Whey protein film containing microcin J25(G12Y) active against E. coli O157 and Salmonella

BLANCO MASSANI MARIANA; POMARES M. FERNANDA; VINCENT PAULA A; CORBALÁN NATALIA S; EISENBERG PATRICIA

Montreal

Congreso; 17th IUFoST World Congress of Food Science and Technology and EXPO; 2014

IUFoST

Food borne outbreaks caused by Escherichia coli O157:H7 and Salmonella are an important issue in food industry [1]. Food safety can be improved by antimicrobial edible films. Microcin J25(G12Y) [MccJ25(G12Y)] is a peptide which is active against Salmonella and E. coli O157:H7. This peptide is potentially applicable as food biopreservative since it is inactivated by digestive enzymes [2]. Edible whey proteins isolate (WPI) films can improve foods´ nutritional value and prolong shelf life. Even when sorbitol (S) plasticized WPI films can lead to an undesirable appearance due to S crystallization on the films surface, the first signs of crystallization take rather long time, and this phenomenon has no effect on films mechanical and barrier properties [3]. This work aims to find the best WPI formulation to obtain an S-plasticized film active against Salmonella and E. coli O157:H7 and potentially applicable in food industry. 10% (w/w) WPI aqueous solutions with various amounts of plasticizer (protein to S ratios (P:S) 2.3:1; 1.5:1; 1:1, respectively) were stirred (75ºC, 30 min) and dried in plates (50ºC, 24h). Mechanical properties (MP), water vapor permeability (WVP) and moisture content (MC) were measured and compared. The filmogenic solution which lead to the optimal film properties was used to formulate the antimicrobial material. MccJ25 (G12Y) concentrations in the final solutions were 2.5 10-1; 2.5 10-2 and 2.5 10-3 mg/ml. Films were evaluated against E. coli AB1133 (INSIBIO-CONICET), considering that E. coli AB1133 has the same behavior as Salmonella and E. coli O157: H7 when exposed to MccJ25 (G12Y). Films´ WVP (2-9 g mm/m 2 h kPa) and MC (11%) were not influenced by filmogenic solution P:S ratio. The best MP (2 MPa stress at break and 20% elongation at break) were obtained for a 1.5:1 P:S ratio. Similar properties were reported by Anker et al, for WPI Splasticized films [3]. Antimicrobial activity was observed for films formulated with 2.5 10-1 and 2.5 10-2 mg/ml of MccJ25(G12Y). These results are in agreement with MccJ25(G12Y) aqueous solution MIC [2], suggesting that compounds included in the film formulation and film forming process did no affect MccJ25(G12Y) antimicrobial activity. An active WPI S-plasticized film containing an original Argentine antimicrobial peptide was obtained. This film could potentially be used in food industry as a coating against Salmonella and E. coli O157:H7.