A Novel Method of a High Pressure Processing Pre-Treatment on the Juice Yield and Quality of Persimmon

This study investigates the effects of a high pressure processing pre-treatment (pre-HPP) on the juice yield of persimmon (Diospyros kaki L.) pulp and the pre-HPP plus HPP or thermal processing (TP) on microorganism inactivation and quality changes of the persimmon juice. The “Gongcheng” persimmon was selected with the highest juice yield (48.9%), and the pre-HPP set at 300 MPa/8 min increased the juice yield by 60% through an increasing pectin methylesterase (PME) activity of 25.03% and by maintaining polygalacturonase (PG) activity. For different processing modes, namely, pre-HPP plus HPP at 550 Mpa/5 min and pre-HPP plus TP treatment at 95 °C/5 min, both of the guaranteed microorganisms in the juice were below 2.0 lg CFU/mL; however, the persimmon juice treated by the pre-HPP plus HPP had higher contents of total phenol and ascorbic acid which were 16.07 mg GAE/100 g and 17.92 mg/100 mL, respectively, a lower content of soluble tannin which was 55.64 μg/mL, better clarity which was 18.6% and less color change where the ΔE was only 2.68.

New Perspectives in Photocatalytic Water Treatment

This Special Issue, entitled “New Perspectives in Photocatalytic Water Treatment”, was planned to cover all relevant topics related to photo-initiated oxidative processes in water treatment, with a special emphasis on pollutant abatement and microorganism inactivation, which were required for improving their practical uses [...]

Effect of high intensity ultrasound on main bioactive compounds, antioxidant capacity and color in orange juice

Ultrasound is a useful alternative to thermal processing that can be applied to many food products and juices to aid with enzymes and microorganism inactivation and to improve the efficiency of unit operations generally applied in the food industry. The aim of this study was to evaluate the effect of a high-intensity sonication treatment (frequency 20 kHz; intensity 39.4 W/cm2) applied for treatment times from 0 to 105 min on the content of polyphenols, vitamin C, organic acids, and carotenoids, and on the hydrophilic and lipophilic antioxidant capacity and color of orange juice. Treatments were performed in triplicate and data was statistically analyzed. Sonication time did not have a significant effect ( P > 0.05) on total polyphenols, total vitamin C, organic acid, and carotenoid contents, lipophilic antioxidant capacity, or juice color. The hydrophilic antioxidant activity and the lutein content increased significantly ( P < 0.05) with increased sonication time. These results may be useful as a baseline for the development of sonication treatments that could be used in combination with other traditional and emerging processing approaches to protect the most important bioactive compounds and quality properties of orange juice.

Multi-wave UV-photocatalysis system (UVA+UVC+VUV/Cu-N-TiO2) for efficient inactivation of microorganisms in ballast water

Ballast Water Treatment System (BWTS) is a system designed to remove biological organisms from ballast water. However, the existing BWTSs often have problems in practical applications. In this study, a multiwave ultraviolet (UV)-modified TiO2 photocatalyst biological inactivation system (longwave UV, UVA+shortwave UV, UVC+vacuum UV, VUV/Cu-N-TiO2) for microorganism inactivation in ballast water was established. The results showed that the UVA+UVC+VUV/Cu-N-TiO2 system improved the UV light quantum yield and catalyst activity in the photocatalytic reaction and fully utilized the synergistic inactivation effect of Cu-N-TiO2 photocatalyst+ multiwave UV light (UVA, UVC, and VUV) on microorganisms. Compared with 8 other photocatalytic systems, the logarithmic algae removal rate and logarithmic sterilization rate of the UVA+UVC+VUV/Cu-N-TiO2 system increased to 1.78 log and 5.86 log, respectively. The turbidity of the seawater affected the microorganism inactivation to a certain extent. The humic acid concentration should be controlled below 2 mg L−1 for the UVA+UVC+VUV/Cu-N-TiO2 system to inactivate microalgae more effectively. The multiwave UV photocatalytic system could significantly increase the lipid peroxidation products in microbial cells, rapidly reduce superoxide dismutase (SOD) activity, and degrade a large amount of chlorophyll within a short hydraulic residence time (HRT). Severe damage to the microbial cell membrane can destroy the normal functions of cells, resulting in the death of microorganisms. In conclusion, the UVA+UVC+VUV/Cu-N-TiO2 system is a potential new ballast water treatment system.

Computational Fluid Dynamics Modelling and Analysis Approach for Estimating Internal Short-Circuiting in Clearwells

Disinfection is an effective microorganism inactivation method that has contributed historically to decreasing waterborne diseases. It is necessary to improve hydraulic efficiency for ensuring disinfection ability without creating disinfection by-products. However, many hydraulic efficiency indices, which are a type of black-box analyses based on residence time distribution curves, have been used to assess short-circuiting and mixing. We propose a novel index (internal short-circuiting index, ISI) and analysis approach (internal short-circuiting estimation method, ISEM) based on computational fluid dynamics (CFD) modelling for understanding the local hydrodynamics. Then, we implement ISEM to quantify the effect of the clearwell configuration with the different length-to-width and shape ratios on the hydraulic efficiency. As the hydraulic efficiency surrogated by T10/T converges to the maximum value, the ISI values at inlet and outlet reduce rapidly, and the recirculation and dead zones shrink in the channel zones. Thus, the ISI curve changes from a V shape to U shape. The ISEM demonstrates that it is applicable under various conditions and it enables engineers to design clearwells for optimizing the disinfection ability. Furthermore, the CFD model in this study can be combined with machine learning techniques in future studies to extract knowledge for reducing the computational cost.

Metal Oxide-Based Photocatalytic Paper: A Green Alternative for Environmental Remediation

The interest in advanced photocatalytic technologies with metal oxide-based nanomaterials has been growing exponentially over the years due to their green and sustainable characteristics. Photocatalysis has been employed in several applications ranging from the degradation of pollutants to water splitting, CO2 and N2 reductions, and microorganism inactivation. However, to maintain its eco-friendly aspect, new solutions must be identified to ensure sustainability. One alternative is creating an enhanced photocatalytic paper by introducing cellulose-based materials to the process. Paper can participate as a substrate for the metal oxides, but it can also form composites or membranes, and it adds a valuable contribution as it is environmentally friendly, low-cost, flexible, recyclable, lightweight, and earth abundant. In term of photocatalysts, the use of metal oxides is widely spread, mostly since these materials display enhanced photocatalytic activities, allied to their chemical stability, non-toxicity, and earth abundance, despite being inexpensive and compatible with low-cost wet-chemical synthesis routes. This manuscript extensively reviews the recent developments of using photocatalytic papers with nanostructured metal oxides for environmental remediation. It focuses on titanium dioxide (TiO2) and zinc oxide (ZnO) in the form of nanostructures or thin films. It discusses the main characteristics of metal oxides and correlates them to their photocatalytic activity. The role of cellulose-based materials on the systems’ photocatalytic performance is extensively discussed, and the future perspective for photocatalytic papers is highlighted.

Effect of radiofrequency heating of vacuum-packed nitrite-free sausage on quality properties and microorganism inactivation

ABSTRACT The effect of radiofrequency (RF) heating technology at 27 MHz and 8 kW on the quality properties of vacuum-packed nitrite-free sausages was investigated. One of the several advantages of RF heating technology is the use of less time compared to retort heating. RF heating at 125 °C for a holding time of 2 min and retort heating at 121 °C for 7 min reduced Bacillus subtilis to 7 log cfu/g. In addition, the textural properties of the RF-heated sausages were better than those of retort-heated samples. Furthermore, the growth of B. subtilis and general live bacteria at 25 °C were not detected after 42 days of shelf life in the sausages that underwent RF heating at 125 °C with a holding time of 2 min.

Effect of Electron-Beam Radiation and Other Sterilization Techniques on Structural, Mechanical and Microbiological Properties of Thermoplastic Starch Blend

This work investigates the potential application of various sterilization methods for microorganism inactivation on the thermoplastic starch blend surface. The influence of the e-beam and UV radiation, ethanol, isopropanol and microwave autoclave on structural and packaging properties were studied. All the applied methods were successful in the inactivation of yeast and molds, however only the e-beam radiation was able to remove the bacterial microflora. The FTIR analysis revealed no significant changes in the polymer structure, nevertheless, a deterioration of the mechanical properties of the blend was observed. The least invasive method was the UV radiation which did not affect the mechanical parameters and additionally improved the barrier properties of the tested material. Moreover, it was proved that during the e-beam radiation the chain scission and cross-linking occurred. The non-irradiated and irradiated samples were subjected to the enzymatic degradation studies performed in the presence of amylase. The results indicated that irradiation accelerated the decomposition of material, which was confirmed by the measurements of weight loss, and mass of glucose and starch released to the solution in the course of biodegradation, as well as the FTIR and thermal analysis.

Influence of Acoustic Oscillations on Continuous-Flow Water Disinfection

Water disinfection and potential sterilization in continuous flow was achieved in a hybrid reactor with a broadband hydrodynamic emitter combined with ultrasonic vibrations at different frequencies and with excess pressure. Such a combination showed synergistic effects by increasing the acoustic power in the reactor vortex flow. The present combined physical treatment, compared with sonication alone, could increase microorganism inactivation by 15–20%.

Biofilm Inactivation using Photodynamic Therapy in Dentistry: a review of literature

Introduction: Photodynamic therapy (PDT) is a therapy involving light and a photosensitising chemical substance, used in conjunction with molecular oxygen in order to elicit cell death (photo-toxicity) and thus ability to kill microbial cells, including bacteria, fungi and viruses. Photodynamic therapy is an alternative method of biofilm disruption and it is considered a new way of microorganism inactivation. It is also an additional procedure to reduce the infection rate in patients, caused by the increasing antimicrobials resistance of bacteria. The aim of this literature review was to evaluate the specific effects and the antibacterial effectiveness of photodynamic therapy using different types of photosensitizers (Erythrosine, Rose Bengal, Toluidine blue, Methylene blue, Ozone, Riboflavin, Curcumin, Chlorhexidine, SAPYR) and a visible light of a specific wavelength for each photosensitizer and to reveal the applications of PDT in periodontics, endodontics, prosthodontics and dental caries. Methods: A research of literature was performed in an attempt to find all the articles published on this topic in the last 10 years. The articles was searched by using a certain combination of different keywords (photodynamic therapy ) and (diode laser ) and (teeth) in PubMed database. Results: A total number of 83 articles were found. After applying inclusion and exclusion criteria, 35 articles were taken into consideration for our study and among them 4 were a manuscript, 3 was a review of literature, 1 was an in vivo evaluation and 27 were in vitro studies. Conclusion: Considering that none of the disinfection methods can completely remove the biofilm, PDT is a therapeutic tool complementary to conventional disinfection, with great applicability in dentistry. PDT showed significantly efficacy in reduction of biofilms. Exposure to light in the presence of a photosensitizing chemical substance helps in the reduction of microbes and the protocols could be recommended for clinical usage, but only together with ‘classic ‘ disinfection.