Acetic Acid Wash Research Articles

Long-Term Effect of Alkaline, Organic Acid, or Hot Water Washes on the Microbial Profile of Refrigerated Beef Contaminated with Bacterial Pathogens after Washing

The effect of 2% (vol/vol) lactic acid, 2% (vol/vol) acetic acid, 12% (wt/vol) trisodium phosphate, water at 72°C and water at 32°C washes on bacterial populations introduced onto beef carcass surfaces after treatment was determined for up to 21 days at 4°C in storage in vacuum packaging. Beef carcass short plates were collected from cattle immediately after slaughter and subjected to the above treatments or left untreated (C). Short plates were then inoculated with low levels (ca. <2 log10) of Listeria innocua, Salmonella typhimurium, Escherichia coli O157:H7, and Clostridium sporogenes cells contained in a bovine fecal cocktail. In general, growth of these four bacteria and of aerobic bacteria, lactic acid bacteria, and pseudomonads was suppressed or not observed when lactic acid or acetic acid treatments were used. Bacteria introduced to trisodium phosphate-treated tissue underwent some growth suppression, but to a lesser extent than on acid-treated tissue, and in some cases grew as well as on untreated beef surfaces. Water washes at 72 or 32°C offered little growth suppression of pathogens during subsequent storage when these bacteria were introduced to beef tissue after treatment. The use of a final lactic or acetic acid wash during the Processing of beef carcasses offers some residual efficacy in suppressing pathogen proliferation during refrigerated storage, should these bacteria be introduced immediately after carcass processing.

Reduction of foodborne micro-organisms on beef carcass tissue using acetic acid, sodium bicarbonate, and hydrogen peroxide spray washes

In an attempt to control beef carcass contamination, a search for effective carcass washing treatments has become a major focus in the area of microbiological meat safety. Spray-wash treatments utilizing 1.0% acetic acid, 3% hydrogen peroxide, 1% sodium bicarbonate, alone or in combination, were performed to evaluate their efficacy in reducing numbers ofEscherichia coli,ListeriainnocuaandSalmonella wentworth. The fascia surface of lean and adipose tissue was inoculated with sterilized fecal slurry containing the designated bacteria to obtain 5 log8cfu cm−2. A pilot scale model carcass washer was used to apply the spray treatment (80 psi, 15 s, 25°C). Control samples received no spray treatments. Following treatments, lean and adipose samples were immediately analyzed or held for 24 h at 5°C for analysis of the treatments, for residual bacterial populations, surface pH, color analysis, and residual hydrogen peroxide. The combination wash of acetic acid/3% hydrogen peroxide (AAHP) resulted in the greatest reductions of 3.97 and 3.69 log8cfu cm−2forE. colion lean or adipose tissue, respectively. Spray washes with AAHP reducedL. innocuaby 3.05 log8cfu cm−2on lean tissue and 3.52 log8cfu cm−2on adipose tissue, whileS. wentworthwas reduced by 3.37 log8cfu cm−2on lean and 3.69 log8cfu cm−2on adipose tissue. A spray-wash treatment consisting of the right combination of safe and acceptable solutions may be effective for improving the microbial safety of beef.

The role of speculoscopy in the diagnosis of cervical dysplasia.

Concern about false negative screening cytology has led to the development of adjunctive tests, among them speculoscopy. Speculoscopy involves cervical examination after acetic acid wash with 5X magnifying loupes under chemiluminescent illumination. Limited data support a role for speculoscopy to improve screening yield and allow triage of patients with borderline cytology, but indications and strategies for use require further definition.

COLPOSCOPIC EXAMINATION OF THE VAGINA

Examination of the vagina must include assessment of the minor vestibular glands and urethral meatus. Vaginal mucosal lesions related to papillomavirus infection and neoplasia are best discovered by the use of acetic acid wash followed by the application of Monsel's solution.

Improved silica gel cleanup method for organophosphorus pesticides

Quantitative recovery of some organophosphorus pesticide residues has not been possible with existing silica gel-cleanup procedures. We have developed a modification that permits quantitative recovery of all organophosphorus pesticides tested except those with a carbamate functional group. The method uses a 3.5 g silica gel column with a 1% acetic acid wash to condition the column prior to the addition of the sample. Percentage recovery and standard deviation of compounds such as phorate and disulfoton are 96 (5.6) and 98 (1.0) respectively. Recoveries range from 92 to 101% for the 11 compounds tested.

Enumeration and Reduction of Campylobacter jejuni in Poultry and Red Meats

This paper compares alternative methods for enumerating Campylobacter jejuni in meat products, the optimal levels of blood supplementation for enrichment recovery of the organism from chicken and ground beef, and means to reduce or eliminate Campylobacters from chicken through organic acid washes or freeze/thaw treatments. Direct plating onto Campy-BAP medium resulted in equivalent or greater recovery of C. jejuni, compared with MPN procedures using two media described in the literature. Subsequent studies employed direct plating, as it was also faster and simpler than the MPN procedures. Enumeration of enrichment cultures from a blood-containing selective enrichment broth indicated that optimal levels of blood supplementation for the recovery of Campylobacters was dependent on the food investigated. Not only did 0% blood supplementation enhance recovery of the organism from inoculated ground beef, but 7% supplementation actually decreased the numbers recovered from this product. The requirement for blood supplementation was reversed when C. jejuni recovery from chickens was assessed. Significant increases were seen when 7% supplementation was employed as compared with either 1 or 0% blood in the enrichment broth. A freeze (−15°C)/thaw treatment of chicken carcasses reduced the numbers of Campylobacter detected by a factor of greater than 100. Finally, 0.5% of either lactic or acetic acid washes of chicken carcasses at 50°C reduced the numbers of C. jejuni present.

Differences in lead isotope composition in the stratiform McArthur zinc-lead-silver deposit

Lead isotopic composition and uranium and lead concentrations have been determined for galena, sphalerite, pyrite and acetic acid soluble material from the McArthur area in order to test the hypothesis of a dual sulphur source suggested by the sulphur isotope data of Smith and Croxford (Sulphur isotope ratios in the McArthur lead-zinc-silver deposit, Nature Phys. Sci. 245, 10–12 (1973)). Galena, sphalerite and the acetic acid washes from the McArthur deposit have uniform isotopic ratios (206Pb/204Pb, 16.07–16.15; 207Pb/204Pb, 15.37–15.47; 208Pb/204Pb, 35.57–35.89) consistent with other conformable ore deposits, whereas the ratios for pyrite are variable and quite radiogenic (206Pb/204Pb, 16.24–16.49; 207Pb/204Pb, 15.42–15.58; 208Pb/204Pb, 35.82–36.98). Acid washes where dolomite is a major dissolved phase are also radiogenic. The lead in the pyrite appears to have been derived from at least two sources: the less radiogenic lead coming from an exhalative source as for galena and sphalerite and the more radiogenic lead probably being leached from the country rocks. It is proposed that analysis of pyrite for isotopic composition and concentration of lead could be used as an indicator for similar types of deposits in this area.

The hazard of acid differentiation in Gomori's method for acid phosphatase.

In his original method for the histochemical demonstration of acid phosphatase, Gomori prescribed differentiation of incubated sections by rinsing them in 14% aqueous acetic acid, to remove the nonspecifically precipitated lead deposits. According to him, the enzymatically produced lead phosphate is not washed out by this procedure. As a result of recent improvements in tissue preparation and shorter incubation time, this staining reaction as it is used now is quite sensitive to an acetic acid wash. If this wash is used as recommended originally, it may completely abolish a truly positive reaction. To avoid falsely negative results, and to compare sections of normal and pathological tissue, omission of this differentiation by acetic acid is essential. The risk of mistaking nonspecific lead precipitates in the interpretation of a positive reaction is very small, and can be avoided by running a negative control slide in which no lead phosphate can be produced enzymatically.