Inhibitory activity against Listeria monocytogenes by soy-protein edible film containing grape seed extract, nisin, and malic acid

The frequent outbreaks of food-borne illness necessitate development of intervention strategies, including the use of natural antimicrobials. Listeria monocytogenes is one of the most important bacterial pathogens that recently has caused a significant number of outbreaks. With the aim of finding potent natural agents that can minimize pathogen contamination concerns, this study evaluated the inhibitory activities against L. monocytogenes of grape seed extract (GSE), malic acid (M), nisin (N), and combinations thereof incorporated into soy-protein edible films. Soyprotein films with/without addition of antimicrobial agents (GSE: 1%, Nisin: 10,000 IU/g, Malic acid: 1%, and their combinations) were prepared and evaluated for anti-listerial activities. The highest inhibitory activity after 1 h incubation at 25°C was found in the treatment containing GSE, nisin, and malic acid, which produced reductions of log 3.7 colony-forming units (CFU)/ ml as compared to control film without the addition of antimicrobial agents. These data demonstrated that the GSE, nisin, and malic acid combination incorporated into soy-protein edible films is very effective in inhibiting L. monocytogenes growth at 25°C and has potential for applications on a variety of food products to help prevent L. monocytogenes contamination and growth

Antilisterial Effects of Gravinol-S Grape Seed Extract at Low Levels in Aqueous Media and Its Potential Application as a Produce Wash

Grape seed extract (GSE) is a rich source of proanthocyanidins, a class of natural antioxidants reported to have wide-ranging bioactivity as anti-inflammatory, anticarcinogenic, and antimicrobial agents. The ability of GSE to rapidly inactivate Listeria monocytogenes in vitro and the generally recognized as safe status of GSE make this extract an attractive candidate for control of Listeria in or on foods. Previously, GSE has been used at relatively high concentrations (1%) in complex food matrices and in combination with other antimicrobials. We sought to characterize the antilisterial effects of a commercial GSE preparation (Gravinol-S) alone at much lower concentrations (0.00015 to 0.125%) in aqueous solution and to test its possible use as an antimicrobial wash for fresh produce surfaces. Based on broth microdilution tests, the MICs of GSE against L. monocytogenes Scott A and Listeria innocua ATCC 33090 were as low as 50 and 78 mg ml21, respectively. GSE was evaluated in 0.85% saline against live cells of L. innocua via flow cytometry, using propidium iodide as a probe for membrane integrity. At sub-MICs and after only 2 min of exposure, treatment with GSE caused rapid permeabilization and clumping of L. innocua, results that we confirmed for L. monocytogenes using fluorescence microscopy and Live/Dead staining. At higher concentrations (0.125%), GSE reduced viable cell counts for L. monocytogenes by approximately 2 log units within 2 min on tomato surfaces. These results suggest the potential for GSE as a natural control of Listeria spp. on low-complexity foods such as tomatoes.This article is from Journal of Food Protection 73(2): 266-273. Posted with permission.</p

Use of antimicrobial edible films and coatings as packaging materials for food safety

In recent years, the packaging industry has also started to research new technologies due to increased consumer demand for the minimally processed foods. One of these new technologies is edible films and coatings produced from natural polymers such as protein, polysaccharide, and lipid derived which are biodegradable and could be used as active packaging material. Researches on the use of edible films as packaging materials continue because of the potential of these films to enhance food quality, food safety, and product shelf life. Edible films and coatings have many advantages such as biodegradability, edibility, bio-compatibility with aesthetic appearance and barrier properties against oxygen, ability to resist physical stress. Edible films and coatings are also can be used as a carrier of natural or chemical antimicrobial agents such as organic acids, chitosan, nisin, lactoperoxidase system, and some other plant extracts and essential oils. So they may reduce the risks of growth of spoilage or pathogenic microorganisms in foods by the addition of antimicrobial substances in edible films and coatings and so can prolong the shelf life of foods. Choosing the active antimicrobial is important to prolong shelf life. For effective antimicrobial selection, some possible interactions must be considered such as between the target microorganisms and antimicrobial, film-forming biopolymer, and other food components. In recent years, effective results have been achieved by using antimicrobial edible films and coatings and some model systems have established. In this chapter, the history of antimicrobial edible films and coatings, evaluation of edible packaging performance, characteristics of biopolymers and antimicrobial substances which are used for preparation of antimicrobial edible film coatings, functional properties, legal and economic aspects, some food applications, and the place and importance of antimicrobial edible films and coatings in future reviewed. © 2014, Springer Science+Business Media New York