Inactivation kinetics of polyphenol oxidase and peroxidase in pineapple juice by dielectric barrier discharge plasma technology

Cold plasma processing of kiwifruit juice: Effect on physicochemical, nutritional, microstructure, rheological properties and sensory attributes

This study aimed to compare the untreated, cold plasma (CP)-optimized (30 kV/5 mm/6.7 min), CP-extreme (30 kV/2 mm/10 min), and thermally treated (TT) (90 ℃/5 min) kiwifruit juices based on the physicochemical (pH, total soluble solids (TSS), titratable acidity (TA), total color change (ΔE)), physical (particle size and rheology), microstructure (optical microscope), bioactive compounds (polyphenol, ascorbic acid, and sugar compounds), and sensory characteristics of kiwifruit juice. The pH, TSS, and TA were not significantly affected in CP and TT juice, whereas the ΔE (6.52) of TT juice lies in the range of "greatly visible." The microstructure characteristics of juice significantly changed after CP and thermal treatment. The cell and tissue disruption in CP-extreme and thermally treated juice was more than CP-optimized. The particle size of juice decreased irrespective of treatment, but the span value of CP-optimized juice was the lowest. Further, the CP treatment showed a lower consistency index, apparent viscosity, and pseudoplasticity of juice than the thermal treatment. The CP-treated juice retained bioactive and nutritional attributes more than thermally treated juice. The CP-optimized, CP-extreme, and thermal treatment reduced the sucrose content by 54, 55, and 23%, while the fructose and glucose content were increased by 17, 12, & 93%, and 17, 11 & 99%, respectively. Among the CP-treated juice, CP-optimized (71.36 mg/100g) contained a higher amount of ascorbic acid than the CP-extreme (64.36 mg/100g). Based on the similarity values in the fuzzy logic analysis, the sensory attributes of CP-optimized treated juice were superior to CP-extreme and thermal treated. PRACTICAL APPLICATION: In this era, non-thermal processing techniques are trending for retaining the nutrition and stability of juice. The old plasma (CP)-treated kiwifruit juice had better nutritional, bioactive compounds, and sensory attributes than the thermally treated juice. Further, the CP-treated juice had higher flowability and lower viscosity, making it ideal for juice processing. The conclusions drawn suggest that CP processing is a better alternative for processing kiwifruit juice than thermal processing.

Air and argon cold plasma effects on lipolytic enzymes inactivation, physicochemical properties and volatile profiles of lightly-milled rice

This study investigated the effectiveness of cold-plasma treatment using air and argon as input gas on deactivation of lipolytic enzymes in lightly-milled-rice (LMR). The results showed no significant inactivation in lipase and lipoxygenase using air-plasma. However, using argon as input gas, the residual activities of lipase and lipoxygenase were reduced to 64.51 % and 29.15 % of initial levels, respectively. Argon plasma treatment resulted in more substantial augmentation in peak and breakdown viscosities of LMR starch, suggesting an enhancement in palatability of cooked LMR with increased stickiness and decreased hardness. In contrast to the decrease in volatile compounds in LMR following argon plasma treatment, the concentrations of several prevalent aroma compounds, including 1-hexanol, 1-hexanal, and 2-pentylfuran, exhibited significant increments, reaching 1489.70 ng/g, 3312.10 ng/g, and 58.80 ng/g, respectively. These findings suggest the potential for enhancing various facets of the commercial qualities of LMR by utilizing different input gases during plasma treatment.

Influence of °Brix/Acid, and flow rate of pineapple juice and electric field strength on the performance of continuous ohmic heating system

A lab-scale continuous ohmic heating (COH) system was developed, and its performance was studied for pineapple juice heating as a model sample. The effect of independent parameters [°Brix/Acid (unstandardized, 18, 22, 26) and flow rate (80-120 mL/min) of juice and electric field strength (EFS: 25-45 V/cm)] were analysed for responses viz. come-up-time, heating rate (HR) and system performance coefficient (SPC). The full factorial experimental design was used for this study. The results showed that with an increase in °Brix/Acid, the % acidity and electrical conductivity decreased significantly (p < 0.05); thus, the come-up-time to reach 90 °C increased significantly. The HR was significantly (p < 0.05) influenced by °Brix/Acid and EFS but less so by flow rates at higher EFS. The SPC was more than 0.90 and reduced significantly (p < 0.05) with an increase in °Brix/Acid and flow rate. The HR was modeled using a feed-forward back-propagation artificial neural network (ANN) with the best topology of 3, 5, and 1 neurons in the input (independent), hidden, and output (response) layers, respectively. The model performed efficiently, which is evident from the high R2 (0.998) and low RMSE (1.255). Thus, the COH, with its high efficiency and HR, can effectively be used to process fruit juice.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05961-x.

Impact of pretreatment with dielectric barrier discharge plasma on the drying characteristics and bioactive compounds of jackfruit slices

BACKGROUND

Hot-air drying is a popular method for preserving the production of jackfruit, but heat treatment damages its nutritional qualities. Cold plasma is one of the pretreatment methods used to preserve quality attributes of fruits before drying. In the present work, we studied the effect of dielectric barrier discharge (DBD) plasma on the drying characteristics, microstructure, and bioactive compounds of jackfruit slices with different pretreatment times (15, 30, 45, and 60 s), followed by hot-air drying at 50, 60, and 70 °C. A homemade DBD device was operated via three neon transformers.

RESULTS

Optical emission spectrophotometry revealed the emitted spectra of the reactive species in DBD plasma, including the N2 second positive system, N2 first negative system, nitrogen ion, and hydroxyl radical. The results showed that the DBD plasma promoted moisture transfer and enhanced the drying rate, related to the changes in the surface microstructure of samples damaged by DBD plasma. The modified Overhults model was recommended for describing the drying characteristics of jackfruit slices. The contents of ascorbic acid, total phenolics, total flavonoids, total polysaccharides, and antioxidant activity in pretreated jackfruit slices were improved by 9.64%, 42.59%, 25.77%, 27.00%, and 23.13%, respectively. However, the levels of color and carotenoids were reduced.

CONCLUSION

Thus, the bioactive compounds in dried jackfruit slices can be improved using the DBD plasma technique as a potential pretreatment method for the drying process. © 2023 Society of Chemical Industry.

Harnessing Non-Thermal Plasma to Supercharge Recovery in Abdominal Surgeries: A Pilot Study

(1) Background: This study aims to evaluate the efficacy and safety of non-thermal plasma (NTP) therapy in accelerating wound healing in patients who have undergone laparoscopic and open surgeries. (2) Methods: NTP was applied using a needle-type reactor with an irradiance of 0.5 W/cm2 on the surgical wounds of fifty patients after obtaining informed consent. Three NTP treatments, each lasting three minutes, were administered hourly. (3) Results: The pilot study showed that NTP-treated surgical wounds healed completely without any signs of infection, dehiscence, pain, or itching. Notably, patients reported minimal pain after the NTP treatment. Visual assessments conducted twenty-four hours after surgery revealed no redness or fluid discharge. Comparisons with traditionally sutured wounds indicated that NTP-treated wounds healed at a rate equivalent to seven days. (4) Conclusions: The application of NTP in laparoscopic and open wounds proved safe and effective, expediting the wound healing process and eliminating clinical risks post-surgery. Significantly, NTP facilitated a healing rate within twenty-four hours, equivalent to seven days for suture-treated wounds, significantly reducing the hospitalization time to a single day. These findings highlight the potential of NTP to be a transformative approach for promoting postoperative recovery.

Electrohydrodynamic drying of citrus (Citrus sinensis L.) peel: Comparative evaluation on the physiochemical quality and volatile profiles

Based on the concept of circular economy, citrus peel was considered a valuable source of bioactive compounds for high-value foods. Electrohydrodynamic (EHD) drying is a novel technology appropriated for the dehydration of heat-sensitive products such as citrus peel. In current work, EHD drying of citrus peel was performed based on alternating current (AC) or direct current (DC) sources at various voltage levels (9, 18, 27, 36, and 45 kV). The effect of EHD on drying characteristics, water retention capacity, enzyme inactivation, phytochemical contents (phenolic compounds and carotenoids), and volatile compounds of citrus peel were evaluated and compared. Results showed that the drying time in the AC electric field was shorter compared to DC electric field at the same applied voltages due to the polarization layer formed by unipolar charges. The applied voltage determined electric field strength as well as the degree of tissue collapse and cell membrane rupture. EHD elucidated the transformation and degradation of phytochemicals including phenolic compounds, carotenoids, and volatile composition in proportion to the applied voltage. The findings indicate that EHD drying with AC improves drying behaviors, inactivates enzymes, and retains the phytochemical properties of citrus peel.

Effect of dielectric barrier discharge nonthermal plasma treatment on physicochemical, nutritional, and phytochemical quality attributes of pineapple [Ananas comosus (L.)] juice

Forward feed multilayered perception and central composite rotatable design were used to model the nonthermal plasma (NTP) experimental data in artificial neural network (ANN) and response surface methodology, respectively. The ANN was found to be more accurate in modeling the experimental dataset. The NTP process parameters (voltage and time) were optimized for pineapple juice within the range of 25-45 kV and 120-900 s using an ANN coupled with the genetic algorithm (ANN-GA). After 176 generations of GA, the ANN-GA approach produced the optimal condition, 38 kV and 631 s, and caused the inactivation of peroxidase (POD) and bromelain by 87.24% and 51.04%, respectively. However, 100.32% of the overall antioxidant capacity and 89.96% of the ascorbic acid were maintained in the optimized sample with a total color change (ΔE) of less than 1.97 at all plasma treatment conditions. Based on optimal conditions, NTP provides a sufficient level of POD inactivation combined with excellent phenolic component extractability and high antioxidant retention. Furthermore, plasma treatment had an insignificant effect (p > 0.05) on the physicochemical attributes (pH, total soluble solid, and titratable acidity) of juice samples. From the intensity peak of the Fourier-transform infrared spectroscopy analysis, it was found that the sugar components and phenolic compounds of plasma-treated juice were effectively preserved compared to the thermal-treated juice.

Modeling of the inactivation kinetics of aerobic mesophiles and yeasts and molds natural microbiota in nonthermal plasma-treated pineapple (Ananas comosus) juice

The nonthermal plasma (NTP) technology is a promising nonthermal technology that can be employed for pasteurization of fruit juice. The effect of NTP on the natural microbiota, namely, aerobic mesophiles (AM), and yeasts and molds (YM) in pineapple juice were examined in the experimental range of 25-45 kV up to 10 min treatment time. At an applied voltage of 45 kV, the AM and YM count reductions of 4.7 and 4.1 log cfu/mL were obtained at the end of the 14-min treatment. The inactivation kinetics of microbes were attempted to be explained using nonlinear models, including Weibull + tail, Geeraerd, log-logistic, Coroller, and Cerf. The residual population (Nres ) model parameter in the Geeraerd model explained the tailing behavior of microbes. Furthermore, the estimated values for the scale parameter and destruction rate constants were used to describe the sensitive and resistant percentages of the microbial population. According to statistical parameters (R2 : 0.978-0.999, RMSE: 0.034-0.277) and validation indicators (accuracy factor: 1.013-1.152, bias factor: 0.985-1.12), all models performed well. Akaike's theory was used to select the best-fit model, and the Coroller model was shown to be the most accurate one for AM and YM, exhibiting the lowest Akaike increment (Δi  = 0). PRACTICAL APPLICATION: Nonthermal plasma may be used as an alternate nonthermal process for this product in order to meet customer appeal for safe and nutritious juice with minimal processing. The goal of this work was to produce a nutritious and safe pineapple juice by using nonthermal processing.

From polyphenol to o-quinone: Occurrence, significance, and intervention strategies in foods and health implications

Polyphenol oxidation is a chemical process impairing food freshness and other desirable qualities, which has become a serious problem in fruit and vegetable processing industry. It is crucial to understand the mechanisms involved in these detrimental alterations. o-Quinones are primarily generated by polyphenols with di/tri-phenolic groups through enzymatic oxidation and/or auto-oxidation. They are highly reactive species, which not only readily suffer the attack by nucleophiles but also powerfully oxidize other molecules presenting lower redox potentials via electron transfer reactions. These reactions and subsequent complicated reactions are capable of initiating quality losses in foods, such as browning, aroma loss, and nutritional decline. To attenuate these adverse influences, a variety of technologies have emerged to restrain polyphenol oxidation via governing different factors, especially polyphenol oxidases and oxygen. Despite tremendous efforts devoted, to date, the loss of food quality caused by quinones has remained a great challenge in the food processing industry. Furthermore, o-quinones are responsible for the chemopreventive effects and/or toxicity of the parent catechols on human health, the mechanisms by which are quite complex. Herein, this review focuses on the generation and reactivity of o-quinones, attempting to clarify mechanisms involved in the quality deterioration of foods and health implications for humans. Potential innovative inhibitors and technologies are also presented to intervene in o-quinone formation and subsequent reactions. In future, the feasibility of these inhibitory strategies should be evaluated, and further exploration on biological targets of o-quinones is of great necessity.

Beeswax: A review on the recent progress in the development of superhydrophobic films/coatings and their applications in fruits preservation

Recently, the design and fabrication of bio-inspired superhydrophobic materials using natural lipid additives such as beeswax (BW) have aroused great attention in food packaging as they can minimize the transfer rate of water molecules and have effective moisture barriers. This review discusses the recent progress in the design and fabrication of BW-containing edible films/coatings (e.g., emulsion and blend films, bilayer materials, bionanocomposites, and antimicrobial materials) and their potential applications on the postharvest life and quality attributes of various fruits. Incorporation of BW into polysaccharides- and proteins-based emulsion films effectively improved their hydrophobicity, water vapor, and UV/visible light barrier properties, as well as the film tensile properties. The addition of nanoparticles to BW-based polymeric matrices often results in improved physico-mechanical properties. BW coatings have been also applied to prolong the shelf-life of various climacteric fruits, however, optimization of the wax concentration can be further investigated to develop targeted food storage systems.

Effect of dielectric barrier discharge (DBD) cold plasma-activated water pre-treatment on the drying properties, kinetic parameters, and physicochemical and functional properties of Centella asiatica leaves

Centella asiatica L. (CA) is a medicinal plant that gained significant commercial and research interest because of its bioactive compounds, which have functional properties such as antioxidant activity. However, it must be dried before use to improve its shelf life and prepare it for food and pharmaceutical applications. Therefore, in this investigation CA leaves were pre-treated with blanching and cold plasma activated water (CPAW), followed by recirculatory hot air and vacuum drying at 40, 50, and 60 °C. Vacuum-drying took 150-720 min, while hot-air drying took 60-180 min to dry. Page and Logarithmic models best fit for leaf drying kinetics, according to AIC, with R² between 0.966 and 0.999 and RMSE between 0.001 and 0.069. CPAW pre-treatment increased leaf quality more than blanching in vacuum drying. Drying leaves at 40 °C boosted antioxidants (4021.462 μg TE (g dw)^-1 and 3.356 mg GAEAC (g dw)^-1), TPC (35.049 mg GAE (g dw)^-1), and TFC (311.274 mg QE (g dw)^-1) and is recommended. Vacuum-drying with CPAW pre-treatment preserved leaf microstructure better than hot-air drying. This study illuminates CA leaf drying behaviour and allow mass production without damaging bioactive components. These results could be used as a roadmap for future technological advances that will make it possible to use the bioactive components of CA in food formulation.

Effect of cold plasma processing on physicochemical and nutritional quality attributes of kiwifruit juice

Cold plasma treatment of kiwifruit juice was studied in the domain of 18-30 kV of voltage, 2-6 mm of juice depth, and 6-10 min of treatment time using the response surface methodology (RSM). The experimental design utilized was a central composite rotatable design. The effect of voltage, juice depth, and treatment time on the various responses, namely peroxidase activity, color, total phenolic content, ascorbic acid, total antioxidant activity, and total flavonoid content, was examined. While modeling, the artificial neural network (ANN) showed greater predictive capability than RSM as the coefficient of determination (R² ) value of responses was greater in the case of ANN (0.9538-0.9996) than in RSM (0.9041-0.9853). The mean square error value was also less in the case of ANN than in RSM. The ANN was coupled with a genetic algorithm (GA) for optimization. The optimum condition obtained from ANN-GA was 30 kV, 5 mm, and 6.7 min, respectively.