Use of an Electrostatic Spraying System or the Sprayed Lethality in Container Method To Deliver Antimicrobial Agents onto the Surface of Beef Subprimals To Control Shiga Toxin-Producing Escherichia coli

Effects of Peroxyacetic Acid on Postharvest Diseases and Quality of Blueberries

Postharvest diseases are a limiting factor in the storage of fresh blueberries. Gray mold caused by Botrytis cinerea and Alternaria rot caused by Alternaria spp. are important postharvest diseases in blueberries grown in California. Control of these fungal pathogens is generally dependent on preharvest sprays of synthetic fungicides, but in California multiple fungicide resistance has already developed in those pathogens, leading to the failure of disease control. Therefore, alternatives to synthetic fungicides are needed for the control of postharvest diseases. Peroxyacetic acid (PAA) is a disinfectant agent that poses low risk to human health. In this study, we evaluated the effects of postharvest use of PAA at 24 µl liter^-1 and 85 µl liter^-1 on fruit decay caused by fungal pathogens and quality of stored blueberry fruit. PAA treatment was applied to four cultivars over three seasons using two methods, dipping or spraying. Dipping blueberries compared with spraying them with PAA and its application at 85 µl liter^-1 were the most effective treatments. For example, when applied to 'Snowchaser' blueberries, this combination reduced naturally occurring decay after 4 weeks of storage at 0 to 1°C from 14.3% among water-treated controls to 2.7% in 2018, and from 25.7% among water-treated controls to 8.6% in 2020. In general, PAA did not adversely affect fruit quality or sensory quality of blueberries. Postharvest use of PAA appears to be a promising means to reduce postharvest decay of blueberries. To reliably obtain an acceptable level of disease control, the best use of PAA may be in combination with other practices rather than using it alone.

Reducing Pathogenic Escherichia coli Surrogates on Fresh Beef Cuts by Water-Reducing Antimicrobial Interventions

ABSTRACT

Water use for antimicrobial intervention application for beef harvest has come under increased scrutiny in recent years in an effort to enhance water conservation during beef harvest and fabrication. We determined the efficacy of beef safety interventions for reducing surrogates of the Shiga toxin-producing Escherichia coli (STEC) on beef cuts while lowering intervention-purposed water use for a small or very small beef establishment. Beef briskets, shoulder/clods, and rounds were inoculated with a gelatin-based slurry containing 6.8 ± 0.3 log CFU/g of nonpathogenic E. coli. After 30 min of attachment, inoculated cuts were treated by conventional lactic acid spray (2.5%, 55°C), lactic acid delivered by an electrostatic spray (2.5%, 55°C) handheld wand, hot water spray (82°C), or recycled hot water spray (82°C), wherein previously applied hot water was collected, thermally pasteurized to 82°C, or left untreated. One hundred milliliters of each treatment was sprayed onto marked surfaces of inoculated cuts, after which time surviving surrogate E. coli were enumerated. Lactic acid spray and electrostatic spray treatments produced greater reductions (1.0 to 1.1 log CFU/300 cm2) than hot water interventions (0.3 to 0.5 log CFU/300 cm2) (P ≤ 0.0001). Recycling of water reduced water losses by no less than 45% on recycled hot water spray-treated beef cuts. Low water beef safety interventions offer small and very small inspected beef establishments opportunities to incrementally reduce water use during intervention application, but not necessarily without loss of pathogen reduction efficacy.

HIGHLIGHTS

Comparison of the Efficacy of Electrostatic versus Conventional Sprayer with Commercial Antimicrobials To Inactivate Salmonella, Listeria monocytogenes, and Campylobacter jejuni for Eggs and Economic Feasibility Analysis

This study was conducted to compare the efficacy of antimicrobials sprayed by electrostatic versus conventional sprayer for inactivation of Salmonella, Listeria monocytogenes, and Campylobacter jejuni on eggs and to determine the economic feasibility of these treatments. Eggs were dip inoculated with overnight cultures (18 h) of Salmonella Typhimurium, Salmonella Tennessee, a two-strain mixture of L. monocytogenes, and a three-strain mixture of C. jejuni (microaerophilic condition). Inoculated eggs were then not sprayed or subjected to electrostatic and conventional spraying with peroxyacetic acid (PAA; 0.1%), lactic acid (5.0%), lactic and citric acid blend (2.5%), sodium hypochlorite (SH; 50 ppm), and SaniDate-5.0 (SD [a mixture of PAA and H₂O₂]; 0.25%) for 30 s (15 s each side). Surviving bacteria on eggshells were recovered on xylose lysine Tergitol 4 agar ( Salmonella), modified Oxford agar ( L. monocytogenes), or Brucella agar ( C. jejuni). Compared with conventional spraying, electrostatic spraying of PAA, SD, and SH achieved significant additional reductions ( P < 0.05) of Salmonella, L. monocytogenes, and C. jejuni of 0.96 to 3.18, 1.19 to 3.05, and 0.96 to 1.62 log CFU per egg, respectively. A simple cost comparison suggests that regardless of the antimicrobial agent used, the cost of using an electrostatic sprayer is 20 to 40% lower than that of a conventional sprayer for a small poultry farm that produces 1,500 eggs per day. Among the five antimicrobials, the total sanitizing cost was lowest for SH, followed by PAA and SD. The results indicated that electrostatic spraying of commercial antimicrobials can be considered an effective and economical approach to enhancing the microbial safety of eggs, especially for small poultry processors.