Microbial levels in Michigan apple cider and their association with manufacturing practices.
ABSTRACT In recent decades, apple cider has been implicated in a series of outbreaks of foodborne illness. The objective of this study was to determine the presence and concentrations of pathogenic and indicator microorganisms in apple cider processed in Michigan and to evaluate the impact of thermal pasteurization, UV light radiation, and implementation of hazard analysis critical control point (HACCP) plans on these microbes. Cider samples were obtained from Michigan mills between 1997 and 2004 and analyzed for Escherichia coli O157:H7, Salmonella, generic E. coli, total coliforms, and aerobic bacteria. Neither E. coli O157:H7 nor Salmonella were detected in any tested cider samples, suggesting a very low frequency of pathogens in Michigan apple cider. The persistent and relatively high frequency of generic E. coli observed in samples obtained in all years indicates a continued risk of pathogen contamination in Michigan apple cider, especially when it is untreated. The use of thermal pasteurization or UV light radiation and reported implementation of HACCP plans were associated with lower frequency and counts of generic E. coli, total coliforms, and aerobic microorganisms. However, the relatively high counts of indicator organisms in some cider samples that were claimed to be treated according to these pathogen reduction measures indicates that some processors had inadequate practices, facilities, or equipment for pathogen reduction or did not consistently or adequately apply practices or pathogen-reduction equipment in an effective manner.
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ABSTRACT: Studies are lacking on the nonthermal pasteurization of liquid foods using UV irradiators that centrifugally form very thin films to overcome the problem of limited penetration depth of UV. Grapefruit juice inoculated with Escherichia coli or Saccharomyces cerevisiae was processed at the following conditions: UV dose 4.8–24 mJ/cm2; treatment time 3.2 s, cylinder rotational speed 450–750 rpm, cylinder inclination angle 15–45°, outlet temperature 11 °C, and flow rate 300 ml/min, and was stored for 35 days. Appropriate dilutions of the samples were pour plated with TSA and TSA + 3% NaCl for E. coli and Sabouraud dextrose agar (SDA) and SDA + 5% NaCl for S. cerevisiae. Nonthermal UV processing at 19 mJ/cm2, 450 rpm and 15° reduced E. coli in grapefruit juice by 5.1 log10. A dose of 14 mJ/cm2 reduced S. cerevisiae by 6.0 log10. Inactivation increased linearly with increasing UV dose. The inactivations at 600 and 750 rpm were similar, and were better than at 450 rpm. The results at 30° and 45° were similar, and were better than at 15°. The occurrence of sublethal injury in either microorganism was not detected. Storing UV processed grapefruit juice at 4 and 10 °C reduced the surviving E. coli to below 1 log10 cfu/ml in 14 days. Processing UV juice reduced the population of S. cerevisiae to less than 1 log10 cfu/ml where it remained for 35 days during refrigerated storage. These results suggest that grapefruit juice may be pasteurized using a nonthermal UV irradiator that centrifugally forms a thin film.Journal of Food Engineering 07/2012; 111(2):241–246. DOI:10.1016/j.jfoodeng.2012.02.026 · 2.58 Impact Factor
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ABSTRACT: This study investigated the antimicrobial effects of guava against E. coli O157:H7 and Salmonella in liquid medium. The minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC) values for each bacterial strain were recorded. In addition, the growth of the individual strain and a combined mixture of the strains in liquid medium over time were assessed. Guava was found to inhibit the growth of all tested strains. The MIC ranged from 200 to 700 μL/mL and the MLC was at least 500 μL/mL. The minimum effective guava extract concentration needed to show significant growth inhibition was 5%. Without guava extract, bacterial population levels reached 7.0–8.0 log CFU/mL. The addition of guava extract caused significant growth inhibition, resulting in bacterial populations remaining within 3.0 log CFU/mL during the incubation. These results indicate guava could be used as a potential effective antimicrobial agent that can be used to ensure food safety.International Journal of Food Properties 01/2011; 14(1):102-109. DOI:10.1080/10942910903147833 · 0.88 Impact Factor