Studies on Disinfection Mechanism of Electrolyzed Oxidizing Water on E. coli and Staphylococcus aureus

Abstract

The effectiveness of using protease and combinations of protease and high-intensity ultrasound for high-purity, high-yield tamarind seed polysaccharide (TSP) production was investigated. Tamarind kernel powder (TKP) suspension was treated with protease alone at 0.16, 0.48, and 0.80 units/mL and with protease-ultrasound combinations over 3 different orders of sequence (before, simultaneous with, and after protease digestion) using combinations of 0.48 units/mL protease and high-intensity ultrasound at 25% and 50% amplitude for 15 and 30 min. The long protease digestion time could produce high-purity isolated TSP, but the polysaccharide yields were lower. The polysaccharide purity and yield were highly improved, even at a shorter protease digestion time, when the protease treatment was combined with high-intensity ultrasound. The increased amplitude level and sonication time decreased the average molecular weight of the polysaccharide. The rheological properties of the TKP and the isolated TSP, from nondestructive oscillatory measurements, demonstrated that the latter present a viscoelastic solution. The decreasing of protein content resulted in better elasticity of the solution. The power law model could be used to fit the down curve between shear rate and shear stress data. The consistency coefficient (K) increased while the flow behavior index decreased with the increased purity of the polysaccharide as a result of increasing increased digestion time, enzyme concentration, sonication power, and sonication time.

Surface physiological changes induced by lactic acid on pathogens in consideration of pKa and pH

“…The results showed that lactic acid could damage the membranes of Salmonella, E. coli and Listeria, resulting in an unbalanced osmotic pressure between intracellular and extracellular ionic concentrations (Zeng et al, 2010). Eventually, the large leakage of K þ led to a great lack of intracellular K þ , which could influence the intracellular physiological functions and even result in the bacterial mortality (Marklund, Behnam-Motlagh, Henriksson, & Grankvist, 2001).…”

Disinfection efficacy and mechanism of slightly acidic electrolyzed water on Staphylococcus aureus in pure culture

“…Setlow et al 2002 reported that the disinfection mechanism of strong acid or alkali treatment on Bacillus subtilis spores was due to the inactivation of the intracellular enzymes and the disruption of the permeability barrier. To date only a few researchers have investigated the disinfection mechanism of electrolyzed oxidizing water (EOW) (Zeng et al, 2010(Zeng et al, , 2011. These researchers reported that EOW caused damage to the cell walls, nucleus and outer membranes, which lead to the rapid leakage of intracellular K þ , DNA and proteins, and a decrease in the dehydrogenase activities of S. aureus.…”

Potential of Electrolyzed Water as an Alternative Disinfectant Agent in the Fresh-Cut Industry

“…Several studies have addressed the mechanism of microbial inactivation by EW. These include the increase of membrane permeability together with leakage of cellular components and the decrease of activity of several key enzymes in bacteria such as E. coli and Staphylococcus aureus (Liao et al 2007;Zeng et al 2010) as well as the yeast Candida albicans . Degradation of chromosomal DNA has been also observed in Pseudomonas aeruginosa (Kiura et al 2002) and cause aggregation of essential bacterial proteins (Winter et al 2008) or interfering bacteria cell protein composition (Cloete et al 2009).…”