jueves, 9 de diciembre de 2010

Antimicrobial nisin given nano boost to fight Listeria for longer

A nanoparticle linked to nisin can hold and release an antimicrobial agent onto food or packaging to control Listeria monocytogenes

A US team has pioneered a technique which allows a nanoparticle to attract and hold nisin, which has strong antibacterial properties. Yuan Yao, an assistant professor of food science at Purdue University, altered the surface of phytoglycogen, a carbohydrate found in sweet corn, which led to the creation of several forms of a nanoparticle.

The nanoparticle can then safeguard the food-based peptide nisin for up to three weeks, combating Listeria monocytogenes, a potentially fatal foodborne pathogen found in meats, dairy and vegetables.

Nisin antibacterial properties have been proved but the problem has been that it is depleted quickly in a food system. Nanoparticles solved this problem by delivering the antimicrobial properties of nisin for extended use.


The scientists employed two strategies to draw nisin to the phytoglycogen nanoparticles. The first involved negatively charging the surface of the nanoparticle and using electrostatic activity to attract the positively charged nisin molecules. The other method saw the creation of a partially hydrophobic condition on the surface of the nanoparticle - which triggers a reaction with partially hydrophobic nisin molecules. When the particles are hydrophobic, or repel water, they become attracted to each other.

Both strategies may work together to allow nanoparticles to attract and stabilize nisin, this could substantially reduce the depletion of nisin in various systems to counteract the Listeria proliferation.

The solution containing the required balance of nanoparticles and free nisin could be sprayed onto foods or included in packaging. Based on work carried out in the lab, it is estimated that a sufficient amount of nisin to combat Listeria could be preserved for up to 21 days.

When the the amount of free nisin is reduced, nanoparticles can re-establish the equilibrium the team is also working to develop other food-based antimicrobial peptides and nano-constructs to combat Listeria other foodborne pathogens such as E. coli O157:H7 and Salmonella spp.

Source: Food Quality News.com

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