Abstract
BackgroundMicrobial activity is a primary cause of deterioration in many foods and is often responsible for reduced quality and safety. Food-borne illnesses associated with E. coli O157:H7, S. aureus, S. enteritidis and L. monocytogenes are a major public health concern throughout the world. A number of methods have been employed to control or prevent the growth of these microorganisms in food. Antimicrobial packaging is one of the most promising active packaging systems for effectively retarding the growth of food spoilage and pathogenic microorganisms. The aim of this study was to determine the mechanical, physico-chemical properties and inhibitory effects of the fish gelatin films against selected food spoilage microorganisms when incorporated with catechin-lysozyme.ResultsThe effect of the catechin-lysozyme combination addition (CLC: 0, 0.125, 0.25, and 0.5%, w/v) on fish gelatin film properties was monitored. At the level of 0.5% addition, the CLC showed the greatest elongation at break (EAB) at 143.17% with 0.039 mm thickness, and the lowest water vapor permeability (WVP) at 6.5 x 10−8 g·mm·h-1·cm-2·Pa-1, whereas the control showed high tensile strength (TS) and the highest WVP. Regarding color attributes, the gelatin film without CLC addition gave the highest lightness (L* 91.95) but lowest in redness (a*-1.29) and yellowness (b* 2.25) values. The light transmission of the film did not significantly decrease and nor did film transparency (p>0.05) with increased CLC. Incorporating CLC could not affect the film microstructure. The solubility of the gelatin based film incorporated with CLC was not affected, especially at a high level of addition (p>0.05). Inhibitory activity of the fish gelatin film against E.coli, S.aureus, L. innocua and S. cerevisiae was concentration dependent.ConclusionsThese findings suggested that CLC incorporation can improve mechanical, physico-chemical, and antimicrobial properties of the resulting films, thus allowing the films to become more applicable in active food packaging.
Highlights
Microbial activity is a primary cause of deterioration in many foods and is often responsible for reduced quality and safety
This was attributed to the interaction between catechin-lysozyme combination addition (CLC) and the gelatin molecules, which resulted in a modification to the protein network in the film
No significant difference of elongation at break (EAB) was observed between the control film and the film added with CLC at the levels of 0.125 to 0.25% (p>0.05)
Summary
Microbial activity is a primary cause of deterioration in many foods and is often responsible for reduced quality and safety. Antimicrobial packaging is one of the most promising active packaging systems for effectively killing, inhibiting, or retarding the growth of food spoilage and pathogenic microorganisms. By these actions, the shelf life of the product is prolonged, and its quality and safety are better preserved [4]. The active compounds can inhibit microorganism growth and food spoilage and thereby extend shelf life of processed foods by either reducing the microbial growth rate or extending the lag-phase of the target microorganisms [12,13] Addition of these compounds to the film based material may affect the principal properties of the host material. Many researchers have reported that various bioactive additives such as enzymes [7], antimicrobial [5,6], and antioxidant agents [11,12] may get entrapped in the porous solid matrices in the gelatin and be immobilized by covalent binding to a solid support, which would result in a change to the resulting film properties [14,15]
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