High Intensity Ultrasound for Salmonella Enteritidis Inactivation in Culture and Liquid Whole Eggs

Abstract

High intensity ultrasound (HIU) continues to be researched as a nonthermal inactivation technology of appeal to food manufacturers. The advantages of HIU include maintenance of product quality, freshness, product homogenization, along with simultaneous inactivation of pathogens. Besides, it is simple, relatively inexpensive, and easily adaptable to most processing environments. This study investigated the effect of HIU for Salmonella Enteritidis inactivation in culture and liquid whole eggs (LWEs) to decrease egg-associated outbreaks. Overnight S. Enteritidis cultures and spiked LWE (both at 8 log CFU/mL) were treated with 20-kHz HIU for 0, 1, 5, 10, and 30 min (n = 6) in a temperature-controlled system, not to exceed 20 °C, and replicated thrice. At each time point, samples were enumerated on XLT4 agar and morphologically analyzed using scanning electron microscopy, with measurements of color and rheological properties. Our results revealed significant reduction of healthy S. Enteritidis cells up to 3.6 log CFU/mL and 2.3 log CFU/25 mL after HIU treatment of merely 10 min of overnight culture and 30 min in LWE, respectively (P < 0.05). After 5 and 10-min HIU treatment, significant reduction of 1.4-log CFU/25 mL healthy S. Enteritidis in LWE was obtained (P < 0.05). Even at 1-min exposure time, HIU showed significant 1.9 log CFU/mL reduction of cultures (P < 0.05); however, no log-reduction was observed in LWE after 1 min. Scanning electron micrographs showed increased cell structural damage using longer HIU exposure. For product color changes, lower redness and yellowness of LWE were observed visually and instrumentally after 5-min HIU treatment (P < 0.05). The rheological properties of LWE measured at 0 to 200 s shear rate, showed that shear stress of HIU-treated LWEs decreased after 5-min HIU exposure, but increased after 30-min treatment. This study demonstrated that HIU shows promise for rapid Salmonella control in LWE and other liquid foods, as an alternative inactivation method for use in hurdle approaches.

The effect of ultrasound treatment in combination with nisin on the inactivation of Listeria innocua and Escherichia coli

“…There are no existing studies which investigate the efficacy of ultrasound in varied systems of controlled composition and complexity with which the present study can be compared. Furthermore, while studies have been carried out in a range of liquids (growth medium, saline solution, wastewater) and liquid foods (fruit juices, liquid whole egg, milk), the experimental set-up, frequency, microbial species and power intensity varies between them making a useful comparison between systems very difficult [4] , [14] , [17] , [18] , [47] , [56] , [57] , [58] , [59] , [60] .…”

“…essential oils, chlorine dioxide, fumaric acid) has been studied in a range of liquid systems such as wastewater, saline solution, and growth medium [4] , [14] , [47] , [55] , [56] , in real liquid food systems i.e. fruit juices, cactus pear juice, liquid whole egg or milk [17] , [18] , [57] , [58] , [59] , [60] , on the surface of solid ready-to-eat food products i.e. lettuce leaves, strawberries, cherry tomatoes, bean sprouts [61] , [62] , [63] , [64] , and also on abiotic surfaces such as stainless steel [65] , [66] .…”

Synergistic Antibiofilm Effects of Ultrasound and Phenyllactic Acid against Staphylococcus aureus and Salmonella enteritidis

“…Ultrasonic sterilization (US) is an effective method that can inactivate bacteria and is more suitable for liquid foods [10]. This method can inactivate common foodborne pathogens, such as Listeria and Escherichia coli, in dairy products and can ensure the preservation of their nutritional composition [11]. In addition, US is environmentally friendly and can be used to clean the surfaces of machines in the food industry [12,13].…”

Rheological and Flow Behaviour of Yolk, Albumen and Liquid Whole Egg from Eggs of Six Different Poultry Species

“…The shear strain rate was gradually increased from 0.2 to 200 s −1 . The shear strain rate range was chosen according the literature [ 4 , 14 ]. This range makes it possible to accurately determine and model the flow behaviour and then correctly classify the type (Newtonian, non-Newtonian–with or without yield stress, shear thinning or thickening) of egg liquids.…”