Optimization of ohmic heating applications for pectin methylesterase inactivation in orange juice

Potential impact of ultrasound, pulsed electric field, high-pressure processing and microfludization against thermal treatments preservation regarding sugarcane juice (Saccharum officinarum)

Sugarcane juice (Saccharum officinarum) is a proven nutritious beverage with high levels of antioxidants, polyphenols, and other beneficial nutrients. It has recently gained consumer interest due to its high nutritional profile and alkaline nature. Still, high polyphenolic and sugar content start the fermentation in juice, resulting in dark coloration. Lately, some novel techniques have been introduced to extend shelf life and improve the nutritional value of sugarcane juice. The introduction of such processing technologies is beneficial over conventional processes and essential for producing chemical-free, high-quality, fresh juices. The synergistic impact of these novel technologies is also advantageous for preserving sugarcane juice. In literature, novel thermal, non-thermal and hurdle technologies have been executed to preserve sugarcane juice. These technologies include high hydrostatic pressure (HHP), ultrasound (US), pulsed electric field (PEF), ultraviolet irradiation (UV), ohmic heating (OH), microwave (MW), microfludization and ozone treatment. This review manifests the impact of novel thermal, non-thermal, and synergistic technologies on sugarcane juice processing and preservation characteristics. Non-thermal techniques have been successfully proved effective and showed better results than novel thermal treatments. Because they reduced microbial load and retained nutritional content, while thermal treatments degraded nutrients and flavor of sugarcane juice. Among non-thermal treatments, HHP is the most efficient technique for the preservation of sugarcane juice while OH is preferable in thermal techniques due to less nutritional loss.

Chemical and Sensory Characteristics of Fruit Juice and Fruit Fermented Beverages and Their Consumer Acceptance

Recent social, economic, and technological evolutions have impacted consumption habits. The new consumer is more rational, more connected and demanding with products, more concerned with the management of the family budget, with the health, origin, and sustainability of food. The food industry over the last few years has shown remarkable technological and scientific evolution, with an impact on the development and innovation of new products using non-thermal processing. Non-thermal processing technologies involve methods by which fruit juices receive microbiological inactivation and enzymatic denaturation with or without the direct application of low heat, thereby lessening the adverse effects on the nutritional, bioactive, and flavor compounds of the treated fruit juices, extending their shelf-life. The recognition of the nutritional and protective values of fruit juices and fermented fruit beverages is evident and is attributed to the presence of different bioactive compounds, protecting against chronic and metabolic diseases. Fermentation maintains the fruit's safety, nutrition, and shelf life and the development of new products. This review aims to summarize the chemical and sensory characteristics of fruit juices and fermented fruit drinks, the fermentation process, its benefits, and its effects.

Positive Influences of Ohmicsonication on Phytochemical Profile and Storage Stability of Not-from-Concentrate Mango Juice

Processing technique and storage conditions are the main factors that affect the phytochemical profile of Not-from-Concentrate (NFC) juice, which could decrease the nutritional and bioactive properties of the corresponding juice. The aim of this study was to evaluate the quality changes that occurred in NFC mango juice after Ohmicsonication (OS) and during storage in comparison to other processing methods such as sonication (S), thermosonication (TS), ohmic heating (OH), and conventional heating (CH). Quality attributes such as polyphenoloxidase (PPO) and pectinmethylesterase (PME) activities, ascorbic acid and hydroxymethyl furfural (HMF) contents, total phenolics, total flavonoids, total carotenoids, electric conductivity, color values and microbial load (total plate count, mold, yeast, and psychrophilic bacteria) were examined. OS and OH treatments demonstrated the highest inactivation of PPO (100%), while CH and TS displaying inhibitions 89% and 90%, respectively and only S treatment exhibited insufficient inactivation of both PPO and microbial load. However, the inhibition of PME followed the order OS (96.5%) > OH (94.9%) > TS (92.5%) > CH (88.5%). The best treatment, with the highest retention of phytochemical contents (ascorbic acid, total carotenoids, antioxidant activity, total flavonoids, and total phenolic content) for NFC mango juice and during storage was obtained with OS treated samples compared to other treatments (in the order from the lowest to highest percentage, OS < OH < TS < CH). Consequently, the results indicated that OS could be applied as a new mild thermal treatment in the production of mango juice with improved quality properties of stored NFC mango juice.

Application and Effects of Ohmic-Vacuum Combination Heating on the Quality Factors of Tomato Paste

Ohmic-vacuum combination heating is a common method used in the food industry as a concentration process. In the present study, an OH-VC combination heating system was developed for producing tomato paste at temperatures of 70, 80, and 90 °C and pressure of 0.3, 0.5, and 0.7 bar and electric field of 1.82, 2.73, and 3.64 V/cm using a central composite design. The effects of heating conditions on the quality and sensory evaluation of tomato paste were also evaluated. Each combination of temperature, pressure, and the electric field was quantified for specific energy consumption, energy efficiency, and productivity. A decrease of 35.08% in the amount of acid ascorbic and lycopene content 19.01%, using conventional heating compared to ohmic-vacuum heating under optimized conditions, was attained. The results also highlighted an increase in the amount of HMF (69.79%) and PME (24.33%) using conventional heating compared to ohmic-vacuum heating under optimized conditions. Ascorbic acid, lycopene, titratable acidity, productivity, energy efficiency was higher than conventional heating; on the other hand, HMF, PME, pH, SEC were lower than conventional heating at the applied OH-VC process. No significant effects between OH-VC and conventional heating on the TSS were observed. In addition, OH-VC heating was highly efficient in the inhibition of bacterial growth. Further, a minor effect on the sensory properties of tomato paste with OH-VC heating compared to the conventional treatment. The obtained results indicate a strong potential for an OH-VC combination heating system as a rapid-heating, high-efficiency alternative for saving electrical energy consumption and preserving nutritional value.

Effect of Ohmic Heating on Sensory, Physicochemical, and Microbiological Properties of "Aguamiel" of Agave salmiana

The use of ohmic heating (OH) processing technologies in beverages might provide a higher quality value to the final product; consumers tended to prefer more natural products with minimum preservative substances. The aim of this work was to evaluate the effect of OH over the presence of microorganisms in "aguamiel" as well as to study the effects on physicochemical analysis like total sugars, soluble solids, electric conductivity pH, and color. The results showed that the conductivity of "aguamiel" was 0.374 s/m, this as temperature increased, conductivity rose as well. During OH a bubbling was observed when reaching 70 °C due to the generation of electrochemical reactions during the OH process. OH had a significant effect in the reduction of E. coli, yeast, and lactobacillus compared to conventional pasteurization, reaching optimal conditions for its total inactivation. Regarding its physicochemical properties, both treatments, conventional pasteurization and OH, did not show negative changes in aguamiel, demonstrating that OH technology can be a feasible option as a pasteurization technique. In conclusion it is important to notice that negative changes were not found in quality, color and sugars of "aguamiel". Therefore, ohmic heating can be an option to replace traditional methods used for pasteurization.

Food preservation techniques and nanotechnology for increased shelf life of fruits, vegetables, beverages and spices: a review

Food wastage is a major issue impacting public health, the environment and the economy in the context of rising population and decreasing natural resources. Wastage occurs at all stages from harvesting to the consumer, calling for advanced techniques of food preservation. Wastage is mainly due to presence of moisture and microbial organisms present in food. Microbes can be killed or deactivated, and cross-contamination by microbes such as the coronavirus disease 2019 (COVID-19) should be avoided. Moisture removal may not be feasible in all cases. Preservation methods include thermal, electrical, chemical and radiation techniques. Here, we review the advanced food preservation techniques, with focus on fruits, vegetables, beverages and spices. We emphasize electrothermal, freezing and pulse electric field methods because they allow both pathogen reduction and improvement of nutritional and physicochemical properties. Ultrasound technology and ozone treatment are suitable to preserve heat sensitive foods. Finally, nanotechnology in food preservation is discussed.

Impact of ohmicsonication treatment on pectinmethylesterase in not-from-concentrate orange juice

The present study investigates the application of ohmicsonication (OS) as a new hurdle technology for pasteurization of Not-from-concentrate orange juice (NFCOJ). OS process parameters to inactivate pectinmethylesterase (PME) activity in NFCOJ were optimized using response surface methodology. The influence of Sonication (S), Thermosonication (TS), Ohmic heating (OH) and OS on inactivation of PME were compared to conventional heat (CH) treatment. Their effects on physical, chemical and microbiological contents were included. In comparison to fresh orange juice, the inactivation of PME was 96%, 95%, 89%, 90% and 29% for OS, OH, TS, CH and S treatments, respectively. Highest cloud value was obtained for OS (1.240 A) treatment. OS treatment gave a lower vitamin C loss compared to TS, OH and CH treatments. A significant increase in the total phenolic content were obtained in the following order OS > TS > OH > CH. OS treated juice also contained the lowest value of hydroxymethyl furfural (0.90 mg/L) compared to OH (0.95 mg/L), TS (1.37 mg/L) and CH (2.72 mg/L) treated samples. Overall, the results indicated that OS can be integrated as a substitute to pasteurization of NFCOJ.

Optimization of ohmic heating parameters for polyphenoloxidase inactivation in not-from-concentrate elstar apple juice using RSM

In this study, optimization of ohmic heating (OH) process parameters (temperature and voltage gradient) to inactivate polyphenoloxidase (PPO) of not-from-concentrate (NFC) apple juice was conducted. Response surface methodology was used for optimization of OH parameters, where the voltage gradient and temperature on the PPO activity in the NFC apple juice was evaluated. Then the optimized condition was used to produce the NFC apple juice and the quality parameters were evaluated and compared to NFC apple juice prepared by conventional heating (CH). The studied parameters were: PPO activity, total phenolic, total carotenoids, ascorbic acid, cloud value, color as well as physical properties (i.e., TSS, acidity, electric conductivity and viscosity). The reduction of PPO activities was 97 and 91% for OH (at 40 V/cm and 80 °C) and CH (at 90 °C and 60 s), respectively. The reduction of the ascorbic acid was 66.8% for OH significantly lower than the 80% for CH treated samples. The total extracted phenolic content was increased by 5.4 and 2.5% with OH and CH treatments, respectively. The decrease in the concentration of total carotenoids for OH (13.17%) was significantly lower than for CH (34.23%). The color values (L*, a*, b* and ΔE) were only significantly increased in the OH treatment. OH is a potential mild thermal treatment in the production of apple juice with improved functional properties instead of conventional methods.

Electric field-based technologies for valorization of bioresources

This review provides an overview of recent research on electrotechnologies applied to the valorization of bioresources. Following a comprehensive summary of the current status of the application of well-known electric-based processing technologies, such as pulsed electric fields (PEF) and high voltage electrical discharges (HVED), the application of moderate electric fields (MEF) as an extraction or valorization technology will be considered in detail. MEF, known by its improved energy efficiency and claimed electroporation effects (allowing enhanced extraction yields), may also originate high heating rates - ohmic heating (OH) effect - allowing thermal stabilization of waste stream for other added-value applications. MEF is a simple technology that mostly makes use of green solvents (mainly water) and that can be used on functionalization of compounds of biological origin broadening their application range. The substantial increase of MEF-based plants installed in industries worldwide suggests its straightforward application for waste recovery.

Effect of Power Levels on Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in Tomato Paste Using 915-Megahertz Microwave and Ohmic Heating

The effect of power levels on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in tomato paste was investigated using 915-MHz microwave heating (MW) and ohmic heating (OH). Heating uniformity, pathogen inactivation, and quality aspects were determined with 1.8-, 2.1-, 2.4-, and 3.0-kW MW and corresponding OH. GInaFit was used to analyze pathogen inactivation. The heating uniformity of MW-treated samples was inferior to that of OH-treated samples at low power levels of 1.8 to 2.4 kW but improved as the power level increased. Pathogen inactivation of MW-treated samples was significantly higher than that of OH-treated samples at low power levels of 1.8 to 2.4 kW (P < 0.05) but was not significantly different at the highest power level of 3.0 kW (P > 0.05). Quality aspects (color, pH, and lycopene content), except for L*, of MW-treated samples were not significantly degraded (P > 0.05) by increased power levels. Our results indicate that increasing power levels of MW ensures heating uniformity and microbiological safety and preserves quality aspects of tomato paste.

Effects of Different Enzymes and Concentrations in the Production of Clarified Lemon Juice

Lemon juice obtained from Interdonato variety was treated with different enzymes at specific concentrations as depectinization processes to produce clear lemon juice and its concentrates. In addition, the best condition obtained from laboratory treatments was carried out in the local fruit juice plant. Effects of the processing steps on some quality parameters were investigated during the lemon juice production and the obtained concentrates were stored at −25°C for 180 days. The results showed that Novozym 33095 had the best depectinization effectiveness. Total pectin content of lemon juices decreased rapidly following the enzyme treatment and could not be detected following the filtration. Viscosity values decreased after pulp separation and the largest reduction was observed with the filtration. At the end of filtration in 40 μL/100 mL concentrations of each of the three enzymes, values of residual pectinmethylesterase (PME) activity were found to be in the lowest amounts.

Ohmic heating as a pre-treatment in solvent extraction of rice bran

Rice bran, which is one of the major by products of paddy contain high quality proteins and edible oil apart from fibre, ash and NFE (nitrogen free extract). The existing solvent extraction method employs n-hexane as the most viable solvent for the extraction of oil from rice bran. But the high cost and scarce availability of n-hexane resulted in uneconomical extraction of rice bran oil. In this study, rice bran was ohmically heated for different time periods(1, 2 and 3 min) with different current values (5, 15 and 20 A) and with different concentration of sodium chloride (1 M, 0.1 M and 0.01 M) as conducting medium. The ohmically heated rice bran was subjected to extraction studies. Ohmic heating of rice bran of paddy varieties Red Triveni and Basmati reduced the extraction time by nearly 75 % and 70 % respectively and gave a maximum quantity of oil extracted when compared to bran, which was not ohmically heated. From the experiments with varying concentrations, residence time of ohmic heating and currents, it was found that ohmically heating the rice bran with 1 M sodium chloride solution and with a current value of 20 A for 3 min gave maximum oil extraction with minimum extraction time.