Nghiên cứu axit hypoclorơ theo ngành - Các kết quả Ngành: Food Ứng dụng: Meat

Electrolyzed water generators are readily available in the food industry as a renewable source of hypochlorous acid that eliminates the need for workers to handle hazardous hypochlorite concentrates. We applied electrolyzed water (EW) directly to multi-strain cocktails of Listeria monocytogenes, E. coli O157:H7, and Salmonella sp. at 250 ppm free available chlorine (FAC) and achieved greater than 6-log reductions in 2 min. Lower EW values were examined as antimicrobial interventions for fresh meat (beef carcasses), processed meats (frankfurters), and food contact surfaces (slicing blades). Little or no reduction relative to controls was observed when generic E. coli-inoculated beef carcasses or L. monocytogenes-inoculated frankfurters were showered with EW. Spray application of EW (25 and 250-ppm FAC) onto L. monocytogenes-inoculated slicing blades showed that greater reductions were obtained with clean (3.6 and 5.7-log reduction) vs. dirty (0.6 and 3.3-log reduction) slicing blades, respectively. Trials with L. monocytogenes-inoculated protein-EW solutions demonstrated that protein content as low as 0.1% is capable of eliminating FAC, reducing antimicrobial activity against L. monocytogenes. EW appears better positioned as a surface sanitizer with minimal organic material that can otherwise act as an effective reducing agent to the oxidizing solution rendering it ineffective.

Slightly acidic electrolyzed water (SAEW), considered as a broad-spectrum and high-performance bactericide are increasingly applied in the food industry. However, its disinfection mechanism has not been completely elucidated. This study aims to examine the disinfection efficacy and mechanism of SAEW on Staphylococcus aureus, compared with that of sodium hypochlorite (NaClO) and hydrochloric acid (HCl). SAEW treatment significantly reduced S. aureus by 5.8 log CFU/mL in 1 min, while 3.26 and 2.73 log reductions were obtained with NaClO and HCl treatments, respectively. A series of biological changes including intracellular potassium leakage, TTC-dehydrogenase relative activity and bacterial ultrastructure destruction were studied following disinfection treatment of S. aureus. The results showed that SAEW decreased the relative activity of TTC-dehydrogenase by 65.84%. Comparing intracellular potassium leakage, the SAEW treatment caused a greater percent of protein leakage (108.34%) than the NaClO (18.75%) or HCl (0.84%) treatments. These results demonstrated the potent impact SAEW had on the permeability of cell membranes. In addition, the ranking of partly agglutinated cellular inclusion formation was HCl > SAEW > NaClO. It appeared that HCl, along with its low pH value, are responsible for most of the cytoplasmic disruptions. Overall, this study demonstrated that the disinfection mechanism of SAEW was disrupting the permeability of cell membrane and the cytoplasmic ultrastructures in S. aureus cells.

The article focuses on investigation of the effects of usage of acidic electrolyzed water (AEW) with different sodium chloride concentration (0.001, 0.01, and 0.1) for the preparation of carrageenan and gelatine hydrosols and hydrogels. To determine physiochemical properties of hydrosols, the pH, oxidation-reduction potential (ORP), available chloride concentration (ACC) and rheological parameters such us gelation and flow temperatures were measured. The samples were also 0.1 w/v). These results suggest that hydrogels and hydrosols incorporated with AEW may be used for food preservation.

The ability of acidic electrolyzed oxidizing water (AEO) and neutral electrolyzed oxidizing water (NEO) to inactivate the murine norovirus (MNV-1) surrogate for human norovirus and hepatitis A virus (HAV) in suspension and on stainless steel coupons in the presence of organic matter was investigated. Viruses containing tryptone (0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) were mixed with AEO and NEO for 1 min. In addition, stainless steel coupons containing MNV-1 with or without organic matter were treated with AEO or NEO for 3, 5, and 10 min. AEO was proven effective and generally killed more MNV-1 and HAV in suspension than NEO. Depending on the EO water generator, free chlorine concentrations are required to inactivate MNV-1 and HAV by 3-log PFU/mL or greater ranged from 30 mg/L to 40 mg/L after a 1 min contact time. The virucidal effect increased with increasing free chlorine concentration and decreased with increasing tryptone concentration in suspension. Both AEO and NEO at 70100 mg/L of free chlorine concentration significantly reduced MNV-1 on coupons in the absence of organic matter. However, there was no significant difference between these two treatments in the presence of organic matter. In addition, the efficacy of these two EO waters on stainless steel coupons increased with the increasing treatment time. Results indicated that AEO and NEO can reduce MNV-1 and HAV in suspension. However, higher free chlorine concentrations and longer treatment times may be necessary to reduce viruses on contact surfaces or in the presence of organic matter.

This study evaluated the efficacy of the individual treatments (slightly acidic electrolyzed water [SAcEW] or fumaric acid [FA]) and their combination to reduce Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, and Salmonella Typhimurium in fresh pork as well as to study the shelf life and sensory quality (color, odor, and texture) of pork during storage at 4 and 10 C. The inoculated pork samples (10 g) were dipped for 3 min in each treatment (tap water [TW], SAcEW, strong acidic electrolyzed water [StAEW], 0.5% FA, or SAcEW + 0.5% FA) with or without mild heat (40 C). Decontamination of fresh pork with SAcEW +0.5% FA at 40 C for 3 min showed greater bactericidal effect compared to other treatments, which significantly (P < 0.05) reduced E. coli O157:H7, L. monocytogenes, S. aureus, and S. Typhimurium by 2.59, 2.69, 2.38, and 2.99 log CFU/g, respectively. This combined treatment significantly (P < 0.05) yielded in a longer lag time of naturally occurring bacteria (TBC) on pork stored at 4 C. This combined treatment also prolonged the shelf life of pork up to 6 days and 4 5 days when stored at 4 C and 10 C, respectively, compared to those of the untreated pork. The results suggest that the combined treatment of SAcEW + 0.5% FA has potential as a novel method to enhance the microbial safety and quality of fresh pork.

The bactericidal efficacy of acidic electrolyzed oxidizing water (AC-EW) (pH = 2.30, free chlorine = 38 ppm) and sterile distilled water (DW) on three pathogens (Escherichia coli O157:H7 Salmonella Typhimurium, and Listeria monocytogenes) inoculated on raw trout skin, chicken legs and beef meat surfaces was evaluated. The decontaminating effect of AC-EW and DW was tested for 0 (control), 1, 3, 5 and 10 min at 22 C. AC-EW significantly (P < 0.05) reduced the three pathogens in the inoculated samples compared to the control and DW. The level of reduction ranged between ca.1.5 1.6 logs for E. coli O157:H7 and S. Typhimurium in the inoculated foods. However, AC-EW exhibited less bactericidal effect against L. monocytogenes (1.1 1.3 logs reduction). AC-EW elicited about 1.6 2.0 log reduction in the total mesophilic count. Similar treatment with DW reduced pathogens load by ca. 0.2 1.0 log reduction and total mesophiles by ca. 0.5 0.7 logs. No complete elimination of the three pathogens was obtained using AC-EW possibly because of the level of organic matter and blood moving from food samples to the AC-EW solution. This study demonstrates that AC-EW could considerably reduce common foodborne pathogens in fish, chicken and beef products.

The objectives of this study were to evaluate the effectiveness of low concentration electrolyzed water (LcEW) and other carcass decontaminants against Escherichia coli O157:H7 and Listeria monocytogenes in fresh pork and to conduct the shelf life/sensory study of pork. Pork samples were inoculated with approximately 5 log cfu/g of afore mentioned pathogens and dip treated with distilled water (DW), aqueous ozone (AO), 3% lactic acid (LA), 3% calcium lactate (CaL), sodium hypochlorite solution (NaOCl), LcEW, strong acidic electrolyzed water (SAEW), and LcEW + CaL for 5 min at room temperature (23 2 C). The greatest reduction (3.0 3.2 log cfu/g) was achieved with LcEW + CaL against pathogens and significantly differed (p < 0.05) from other treatments. This combination also extended shelf life of pork up to 6 days at 4 C storage.

The objective of this study was to develop a model of the growth of Listeria monocytogenes in pork untreated or treated with low concentration electrolyzed water (LcEW) and strong acid electrolyzed water (SAEW), as a function of temperature. The experimental data obtained under different temperatures (4, 10, 15, 20, 25, and 30 C) were fitted into the modified Gompertz model to generate the growth parameters including specific growth rate (SGR) and lag time (LT) with high coefficients of determination (R2 >0.97). The obtained SGR and LT were employed to develop square root models to evaluate the effects of storage temperature on the growth kinetics of L. monocytogenes in pork. The values of bias factor (0.924-1.009) and accuracy factor (1.105-1.186), which were regarded as acceptable, demonstrated that the obtained models could provide good and reliable predictions and be suitable for the purpose of microbiological risk assessment of L. monocytogenes in pork.

In 1999 the foodborne pathogens Salmonella, Listeria, Campylobacter, and Escherichia coli (both O157 and non-O157) were estimated to cause more than 6 million illnesses and approximately 9000 deaths each year. However, the most recent Centers for Disease Control and Prevention report on the sources and incidence of foodborne disease, released in 2004, has shown a dramatic decrease in E. coli O157:H7 infections. Since raw beef products are the most frequently foodborne sources of these pathogens, the results of this report demonstrate that the microbiological quality of raw beef has improved greatly. During the intervening years, post-harvest interventions have continually improved, with new attention to hide decontamination and innovative treatments of carcasses. In addition, a system to hold and test beef trim or ground beef for E. coli O157:H7 before its release into commerce has provided an even greater level of safety. In this paper, we review the latest information on the prevalence of E. coli O157:H7 and other pathogens on beef, the evidence identifying the hide as the primary source of pathogens on beef carcasses, the efficacy of various hide and carcass interventions, and other developments that have led or have the potential to lead to even greater improvements in the microbial quality of beef.

Experiments were conducted to determine the effectiveness of acidic (EOA) or basic electrolyzed oxidizing (EOB) water, alone or in combination, on ready-to-eat (RTE) meats to reduce Listeria monocytogenes (LM). Frankfurters or ham surfaces were experimentally inoculated with LM and subjected to dipping or spraying treatments (25 or 4 C for up to 30 min) with EOA, EOB, and other food grade compounds. LM was reduced the greatest when frankfurters were treated with EOA and dipped at 25 C for 15 min. A combination spray application of EOB/EOA also resulted in a slight reduction of LM on frankfurters and ham. However, reductions greater than 1 log CFU/g were not observed for the duration of the study. Even with a prolonged contact time, treatments with EOA or EOB were not enough to meet regulatory requirements for control of LM on RTE meats. As such, additional studies to identify food grade antimicrobials to control the pathogen on RTE meats are warranted.

To date, the effectiveness of electrolyzed oxidizing (EO) water against bacteria associated with fresh pork has not been determined. Using a hand-held, food-grade garden sprayer, distilled water (W), chlorinated water (CL; 25 ppm), 2% lactic acid (LA), acidic EO water (EOA), or aged acidic EO water (AEOA; stored at 4 C for 24 h) was sprayed (15 s) onto pork bellies inoculated with feces containing Listeria monocytogenes (LM), Salmonella typhimurium (ST), and Campylobacter coli (CC). Remaining bacterial populations were determined immediately following treatment, after 2 days of aerobic storage, and again after 5 days of vacuum-packaged, refrigerated storage (day 7). While LA and EOA significantly reduced (p<0.05) populations of CC at days 0 and 7, there was no significant difference (p>0.05) between antimicrobial treatments when applied to pork inoculated with ST or LM. This study demonstrates that a 15-s spray with EOA has the ability to reduce CC associated with fresh pork surfaces. However, longer contact times may be necessary to reduce other microbial contaminants.

An electrochemical treatment system consisting of a pulsed electrical power supply and an electrical treatment chamber was designed and evaluated for inactivation Listeria monocytogenes in recirculated brine for chilling processed bacons. The brine was tested under different currents and temperatures. An average D-value of 1.61 min in the storage tank could be achieved at 7 mA/cm3 current with the fresh brine (t = 0 h). For the spent brine (t = 20 h), the D-value was 2.5 min in the treatment chamber at 35 mA/cm3. The average D-values in the treatment chamber were approximately 2.5 min at all three temperatures (4, 0, -8 8C) at 35 mA/cm3.