Novel dual-function GC/MS aided ultrasound-assisted hydrodistillation for the valorization of Citrus sinensis by-products: phytochemical analysis and anti-bacterial activities

Abstract

A huge-amount of citrus by-products is being wasted every-year. There is a high-need to utilize these by-products with high-efficiency. This study focuses on the essential oil (EO) isolation from the zest of Citrus sinensis (CS) by-products, using a novel dual-function gas-chromatography mass-spectrometry optimized ultrasound-assisted hydrodistillation-prototype (DF-GC/MS-HUS). The CS-EO was GC-analyzed by MS-detector (GC/MS) and optimized by flame-ionization detector (GC/FID). Ultrasound-assisted hydrodistillation (HUS) had a dual-function in CS-EO isolation by utilizing an adequate-energy to break-open the oil-containing glands, and by functioning-as a dispersing-agent to emulsify the organic-phase. The most effective DF-GC/MS-HUS optimized-conditions were isolation under 38 °C and 10 min of 28.9 Hz sonication. The main-components of CS-EO were limonene, β-myrcene, and α-pinene (81.32%, 7.55%, and 4.20%) in prototype, compared to (60.23%, 5.33%, and 2.10%) in the conventional-method, respectively. The prototype CS-EO showed natural antibacterial-potentials, and inhibited the bio-film formation by Staphylococcus aureus, Listeria monocytogenes, and E. coli more-potent than the conventional-method. Compared to conventional-method, the prototype-method decreased the isolation-time by 83.3%, lowered energy-consumption, without carbon-dioxide production, by reducing isolation-temperatures by more-than half, which protected the thermolabile-components, and increased the quantity by 2514-folds, and improved the quality of CE-EO composition and its antibacterial-potentials. Therefore, the DF-GC/MS-HUS prototype method is considered a novel green-technique that minimized the energy-utilization with higher-efficiency.

Figure 1

Dual-function GC/MS optimized ultrasound-assisted hydrodistillation prototype (DF-GC/MS-HUS). (A) Modified Clevenger hydro-distillator (upper-part). (B) Imbedded ultrasound transducer (lower-part). (C) Ultrasound control. (D) Central Control. (E) GC–FID–MS.

Figure 2

A comparison of the first-order and second-order kinetic models with the experimental results for the extraction of orange oil by (A) Conventional hydrodistillation method and (B) Dual function GC/MS optimized Ultrasound-Assisted Hydrodistillation Prototype method (DF-GC/MS-HUS).

Figure 3

In-vivo CAT antioxidant analysis. NORM normal animals, VEH vehicle treated animals, CCH conventional Clevenger hydro-distillation (10 mg/kg), DF-GC/MS-HUS dual function GC/MS optimized ultrasound-assisted hydrodistillation prototype (10 mg/kg), VC 7 mg/kg vitamin C.

Figure 4

DPPH scavenging assay. VEH vehicle control, CCH conventional Clevenger hydro-distillation isolated essential oil, DF-GC/MS-HUS dual function GC/MS optimized Ultrasound-Assisted Hydrodistillation Prototype isolated essential oil, VC 500 μg/mL vitamin C, “*” means significant (p < 0.05) when compared to vehicle control (n = 3).

Figure 5

Microscopic visualization of the effect of E.Os on biofilm (a) Staphylococcus aureus (b) Listeria monocytogenes (c) E.coli compared to control. C. O2: conventional Clevenger hydro-distillation isolated essential oil. E.O: Dual function GC/MS optimized Ultrasound-Assisted Hydrodistillation Prototype isolated essential oil.