Enhancement of physicochemical stability and reduction in enzyme and microbial activity of apple juice by hydrodynamic cavitation processing

Conventional thermally processed apple juices are nutritionally depleted because the heat sensitivity degrades the bioactive compounds that comprise them. This study proposed a non-thermal technique, hydrodynamic cavitation (HC), to preserve the nutritional content and prevent the loss of bioactive components in apple juice. In addition, the effect of hydrodynamic cavitation on the physicochemical, nutrition, and enzyme inactivation of freshly expressed apple juice has been studied. The design expert software has been used for process optimization, while fuzzy logic was applied for sensory. Hydrodynamic cavitation has been used on freshly extracted apple juice with inlet pressure in the range of (34.47–103.421 kPa) for a treatment time of (0–30 min). The apple juice was treated thermally at 90 °C for 2.5 min to compare the cavitation results. The settling of particles in the cavitation sample was 7%, which was lower than the heat-treated sample (10%) and untreated control sample (39%) and had a noticeable effect on the cloud value and stability of the apple juice. The HC treatment reduces the particle size of fresh apple juice from 8934.09 nm to 1112 nm, resulting in a homogenizing effect, a decrease in viscosity, and improved juice stability. Hydrodynamic cavitation reduced the antioxidant activity from 0.4987 mg GAE mL−1 (control) to 0.3951 mg GAE mL−1 yet retained better activity than the heat-treated apple juice (0.3489 ± 0.34 mg GAE mL−1) with microbial log reduction of 0.9 at 103.42 kPa treated for 30 min. After 15 days of storage at 4 °C, HC-treated juice had higher quality features and nutrient retention than heat-treated apple juice

Copper Core–Porous Manganese Oxide Shell Nanoparticles

Core-shell nanoparticles, especially those with nanoporous oxide shells, exhibit chemical and physical properties that are distinct from those of the bulk materials due to the atomic-level proximity and morphology of the core and shell atoms. Here, we demonstrate a wet-chemical method for the synthesis of Cu core (∼6.1 nm)-porous Mn3O4 shell (∼3.4 nm thick) nanoparticles. Various characterization techniques, including synchrotron radiation-based small-angle X-ray scattering (SAXS) and X-ray absorption near edge structure (XANES) tools, confirm the core-shell structure. Both the chemical and physical properties of these Cu-based nanoparticles are influenced by the Mn3O4 shell. For example, the magnetic properties of the core-shell particles are found to be similar to those of Mn 3O4 nanoparticles reported in the literature. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results demonstrate that these materials are catalytically active for CO adsorption and hydrogenation. © 2011 American Chemical Society