Comparison of Current Almond Pasteurization Methods and Electron Beam Irradiation as an Alternative

Two outbreaks of salmonellosis were linked to the consumption of raw California almonds in 2001 and 2004. Current federal regulations mandate that all almonds grown in California are to be treated with a process that results in a 4-log reduction of Salmonella. Since four out of the five approved technologies to pasteurize almonds rely on the application of heat to control Salmonella, the evaluation of alternative technologies against heat resistant Salmonella Senftenberg was imminent. In this study, almonds that were inoculated with S. Enteritidis PT 30 and S. Senftenberg, were treated with electron beam irradiation (e-beam), blanching and oil roasting. The thermal death time (D-value) for S. Enteritidis PT 30 when treated with e-beam was 0.90 kGy, 15 s when subjected to blanching at 88 degrees C, and 13 s when treated with oil at 127 degrees C. Irradiation and thermal resistance of S. Senftenberg was not significantly different (P > 0.05) from S. Enteritidis PT 30. The commercial application of e-beam as a pathogen intervention was assessed through Monte Carlo simulations (MCS) and experimental measurements. The sensory characteristics of almonds commercially treated by e-beam, blanching and roasting were assessed by a consumer panel. Irradiated and blanched almonds did not differ in consumer overall like (P > 0.05). Bitterness and rancidity attributes of irradiated almonds were between a "dislike slightly" and "dislike moderately", whereas blanched and roasted almonds were between "neither like nor dislike" and "like slightly". Almonds commercially irradiated, blanched and roasted were subjected to an accelerated shelf-life test (ASLT) evaluating percentage free fatty acids, peroxide value, and 2-thiobarbituric acid reactive substances (TBARs). No clear differences between treatments were observed at any given point in time in any of the chemical tests. A gas chromatography-mass-spectrometry-olfactometry (MDGC-MS-O) technology was used to compare full aroma and flavor profiles from raw and e-beam irradiated almonds. Differences in the aroma/odor profile and the taste analysis revealed that the difference between raw and irradiated almonds is extremely subtle. In conclusion, e-beam may be a feasible technology to control Salmonella in almonds if used at low doses, as a part of a series of interventions

Effect of natural antimicrobials against Salmonella, Escherichia coli o157:h7 and Listeria monocytogenes

Salmonella, Escherichia coli O157:H7 and Listeria monocytogenes are pathogens that have caught the attention of federal agencies and researchers due to their great economic impact when illnesses occur. To reduce the presence of these pathogens, different approaches have been used. However, since the global consumer’s demand for natural ingredients is steadily increasing, the investigation of the effectiveness of potential natural antimicrobials is necessary. In this study, the in vitro antimicrobial activity of Hibiscus sabdariffa L extracts against Salmonella, E. coli O157:H7 and L. monocytogenes was investigated. Furthermore, H. sabdariffa L and ε-polylysine were evaluated to reduce populations of Salmonella and E. coli O157:H7 in ground beef. The minimum inhibitory concentration (MIC) of H. sabdariffa L extracts against Salmonella and E. coli O157:H7 was 6,489 μg/mL and for L. monocytogenes, 5,309 μg/mL. The minimum bactericidal concentration (MBC) of H. sabdariffa L extracts against Salmonella, E. coli O157:H7 and L. monocytogenes was 19,467, 58,400 and 29,200 μg/mL, respectively. The exposure to 58,400 μg/mL of H. sabdariffa extract at 25 oC for 12 h resulted in reductions of more than 6.0 log CFU/mL for any of the 3 pathogens tested. Ground beef inoculated with S. Agona (GFP) and E. coli O157:H7 (RFP) was subjected to 5 decontamination treatments. Three of the treatments were using H. sabdariffa L and the remaining ε-polylysine. S. Agona (GFP) was reduced in 1.1 log cycles using 10% of ground H. sabdariffa L and E. coli O157:H7 (RFP) was reduced 0.9 log cycles using 400 ppm of ε-polylysine. If these natural antimicrobials are combined with current antimicrobial technologies to form a hurdle effect, higher pathogen reductions could be achieved. Reductions in the presence of pathogens in food may lead into reductions in the incidence of foodborne diseases

Aluminum-rich belite sulfoaluminate cements: clinkering and early age hydration

Belite sulfoaluminate (BSA) cements have been proposed as environmentally friendly building materials, as their production may release up to 35% less CO2 into the atmosphere when compared to ordinary Portland cements. Here, we discuss the laboratory production of three aluminum-rich BSA clinkers with nominal mineralogical compositions in the range C2S (50-60%), C4A3$(20- 30$, i.e. a value as close as possible to the nominal composition. Under these experimental conditions, three different BSA clinkers, nominally with 20, 30 and 30 wt% of C4A3$, had 19.6, 27.1 and 27.7 wt$ respectively, as determined by Rietveld analysis. We also studied the complex hydration process of BSA cements prepared by mixing BSA clinkers and gypsum. We present a methodology to establish the phase assemblage evolution of BSA cement pastes with time, including amorphous phases and free water. The methodology is based on Rietveld quantitative phase analysis of synchrotron and laboratory X-ray powder diffraction data coupled with chemical constraints. A parallel calorimetric study is also reported. It is shown that the b-C2S phase is more reactive in aluminum-rich BSA cements than in standard belite cements. On the other hand, C4A3$ reacts faster than the belite phases. The gypsum ratio in the cement is also shown to be an important factor in the phase evolution