Date Published: June 30, 2017
Publisher: Tabriz University of Medical Sciences
Author(s): Parizad Piran, Hossein Samadi Kafil, Saeed Ghanbarzadeh, Rezvan Safdari, Hamed Hamishehkar.
Purpose: Due to the antimicrobial property, menthol have significant potential for food preservation and foodstuff shelf life improvement. Nevertheless, menthol instability, insolubility, and rapid crystallization in aqueous media make it unsuitable for used in food products. This work was aimed to prepare menthol-loaded nanostructured lipid carriers (NLCs) to enhance its antimicrobial activity.
Increased concern of consumers on the various side effects of synthetic preservatives and development of antibiotic resistant strains have attracted great attention to the use of natural compounds with antimicrobial activity in food and pharmaceutical industries.1 Essential oils are volatile, natural, aromatic oily liquids that can be obtained from several parts of the plants such as leaves and flowers. Due to the aromatic property of essential oils, they have been widely used in cosmetic industries for the production of soaps, perfumes, and toiletries.2 The large bioactivity of essential oils has been confirmed by several studies, including antibacterial, antiviral, anti-inflammatory, antifungal, antimutagenic, anticarcinogenic, and antioxidant activities. This group of oils may provide the natural antimicrobials that food industry requires leading to reduced need for synthetic preservative excipients.3,4 The main constituents of essential oils have unsaturated carbon chains, which is well-known that are susceptibility to oxidation mediated by light or heat. The high volatility of essential oils also limits their free use without a vehicle. Furthermore, the low aqueous solubility limits the possible application of essential oils in aqueous based foodstuffs such as beverages. All of these factors limit the application of essential oils as candidates for preserving food solutions.5 Menthol is a monocyclic monoterpene alcohol naturally obtained from peppermint or other mint oils. It is widely used as a flavoring agent for toothpaste, hygiene products, chewing gum, etc. Menthol is generally available in the form of crystals or granules with a melting point at 41-43 °C. Although, previous researches have shown that menthol has antibacterial and antifungal activity, its high volatility, instability, insolubility, and rapid crystallization in aqueous mediums are the crucial problems concerning its applications and shelf life.6 The microencapsulation method is an appropriate technique to solve above mentioned problems. In this perspective, encapsulation procedures provide an effective protection of naturally compounds against chemical reactions and undesirable interactions with other components in food. Furthermore, it improves solubility, diminish migration, and preserve the bioactive compounds stability during food processing and storage.7 In food engineering, protection of bioactive compounds such as vitamins, antioxidants, proteins, and lipids could be achieved using nano encapsulation technique to produce functional foods with enhanced functionality and stability.8 As lipid based nanoparticles are composed by lipids, they have the ability of interaction with several bacterial and fungal cell types.9,10 Therefore, in the present study menthol-loaded nanostructured lipid carriers (NLCs) were prepared to improve the solubility, stability, and antimicrobial efficacy of menthol for potential application as preservative in food industry.
Menthol was successfully loaded into NLCs in the amorphous structure in the ratio of 1:10 Menthol:lipid by dissolving in the oil phase. Menthol-loaded NLCs were around 100 nm with narrow size distribution (PDI 0.2). The antimicrobial efficiency of the encapsulated menthol was tested on four different microorganisms, demonstrating that MIC and MBC values in the case of NLCs were lower than the menthol emulsion. It can be concluded that essential oils could be used as antibacterial supplement and food preserving agents; however, further investigations are required on the potential antibacterial applicability of this nanostructure in other applications such as topical and oral uses especially against the drug-resistant microorganisms.
This paper was financially supported by Tabriz University of Medical Sciences.
The authors declare no conflict of interests.