen is less understood. Gamma irradiation was evaluated for the inactivation of tobacco mosaic virus (TMV). TMV infectivity has gradually decreased following irradiation in a dose-dependent manner and virus was completely inactivated at a dose over 40 kGy. Transmission electron microscopy revealed that increased gamma irradiation disrupts the virion structure and degrades viral proteins, which results in TMV inactivation. The mechanisms, through which gamma irradiation inactivates TMV, can be directly associated with the damage to the virus constituents.

Study on Power Ultrasound Optimization and Its Comparison with Conventional Thermal Processing for Treatment of Raw Honey.

The present study was done to optimize the power ultrasound processing for maximizing diastase activity of and minimizing hydroxymethylfurfural (HMF) content in honey using response surface methodology. Experimental design with treatment time (1-15 min), amplitude (20-100%) and volume (40-80 mL) as independent variables under controlled temperature conditions was studied and it was concluded that treatment time of 8 min, amplitude of 60% and volume of 60 mL give optimal diastase activity and HMF content, i.e. 32.07 Schade units and 30.14 mg/kg, respectively. Further thermal profile analyses were done with initial heating temperatures of 65, 75, 85 and 95 ºC until temperature of honey reached up to 65 ºC followed by holding time of 25 min at 65 ºC, and the results were compared with thermal profile of honey treated with optimized power ultrasound. The quality characteristics like moisture, pH, diastase activity, HMF content, colour parameters and total colour difference were least affected by optimized power ultrasound treatment. Microbiological analysis also showed lower counts of aerobic mesophilic bacteria and in ultrasonically treated honey than in thermally processed honey samples complete destruction of coliforms, yeasts and moulds. Thus, it was concluded that power ultrasound under suggested operating conditions is an alternative nonthermal processing technique for honey.

The Effect of High Pressure Processing on Milk: An Overview

High pressure processing (HPP) is a non-thermal processing technique or cold pasteurization technique used for preservationof different types of food products, due to its lethal effect on pathogenic and spoilage microorganisms, while causing minor effect on food quality and sensorial attributes. Thus, HPP is currently being applied to a variety of food products, especially fruits, vegetables, and meat products, but dairy industry has not implemented the technology yet. This overview presents firstly a brief description of the thermodynamic principles of HPP followed by a description of the high pressure effect on milk components. Generally, HPP treatment of milk in the range of 100–600 Mega Pascal has very significant implications for its constituents depending on pressure level, holding time and temperature. Pressure-induced changes of the milk characteristics includes inactivation of bacteria, disruption of the casein micelles, denaturation of whey proteins, and solubilization of minerals associated with the micelles. In addition, HP treatment of milk at higher temperatures generally increases inactivation of alkaline phosphatase.