P70: Withdrawn: Effect of sugars, temperature and time on the production of inhibitory agents in microbiological media containing sugar and casein (Maillard Reaction)

The non-enzymatic (Maillard) reaction between sugars and proteins takes place in many processes and is responsible for the formation of a large variety of compounds. These compounds are coloured and flavoured and are often characteristic of specific foods. However, the growth of bacteria is severely inhibited in a media containing reducing sugars and protein due to the formation of some Maillard reaction products. It was observed in our studies that these inhibitory agents were formed when honey (2 % (v/v)) was added to Mueller-Hinton medium and autoclaved. The aim of this study was to determine the effect of the Maillard reaction on the production of inhibitory agents synthesized from adding different reducing sugars (glucose, fructose and ribose) or honey to bacterial growth medium before autoclaving. This study also focused on the factors that affect the production of these agents including the time and heating temperature. Adding honey or ribose to media caused the production of an inhibitor which was fatal against Campylobacter jejuni. No lethal effects were observed in autoclaved media containing glucose or fructose. Heating the mixture at lower temperatures (100°C or 80 °C) for the same length (15 min) had no effect. However, a prolonged incubation (72 h) at 55 °C enhanced the inhibitory property of the media. The autoclaved mixture was also bacteriostatic against MRSA and H. pylori. No effect was reported against E. coli. Maillard reaction produces have different inhibitory agents. More studies are needed on Maillard reaction between microbiological media and added ingredients.