IAFP 2009 Program Book and Abstract Book - AB54

Purpose: The objectives of the present study were: (1) to identify the specific spoilage organisms (SSO) and spoilage level (SL) of 4 commercial traditional Greek appetizers namely, pepper-salad, aubergine salad, legume salad and garlic-based salad; and, (2) to develop and validate predictive models for the growth of SSOs. Methods: Commercial packages of salads were supplied by a Greek Industry and stored at 4, 10, 15 and 20°C until the occurr-ence of spoilage. Enumeration of total viable counts, lactic acid bacteria (LAB), and yeasts/moulds were carried out at regular time intervals, in parallel to measurements of titratable acidity, pH, aw, organic acids (HPLC) and sensory analysis by industrial panels. The growth of LAB was modelled through primary models, and their kinetic parameters were further modelled as a function of temperature with square root models. Results: Different aciduric LAB (e.g. Lactobacillus plantarum), determined by SDS-PAGE, dominated the spoilage flora of these products at different temperatures. Products were spoiled when LAB exceeded 8 log CFU/g, causing marked increase in titratable acidity (e.g. from 0.6 ml initially to 2.9 ml of 0.1N NaOH at the occurrence of spoilage), production of acetic acid, CO2 and ethanol and appearance of sour taste. Based on sensory analysis, spoilage occurred at 25, 50, 70 and 90 days of storage at 20, 15, 10 and 4°C, respectively. The slope of maximum specific growth rate of LAB versus temperatures from 15 to 20°C was different from that versus 4 to 10°C, possibly due to the different LAB dominating at each temperature range. Validation of models under dynamic temperature conditions showed satisfactory performance for all 4 salads. Significance: The results suggest that traditional Greek appetizers are prone to spoilage by LAB and predictive models may assist in monitoring of their microbial quality along the food-supply chain. Therefore, such decision-support systems may effectively assist in the management of products distribution. T8-01 Effect of Antimicrobial Sanitizers and High Power Ultrasound on Murine Norovirus on Romaine Lettuce DSC XUEYAN LIU, Darren Bates, Stephen F. Grove and Alvin Lee Illinois Institute of Technology, National Center for Food Safety and Technology, Summit-Argo, IL, USA Introduction: Human noroviruses (NoV) are the leading cause of foodborne viral gastroenteritis worldwide. Foods commonly implicated in NoV outbreaks are those that have undergone minimal processing, such as fresh produce. Sodium hypochlorite and peroxyacetic acid are antimicrobial sanitizers used in the fresh produce industry, but their effect on NoV has not been well studied. High power ultrasound (HPU) is a technology that has the potential to improve the antimicrobial effects of these sanitizers on contaminated produce items. Purpose: To investigate the effect of sodium hypochlorite and peroxyacetic acid in combination with HPU on murine norovirus (MNV-1) inoculated on lettuce. Methods: Romaine lettuce leaves (5 cm2) were spot-inoculated with 50 µl MNV-1 (approximately 8-log PFU/ml). Once dried, inoculated leaves were immersed in 25 or 100 ppm sodium hypochlorite (pH 7.0) or 80 ppm peroxyacetic acid, with or without HPU, for 1 min at 10°C. Virions were recovered from leaves by vortexing in 3% beef extract, pH 8.0, and quantified by plaque assay in RAW 264.7 cells. Results: Treatment with 25 or 100 ppm sodium hypochlorite reduced infectious MNV-1 titer by 1.66 log and 2.27 log units, respectively, and the addition of HPU during treatment increased reduction to 2.65 log and 3.14 log units, respectively. Similar reductions were recorded in treatments with 80 ppm peroxyacetic acid, with a 2.13 log reduction achieved alone and a 2.88 log reduction when combined with HPU. Further investigation into the ratio of lettuce leaves to sodium hypochlorite volume indicated that the efficacy of the combined treatment with HPU was unaffected between 1:500 and 1:50 (w/v). Significance: The results indicate that HPU can improve the antimicrobial effect of either of two sanitizers tested on MNV-1 on lettuce. T8-02 Thermal Inactivation of Escherichia coli O157:H7 at Different Depths of Panbroiled and Roasted Non-intact DSC Steaks JEREMY M. ADLER, Ifigenia Geornaras, Keith E. Belk, Gary C. Smith and John N. Sofos Colorado State University, Dept. of Animal Sciences, Fort Collins, CO, USA Introduction: Escherichia coli O157:H7 transferred to internal muscle tissue during tenderization is a potential cause of foodborne illness if the meat is undercooked. Purpose: This study evaluated thermal inactivation of E. coli O157:H7 at different depths in non-intact steaks cooked by panbroiling or roasting to a sublethal temperature. Methods: Fresh beef (Semitendinosus; 3% fat) was cut (3 mm thickness) and eight slices were stacked on each other and tenderized (4.8 blades/cm2), using a Supertendermatic™ hand-held tenderizer to form 50 × 60 × 24 mm non-intact steaks. Steaks were inoculated with rifampicin-resistant E. coli O157:H7 (8 strains; 3.7 log CFU/cm2) on the surface (0 mm) or between the slices at a depth of 3, 6, 9 or 12 mm. Each steak was vacuum-packaged, stored (4°C, 12 h) and cooked by panbroiling, with turning every 2 min, or roasting at 149°C, to a geometric center temperature of 60°C. The temperature of the geometric center and depth of inoculation (3, 6, 9 or 12 mm) of each steak was recorded with thermocouples. After cooking, a core sample (1.61 cm2 × 24 mm) was excised from the center of each steak and analyzed for E. coli O157:H7 on Tryptic Soy Agar containing 0.1% sodium pyruvate and 100 µg/ml rifampicin. The experiment was repeated twice, with six samples per replicate. Data were analyzed by cooking method as a single factor (inoculation depth) ANOVA in Proc Mixed of SAS. Means were separated using a F-protected t-test. Results: Cooking times to reach a geometric center temperature of 60°C by panbroiling and roasting were 11.5 ± 1.2 and 26.2 ± 4.3 min, respectively. Higher internal temperatures were observed during cooking by panbroiling than roasting at 3 (88.0 ± 7.3 vs 63.4 ± 4.8°C), 6 (73.7 ± 8.9 vs 59.6 ± 10.0°C) and 9 (64.5 ± 4.8 vs 60.5 ± 2.1°C) mm depths of inoculation. Surviving pathogen populations increased (P < 0.05) from 0.3 ± 0.6 log CFU/cm2 at 0 mm to 2.5 ± 0.6 log CFU/cm2 at 12 54 — Abstract Book Technical

IAFP 2009 Program Book and Abstract Book

Table of Contents for the Digital Edition of IAFP 2009 Program Book and Abstract Book