Mycotoxins present in food products are related to several health problems in both humans and animals, likewise, they are known to cause economic loses in the food and feed industries. Over the last decades there have been an increasing interest in reducing mycotoxins contamination in food and feed products, either by stopping fungal proliferation or by removal of mycotoxins. The first approach includes the application of fungicidal products and several chemical and thermal process. One of the most interesting approaches for fungal control in food and feed products is photoinactivation by using natural and biocompatible products as photosensitisers. Curcumin a polyphenol extracted from turmeric (Curcuma longa) has shown great potential as a photosensitizer in food and feed products, as it is safe for both human and animal consumption, it is relative cheap and biochemically stable, however its application can be limited by its low water solubility. In this work we developed curcumin loaded nanoemulsions, as a way to increase its water solubility and studied its application in the photoinactivation of Aspergillus niger spores. Curcumin loaded nanoemulsions were formed using a low-energy method, with orange oil as the oil phase and Tween 80 as surfactant. Mean particle size, encapsulation efficiency x-potential and curcumin photodegradation with white and blue (450 nm) light were measured. Results showed that mean particle decreased as curcumin concentration was increased up until 5 µg/mL. Furthermore, nanoencapsulation reduced curcumin photodegradation, maintaining 90% of curcumin molecules after 30 min of both white and blue light exposure, while non-encapsulated curcumin reached values below 40%. Finally, A. niger spores were inoculated with different concentrations of nanoencapsulated curcumin and subjected to blue light pulses (30, 60, 90 and 120 s), non-encapsulated curcumin was used as a comparison. Results showed that curcumin loaded nanoemulsions in dark conditions inhibited up to 20% of the A. niger spores. Inhibition (%) was increased by the use of the blue light pulses, with values reaching 80% after 60 minutes of irradiation.

Photoinactivation of Aspergillus niger spores by curcumin loaded nanoemulsions

ACS Fall 2021

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