Use of Micellar Delivery Systems to Enhance Curcumin’s Stability and Microbial Photoinactivation Capacity

Victor Ryu,Lynne A Mclandsborough,David Julian Mcclements,Silvette Ruiz-Ramirez,Piyanan Chuesiang,Maria G Corradini

doi:10.3390/foods10081777

Abstract

Microbial photoinactivation using ultraviolet (UV) or visible light can be enhanced by photosensitizers. This study assessed the efficacy of encapsulating a food-grade photosensitizer (curcumin) in surfactant micelles on its water dispersibility, chemical stability, and antimicrobial activity. Stock curcumin-surfactant solutions were prepared with Surfynol 465 (S465) or Tween 80 (T80) (5 mM sodium citrate buffer). The antimicrobial activity of curcumin-loaded surfactant solutions was determined by monitoring the inactivation of Escherichia coli O157: H7 and Listeria innocua after 5-min irradiation with UV-A light (λ = 365 nm). The solutions mixed with the bacterial suspensions contained 1 µM curcumin and each surfactant below, near, and above their critical micelle concentrations (CMCs). The addition of surfactants at any level to the curcumin solution enhanced its dispersibility, stability, and efficacy as a photosensitizer, thereby enhancing its antimicrobial activity. Gram-positive bacteria were more susceptible than Gram-negative bacteria when curcumin-loaded micelles were used against them. The photoinactivation efficacy of curcumin-surfactant solutions depended on the pH of the solution (low > high), surfactant type (S465 > T80), and the amount of surfactant present (below CMC ≥ near CMC > above CMC = unencapsulated curcumin). This result suggests that excessive partitioning of curcumin into micelles reduced its ability to interact with microbial cells. Synergistic antimicrobial activity was observed when S465 was present below or near the CMC with curcumin at pH 3.5, which could be attributed to a more effective interaction of the photosensitizer with the cell membranes as supported by the fluorescence lifetime micrographs. The use of a micelle-based delivery system facilitates adsorption and generation of reactive oxygen species in the immediate environment of the microbial cell, enhancing photoinactivation.

Highlights

Effective sanitation of food-contact surfaces reduces the risk of contamination of food products with pathogenic or spoilage microorganisms [1]
The antimicrobial activity of non-encapsulated curcumin was evaluated in different buffer solutions containing 6 Log CFU/mL of E. coli O157:H7 placed in a multi-well plate
Our study showed that at lower pH values (i.e., 3.5), there was a distinct enhancement in antimicrobial activity when both curcumin and Surfynol 465 (S465) micelles were present (Figure 7)

Summary

Introduction

Effective sanitation of food-contact surfaces reduces the risk of contamination of food products with pathogenic or spoilage microorganisms [1]. Prior to sanitizating in the food industry, a cleaning stage is carried out, the effectiveness and safety of chlorinated water. Prior to sanitizating in the food industry, a cleaning stage is carried out, the effectiveness and safety of chlorinated water as a sanitizer could be compromised by the presence of remaining organic matter on the surface as atosanitizer could beofcompromised by the presence of remainingsuch organic matter due the rapid depletion chlorine and the formation of by-products as trihaloon the surface due the rapid depletion of chlorine and the formation of contact by-products methanes, which aretocarcinogenic [3,4,5]. Alternative sanitation methods for sursuch as trihalomethanes, which are carcinogenic [3,4,5]

Methods

Results

Conclusion