Evaluation of the direct epifluorescent filter technique for assessing the hygienic condition of milking equipment

1983 ◽  
Vol 50 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Alastair C. Hunter ◽  
Rhona M. McCorquodale
Keyword(s):  
Heat Treatment ◽  
Correlation Coefficients ◽  
Testing Methods ◽  
Hygienic Condition ◽  
Filter Technique ◽  
Ringer’S Solution ◽  
Streptococcus Lactis ◽  
Bright Orange ◽  
Living Organisms ◽  
Direct Epifluorescent Filter Technique

SummaryThe hygienic condition of 6 milking installations, 3 sanitized by circulation cleaning (CC) with chlorine-based chemicals and 3 by flushing with acidified boiling water (ABW), was tested using rinses of quarter strength Ringer's solution. The bacterial content of the rinses was determined using both colony counts and the direct epifluorescent filter technique (DEFT). A comparison of testing methods gave correlation coefficients between colony count and DEFT of 0·82 for plants using CC and 0·46 for plants using ABW.Five strains of bacteria belonging to different genera and commonly found on milking equipment were exposed to various degrees of heat and to various concentrations of chlorine. The effects of such treatments on the staining characteristics of the organisms were studied. It was observed thatStaphylococcus aureusandStreptococcus lactis, although killed by heat treatment, stained a bright orange when treated with acridine orange dye.Pseudomonas fluorescens, Escherichia coliand vegetative cells ofBacillus cereusdid not take up the orange stain after heat treatment, nor did any of the 5 strains stain orange after treatment with NaOCl. It is suggested that the DEFT is a useful and rapid means of counting bacteria in rinses of equipment where sterilization is due primarily to chlorination, but in the absence of a stain which can differentiate more accurately between dead and living organisms its use is limited where sterilization is carried out solely by heat.

Determination of Viable Bacterial Populations in Raw Milk within 20 Minutes by Using a Direct Epifluorescent Filter Technique

1997 ◽  
Vol 60 (7) ◽  
pp. 874-876 ◽  
Author(s):  
CLAUDE P. CHAMPAGNE ◽  
NANCY J. GARDNER ◽  
JULIE FONTAINE ◽  
JACQUES RICHARD
Keyword(s):  
Raw Milk ◽  
Plate Count ◽  
Bacterial Populations ◽  
Filter Technique ◽  
Milk Samples ◽  
Standard Plate ◽  
Plate Counts ◽  
Direct Epifluorescent Filter Technique ◽  
Triton X

The results from a shortened procedure for the direct epifluorescent filter technique (DEFT) determination of viable bacterial populations in raw milk were compared to standard plate counts. Shortening the prefiltration trypsin-Triton X-100 incubation period from 10 to 3 min enabled the completion of the analysis within 20 min. The short DEFT method results had a correlation coefficient (r) of 0.81 with plate counts. With respect to precision, the average difference between values of duplicate plate count analyses was 0.16 log units; that of the short DEFT was 0.14 log units. The slopes of the regressions equations were less than 1, indicating that a direct correlation is not achieved. Short DEFT values were 0.17 log units higher than those of plate counts on milk samples containing less than 10,000 CFU/ml. For milk samples containing counts over 10,000 CFU/ml, short DEFT values averaged only 0.05 log units above plate count readings. Daily preparation of the stain appears unnecessary since acridine orange solutions stored for up to 2 days at 4°C did not produce results significantly (P > 0.05) different from those obtained with fresh solutions. The short DEFT method has potential for the assessment of the bacteriological quality of raw milk in tanker deliveries.

The Limulus Amoebocyte Lysate Assay and the Direct Epifluorescent Filter Technique as Estimators of Potential Shelf-life of Pasteurized Fluid Milk

1990 ◽  
Vol 53 (2) ◽  
pp. 151-153 ◽  
Author(s):  
ROBERT D. BYRNE ◽  
J. RUSSELL BISHOP
Keyword(s):  
Shelf Life ◽  
Benzalkonium Chloride ◽  
Detection Techniques ◽  
Filter Technique ◽  
Psychrotrophic Bacteria ◽  
Limulus Amoebocyte Lysate ◽  
Whole Milk ◽  
Before And After ◽  
Direct Epifluorescent Filter Technique ◽  
Fluid Milk

The Limulus Amoebocyte Lysate Assay, Direct Epifluorescent Filter Technique and modified Psychrotrophic Bacteria Count were used to indicate potential shelf-life of pasteurized fluid milk. Commercial whole milk samples, stored at 7°C, were analyzed for bacterial and biochemical parameters, as well as for potential shelf-life by daily sensory evaluation. Each sample was evaluated before and after the following preliminary incubations: milk alone, milk with benzalkonium chloride, milk and broth, and milk and broth with benzalkonium chloride. The Limulus Amoebocyte Lysate Assay, Direct Epifluorescent Filter Technique, and modified Psychrotrophic Bacteria Count in conjunction with the preliminary incubations, produced relatively high correlations to shelf-life (−0.78, −0.85, and −0.86 respectively). Thus, these bacterial detection techniques could be used as rapid methods of shelf-life estimation.

CANADIAN WILTSHIRE BACON: XII. EFFECT OF HEAT TREATMENT ON THE COLOUR AND COLOUR STABILITY OF BACON

1940 ◽  
Vol 18d (8) ◽  
pp. 289-299 ◽  
Author(s):  
C. A. Winkler ◽  
J. W. Hopkins
Keyword(s):  
Heat Treatment ◽  
Relative Humidity ◽  
Correlation Coefficients ◽  
The Other ◽  
Average Intensity ◽  
Colour Stability ◽  
Lower Intensity ◽  
Subsequent Exposure ◽  
Duration Of Heating ◽  
Nitrite Content

The colour of quadruplicate pieces of factory-cured bacon heated at temperatures of 20, 40, 50, 60, 70, and 80 °C. for 5, 10, 20, and 40 hr. was measured at the conclusion of heating, and also after subsequent exposure of the samples for 12, 20, and 96 hr. at 10 °C. and 95% relative humidity. Interacting effects of time and temperature of heating on colour at the conclusion of treatment were demonstrable. At 40 and 50°, total intensity increased with the duration of heating; at 60 and 70°, there was no definite trend, and at 80° it diminished markedly as the period of heating was prolonged. The maximum average intensity resulted from heating at 70°.The decrease in intensity after 12 hr. exposure was related to the duration, but not to the temperature, of previous heating. There was no significant change in intensity between 12 and 20 hr., but a further decrease was evident at the end of 96 hr. The decrease in green intensity was still related to the duration, rather than to the temperature, of heat treatment, but the effects of duration of heating on red and blue stability, noted at 12 and 20 hr., were now replaced by temperature effects.Partial correlation coefficients indicate that increased nitrite content of the meat at the conclusion of heating tended to be associated with a lower intensity of colour. On the other hand, both nitrite content and loss in weight (chiefly moisture) on heating were correlated with increased colour stability on exposure.

Effect of Agitation on Bacterial Aggregates in Pure Cultures and Raw Milk

1983 ◽  
Vol 46 (8) ◽  
pp. 681-685 ◽  
Author(s):  
ROBYN E. O'CONNOR ◽  
K. N. EWINGS ◽  
NEIL W. HOLLYWOOD
Keyword(s):  
Raw Milk ◽  
Mechanical Agitation ◽  
Filter Technique ◽  
Milk Samples ◽  
Pure Cultures ◽  
Plate Counts ◽  
Bacterial Aggregates ◽  
Direct Epifluorescent Filter Technique ◽  
Clump Size

A comparison of the effects of various mechanical agitation treatments on bacterial aggregates was performed on 8 pure cultures and 27 raw milk samples. Although both syringing and blending produced significant increases in total counts and psychrotroph counts, blending for 2 min gave the greatest increase in count. Use of the direct epifluorescent filter technique (DEFT) confirmed that syringing and blending reduced bacterial clump size to approximately 2 cells. These agitation treatments markedly improved the correlation between DEFT counts and plate counts.

THE DEVELOPMENT OF BACTERIAL POPULATIONS IN MILK

1957 ◽  
Vol 3 (2) ◽  
pp. 203-213 ◽  
Author(s):  
T. Gibson ◽  
Y. Abd-El-Malek
Keyword(s):  
Heat Treatment ◽  
Bacillus Cereus ◽  
Raw Milk ◽  
Coagulase Negative Staphylococci ◽  
Bacterial Populations ◽  
Gram Negative ◽  
Streptococcus Lactis ◽  
Plate Counts ◽  
Group A ◽  
Dominant Bacteria

The dominant bacteria in different classes of milk have been identified by taking samples of the colonies on quantitatively inoculated plates. Many of the bacteria that occur commonly in milk find it a relatively unfavorable medium. In the temperature range 10°–22 °C. the organisms that multiply actively are the Streptococcus lactis group, a species of Leuconostoc, coagulase-negative staphylococci, and Gram-negative rods (chiefly Alcaligenes viscosus and fluorescent and non-fluorescent pseudomonads). Plate counts of organisms that resist pasteurization for 30 minutes at 63 °C. are unsuitable for demonstrating the multiplication of Leuconostoc or Alcaligenes tolerans, which show variable and frequently low rates of survival in the heat treatment. In laboratory-pasteurized milk incubated without recontamination, the surviving organisms, unlike the populations of raw milk, do not show distinctly the effects of a differential selection. The only thermoduric organism that was found to produce rapid deterioration of milk is Bacillus cereus (including B. mycoides).

Mechanical and Corrosion Properties of Ni-Free Austenitic Stainless Steel/Hydroxyapatite Nanocomposites

2009 ◽  
Vol 151 ◽  
pp. 213-216 ◽  
Author(s):  
Maciej Tulinski ◽  
Mieczyslaw Jurczyk
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stainless Steels ◽  
Bulk Material ◽  
Hard Tissue ◽  
Corrosion Properties ◽  
Ringer’S Solution ◽  
Tissue Replacement ◽  
Mechanical And Corrosion Properties

In the present work, a nanocrystalline nickel-free stainless steels as well as nickel-free stainless steel/hydroxyapatite nanocomposites have been synthesized by the combination of mechanical alloying (MA), heat treatment and nitriding. The microhardness of the final bulk material was studied using Vickers method. Corrosion potentiodynamic tests were performed in Ringer’s solution. The results show that nickel-free stainless steel/hydroxyapatite nanocomposites could be promising bionanomaterials for use as a hard tissue replacement implants.

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