Surface conditioning of stainless steel coupons with skim milk solutions at different pH values and its effect on bacterial adherence

Food Control ◽  
2010 ◽  
Vol 21 (12) ◽  
pp. 1769-1773 ◽  
Author(s):  
Nguyen Manh Dat ◽  
Daisuke Hamanaka ◽  
Fumihiko Tanaka ◽  
Toshitaka Uchino
Keyword(s):  
Stainless Steel ◽  
Skim Milk ◽  
Bacterial Adherence ◽  
Surface Conditioning ◽  
Ph Values

Surface conditioning of stainless steel coupons with skim milk, buttermilk, and butter serum solutions and its effect on bacterial adherence

Food Control ◽  
2014 ◽  
Vol 42 ◽  
pp. 94-100 ◽  
Author(s):  
Nguyen Manh Dat ◽  
Le Duc Manh ◽  
Daisuke Hamanaka ◽  
Duong Van Hung ◽  
Fumihiko Tanaka ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Skim Milk ◽  
Bacterial Adherence ◽  
Surface Conditioning

Growth Media and Surface Conditioning Influence the Adherence of Pseudomonas fragi, Salmonella typhimurium, and Listeria monocytogenes Cells to Stainless Steel

1997 ◽  
Vol 60 (9) ◽  
pp. 1034-1037 ◽  
Author(s):  
SCOTT K. HOOD ◽  
EDMUND A. ZOTTOLA
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Skim Milk ◽  
Epifluorescence Microscopy ◽  
Growth Media ◽  
Pseudomonas Fragi ◽  
Acridine Orange Staining ◽  
Surface Conditioning ◽  
Food Contact Surfaces

Microorganisms have been shown to adhere to food-contact surfaces and may provide a route for the contamination of processed food. To better understand this phenomenon, the effects of growth media and surface conditioning on the adherence of Pseudomonas fragi, Salmonella typhimurium and Listeria monocytogenes cells to stainless steel were studied. The microorganisms were grown in tryptic soy broth (TSB), 1% reconstituted skim milk (RSM) and RSM with 1% sucrose (RSM + S). Stainless-steel surfaces were conditioned by immersion in growth media for 1 h and then were rinsed in phosphate-buffered saline (PBS) prior to the adherence assay. After growing in each medium, cells were harvested, resuspended in PBS, and then allowed to contact the stainless steel for 30 min. Adherence was quantified by acridine orange-staining the cells and viewing under epifluorescence microscopy. Growth media had little influence on adherence to stainless steel that had not been preconditioned. P. fragi and L. monocytogenes cells adhered in the highest numbers when grown in RSM plus sucrose. S. typhimurium cells showed the highest level of adherence when grown in TSB. Analysis of variance yielded P values of less than 0.01, indicating that both growth media and surface conditioning were significant in the level of adherence observed.

Inhibition of bacterial adherence on stainless steel coupons by surface conditioning with selected polar lipids

2022 ◽  
Author(s):  
Nguyen Manh Dat ◽  
Thai Minh Phuong ◽  
Nguyen Thi Thu ◽  
Thai Khanh Phong ◽  
Toshitaka Uchino
Keyword(s):  
Stainless Steel ◽  
Bacterial Adherence ◽  
Polar Lipids ◽  
Surface Conditioning

scholarly journals Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface

2012 ◽  
Vol 32 (1) ◽  
pp. 142-150 ◽  
Author(s):  
Danila Soares Caixeta ◽  
Thiago Henrique Scarpa ◽  
Danilo Florisvaldo Brugnera ◽  
Dieyckson Osvani Freire ◽  
Eduardo Alves ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stainless Steel ◽  
Biofilm Formation ◽  
Skim Milk ◽  
304 Stainless Steel ◽  
Stainless Steel Surface ◽  
Aisi 304 ◽  
Pseudomonas Species ◽  
Sodium Dichloroisocyanurate ◽  
Different Temperatures

The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1) when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.

Behavior of Listeria monocytogenes at 4 and 22°C in Whey and Skim Milk Containing 6 or 12% Sodium Chloride

1989 ◽  
Vol 52 (9) ◽  
pp. 625-630 ◽  
Author(s):  
DEMETRIOS K. PAPAGEORGIOU ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Skim Milk ◽  
Salt Tolerant ◽  
Ph Values ◽  
Generation Times ◽  
Order Of Magnitude ◽  
Entire Experiment

Autoclaved samples of skim milk and deproteinated whey were fortified with 6 or 12% NaCl, inoculated with Listeria monocytogenes strains Scott A or California (CA), to contain ca. 1.0 × 103 cfu/ml (in the products with 6% salt) or ca. 5.0 × 103 cfu/ml (in the products with 12% salt) and incubated at 4 and 22°C. The pH values of the 6% salted whey, 6% salted skim milk, 12% salted whey, and 12% salted skim milk were 5.65, 6.20, 5.50, and 6.00 respectively. These values remained relatively constant during the entire experiment. Listeria counts were obtained by surface-plating appropriate dilutions and/or undiluted samples on Trypticase Agar (TA). Samples in which L. monocytogenes was not detected, were re-examined after 2, 4, 6 and 8 weeks of cold-enrichment. Generation times of L. monocytogenes in 6% salted whey at 22°C (3.67 h and 3.56 h for strains Scott A and CA, respectively) were significantly shorter than those in 6% salted skim milk at 22°C (4.31 and 4.42 h for the two strains, respectively). Generation times in 6% salted products at 4°C ranged between 37.49 h and 49.43 h. Maximum populations reached at 22 and 4°C ranged from 7.58 to 8.10 Log10 cfu/ml, and were significantly higher in 6% salted whey than in 6% salted skim milk. In 12% salted whey and skim milk incubated at 22°C, L. monocytogenes gradually decreased in numbers. Strain CA was inactivated within 85 d in 12% salted skim milk or within 110 d in 12% salted whey, and was significantly less salt tolerant than strain Scott A which survived for more than 130 d under the same conditions. Loss of viability by both strains was similar in 12% salted whey and skim milk after 130 d of storage at 4°C, and the decreases in population were less than 0.7 order of magnitude.

Studies on the manufacture of sweet cream starter butter: II. Effect of variation in proportion of starter added to cream

1960 ◽  
Vol 27 (1) ◽  
pp. 91-102 ◽  
Author(s):  
F. H. McDowall ◽  
J. A. Singleton ◽  
B. S. Le Heron
Keyword(s):  
Lactic Acid ◽  
Low Temperatures ◽  
Starter Culture ◽  
Skim Milk ◽  
Ph Values ◽  
Commercial Scale ◽  
Increase With Increase ◽  
Keeping Quality ◽  
Higher Temperature

SummaryProduction of diacetyl and acetoin by starters in cold skim-milk and cream was shown to increase with increase in the proportion of starter culture added, with some limitations at the higher rates of starter addition.With Streptococcus diacetilactis starter in skim-milk at 50°F the relation between proportion of starter added and production of diacetyl was linear up to addition at the 4% level, whereas at 43°F it was approximately linear up to the 10% level. At both 50 and 43°F the relation between the proportion of starter added and the production of acetoin was linear up to the 10% level.With Camb starter in skim-milk at both 50 and 43°F there were regular increases in production of diacetyl up to the 4% level of addition, but only minor changes thereafter with increase in the proportion of starter added up to 10%. At both temperatures the maximum production of acetoin was reached with the 7% rate of addition.Production of diacetyl and acetoin in skim-milk was greater at 50°F than at 43°F with both starters for all proportions up to 10%, and it was greater for Str. diacetilactis than for the mixed cultures.Except at the higher rates of addition of starter and at the higher temperature there were no concomitant increases in the acidity of the milk or lowering of the pH values. It appears that at low temperatures production of diacetyl by starters in sweet milk and cream proceeds independently of production of lactic acid.Similar results were obtained in a series of experimental buttermaking trials and some small commercial-scale trials, in which varying proportions of starter were added to creams after pasteurizing and before holding overnight for churning. With the cream-holding temperatures used, mainly 40–50°F, the pH values of the butters were not appreciably lowered by the starter additions to the cream. At all the rates of addition there were with Str. diacetilactis starter higher contents of diacetyl in the butter than with Camb starter. There was no indication of any relationship between the proportion of starter added and the keeping quality of the butter.

Evaluation of a Recirculating Dipper Well Combined with Ozone Sanitizer for Control of Foodborne Pathogens in Food Service Operations

2016 ◽  
Vol 79 (9) ◽  
pp. 1537-1548 ◽  
Author(s):  
GISELLE ALMEIDA ◽  
KRISTEN E. GIBSON
Keyword(s):  
Stainless Steel ◽  
Exposure Time ◽  
Service Industry ◽  
Control Point ◽  
Food Service ◽  
Skim Milk ◽  
Extended Period ◽  
E Coli ◽  
Critical Control Point ◽  
Retail Food

ABSTRACT In the retail food service industry, small countertop sinks, or dipper wells, are utilized to rinse and store serving utensils between uses. These dipper wells are designed to operate under a constant flow of water, which serves both to prevent the accumulation of microorganisms and to aid in the cleanliness of the dipper well itself. Here, a recirculating dipper well ozone sanitation system (DWOSS) was evaluated for the control and inactivation of Escherichia coli, Listeria innocua, PRD1 bacteriophage, and Staphylococcus aureus present on a stainless steel disher. In a low ozone (O3) demand medium, the DWOSS achieved over a 5-log reduction for E. coli, L. innocua, and PRD1 at 30 s when exposed to 0.45 to 0.55 ppm of residual O3. A greater than 5-log total CFU reduction was achieved for S. aureus at a 600-s exposure time and 0.50 ppm of residual O3. When evaluated in the presence of high O3 demand medium (10% skim milk), the DWOSS performed significantly better (P < 0.05) for all microbe–exposure time combinations compared with a conventional dipper well with respect to the reduction of microbes on the stainless steel disher. For example, at 30 s, the DWOSS achieved 4.37, 2.48, 1.38, and 1.31 greater log (CFU or PFU) reduction of E. coli, L. innocua, PRD1, and S. aureus, respectively, than a conventional dipper well. In addition, the DWOSS was evaluated under two neglect scenarios to determine its ability to control microbes in 10% skim milk medium on the stainless steel disher and within the dipper well basin itself over an extended period of use (2 h of use per day over 5 days). Considering the efficacy of the DWOSS unit against the microbes evaluated here, the integration of ozone into a dipper well could be a potential critical control point to reduce the incidence of microbial contamination during retail food service. To our knowledge, a dipper well with a cleaning-in-place sanitizing system is not currently available for use in the food service industry; and, thus, this is the first study to evaluate the efficacy of a cleaning-in-place dipper well.

Changes in Size of Casein Micelles Caused by Growth of Psychrotrophic Bacteria in Raw Skim Milk

1984 ◽  
Vol 47 (1) ◽  
pp. 16-19 ◽  
Author(s):  
JONATHAN P. BURLINGAME-FREY ◽  
ELMER H. MARTH
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Skim Milk ◽  
Bacterial Activity ◽  
Casein Micelles ◽  
Psychrotrophic Bacteria ◽  
Ph Values ◽  
Psychrotrophic Bacterium ◽  
Transmission Electron

Raw skim milk was inoculated (1%, v/v) with a proteolytic psychrotrophic bacterium that previously was isolated from milk. The inoculated skim milk was incubated at 7°C for 0, 3, 5 and 7 d. The pH values for the milk were 6.6, 6.5, 6.45 and 5.95, and the numbers of psychrotrophs/ml were 1.0 × 104 8.9 × 107, 9.0 × 108 and 2.5 × 108 for days 0, 3, 5 and 7, respectively. Samples of milk were negatively stained, examined with transmission electron microscopy and distribution of sizes of casein micelles was determined. The average and (mode) sizes of micelles were 849 (789), 1030 (634), 761 (634) and 405 (316) Angstroms for milks after days 0, 3, 5 and 7, respectively. Another set of samples was prepared from skim milk immediately after it was acidified to pH values of 6.6, 6.5, 6.45 and 5.95. The average and (mode) sizes of micelles were 891 (766), 875 (615), 913 (766) and 840 (615) Angstroms for milks having pH values of 6.6, 6.5, 6.45 and 5.95, respectively. Changes in size of micelles in the incubated samples resulted from bacterial activity other than small changes in pH.

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