Food applications
Encapsulation technology had been exploited as an alternative to protect antimicrobials, potentially enhancing their efficacy and stability in foods (Mozafari et al. 2008). Current research focused on bacteriocin food biotechnologies delivered the antimicrobials via continuous or sustained release (Chi-Zhang et al. 2004).
Controlled delivery improves the efficacy of bacteriocins by ensuring the peptides successfully overcome physiological barriers and preserve structure and functionality (Duncan 2011). Three leading methods was involved bacteriocin in food: through the addition of purified bacteriocin to food products, the inoculation of a food with a lactic acid bacterium (LAB), which produces the bacteriocin itself, or the incorporation of an ingredient that was previously fermented with the bacteriocin-producer bacterium (Jones et al. 2005). Nisin encapsulated in alginate-cellulose nanocrystal beads containing 16, 31 and 63 µg/mL nisin, significantly reduced the L. monocytogenes counts by 2.65, 1.50 and 3.04 log CFU/g after 28 days of storage compared with free nisin (Huq et al. 2014). Recently, inventors claimed for a prolonged efficacy of a bacteriocin combined with carbohydrate nanoparticles against L. monocytogenes (Bhunia 2012). Other group assertion for spray dried bacteriocin lactocin 3147 that showed effective antimicrobial activity in foodstuff using conjunction with hydrostatic pressure (Ross 2004). Nisin embedded as packaging materials or nisin adsorbed solid surfaces such as polyvinylic or polysaccharide films allowed for prolongation of the biological activity (Cha et al. 2003; Coma et al. 2001; Hoffman et al. 2001; Natrajan and Sheldon 2000a; Natrajan and Sheldon 2000b). Antimicrobial activity of edible hydroxyl propyl methyl cellulose (HPMC) film was obtained by the incorporation of nisin into the fatty acid (stearic acid) film-forming solution.
The effect of stearic acid was reducing the inhibitory activity of HPMC film against selected strains, L. innocua and S. aureus. This result was described by electrostatic interactions between the cationic nisin and the anionic stearic acid (Coma et al. 2001).
Nilsson et al., 2000 examined the synergistic model of carbon dioxide and nisin evaluated against L. monocytogenes Scott A wild-type and nisin-resistant (Nisr) cells grown in broth at 4°C. This synergism was examined mechanistically by carbon dioxide (CO2) enhanced nisin-induced CF (carboxyfluorescein) leakage occurs at the cytoplasmic membrane (Lilian Nilsson 2000). Bacteriocin activated plastic films were involved in storage of milk, hamburgers (Mauriello et al. 2005) frankfurters (Ercolini et al. 2010), cold smoked salmon (Neetoo et al. 2008), etc. Among the known bacteriocin, nisin was currently allowed in food as a pure substance (Deegan et al. 2006; Galvez et al. 2007; Settanni and Corsetti 2008). Some inventors (Nauth 2000) patented a stabilized mayonnaise spread with nisin-containing whey inhibiting the growth of a contaminating microorganism. Enterocin 416K1, a bacteriocin produced by Enterococcus casseliflavus IM 416K1, was a promising effect for nisin-alternative food packaging films (Iseppi et al. 2008). Partially purified active bacteriocin isolated from L. curvatus, lactocin 705 and lactocin AL705, was loaded onto multiple layers of packaging films and retained activity against L. innocua and L. plantarum for up to 45 days (Blanco Massani et al. 2012). Table 4 present some published articles concerning bacteriocin coated films in food applications.
