Natural compounds to control the growth of food spoilage moulds

Fungi are important spoilage agents of several foods causing great economic losses worldwide. Some moulds are capable of producing toxic metabolites that may be carcinogenic and therefore constitute a public health risk, whereas the growth of spoilage fungi results in nutritional and chemical changes leading to the consumer rejection. Several techniques and chemical additives, including antibiotics, are used for food preservation. However, consumer demands for minimally processed foods have caused an increased pressure to reduce or eliminate chemical additives and stimulated the use of alternative substances able to prevent the growth of moulds ensuring high quality and safe foods. The objective of this study was to evaluate the effects of natural compounds and microbial metabolites, including several furanones, free fatty acids and monoglycerides, on Aspergillus, Penicillium, Fusarium, Botrytis and Rhizopus species. More than 25 natural compounds were screened for their antifungal activity against 30 mould strains. The minimal inhibitory concentration values of the compounds were established for all moulds. Moreover, their ability to inhibit the growth of moulds in liquid medium was evaluated. Decanoic acid and rac-1-lauroylglycerol resulted to be the most active free fatty acid and monoglyceride respectively, being able to inhibit completely the growth of all the strains tested. Among furanones, -angelica lactone showed a strong activity inducing a complete inhibition of 75% of the strains. Varying sensitivities to the antimicrobial properties of hexanal and 5-ethyl-3-hydroxy-4-methyl-2 (5H) furanone were observed. Rhizopus arrhizus resulted to be the less sensitive strain being not inhibited by any of the substances tested. The most effective substances were also tested on real systems.