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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Healthy Processed Foods Research » Research » Publications at this Location » Publication #314719
Title: Antimicrobial fish gelatin films with olive leaf extract for inactivation of Listeria monocytogenes on ready-to-eat smoked salmon (abstract)

Author
item ALBERTOS, IRENE - Instituto Tecnológico Agrario De Castilla Y León (ITACYL)
item Du, Wen-Xian
item Takeoka, Gary
item McHugh, Tara
item RICO, DANIEL - Instituto Tecnológico Agrario De Castilla Y León (ITACYL)
item Avena-Bustillos, Roberto

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/23/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Olive leaf is a sizable by-product from the olive industry. Its use as antimicrobial/antioxidant ingredient in edible films for fish preservation was evaluated. Olive leaf powder (OLP) and its water/ethanol extract (OLPE) were tested against three foodborne pathogens: Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella enterica using agar diffusion test. Fish gelatine films (FGF) with different level of OLPE (0%, 25%, 50% and 75%) were formulated and their color, water vapour permeability (WVP), total soluble phenolics, and antioxidant capacity were studied. FGF containing 75% OLPE was evaluated as antimicrobial treatment on cold-smoked salmon inoculated with L. monocytogenes. Control and treated salmon samples were stored at 23 ºC and 60% RH. Salmon samples were taken at day 0, 1, 2, 4 and 6 for survival of L. monocytogenes. OLP and OLPE only showed antibacterial activity against L. monocytogenes in agar diffusion test, and the inhibition radius around the film disc increased from 8.2 to 451.6 mm for OLP and OLPE, respectively. Main flavonoids and phenylethanoids determined in OLP (mg/g) were luteolin-7-glucoside (11.3), verbascoside (4.8), apigenin-7-glucoside (5.6) and oleuropein (235.8). Films with 75% OLPE showed the highest L. monocytogenes inhibition in agar diffusion test and were selected to study antimicrobial effect against L. monocytogenes in smoked salmon. Lightness was not significant modified with increasing OLPE addition in the films. Whereas a* and b* increased directly related to the OLPE concentration. Addition of 50% and 75% OLPE to FGF increased the WVP of the OLPE films compared to those of control and 25% OLPE films. Total soluble phenolic content and antioxidant capacity increased with increasing OLPE concentration. OLPE films significantly reduced the growth of L. monocytogenes in smoked salmon during storage. This study highlights the effectiveness of FGF incorporating 75% of OLPE for diminishing the growth of L. monocytogenes on smoked salmon. KEY WORDS: Olive leaf, gelatin, film, antimicrobial, antioxidant, Listeria monocytogenes.