Particle engineering to stabilise microsuspensions via electrostatic and conventional spray drying

Among the pests that attack the maize crop, the maize leafhopper, which causes direct damages by sap sucking and indirect ones, stands out as being a vector of pathogens and viruses, and can cause losses of up to 100% of the production. An alternative to improve the chemical control of this pest is the use of electrostatic spraying technology, however, there is no research support. This study aimed to evaluate the deposition of spray in the maize crop and the effectiveness in the chemical control of the maize leafhopper, using the electrostatic spraying system, at different application rates, compared to the conventional spraying system. The experiment was conducted in a randomized block design with five treatments, in a 2x2 + 2 factorial scheme: presence or absence of electrostatic spraying system, two application rates (35 and 50 L ha-1), an additional treatment using a hydraulic spraying and a rate of 100 L ha-1, and other additional treatment without the application of insecticide, in order to support the study of pest infestation. Each treatment consisted of eight replicates, in which the spray deposition in the maize canopy and the efficiency in the control were evaluated. For the insecticide applications, a rod sprayer with induction electrostatic spraying system was used with indirect electrification. To evaluate the deposition, the Brilliant Blue FCF marker was added to the spray to be detected by absorbance in spectrophotometry. For the efficacy control of the maize leafhopper, the insecticide composed of thiamethoxam and lambda-cyhalothrin was used, comparing with the control without the application. There was a significant increase in the spray deposition, both in the upper and lower maize leaves, with the use of electrostatic spray technology compared to the conventional spray system. The crop protection control of the maize leafhopper was also superior. The electrostatic spraying also made it possible to reduce the application rate by approximately three times in relation to that used in conventional hydraulic spraying.

The objective of this study was to evaluate the effectiveness of antimicrobial interventions using peroxyacetic acetic acid (PAA) followed by novel organic acids on beef trimmings prior to grinding with conventional spray (CS) or electrostatic spray (ES) on ground beef microbial populations and color. Beef trimmings (80/20; 25kg) were inoculated with E. coli O157:H7, non- O157:H7 shiga toxin producing (STEC) E. coli (EC) and Salmonella spp. (SA) at 105 CFU/g. Inoculated trimmings (1.5 kg /treatment/replicate, 2 replicates) were treated with CS application of 0.02% PAA alone or followed by CS or ES application of 3% octanoic acid (PO), 3% pyruvic acid (PP), 3% malic acid (PM), saturated solution of fumaric acid (PF) or deionized water (W). Findings from this study suggest that PA as a single or multiple chemical hurdle approach with malic, pyruvic, octanoic and fumaric acid on beef trimmings may be effective in reducing E. coli O157:H7 as well as non-STEC serotypes and Salmonella in ground beef up to day 2 of simulated retail display. Results of this study showed that instrumental color properties of ground beef treated with peroxyacetic acid followed by organic acids had little or no difference (P > 0.05) compared to the untreated un-inoculated control ground beef samples. The results also indicate that ES application of some organic acids may have similar or greater efficiency in controlling ground beef microbial populations compared to the CS application of the same acid providing a more economical and waste manageable decontamination approach.

Pesticide spray drift, which is the movement of pesticide by wind to any location other than the intended area, is hazardous to human, animal, food safety and environmental health. It is not possible to completely eliminate spray drift during spraying with field crop sprayers, but spray drift can be reduced by developing new technologies. The most common methods to reduce spray drift are carrying the droplets to the target with air-assisted spraying, electrostatic spraying, preferring air induction nozzles and boom shields. With these methods, it is not possible to make a change on the sprayer depending on the wind intensity during spraying. In this study, a novel servo-controlled spraying system was designed and developed to change the nozzle orientation angle in the reverse direction of the wind current to reduce the ground spray drift in real time and automatically in a wind tunnel. The displacement in the spray pattern (Dc ) was used as a ground drift indicator for each nozzle to evaluate the spray drift. The developed system, operated by LabVIEW software, calculated different nozzle orientation angles depending on nozzle types, wind velocities and spraying pressures. Orientation angles calculated for different test conditions achieved in reduction were up to 49.01% for XR11002 nozzle, 32.82% for AIXR11002 nozzle and 32.31% for TTJ6011002 nozzle at 400 kPa spray pressure and 2.5 m s-1 wind velocity. The developed system, which has a self-decision mechanism, calculated the nozzle orientation angle instantaneously according to the wind velocity. It has been observed that the adjustable spraying nozzle system, sprayed with high precision towards the wind in the wind tunnel, and the developed system have advantages compared to conventional spraying systems. This article is protected by copyright. All rights reserved.

Analysis of potential impaction and phytotoxicity of surfactant-plant surface interaction in pesticide application

Microbial contamination of food products is one of the main transmission routes of disease in the world today, which is responsible for about two-thirds of all food-borne disease outbreaks although the hygiene process was improved recently. Improving microbial safety and implementing a good food management system are important elements to reduce microbial contamination and improve food safety and security. To improve microbial safety, I conducted inactivation studies on food pathogens and further explored antibiotic resistant risks. Initial research evaluated the efficacy of commercial antimicrobials distribution by comparing electrostatic sprayer with conventional sanitization process. The antibiotics applied by electrostatic spraying achieved significant additional reductions on the foodborne pathogen and more economically feasible compare to the conventional spraying method. Further exploration was carried out building inactivation model analysis on foodborne pathogens under thermal dynamic conditions. Thermal kinetics of foodborne pathogen on moisture enhanced meat were determined and a potential surrogate of Salmonella was identified. Finally, an investigation of the knowledge and attitude of antibiotic resistant issues among local food processors was conducted and results provided suggestions regarding antibiotic risks for local government agencies policy improvement. These studies combined to identify and improve microbial safety on food products by using technologies and statistical analysis.

Electrostatic spray drying (ESD) of a milk protein matrix comprising whey protein isolate (WPI), skim milk powder (SMP), and lactose was compared to conventional spray drying (CSD) and freeze-drying (FD). ESD and CSD were used to produce powders at low (0.12–0.14), medium (0.16–0.17), and high (0.31–0.36) levels of water activity (aw), while FD powders targeted low aw (0.12). Maillard reaction indicators were studied after drying and during storage for up to 28 days at 20, 40, or 60 °C by measuring free -NH2 groups, as an indicator of available lysine, and 5-hydroxymethylfurfural (HMF). After drying, levels of residual free -NH2 groups were ~15% higher in ESD and FD powders than in their CSD counterparts. CSD powders also had ~14% higher HMF concentrations compared to their ESD and FD counterparts. Storage led to reductions in free -NH2 groups and increases in HMF content in all powders, the extent of which increased with increasing storage temperature. Reductions in free -NH2 groups followed first-order reaction kinetics at 20 and 40 °C but second-order reaction kinetics at 60 °C. Lactose crystallization was detected in high-aw CSD powders after 14 d at 40 °C and in both CSD and ESD powders after 7 d at 60 °C. Overall, we found that ESD is a gentle drying technology which enables production of powders with lower Maillard reaction markers.

The aim of this study was to produce micron-sized spherical agglomerates of pure drug nanoparticles to achieve improved aerosol performance in dry powder inhalers (DPIs). Sodium cromoglicate was chosen as the model drug. Pure drug nanoparticles were prepared through a bottom-up particle formation process, liquid antisolvent precipitation, and then rapidly agglomerated into porous spherical microparticles by immediate (on-line) spray drying. Nonporous spherical drug microparticles with similar geometric size distribution were prepared by conventional spray drying of the aqueous drug solution, which together with the mechanically micronized drug particles were used as the control samples. The three samples were characterized by field emission scanning electron microscopy, laser diffraction, Brunauer–Emmett–Teller analysis, density measurement, powder X-ray diffraction, and in vitro aerosol deposition measurement with a multistage liquid impinger. It was found that drug nanoparticles with a diameter of ~100 nm were precipitated and agglomerated into highly porous spherical microparticles with a volume median diameter (D50 %) of 2.25 ± 0.08 μm and a specific surface area of 158.63 ± 3.27 m2/g. In vitro aerosol deposition studies showed the fine particle fraction of such spherical agglomerates of drug nanoparticles was increased by more than 50 % in comparison with the control samples, demonstrating significant improvements in aerosol performance. The results of this study indicated the potential of the combined particle engineering process of liquid antisolvent precipitation followed by immediate (on-line) spray drying in the development of novel DPI drug products with improved aerosol performance.