Effects of MS bacteriophages, ultraviolet light, and organic acid applications on beef trim contaminated with STEC O157:H7 and the "Big Six" serotypes after a simulated High Event Period Scenario.

A high event period (HEP) occurs when beef processing facilities experience an elevated rate of STEC positive trim samples. In order to avoid contaminated vacuum-packaged beef entering into commerce, primals and subprimals associated to positive trim must be treated with antimicrobials, repackaged, and retested for STEC to ensure product wholesomeness. In this study, we evaluated the efficacy of Bacteriophages (P), Peroxiacetic Acid (PAA), Acidified Sodium Chlorite (ASC), and Ultraviolet light (UV) to reduce the O157:H7 and the Big Six STEC in beef after a simulated HEP scenario. In vacuum conditions and under aerobic conditions, phage applications and a combination of P + UV led to the greatest STEC reduction, respectively (P < 0.001). Overall, treatments including bacteriophage provided best reductions when compared to non-phage treatments (P < 0.001, for both vacuum and aerobic conditions). Bacteriophage solutions provided improved control of STEC O157:H7 and the Big Six serotypes when reworking beef after a simulated HEP scenario.

Effects of bacteriophages and peroxyacetic acid applications on beef contaminated with Salmonella during different grinding stages.

Research has suggested that the incidence of Salmonella in ground beef may be associated with contaminated lymph nodes that are not removed from trimmings destined for grinding. In this study, we tested the application of bacteriophages and peroxyacetic acid solutions on trimmings and on coarse and fine ground beef to simulate different scenarios of contamination. Overall, peroxyacetic acid applications did not reduce Salmonella loads on ground beef when applied on trimmings or at any stage of grinding. When applied on contaminated trim, bacteriophage solutions at 1 × 108 PFU/g and 1 × 109 PFU/g reduced more than 1 log cfu/g of Salmonella. When applied directly on contaminated coarse or fine ground beef, bacteriophage solutions at 1 × 109 PFU/g reduced approximately 1.6 log cfu/g. Results of this study suggest that bacteriophage applications on contaminated, comminuted beef may be used as an aid to decrease Salmonella loads.

Efficacy of bacteriophage and organic acids in decreasing STEC O157:H7 populations in beef kept under vacuum and aerobic conditions: A simulated High Event Period scenario.

After High Event Periods, beef subprimals are usually removed from vacuum and treated with antimicrobials. After re-packaging, subprimals are tested to verify the presence of STEC. In this study, bacteriophage and organic acids were applied on beef contaminated with STEC O157:H7 to evaluate the efficiency of industry practices. Beef samples inoculated with STEC were treated with bacteriophage, lactic acid, and peroxyacetic acid and kept under vacuum or aerobic conditions. STEC loads were evaluated 30 min and 6 h after antimicrobial applications. Under aerobic conditions for 30 min and 6 h, phage reduced STEC in beef by approximately 1.4 log whereas organic acids led to a 0.5 log reduction. Under vacuum for 30 min, bacteriophage significantly reduced STEC by 1 log. No effects were observed when samples were treated with organic acids. Under vacuum after 6 h, bacteriophage reduced STEC loads by 1.4 log, lactic acid reduced by 0.6 log, and no effects were observed when peroxyacetic acid was applied.

Physiological performance of quails that underwent dietary and pharmacological manipulation of cholesterol.

The present work evaluated whether dietary and pharmacological interference on cholesterol synthesis were capable of inducing alterations in blood and yolk cholesterol levels and the secretion of corticosterone metabolites. Forty-five 40-day-old quails were divided into three experimental groups: vegetal fat diet, 2% beef fat (tallow) diet and vegetal fat diet with simvastatin administration (3.13 mg/kg/day). During all experiments, the animal weights and food consumption were recorded and blood and faecal samples (days 0, 15, 30, 45 and 60), as well as eggs (days 30, 45 and 60), were collected. Analysis of serum and yolk cholesterol was performed and faecal corticosterone levels were measured. No differences were observed on blood cholesterol or faecal corticosterone between all treatments, despite a tendency of increased cholesterol in the group with the animal fat diet. However, quails submitted to an animal fat diet displayed an increase in yolk cholesterol at day 30 of the treatment and the egg yolks of quails treated with simvastatin exhibited a decrease in cholesterol content by the end of the treatment at 60 days. These results improved the knowledge regarding the physiology of quails and offered support to other studies concerning the consequences of the pharmacological treatment and the dietary manipulation of cholesterol levels.