Abstract
<span style="font-family: Times New Roman; font-size: small;"> </span><p>Nisin is an antimicrobial peptide produced by <em>Lactococcus</em><em> </em><em>lactis</em> spp. <em>lactis</em> widely investigated for use in foods as a natural antimicrobial. However, its effective use in meat products is restricted notably by its reaction with meat constituents (including glutathione) in raw meat. The purpose of this study was to develop an encapsulation system that would optimize nisin activity when used in meat. To achieve this goal, an encapsulation in dipalmitoylphosphatidylcholine (DPPC) liposomes was developed. DPPC liposomes were formed in phosphate buffer with or without nisin. The encapsulation efficiency of nisin in liposomes was greater than 46 ± 2%. The median size of nisin-loaded liposomes was 495 nm, compared to 170 nm for empty liposomes. The liposomes containing nisin were stable for up to 7 days at 4°C but a zone of inhibition was observed afterwards. Stability of the liposome to heat was also tested and demonstrated that above 37°C nisin was released from the melted liposomes to form zones of inhibition. Activity of free and encapsulated nisin was tested in raw and cooked ground beef (71°C). Free nisin lost its activity in raw beef but DPPC-encapsulated nisin remained active and was released upon melting of the liposome during heat treatment.</p><span style="font-family: Times New Roman; font-size: small;"> </span>
Highlights
Bacteriocins are antimicrobial peptides, which are produced by bacteria to inhibit the growth of other closely related organisms and can be potentially used as natural preservative (Cleveland, Montville, Nes, & Chikindas, 2001; de Arauz, Jozala, Mazzola, & Penna, 2009)
Nisin is an antimicrobial peptide produced by Lactococcus lactis spp. lactis widely investigated for use in foods as a natural antimicrobial
It is used as a food preservative because of its antimicrobial activity against several pathogenic Gram-positive bacteria that can be present in food, such as Listeria monocytogenes, Staphylococcus aureus, spores of Bacillus cereus and Clostridium botulinum (Najjar, Chikindas, & Montville, 2007)
Summary
Bacteriocins are antimicrobial peptides, which are produced by bacteria to inhibit the growth of other closely related organisms and can be potentially used as natural preservative (Cleveland, Montville, Nes, & Chikindas, 2001; de Arauz, Jozala, Mazzola, & Penna, 2009). Nisin is a 3.5 kDa cationic peptide produced by Lactococcus lactis subsp. It is used as a food preservative because of its antimicrobial activity against several pathogenic Gram-positive bacteria that can be present in food, such as Listeria monocytogenes, Staphylococcus aureus, spores of Bacillus cereus and Clostridium botulinum (Najjar, Chikindas, & Montville, 2007). Nisin is a permitted food additive in more than 50 countries, including the US and Europe, where it is used notably in processed cheeses, dairy products and canned foods (Delves-Broughton et al, 1996)
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