Lysozyme and nisin are both antimicrobial proteins effective against gram-positive bacteria. The use of these antimicrobials in combination with chelating agents displays increased effectiveness against gram-negative bacteria. Packaging films with lysozyme or nisin incorporated into the film structure were tested separately for inhibition against Lactobacillus plantarum. Both lysozyme and nisin were used in combination with EDTA in films and were evaluated for inhibition against Escherichia coli. Two packaging film-forming methods were used to incorporate lysozyme or nisin into biodegradable protein films to determine if antimicrobial properties could be induced in the film. Heat-press and casting methods were used to produce films made from soy protein and corn zein. Circular samples were cut from the finished films, which were then placed on a bacterial lawn, incubated, and measured for any zones of inhibition. Both cast and heat-press films with added lysozyme or nisin formed excellent films and exhibited inhibition of bacterial growth. The lysozyme and nisin retained their bacteriocidal properties throughout both the heat-press and cast film-forming processes. The cast films exhibited larger inhibitory zones, as compared to the heat-press films, when the same levels of lysozyme or nisin were incorporated. L. plantarum was inhibited by films containing nisin or lysozyme. The addition of EDTA increased the inhibitory effect of films against E. coli.
A survivor swap (SS) is an agreement to exchange cash flows in the future based on the outcome of at least one survivor index. This article discusses the possible uses of SSs as instruments for managing, hedging, and trading mortality-dependent risks. SSs are especially useful for insurance companies, but also offer other interested parties low beta avenues into the acquisition of mortality risk exposure. The article also investigates vanilla SSs in some detail, and suggests how their premiums and values might be determined in an incomplete market setting. Copyright The Journal of Risk and Insurance, 2006.
Bacterial growth during food transport and storage is a problem that may be addressed with packaging materials that release antimicrobials during food contact. In a series of five experiments, EDTA, lauric acid (LA), nisin, and combinations of the three antimicrobial agents were incorporated into a corn zein film and exposed to broth cultures of Listeria monocytogenes and Salmonella Enteritidis for 48 h (sampled at 2, 4, 8, 12, 24, and 48 h). Four experiments used starting cultures of 10(8) CFU/ml in separate experiments tested against each bacterium; the fifth experiment examined the inhibitory effect of selected antimicrobial agents on Salmonella Enteritidis with an initial inoculum of 10(4) CFU/ml. L. monocytogenes cell numbers decreased by greater than 4 logs after 48 h of exposure to films containing LA and nisin alone. No cells were detected for L. monocytogenes (8-log reduction) after 24-h exposure to any film combination that included LA. Of all film agent combinations tested, none had greater than a 1-log reduction of Salmonella Enteritidis when a 10(8)-CFU/ml broth culture was used. When a 10(4) CFU/ml of Salmonella Enteritidis initial inoculum was used, the films with EDTA and LA and EDTA, LA, and nisin were bacteriostatic. However, there was a 5-log increase in cells exposed to control within 24 h. The results demonstrate bacteriocidal and bacteriostatic activity of films containing antimicrobial agents.
Four commercial rosemary oleoresin preparations were added to ground chicken thigh meat at the recommended levels of the manufacturer then packaged in 80% O(2)-20% CO(2) modified atmosphere trays. The rosemary preparations differed in oil and water solubility, dispersion properties, or both. Addition of rosemary to ground chicken had an overall positive effect on raw meat appearance during storage and cooked meat flavor. No effect on bacterial growth was observed due to rosemary addition. However, oxidation was slowed in meat with added rosemary as indicated by lower TBA values, lower hexanal concentrations, and sensory scores. Color (redness) was more stable in meat with added rosemary compared with meat without rosemary, as reflected in redness (a*) values, hue angles, and visual scores. Of the 4 rosemary preparations tested, the oil-soluble, most concentrated preparation (HT-O) was most effective in maintaining meat quality compared with the other 3 types tested.
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