The objective is to identify and assess a range of natural antimicrobial systems for their potential as a novel means of extending the safety and improving the quality of food.
Research was carried out to identify and assess a range of natural antimicrobial systems for their potential as a means of extending the safety and improving the quality of food.
A wide range of lactic acid bacteria from cheese, other milk and dairy sources, meat, fruit and vegetables were screened. Antimicrobial bacteriocin activity was determined against food spoilage and pathogenic organisms such as Pseudomonas fraqi, Staphylococcus aureus, Listeria innocua and Clostridium tyrobutyricum.
A study took place of 5 classes of natural antimicrobials from animal and plant sources. 3 of these were tested against 9 target organisms, 4 moulds, 1 yeast and 4 bacteria, while the last 2 were tested against the yeast and moulds and 7 specific spoilage yeasts from beverages. 3 classes of compounds showed promise for further studies (chitosan, lyticase and a cell wall degrading enzyme preparation).
There has been an initial study of microbial resistance to the inhibitory action of oleuropein, a phenolic glycoside from olives. This was coupled wth studies of the antimicrobial effect of oleuropein and phenolic extracts from Greek tea and herbs, on Staphylococcus aureus at different temperatures and pH values.
Phenolic extracts from olives and tea delayed the growth of Staphylococcus aureus and reduced the amount of toxin produced. Herb extracts had variable inhibiting effects and toxin production was lower in the nonfat milk. Oleuropein had an increasing effect as the inoculum size decreased and was less effective at a lower pH.
Finally, there has been a study of the fate of Salmonella enteriditis in food systems, alone and in conjunction with Lactobacillus fructivorum or Zygosaccharomyces baillii, when challenged with natural antimicrobial agents such as mustard, garlic and pepper at various temperatures and pH values.
More specifically, the content and activity of natural antimicrobial agents in plant, animal and microbial systems will be assessed. The ease of extraction, purification and their antimicrobial effectiveness will be examined.
The activity of the new antimicrobials will be tested individually, as well as in combination with traditional preservation techniques, against food spoilage and poisoning organisms in laboratory media and foods.
The study will also examine technological aspects of antimicrobial production in relation to the quality of the end product, and the environmental impact of the process.
Funding SchemeCSC - Cost-sharing contracts
BA2 7AY Bath
MK44 1LQ Sharnbrook