Nanoemulsion of cashew gum and clove essential oil (Ocimum gratissimum Linn) enhancing antioxidant and antimicrobial properties -

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Nanoemulsion of cashew gum and clove essential oil (Ocimum gratissimum Linn) enhancing antioxidant and antimicrobial properties

In this research addressing concerns over foodborne illnesses, additives play a crucial role in reducing microbial contamination and extending shelf life. Plant essential oils (EOs) are recognized for their natural antimicrobial and antioxidant properties. Specifically, EO from Ocimum gratissimum demonstrates stability over 12 months, making it a promising industry application. Originating from Sri Lanka, India, Iran, Africa, and Madagascar, Ocimum gratissimum is widely used in folk medicine against various ailments. Despite its medicinal uses, EOs face challenges like low water solubility, strong flavor, and limited stability. Nanotechnology provides a solution, offering improved stability and effectiveness for bioactive compounds in the food industry.

Biopolymers, particularly polysaccharides like cashew gum (CG), are employed as carrier materials to protect EOs during encapsulation. CG, derived from Anacardium occidentale Linn, proves non-cytotoxic and is considered a potential alternative to Arabic gum in the food industry. The present study focuses on formulating and characterizing nanoemulsions with O. gratissimum EO and cashew gum, employing both low and high-energy synthesis methods suitable for the food industry. The aim is to create nanoformulations with antibacterial and antioxidant properties for potential application in food preservation packaging.

Material and Methods:

 Materials: Cashew exudate (Anacardium occidentale L.) and Ocimum gratissimum leaves were collected and registered in the National System for the Management of Genetic Heritage. Essential oil extraction utilized hydrodistillation, following established protocols. Chemical reagents were of analytical or HPLC grade.

 Isolation, Purification, and Characterization of Cashew Gum: Cashew gum was isolated, purified, and characterized based on a modified method. Composition analysis revealed specific percentages of various components. Molecular weight was estimated using size exclusion chromatography, and NMR spectra were obtained.

Analysis of Essential Oil by GC/MS:Gas Chromatography coupled to Mass Spectrometry was employed for qualitative analysis of the essential oil. Identified components were quantified based on the relative peak area of the total ion chromatogram.

Formulation of Nanoemulsions: Oil-in-water nanoemulsions were formulated using cashew gum and Ocimum gratissimum essential oil. Two synthesis methods, low and high-energy, were applied.

Characterization of Nanoemulsions: Hydrodynamic Diameter, Polydispersity Index, and Zeta (ζ) Potential: Measured by dynamic light scattering on specific days post-synthesis.

Encapsulation Efficiency: Determined through UV-visible spectrophotometry.FTIR Analysis: Conducted to identify functional groups in the essential oil, polysaccharides, and nanoemulsion.

Nanoparticle Tracking Analysis (NTA): Employed for size and concentration data.

Atomic Force Microscopy (AFM): Used for imaging and size determination of nanoparticles.

 Evaluation of Antibacterial Activity: Antimicrobial activity against common pathogenic bacteria was assessed through MIC and MBC determinations. Atomic Force Microscopy was employed for bacterial strain analysis.

Antioxidant Activity: Antioxidant potential was evaluated by scavenging the ABTS radical, and the total antioxidant capacity was expressed as a percentage of inhibition.

Result and Summary:  The synthesis methods employed successfully formulated polymeric nanoemulsions, leveraging the presence of cashew gum to achieve smaller particles with a monomodal distribution. These nanoemulsions exhibited enhanced antibacterial and antioxidant activities of the Ocimum gratissimum essential oil (EO). Notably, a low-energy synthesis method using cost-effective equipment maintained stable EO content, preserving its antibacterial efficacy over 37 days of cold storage. The results suggest the potential of this formulation as a natural antimicrobial agent against foodborne pathogens. Future studies should explore the interaction of nanoemulsions with food matrices and pathogens, addressing aspects of food preservation and safety. The research specifically focused on producing EO nanoemulsions using cashew gum, analyzing EO constituents, confirming encapsulation efficiency, and evaluating antibacterial and antioxidant activities. The study emphasized the superiority of nanostructured EO in antibacterial action against pathogenic species and highlighted the improved stability of the low-energy synthesis over an extended storage period.

Reference:

ARAUJO, T.D.S., DA COSTA, J.M.A.R., RIBEIRO, F.D.O.S., DE JESUS OLIVEIRA, A.C., DO NASCIMENTO DIAS, J., DE ARAUJO, A.R., BARROS, A.B., DA PAIXÃO BRITO, M., DE OLIVEIRA, T.M., DE ALMEIDA, M.P. AND DE CARVALHO CASTRO, K.N., 2021. Nanoemulsion of cashew gum and clove essential oil (Ocimum gratissimum Linn) potentiating antioxidant and antimicrobial activity. International Journal of Biological Macromolecules, 193, pp.100-108.