Alternatives to antibiotics: chemical and physical antimicrobial interventions and foodborne pathogen response

Synergistic inhibition of Listeria monocytogenes in vitro through the combination of octanoic acid and acidic calcium sulfate

It has been hypothesized that inhibition of foodborne pathogens can be enhanced by using antimicrobials in combination. A broth dilution assay was devised to determine whether inhibition of Listeria monocytogenes exposed to the combination of the fatty acid octanoic acid (OCT) and the organic acid-containing antimicrobial acidic calcium sulfate (ACS) was enhanced compared with the inhibition of the pathogen exposed to either antimicrobial applied singly. MICs for OCT and ACS were 25.00 μg/g and 1.56 ml/liter, respectively, for all strains of the pathogen tested. Fractional inhibitory concentrations (FICs) from the combination exposures were calculated for use in characterizing the antimicrobial interaction as antagonistic, additive indifferent, or synergistic with respect to L. monocytogenes inhibition. Combining OCT and ACS resulted in observed synergistic inhibition of L. monocytogenes; isobolograms for all strains curved toward the origin, and FIC indices (FIC(I)s) were <1.0. Future investigations of the antimicrobial combination should focus on determining the mechanism of action of combined antimicrobials and the levels of antimicrobials required for pathogen inhibition on the surfaces of ready-to-eat meats.

Impact of irradiation on the safety and quality of poultry and meat products: a review

For more than 100 years research on food irradiation has demonstrated that radiation will make food safer and improve the shelf life of irradiated foods. Using the current food safety technology, we may have reached the point of diminishing returns even though recent figures from the CDC show a significant drop in the number of foodborne illnesses. However, too many people continue to get sick and die from eating contaminated food. New and under utilized technologies such as food irradiation need to be re-examined to achieve new levels of safety for the food supply. Effects of irradiation on the safety and quality of meat and poultry are discussed. Irradiation control of the principle microbial pathogens including viruses, the differences among at-risk sub-populations, factors affecting the diminished rate of improvement in food safety and published D values for irradiating raw meat and poultry are presented. Currently permitted levels of irradiation are probably not sufficient to control pathogenic viruses. Typical gram-negative spoilage organisms are very sensitive to irradiation. Their destruction leads to a significant increase in the acceptable shelf life. In addition, the destruction of these normal spoilage organisms did not provide a competitive growth advantage for irradiation injured food pathogens. Another of the main focuses of this review is a detailed compilation of the effects of most of the food additives that have been proposed to minimize the negative quality effect of irradiation. Most of the antimicrobials and antioxidants used singly or in combination produced an increased lethality of irradiation and a decrease in oxidation by-products. Combinations of dosage, temperature, dietary and direct additives, storage temperature and packaging atmosphere can produce meats that the average consumer will find indistinguishable from non-irradiated meats. A discussion of the production of unique radiological by-products is also included.

Methodological Quality Assessment of Review Articles Evaluating Interventions to Improve Microbial Food Safety

Review articles are a means of summarizing the potentially vast volume of research on a topic. However, the methodological quality of review articles varies, and reviews on the same topic may reach different conclusions. We evaluated 65 review articles published between 2000 and 2005 that addressed the effectiveness of microbial food safety interventions, using criteria for methodological soundness developed in the medical field. Overall, the methodological quality of the review articles was poor, with none of the reviews providing information on the method of locating primary research studies or the inclusion/exclusion criteria for selecting primary studies. None of the reviews included a critical appraisal of the methodological quality of the primary studies. Less than half of the reviews stated a focused research question, explored possible reasons for differences in the results of primary studies, discussed the generalizability of results, or proposed directions for future research. There is a need to improve the methodological quality of review articles on microbial food safety interventions if they are to be of use in policy and decision making.

Effect of dietary oligochitosan supplementation on ileal digestibility of nutrients and performance in broilers

The effect of dietary chitosan oligosaccharides (COS) supplementation on ileal digestibilities of nutrients and performance in broilers was assessed by feeding graded levels (0, 50, 100, 150 mg/kg) of COS. Two thousand four hundred male commercial Avian broilers (1-d-old) were assigned randomly to 5 dietary treatment groups (60 birds per pen with 8 pens per treatment). Diet A was a typical corn- and soybean meal-based diet supplemented with 6 mg/kg of an antibiotic flavomycin (positive control). Diet B was the basal diet without any supplement. Diets C, D, and E were formulated by adding 50, 100, and 150 mg/kg of COS to the basal diet, respectively. On the morning of d 21 and 42, 64 birds (8 per pen with 8 pens per treatment) from the growth trial for each age group were killed by cervical dislocation for determination of the ileal digestibilities of nutrients. Dietary supplementation with COS and antibiotic enhanced (P < 0.05) the ileal digestibilities of DM, Ca, P, CP, and all amino acids (except for alanine in the 21-d-old birds or phenylalanine, glutamate, and glycine for the 42-d-old birds). Feed efficiency was improved (P < 0.05) in response to dietary supplementation of an antibiotic or COS (150 mg/kg for d 1 to 21, and 100 and 150 mg/kg for d 21 to 42). The results demonstrate for the first time to our knowledge that dietary COS supplementation was effective in increasing the ileal digestibilities of nutrients and feed efficiency in broilers. Our findings may explain a beneficial effect of COS on chicken growth performance.