In the present study, a well-defined set of chitosans, with different degrees of acetylation (DA) and degrees of polymerization (DP), were processed by solution electrospraying from a water-based solvent. The solution properties, in terms of surface tension, conductivity, viscosity, and pH, were characterized and related to the physico-chemical properties of the chitosans. It was observed that both DA and DP values of a given chitosan, in combination with biopolymer concentration, mainly determined solution viscosity. This was, in turn, the major driving factor that defined the electrosprayability of chitosan. In addition, the physico-chemical properties of chitosans highly influenced solution conductivity and results indicated that the chitosan solutions with low or low-to-medium values of conductivity were the most optimal for electrospraying. The results obtained here also demonstrate that a good process control can be achieved by adjusting the working conditions, i.e . applied voltage, flow-rate, and tip-to-collector distance. Finally, it was also shown that electrosprayability of chitosan with inadequate physico-chemical properties can be improved by solution mixing of very different kinds of this polysaccharide. The resultant electrosprayed submicron chitosan capsules can be applied for encapsulation of food additives and to develop bioactive coatings of interest in food packaging, where these particles alone or containing functional ingredients can be released from the package into the food to promote a health benefit.

BACKGROUND: Quantification of spray deposition on a target crop is of vital importance to optimize pesticide application. In traditional determinations of spray deposition, a large amount of organic solvent is used to extract pesticides from the target crops. In this study, a water‐soluble food dye of Allura Red was developed as a tracer to determine pesticide spray deposition on a rice target crop. RESULTS: The addition of Allura Red does not obviously alter the physicochemical properties of pesticides (viscosity, density and surface tension) and droplet spectra. An ultra‐performance liquid chromatography (UPLC) analytical method was developed and validated to determine the deposition amount of Allura Red on rice plants. Method accuracy and precision for Allura Red were found to be satisfactory with recoveries of 96.07% to 107.48%. To validate the method, comparative deposition analyses were carried out using representative systematic and non‐systematic pesticides (nitenpyram and chlorothalonil) under the same spraying scenarios using a Potter spray tower. Allura Red and pesticides showed comparable deposition under the same application conditions with ratios from 0.98 to 1.21. A field trial using an unmanned aerial vehicle sprayer further indicated that the deposition rates for Allura Red and nitenpyram on rice seedling were 13.04% and 11.07%, with corresponding relative standard deviation values (n = 5) of 16.39% and 18.79%. CONCLUSION: A laboratory test and field trial confirmed that the developed method of using Allura Red as a tracer for spray deposition assessment is feasible and practicable. © 2019 Society of Chemical Industry

In this study, the effect of high‐intensity ultrasound (HIUS) (200 and 400 W for 0, 5, 10 and 15 min respectively) on conformational changes, physicochemical, rheological and emulsifying properties of scallop (Patinopecten yessoensis) myofibrillar protein (SMP) was investigated. HIUS‐treated SMP had lower α‐helix content and higher β‐sheet content compared with the native SMP. HIUS treatment induced the unfolding of SMP and increased the surface hydrophobicity. The particle size of SMP decreased and the absolute zeta‐potential increased after ultrasonication, which in turn increased the solubility of SMP. The conformational changes and the improvement of physicochemical properties of SMP increased the ability for SMP to lower the interfacial tension at the oil–water interface and increased the percentage of adsorbed protein. As a result, the emulsifying properties, rheological properties of SMP and storage stability of emulsions were also improved. In conclusion, HIUS treatment has future potential for improving the emulsifying properties of SMP.

In this study, oil-in-water emulsions made of medium-chain triglycerides (MCT), mucilage from Dioscorea opposita (DOM), and food-grade polysaccharides (guar gum [GG], xanthan gum [XG] and pectin [Pec]) were prepared using high-pressure homogenisation. The droplet size distributions, microstructure, turbidity, interfacial tension, creaming index, and stability of emulsions were investigated and compared with those of DOM, GG, XG and Pec. The results showed that 0.4 wt% food-grade polysaccharides (GG, XG, and Pec) with 2 wt% DOM contributed more to the stability of the emulsion during storage. In particular, low concentrations of pectin and DOM emulsions presented smaller droplet size distribution, in the range of 86.34–111.30 nm. Hence, DOM has synergistic effects with food-grade polysaccharides, which could improve the stability of emulsions, suggesting that mucilage from Dioscorea opposita has good potential for use as a natural emulsifier.