This work proposed a zero waste approach based on microwave (MW) extraction combining hydrodiffusion and gravity for preserving all valuable compounds in the form of dried ginger, ginger essential oil (EO), and juice. A rotatable apparatus was developed from a domestic MW oven to ensure a uniform exposure of the material, resulting in a uniform dried ginger product with EO content more than 0.33% and moisture content less than 10%. The optimum conditions of MW density and energy, which were determined using response surface methodology, are 1 W/g and 1 Wh/g, respectively. They are much lower comparing with that required for hydrodistillation (HD). Significant difference in extraction yield obtained by MW extraction (0.6384 ± 0.0195) and HD (1.1939 ± 0.0679) was observed; however, the quality of EO derived from MW extraction in terms of antibacterial activity was higher than that of the one derived from HD, whereas the physical properties of both EOs were similar. Practical applications In this study, the applicability of microwave (MW) extraction combining hydrodiffusion and gravity for ginger processing to produce dried ginger, ginger essential oil (EO), and juice without generating waste was confirmed. Although the EO yield obtained by the proposed extraction method is smaller than that obtained by hydrodistillation (HD), it was proved to be greener and more efficient than HD in terms of extraction time, EO preserving capability, resources’ consumption, and waste generation. In addition, the EO derived from MW extraction was observed to be more active in antibacterial activity due to its high content of oxygenated and monoterpene compounds. Moreover, this modified rotatable apparatus, which was simply developed from a cheap domestic MW oven to ensure uniform dried product, could be considered technically and economically feasible for actual deployment at small‐scale processing unit.

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In this study, green orange peel (GOP) was feasibly evidenced in preparing selenium nanoparticles (SeNPs). Acting as reducing agents, polyphenolic compounds were extracted from GOP at the optimal extraction conditions (at 70 °C for 1.5 h, mass ratio of dried orange peel/distilled water of 5/100). The formation of SeNPs was observed at the wavelength range of 250–300 nm by ultraviolet–visible spectroscopy (UV–vis), and their highest yield could be reached at the following conditions: volume ratio of extract/selenious acid solution (V Ext/V Se) of 40/10, synthesis duration of 4 h, selenious acid concentration (C Se) of 80 mM, and reaction temperature of 120 °C. The highly crystalline structure of SeNPs in the hexagonal phase was characterized by powder X-ray diffraction (XRD) with a lattice parameter of 4.3 Å; meanwhile, their spheres with an average crystal size of 18.3 nm were estimated by high-resolution transmission electron microscope (HR-TEM). The rationale of bioreducing agents extracted from green orange peel for the formation of SeNPs was also recognized by Fourier-transform infrared spectroscopy (FT-IR). The antibacterial investigation of the SeNP sample was assessed against antibiotic-resistant bacteria, typically methicillin-resistant Staphylococcus aureus (MRSA), by executing the zone of inhibition and the minimum inhibitory concentration (MIC) tests. The SeNP sample demonstrated excellent antibacterial activity with an average diameter of inhibition zones of 20.0 ± 0.7 mm and an MIC of 4.94 μg/L. A comparison of the physicochemical properties of SeNPs synthesized from GOP extract by the hydrothermal method with SeNP products from other green reducing agents and other methods as well as its antibacterial activity compared with other nanoparticles and some antibiotics was conducted to highlight the superiority of GOP-mediated green-synthesized SeNPs.

The synthesis of fungicides in eco-friendly and costeffective ways is significantly essential for agriculture. Plant pathogenic fungi cause many ecological and economic issues worldwide, which must be treated with effective fungicides. Here, this study proposes the biosynthesis of fungicides, which combines copper and Cu 2 O nanoparticles (Cu/Cu 2 O) synthesized using durian shell (DS) extract as a reducing agent in aqueous media. Sugar and polyphenol compounds contained in DS, as the main phytochemicals acting in the reduction procedure, were extracted under different temperatures and duration conditions to obtain the highest yields. We confirmed the extraction process performed at 70 °C for 60 min to be the most effective in extracting sugar (6.1 g/L) and polyphenols (22.7 mg/L). We determined the suitable conditions for Cu/Cu 2 O synthesis using a DS extract as a reducing agent for a synthesis time of 90 min, a volume ratio of DR extract/Cu 2+ of 15:35, an initial pH solution of 10, a synthesis temperature of 70 °C, and a CuSO 4 concentration of 10 mM. The characterization results of as-prepared Cu/Cu 2 O NP showed a highly crystalline structure of Cu 2 O and Cu with sizes estimated in the range of 40−25 nm and 25−30 nm, respectively. Through in vitro experiments, the antifungal efficacy of Cu/Cu 2 O against Corynespora cassiicola and Neoscytalidium dimidiatum was investigated by the inhibition zone. The green-synthesized Cu/Cu 2 O nanocomposites, which are potential antifungals against plant pathogens, exhibited excellent antifungal efficacy against both Corynespora cassiicola (MIC = 0.25 g/L, the diameter of the inhibition zone was 22.00 ± 0.52 mm) and Neoscytalidium dimidiatum (MIC = 0.0625 g/L, the diameter of the inhibition zone was 18.00 ± 0.58 mm). Cu/Cu 2 O nanocomosites prepared in this study could be a valuable suggestion for the control of plant pathogenic fungi affecting crop species globally.