bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Enterococci in Cheddar Cheese: Free Fatty Acid Appearance and Citric Acid Utilization1
Authors: JENSEN JANEP. , REINBOLD G. W. , WASHAM C. J. , VEDAMUTHU E. R.
Published: December 2016

Eight lots of Cheddar cheese were manufactured to determine the microbiological response and biochemical effects of two strains each of Streptococcus faecalis and Streptococcus durans used as supplemental starters in combination with a commercial lactic culture. Each lot consisted of a control vat of cheese manufactured with the lactic starter only and an experimental vat of cheese containing the lactic starter and one of the enterococcus strains. Combinations of two curing temperatures (7.2 and 12.8 C) and two early cooling treatments (air vs. brine cooling) were used for cheeses from each vat to determine environmental effects on the cheeses. Cheeses manufactured with S. faecalis had a somewhat lower content of free fatty acids than did control cheeses, possibly because of early conversion of acids to neutral compounds. Cheeses manufactured with S. durans showed a fluctuating, but consistent, free fatty acid content among treatments, with overall amounts being greater than in the control cheeses or in cheeses made with S. faecalis. Cheeses cured at 12.8 C showed greater free fatty acid liberation, but the effects of early cooling rates were not significant. Citric acid in cheeses made with S. faecalis and in control cheeses was utilized most rapidly in 30 days at 12.8 C and extending to 60 days when cured at 7.2 C, after which no more breakdown seemed to occur. Cheeses made with S. durans 9–20 followed approximately the same pattern although some utilization took place between 90 and 180 days. In cheeses made with S. durans 15–20, however, citric acid utilization was continuous up to 180 days, and in cheeses cured at 12.8 C, citric acid was nearly depleted at 180 days. Cheeses made with S. durans 15–20 and cured at 12.8 C exhibited excessive gas production.
A Membrane-Filter Technique to Test for the Significance of Sublethally Injured Bacteria in Retail Pasteurized Milk
Authors: CLAYDON T. J.
Published: December 2016

A membrane transfer procedure previously described was used to study the possible role of sublethally injured bacteria in the keeping quality of retail pasteurized milk. Trypticase soy broth (TSB) was used as nonselective medium and TSB plus NaCl at pH 6.0 (TSBS 6.0), as the selective medium inhibitory to injured organisms. In pasteurized milk at early stages of storage, colony counts on the latter medium were much lower than on the former. Subsequent transfer of the TSBS 6.0 filters to fresh TSB and further incubation usually increased the counts to about the initial TSB range. Generally the organisms presumed injured and subsequently recovered were the same types as those considered uninjured. They were mainly streptococci and micrococci that produced only slow changes in litmus milk at 5 C, so they are of doubtful significance in the shelf life of retail milk at refrigerator temperatures.
Role of Enterococci in Cheddar Cheese: Organoleptic Considerations1
Authors: JENSEN JANE P. , REINBOLD G. W. , WASHAM C. J. , VEDAMUTBU E. R.
Published: December 2016

Eight lots of Cheddar cheese were manufactured with two strains each of Streptococcus faecalis and Streptococcus durans and subjected to combinations of two early cooling treatments (air vs. brine cooling) and two curing temperatures (7.2 and 12.8 C). The enterococcus cultures were used as supplemental starters in combination with a commercial lactic culture. These cheeses were analyzed for microbiological growth and survival, proteolysis, lactic acid development, free fatty acid appearance, and citric acid utilization—each being compared with a control cheese made without enterococci. Results were presented in three previous articles. This series is concluded with the results of organoleptic ana1ysis of the cheeses. Cheeses made with S. faecalis were either comparable to or less desirable than their respective control cheeses. Those made with S. durans, however, were in all instances more desirable than their controls. Cheeses cured at 7.2 C were always given the better scores, but there was no statistically significant difference between air- and brine-cooled cheeses.
A Comparison of Cultural Methods used with Microcolony and Direct Fluorescent-Antibody Techniques to Detect Salmonellae
Authors: INSALATA N. F. , DUNLAP W. G. , MAHNKE C. W.
Published: December 2016

A comparison of various cultural methods for use with microcolony and direct fluorescent-antibody (FA) techniques to detect salmonella was conducted using 102 naturally contaminated samples. The methods were: (a) a 27-h microcolony technique, (b) a 51-h selenite-F FA microcolony technique, (c) a 51-h tetrathionate brilliant green FA microcolony technique, and (d) a 53-h FA technique from a broth enrichment. All were compared to an F.D.A. approved modification of the AOAC method. The 51-h FA microcolony technique, which employed tetrathionate brilliant green broth and brilliant green agar plates, produced 4.9% false-positives and no false-negatives, and produced the greatest frequency of salmonellae detection.
Growth of Salmonella heidelberg at Room Temperature in Irradiated and Nonirradiated Potato Chip Dip
Authors: WEKELL MARLEEN M. , MARTINSEN CHARLENE S.
Published: December 2016

Irradiated and nonirradiated cottage cheese-based potato chip dips were inoculated with low (101 cells/ml) and high numbers (106 cells/ml) of Salmonella heidelberg. At room temperature, both samples supported growth of Salmonella, but highest counts were found in the nonirradiated samples. Salmonella inoculated at low levels reached 106 cells/ml after 18 h but little change occurred with the high inoculum after 2.5 h. Growth of Salmonella was detected by both the conventional plate count and by a modified radiometric technique. Radiometric detection times were 2.5 and 18 h for samples inoculated with high and low numbers of Salmonella respectively, which corresponded to 106 cells/ml at the time of detection.
Flow Behavior of Concentrated Suspensions of Yeast Grown on Sauerkraut Waste1
Authors: RAO M. A. , HANG Y. D.
Published: December 2016

The flow behavior of suspensions of yeast (Candida utilis) grown on sauerkraut waste was studied as a function of concentration at 25.8 C. Suspensions containing 5.8, 21.7, 22.6, 23.6, 24.7 and 27.0% dry solids behaved as Newtonian fluids. The viscosity of these suspensions increased exponentially with the concentration of dry solids. A 29.2% suspension showed time dependent shear-thinning behavior. The non-Newtonian characteristics of the suspension could be described by both the Power law and the Casson flow models.
Rapid Enumeration of Psychrotrophic Bacteria in Raw Milk by the Microscopic Colony Count1
Authors: JUFFS H. S. , BABEL F. J.
Published: December 2016

Psychrotrophic bacteria were enumerated in raw milk by the microscopic colony count and counts were compared with those obtained by standard methods. Incubation conditions were 7 C for 10 days for the standard procedure and 7 C for 48 and 72 h or 21 C for 13.5 and 16.5 h for the microscopic colony count. Though each of the microscopic colony counts differed from the standard psychrotroph count (P < 0.01), there was a good general relationship in each instance (correlation coefficients ≥ 0.94). Wide variations in ratios of microscopic colony counts to standard psychrotroph counts made interpretations difficult. Generally, microscopic colony counts after 48 and 72 h at 7 C were less than standard psychrotroph counts. Incubation at 21 C yielded microscopic colony counts that were similar to standard psychrotroph counts for most samples; however, some microscopic colony counts at this temperature were substantially higher than the standard psychrotroph counts.
Effect of Thawing on Growth of Staphylococcus Aureus in Frozen Convenience Food Items1
Authors: OSTOVAR K. , BREMIER MARGARET J.
Published: December 2016

The appearance of convenience food items in the supermarkets and their consumption by wide segments of population has increased in recent years, and hence a study was done on presence of Staphylococcus aureus in these items and possible growth of the organism during defrosting of the foods. Using different selective agar media (Baird-Parker, Vogel-Johnson, Tellurite-polymyxin-egg yolk. and Mannitol-salt), various commercially available food items were examined. All suspected cultures were confirmed by coagulase test and Gram stain. Their enterotoxigenicity was also examined. Thawing the products at room temperature for 12 h generally resulted in a two-log increase in S. aureus population. Presence of S. aureus was observed in 18.3% of beef and poultry products; 12.5% of seafood products; and 8.3% of ready-to-eat frozen desserts. Most isolates produced types A or B enterotoxins. Of four selective agar media used. Baird-Parker was most efficient in isolating coagulase-positive staphylococci from frozen foods.
Fluorescent light-Activated Flavor in Milk1
Authors: HANSEN A. P. , TURNER L. G. , AURAND L. W.
Published: December 2016

Homogenized milk packaged in polyethylene containers exposed to fluorescent lights showed flavor and vitamin deterioration. Off-flavor development began within 2 to 4 h after exposure to a lighting system simulating commercial display cases. Detection of light-induced flavor was slight, medium, and strong after 4, 7 and 24 h of exposure. Decreases in riboflavin and ascorbic acid were directly proportional to the amount of light exposure. Various types of colored lamps and lamp filters were tested to prevent this off-flavor and vitamin degradation in milk. Yellow lamps or yellow and green filters protected milk from off-flavor development for 30 to 40 h. It is evident that light-induced off-flavors and vitamin destruction in fluid milk packaged in polyethylene containers can be reduced by colored lamps and lamp filters.
Growth of Microorganisms in Chilled Orange Juice
Authors: MURDOCK D. I. , HATCHER W. S.
Published: December 2016

Growth of lactic acid bacteria and yeasts in chilled orange juice was investigated. Three suspensions were prepared, each consisting of four strains of Lactobacillus, four of Leucomostoc, and four of yeast. Each composite suspension was inoculated into a series of bottles containing sterile prechilled orange juice to obtain a final concentration of 1,100, and 1,000 organisms/ml. Samples were stored at 35, 40, 45, and 50 F (1.7, 4.5, 7.2, and 10 C), and were plated periodically throughout the test period. Yeasts grew at all temperatures investigated, their rates of growth increasing with the temperature. Lactobacillus organisms grew at 50 F but not at 45 F or below, Leuconostoc strains did not grow at 35 F, but grew slowly at 40 F, and rapidly at 45 F and 50 F. Fermentation by yeasts, depending on the level of inoculation, occurred in 1 week or less at 50 F and in 1 to 2 weeks at 45 F. At 35 and 40 F it occurred in 3 weeks but was satisfactory at 35 F for the lowest level of inoculation. Spoilage from growth of Lactobacillus was detected between 1 and 2 weeks at 50 F. It did not occur at 45 F or below. Leuconostoc required 13 days to 5 weeks at 40, 45, and 50 F. Spoilage did not occur at 35 F. Shelf life of chilled orange juice is dependent upon the initial microbial population at time of packaging and temperature maintained until it reaches the consumer.
The Influence of Temperature on Growth, Sporulation, and Heat Resistance of Spores of Six Strains of Clostridium perfringens
Authors: REY C. R. , WALKER H. W. , ROHRBAUGH P. L.
Published: December 2016

The influence of temperature on growth, sporulation, and heat resistance of six strains of Clostridium perfringens was examined. The range of temperatures for growth and sporulation varied between strains and was influenced by the culture medium. Optimum growth occurred in Thioglycolate medium between 30 and 40 C for all strains. Optimum sporulation in Ellner's medium occurred in the 37 to 40 C range for all strains. The maximum number of spores produced varied with the strain. Heat resistance of the spores varied between strains but was not modified by temperature of incubation.
Botulism in Commercially Canned Foods
Authors: LYNT RICHARD K. , KAUTTER DONALD A. , READ R. B.
Published: December 2016

Occasionally, a problem thought to be well under control returns to plague us. This is the case with botulism in commercially canned foods. These foods have had a remarkably good record over the last 45 years with approximately 775 billion cans of commercially canned foods being consumed with only four known deaths through 1971. Beginning in 1971, however, botulinal toxin and/or Clostridium botulinum has been found in commercially canned vichyssoise, chicken vegetable soup, peppers, marinated mushrooms, tuna fish, beef stew, and in 41 cans of mushrooms from 20 lots packed by seven domestic and two foreign producers. The typical cause of botulism in canned foods is underprocessing which may result from inadequate equipment, improper operating procedures, and scheduled processes which are not appropriate for the actual operating conditions being used.
The Effect of Salting on the Microbiology of Poultry Meat
Authors: JUVEN B. J. , GERTSHOVKI R.
Published: December 2016

An investigation was carried out on the effect of salting on microbiology of chilled poultry meat, with particular emphasis on possible selective influence of salt on predominant spoilage organisms. A significant reduction in total aerobic counts at 4.5 and 20 C and Enterobacteriaceae counts on the skin surface of fresh broiler carcasses was achieved by salting; the mean log reductions per cm2 being 1.19, 1.32, and 1.35, respectively. The two major genera found on the carcasses at the time of spoilage at 4.5 C were Moraxella and Pseudomonas. The percentage of Moraxella Increased from 48 in untreated to 68% in salt-treated samples, while pigmented Pseudomonas decreased from 31 (untreated) to 12% (salt-treated) of the total isolates. The recovery of isolates of Pseudomonas and Moraxella, in mixed populations, from heart infusion broth containing NaCl concentrations from 0.09 (aw 0.990) to 5.22 M (aw 0.814) was studied in 4 h-periods at 4.5 and 20 C. After 1 h incubation, as NaCl concentration was increased, the numbers of Pseudomonas were increasingly reduced both at 4.5 and 20 C, whereas numbers of Moraxella remained almost unchanged. The reduction of Pseudomonas counts, even at low NaCl concentrations, persisted after 2 h and 4 h incubation. Some reduction in Moraxella counts became apparent only after 4 h. and in concentrations higher than about 4.0 M (ca. aw 0.85). It is concluded that the much higher salt tolerance of Moraxella as compared with that of Pseudomonas, accounts for the increase in the percentage of Moraxella in the bacterial population, as salt was added to the poultry meat.
Chemical and Microbial Changes in Dehulled Confectionery Sunflower Kernels during Storage Under Controlled Conditions
Authors: ROBERTSON J. A. , THOMAS J. K.
Published: December 2016

Samples of freshly dehulled, confectionery sunflower kernels were adjusted to moistures of 5.2, 10.5, and 14.7%, sealed in plastic bags and stored at 35, 75, and 95 F (1.7, 23.9, and 35 C) for 12 weeks. At 2-week intervals aliquots were removed for flavor, chemical, and microbiological analyses. Acid values of oil extracted from stored kernels increased with temperature, moisture content, and storage time. At acid values of 4 or higher, kernels had a sour flavor. In general, the peroxide value decreased with increased moisture at each temperature and storage period. The initial aerobic plate count of the sunflower kernels was log 6.83/g, the Enterobacteriaceae count was log 6.15/g, and the yeast and mold count was log 3.65/g. From countable plates randomly selected, about 80% of the Enterobacteriaceae were identified as Enterobacter agglomerans (Erwinia herbicola). At 35 F microbial counts generally changed little. At 75 F, however, counts decreased rapidly; and at 95 F, yeast and mold counts of 14.7% moisture kernels increased, Enterobacteriaceae counts decreased, and aerobic plate counts decreased except in high moisture samples. A microbiological survey of whole sunflower seed and dehulled kernels from three dehulling operations indicated that contamination of the dehulled kernels was primarily from sunflower hulls rather than from processing equipment.
Postmilking Teat Dipping in a Herd of Low Infection Incidence
Authors: SCHULTZE W. D. , DOWLEN H. H. , MOORE E. D. , ARAPIS S. C. , OWEN J. R.
Published: December 2016

A commercial teat dipping preparation formulated to have good detergence and emollience but no germicidal activity and a commercial iodophor teat dip of 1% available iodine were tested sequentially for efficacy in preventing new intramammary infection. Teats on one side of the udder of 150 Jersey cows were dipped in the test material after each milking; the opposite teats were undipped controls. Duration of the trials was 12 months for the detergent-emollient dip and 8 months for the iodophor dip. Intramammary infection was determined by bacteriological evaluation of monthly quarter foremilk samples. Neither dip was associated with reduction in new infection rate. Possibly because of its low level of total infection and of Staphylococcus aureus and its lack of Streptococcus agalactiae, this herd was unable to demonstrate prophylaxis against intramammary infection by postmilking teat dipping and was unsuitable for testing efficacy of the tested products.
Evaluation of Colony Growth of Bacteria and the Surface Environment of Beef1
Authors: MAXCY R. B.
Published: December 2016

Bacterial growth in or on solid and semi-solid foods primarily involves growth of micro-colonies, which are influenced by restrictive factors of little consequence in liquid foods. To evaluate bacterial growth on solid foods, methods were developed to study colony growth with emphasis on the early stages. Pure cultures of Escherichia coli, Lactobacillus bulgaricus. Pseudomonas fluorescens, and Staphylococcus aureus had distinctly different microscopic colony appearance. Growth expressed as numbers of cells per colony was exponential and linear when expressed as diameter. Mature colonies had a population density of approximately 1010 viable cells. Microcolonies of bacteria were particularly resistant to dispersion and required the presence of physical agents such as sea sand in the dispersion process. Colony growth on small test strips of beef was extremely susceptible to the relative humidity of the environment. Furthermore, availability of nutrients on the surface of beef apparently influenced growth. Pregrowth of P. fluorescens followed by destruction with gamma rays enhanced subsequent growth of L. bulgaricus. Bacterial growth at the micro-colony stage can present some unique considerations in evaluating the microenvironment of solid foods.
Coliform Analyses at 30 C1
Authors: HARTMAN PAUL A. , HARTMAN PHILIP S.
Published: December 2016

The literature directly pertinent to coliform analyses at 30 C was reviewed. Original data were presented on effects of time of incubation of violet red bile (VRB) agar plates at 30 C and the effects of autoclave-sterilization and storage of VRB agar. When boiled VRB agar was used, an incubation period of at least 24 h was required for dairy products; an incubation period of 48 h was required for water, frozen vegetables, and other materials that contained coliforms that were slow in growth initiation. Additional observations should be made after incubation of plates for another 24 h to discover if substantial increases in colony count occurred. If autoclave-sterilized VRB agar was used, the recommended incubation periods should be extended for an additional 12–24 h. The pH of prepared VRB agar should be 7.2. A pH of 6.9 or below was indicative of extensive flaws in the method of preparation and/or storage. although some deterioration occurred in the absence of marked pH changes.
Heat-sensitive Inhibitor(s) Produced in Poor Quality Raw Milk1
Authors: DUTHIE A. H. , WOELFEL C. G. , NILSON K. M. , ATHERTON H. V.
Published: December 2016

As bacterial numbers in raw milk increased to millions and pH decreased to 6.3 and lower, inhibitory substances were produced that gave positive tests by the Bacillus subtilis disc assay and Sarcina lutea cylinder plate method. These substances were inactivated by heat treatment. The inhibitor was not lactic acid. Results of our study emphasized that all laboratories that test raw milks for antibiotics must be certain to heat samples before reporting a positive test result for inhibitor. If a heat-sensitive inhibitor is found in raw milk, one should evaluate the quality control program.
Electronic Somatic Cell Count—Chemical Method, DMSCC, and WMT Tests for Raw Milk
Authors: THOMPSON D. R. , PACKARD V. S. , GINN R. E.
Published: December 2016

The Direct Miscroscopic Somatic Cell Count — field method (DMSCC), Wisconsin Mastitis Test (WMT), and Electronic Somatic Cell Count (ESCC) were studied to determine variability and relationship to each other. The coefficients of variation computed at a DMSCC count near one million were 15.6% (DMSCC), 6.3% (WMT), and 4.2% (ESCC). Linear regression equations were determined for predicting DMSCC results by WMT and ESCC. The approximate width of the 95% confidence intervals for ESCC predicting DMSCC were ± 275,000 and for WMT predicting DMSCC were ± 600,000. The prediction of square root and log transformations of DMSCC by WMT exhibited narrower confidence intervals for low somatic cell counts, but wider intervals for high counts (greater than 1,000,000).
Foodborne Disease Outbreaks Traced to Poultry, United States, 1966–1974
Authors: HORWITZ MARCUS A. , GANGAROSA EUGENE J.
Published: December 2016

To determine the epidemiologic characteristics of foodborne disease outbreaks traced to poultry, we reviewed records of all 352 such outbreaks reported to the Center for Disease Control 1966–1974; 217 (62%) outbreaks were traced to turkey, 129 (37%) to chicken, 5 (1%) to both turkey and chicken, and 1 (0.3%) to cornish hen. Outbreaks from poultry accounted for 12% of all foodborne disease outbreaks reported from 1966 through 1974, but the number and percentage has been decreasing since 1969; these outbreaks involved 30,606 cases of gastrointestinal illness (20% of all cases of foodborne disease) and 14 deaths. Food-service establishments were responsible for mishandling the food in 79% of outbreaks, homes in 19%, and food-processing establishments in 2%. In 85% of the outbreaks, the food-handling error was storage of food at improper holding temperatures. In outbreaks reported 1972–1974 in which an etiologic agent was indentified, Salmonella spp. were responsible for 44%, Clostridium perfringens for 26%, and Staphylococcus aureus for 26%. The number of reported outbreaks from turkey increased dramatically during the Thanksgiving-Christmas holiday season. The downward trend in the number and percentage of poultry outbreaks since 1969 may reflect public education efforts.
Coagulation of Milk with Immobilized Proteases: A Review
Authors: TAYLOR M. J. , RICHARDSON T. , OLSON N. F.
Published: December 2016

Enzymatic coagulation of milk by immobilized proteases, and their potential application to cheese manufacture, is reviewed. Particular emphasis is given to the immobilized protease catalyst and to the reactor design for coagulation of milk. Pepsin and chymotrypsin retained more activity and greater stability than the other immobilized proteolytic enzymes. Porous glass beads, several anion exchange resins, and the copolymer ethylene-maleic anhydride gave best results among the support materials that were evaluated. Covalent attachment of enzyme to support is preferable to adsorption techniques but may be too costly. Perhaps the best catalyst is one using a lengthy procedure for covalent immobilization of enzyme on glass beads but good results were also obtained with simpler adsorption techniques. Catalysts varied greatly in initial activity but all lost activity upon exposure to milk. Stirred tank, packed bed, and fluidized bed reactor designs were used. Continued research is required to make enzymic milk coagulation with immobilized proteases economically feasible.
Effects of Added Copper on Concentrations of Volatile Materials Produced in Milk
Authors: BASSETTE R.
Published: December 2016

Analyzing the steam distillate from milk enabled measurement of increases in concentrations of n-hexanal, n-pentanal, propanal, acetaldehyde in raw, laboratory-pasteurized, and plant-pasteurized-homogenized milk exposed to 0 and 5 ppm added copper. Greatest changes were in the copper-treated laboratory-pasteurized milk and the least in Vacu-Therm pasteurized-homogenized milk. The 2-thiobarbituric acid values (TBA) in the exposed milk, laboratory pasteurized, .090; raw, .078; plant pasteurized, .056, reflected changes in volatile materials. Acetaldehyde concentrations increased about the same in whole pasteurized-homogenized milk as in skimmilk exposed to 1 or 2 ppm copper. The other carbonyl compounds increased consistently in whole milk, but little or none in skimmilk. Increases in concentration of the carbonyl compounds (other than acetaldehyde, acetone, and butanone) produced in pasteurized-homgenized milk exposed to 4 ppm copper for 44 h were reduced by adding 150 mg of ascorbic acid per liter of milk. However, the concentrations were greater in ascorbic acid-copper-treated milk than in milk not treated with copper. Adding the steam distillate from copper-oxidized milk produced the typical copper-oxidized flavor in good-flavored milk.
Planning for Food Protection During the Bicentennial Celebration in the Nation's Capital
Authors: WALKER BAILUS , BECK ROBERT N.
Published: December 2016

The potential for foodborne disease outbreaks is increased during mass feeding activities and periods in which food services are overtaxed; this is a major concern of health agencies throughout the United States as they prepare for the Bicentennial celebration. As the District of Columbia government has had some experience in planning food protection services for intense activities generated by large influxes of people, it has developed a comprehensive food protection program in preparation for the Bicentennial activities. Included in the District government's plans is the implementation of a “self-inspection” program to be conducted by trained and certified food service workers in selected food service establishments throughout the city. While the District government cannot guarantee that no food borne diseases will occur during the Bicentennial celebration, the food protection program will maximize its efforts to ensure that consumers are protected against food-borne health hazards.
Production of Rubratoxin by Penicillium rubrum in a Soy Whey-Malt Extract Medium
Authors: EMEH C. O. , MARTH E. H.
Published: December 2016

Sterile soy whey (1.75% dissolved solids) was fortified with malt extract and inoculated with spore suspensions of Penicillium rubrum strains P-13, 1062, 2120, 2123, and 3290. Samples were incubated quiescently at 28 C from 1 to 28 days and as shake cultures for 3, 5, and 7 days. Rubratoxin was recovered from culture filtrates by alcohol-acetone extraction and resolved by thin-layer chromatography. Toxin was not produced in shake cultures. Rubratoxins A and B were produced in quiescent soy whey cultures of all P. rubrum strains except P. rubrum P-13 which produced only rubratoxin B. Toxin production increased as the concentration of malt extract increased from 0.5 to 10% (w/v). Rubratoxin formation also increased with an increase in incubation time from 3 to 17 days but the amount of toxin in cultures declined rapidly thereafter. Yields of rubratoxin A ranged from 0.83 to 31.53 mg/100 ml in cultures of P. rubrum 1062 and from 1.89 to 22.70, 0.53 to 25.13, and 2.07 to 31.20 mg/100 ml in P. rubrum 2120 2123, and 3290 cultures, respectively. Yields of rubratoxin B ranged from 0.77 to 105.30, 1.03 to 94.83, 2.13 to 91.57, 0.82 to 78.53, and 1.3 to 85.57 mg/100 ml in cultures of P. rubrum 13, 1062, 2120, 2123, and 3290, respectively. After maximum production, toxin content in cultures leveled off and then decreased. Amounts of toxin declined more rapidly than did mold growth (as measured by mycelial dry weight). Although malt extract stimulated fungal growth, toxin production was enhanced more than mold growth.
Microbiology and Hospital Feeding Systems1
Authors: KUNDSIN RUTH B. , BODMAN HOLLIS A.
Published: December 2016

Food service in a hospital involves the close collaboration of physicians, dietitians, and microbiologists. The hygienic environment recognized as essential for patient care areas is equally essential for food preparation areas. The food preparation for critically ill patients with individualized nutritional requirements involves not only house diets and their modifications, but food fed in highly specialized ways such as tube feeding via nasogastric tube and hyperalimentation parenterally infused. Opportunities exist for microbial contamination in these unique situations which require alert microbiologic intervention for patient protection.
Experience in Adaptation and Comparative Evaluation of the Coulter Counter and Direct Microscopic Somatic Cell Count (DMSCC) Method for Determining Somatic Cell Counts in Milk
Authors: MACAULAY D. M. , GINN R. E. , PACKARD V. S.
Published: December 2016

A Coulter Counter, Model ZBI, was introduced into a provincial government laboratory and adapted for use in counting somatic cells in milk. The procedure followed was a modification of the International Dairy Federation method, the main difference being in the formulation of the fixative and a slight change in diluent make-up. The procedure was further modified in operating details to enhance routine analytical work. During one year of use in the ongoing provincial laboratory program, 8130 milk samples were checked for somatic cells by the Coulter Counter. Of this number, 509 were selected at random and checked by the Direct Microscopic Somatic Cell Count (DMSCC) method. The correlation coefficient for these samples for the two methods was 0.973. The mean cell counts were 841.600 and 839,900 for the DMSCC and Coulter Counter methods, respectively. The regression formula for estimating DMSCC from Coulter Counter results was determined to be ŷ= 0.8023(x) + 163.45.
Rapid Enumeration of Psychrotrophic Bacteria in Raw and Pasteurized Milk
Authors: OLIVERIA J. S. , PARMELEE C. E.
Published: December 2016

A plating method was developed to enumerate psychrotrophic bacteria in raw and pasteurized milk. Standard Methods agar plates were prepared according to Standard Methods for the Examination of Dairy Products, and incubated at 21 C for 25 h (21 C-25 h). Counts obtained by this method were in very good agreement with those obtained by the standard psychrotrophic count. The correlation coefficients between counts obtained by the 21 C-25 h method and by the standard psychrotrophic count method for 132 samples of raw milk and 190 samples of pasteurized milk were 0.992 and 0.996, respectively.
Flavor Acceptability of Unfermented and Lactic-Fermented Soy Milks
Authors: MITAL B. K. , STEINKRAUS KEITH H.
Published: December 2016

Soy milks prepared from whole Harosoy soybeans by a hot grind process and milks prepared from soybean flour defatted by a Cornell University patented process were evaluated for flavor acceptability by a 27 member taste panel at the New York State Agricultural Experiment Station using fresh homogenized cow's milk as standard. Hot grind soy milk was rated significantly different and distinctly inferior to cow's milk in flavor. Soy milk prepared from defatted flour (U.S. Patent No. 3,721,569) by aqueous extraction and addition of 2.5% refined soy oil and 2% sucrose was rated slightly inferior to fresh cow's milk in flavor. Soy milk from the defatted flour was also lactic fermented to prepare a yogurt-like product whose flavor acceptability was compared with fermented cow's milk. The fermented soy milks had a satisfactory gelatinous curd and an acceptable flavor; however, the taste panel preferred the higher acidity of the fermented cow's milk.
Effect of Copper on Ascorbic Acid Content, Redox Potential and Development of Oxidized Flavor in Milk of Cows and Buffaloes
Authors: UNNIKRISHNAN V. , RAO D. SETHU , RAO M. BHIMASENA
Published: December 2016

The effect of copper on ascorbic acid content, redox potential (Eh) of milk, and development of oxidized flavor is discussed. Oxidized flavor appeared in cow milk only after a marked rise in Eh due to the oxidation of ascorbic acid, whereas in buffalo milk oxidized flavor developed without any appreciable change in Eh. In buffalo milk, copper at low concentrations failed to cause sufficient oxidation of ascorbic acid to effect an increase in Eh. The Eh of cow milk began to rise appreciably when more than half of the ascorbic acid normally present in milk was oxidized. The pro-oxidant action of ascorbic acid in cow milk at concentrations normal to milk is not merely due to conversion of copper to cuprous form; it is suggested that the activation energy involved in this conversion is an important factor in the lipid oxidation which follows. Ascorbic acid did not promote copper-catalyzed oxidation of buffalo milk as it is not involved in the reversible oxidation.
Proposed Microbiological Standards for Ground Beef Based on a Canadian Survey
Authors: PIVNICK H. , ERDMAN I. E. , COLLINS-THOMPSON D. , ROBERTS G. , JOHNSTON M. A. , CONLEY D. R. , LACHAPELLE G. , PURVIS U. T. , FOSTER R. , MILLING M.
Published: December 2016

Microbiological standards are proposed for ground beef sold in Canada. The proposal is based on a national survey conducted in 1974–75. The proposed standards are: aerobic colony count (35 C), ⩽ 107 for non-frozen and ⩽106 for frozen products; Escherichia coli, ⩽102; Staphylococcus aureus, ⩽102 per g; and Salmonella, absent in 25-g portions from each of five subsamples. To accomodate the variable distribution of bacteria between packages in a single lot of product, three-class plan based on a format suggested by the International Commission on Microbiological Specifications for Foods is used.
Effect of Oxidation-Reduction Potential upon Growth and Sporulation of Clostridium perfringens1
Authors: PEARSON CHRISTINE B. , WALKER HOMER W.
Published: December 2016

Three strains of Clostridium perfringens were examined for the influence of oxidation-reduction potential on growth and sporulation. The limiting Eh7 for growth was + 350 mv; the cultures slowly died at this Eh. Sporulation occurred at numbers typical for the individual strains as long as growth occurred.
Thermal Stability of Enterotoxins in Food
Authors: TATINI S. R.
Published: December 2016

Biological and serological properties of staphylococcal enterotoxins exhibit remarkable thermal stability. The slope of the thermal destruction curve (z value) for enterotoxin A or D is 27–28 C and it is 32 C for enterotoxin B regardless of the initial concentration of enterotoxin, the heating medium, or the assay system used to detect the enterotoxin. Thermal stability of enterotoxins is influenced by the nature of the food, pH, presence of NaCl, etc., and the type of enterotoxin; enterotoxin A is relatively more stable to heat at pH 6.0 (or higher) than at pH 4.5–5.5. Enterotoxin D is relatively more stable at pH 4.5–5.5 than at pH 6.0 or greater. Heat treatments commonly used in food processing, that is pasteurization (72 C for 15 sec) or ultrahigh temperature heating (290 F for 9 sec) in a “Spiratherm” Unit of Fluid whole milk, or smoking and heating of cured sausage to 70–100 C, or heating of Cheddar cheese to 70–90 C, are not effective for complete destruction (to levels below detection by the microslide serological assay) of enterotoxin A or D when present initially at levels normally expected to be found in foods (0.5–1.0 μg per 100 ml or g). Enterotoxin A or B (30 μg/ml) heated at 100 C for 25 min in saline, containing 2% gelatin and 0.3% proteose peptone and at pH 7.0, retained biological activity toward humans with a suggestion of increased biological activity after heat treatment, especially with enterotoxin A. The length of time required at a given temperature for complete destruction of enterotoxin in a given food system depends upon the sensitivity of the detection system used and the amount of food sample used for recovery of the enterotoxin. Treatment of heated enterotoxin A or D with urea and its removal by dialysis before serological assay, increased the recovery of enterotoxin by almost 4-fold as compared to controls which were simply heated and were not treated with urea. Enterotoxin A or D present initially at 1 μg/ml in whole milk (using 2 ml for recovery of enterotoxin with urea treatment following heating and assay by the micro slide method of Casman and Bennett) was found to withstand heating of milk at 121.1 C for 15 min. In the absence of urea treatment of heated toxins in milk, both toxins were found to be inactivated (to less than 0.02 μg/ml (within 15 min at 121.1 C; between 13.8–14.8 min for toxin A and 12.8–13.8 min for toxin D.
Plate Loop Method for Determining Total Viable Count of Orange Juice
Authors: MURDOCK D. I. , HATCHER W. S.
Published: December 2016

The plate loop count as described in Standard Methods for the Examination of Dairy Products. 13th Edition, was evaluated as a simplified technique for determining total viable counts in single strength orange juice. This procedure requires use of standardized loops (0.01 and 0.001 ml) for making serial dilutions instead of pipets and dilution bottles. Data show there is a statistically significant difference in results between the plate count and plate loop count procedures for determining total viable population of orange juice. However, since the difference is so small for normal operating conditions, the plate loop method is a reliable alternate to routine plating procedure. It can also be done without flaming the loop between samples. The plate loop count saves time and equipment, but requires analysts to be specially trained to maintain this degree of accuracy.
Use of the Microslide Technique to Measure Staphylococcal Enterotoxin B
Authors: FUNG DANIEL Y. C. , REICHERT CHARLOTTE A. , MEDWID RICHARD D.
Published: December 2016

A procedure to quantify staphylococcal enterotoxin B by use of the microslide technique was developed. This method consists of matching toxin activity against a series of standard curves obtained with microslides. The procedure was found to be useful in quantifying unheated as well as heated and reactivated staphylococcal enterotoxin B.
Sporicidal Properties of Chlorine Compounds: Applicability to Cooling Water for Canned Foods1,2
Authors: ODLAUG THERON E. , PFLUG IRVING J.
Published: December 2016

Sporicidal effects of chlorine compounds as measured by many authors are reviewed. Since spore destruction rates and hypochlorous acid concentration appear to be related, the data from the several reports were recalculated in terms of time required for a 90% reduction in spores as a function of hypochlorous acid concentration. From these data a single graph was prepared. Results of the analysis indicate that Bacillus spores are more resistant to chlorine than Clostridium spores. The sporicidal effect of chlorine solutions increases with (a) an increase in free available chlorine, (b) a decrease in pH, and (c) an increase in temperature. Numbers of Clostridium botulinum and other spore-forming organisms in canning plant cooling water will depend on water quality factors such as the quantity of soil and organic matter, pH, temperature, and chlorine level. Control of these variables to desired levels in cooling water will reduce the probability of post-process infection of low-acid canned foods.
60-Day Aging Requirement Does Not Ensure Safety of Surface-Mold-Ripened Soft Cheeses Manufactured from Raw or Pasteurized Milk When Listeria monocytogenes Is Introduced as a Postprocessing Contaminant
Authors: D'AMICO DENNIS J. , DRUART MARC J. , DONNELLY CATHERINE W.
Published: December 2016

Because of renewed interest in specialty cheeses, artisan and farmstead producers are manufacturing surface-mold-ripened soft cheeses from raw milk, using the 60-day holding standard (21 CFR 133.182) to achieve safety. This study compared the growth potential of Listeria monocytogenes on cheeses manufactured from raw or pasteurized milk and held for >60 days at 4°C. Final cheeses were within federal standards of identity for soft ripened cheese, with low moisture targets to facilitate the holding period. Wheels were surface inoculated with a five-strain cocktail of L. monocytogenes at approximately 0.2 CFU/cm2 (low level) or 2 CFU/cm2 (high level), ripened, wrapped, and held at 4°C. Listeria populations began to increase by day 28 for all treatments after initial population declines. From the low initial inoculation level, populations in raw and pasteurized milk cheese reached maximums of 2.96 ± 2.79 and 2.33 ± 2.10 log CFU/g, respectively, after 60 days of holding. Similar growth was observed in cheese inoculated at high levels, where populations reached 4.55 ± 4.33 and 5.29 ± 5.11 log CFU/g for raw and pasteurized milk cheeses, respectively. No significant differences (P < 0.05) were observed in pH development, growth rate, or population levels between cheeses made from the different milk types. Independent of the milk type, cheeses held for 60 days supported growth from very low initial levels of L. monocytogenes introduced as a postprocess contaminant. The safety of cheeses of this type must be achieved through control strategies other than aging, and thus revision of current federal regulations is warranted.
Aqueous Matrix Compositions and pH Influence Feline Calicivirus Inactivation by High Pressure Processing†
Authors: KINGSLEY DAVID H. , CHEN HAIQIANG
Published: December 2016

The individual effects of pH (pH 3 to 8), NaCl (0 to 21%), sucrose (0 to 70%), and whey protein (0 to 2%) on pressure resistance of feline calicivirus (FCV) in Dulbecco's modified Eagle medium with 10% fetal bovine serum were determined. At pH 3 through 8, the virus was more resistant to pressure at a pH of ≤5.2. For FCV samples with sucrose (up to 40%) or NaCl (up to 12%), the amount of FCV inactivated by pressure was inversely proportional to the sucrose or NaCl concentration. For example, a treatment of 250 MPa at 20°C for 5 min reduced the FCV titer by 5.1 log PFU/ml without added sucrose and by 0.9 log PFU/ml with 40% sucrose. Reduced pressure sensitivity with increasing NaCl and sucrose concentrations was not a simple function of water activity. Different PFU reductions were observed for NaCl and sucrose samples with equivalent water activity. Whey protein at concentrations up to 2% did not provide a protective effect. The combined effect of NaCl and sucrose at 4 and 20°C on pressure resistance of FCV also was examined. When both NaCl and sucrose were added to the FCV stock, they had an additive effect on increasing the pressure resistance of FCV. The individual (6% NaCl or 20% sucrose) and combined (6% NaCl plus 20% sucrose) resistance effects did not abrogate enhanced inactivation for pressure treatments at 4°C compared with those at 20°C. Aqueous matrix compositions, in particular different concentrations of NaCl and sucrose or different pH values, can substantially alter the efficiency of virus inactivation by high pressure processing.
Carvacrol and Cinnamaldehyde Facilitate Thermal Destruction of Escherichia coli O157:H7 in Raw Ground Beef†
Authors: JUNEJA VIJAY K. , FRIEDMAN MENDEL
Published: December 2016

The heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of the antimicrobials carvacrol and cinnamaldehyde was tested at temperatures ranging from 55 to 62.5°C. Inoculated meat packaged in bags was completely immersed in a circulating water bath, cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5°C, and then held for predetermined lengths of time ranging from 210 min at 55°C to 5 min at 62.5°C. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time for the bacteria to decrease by 90%) in the control beef ranged from 63.90 min at 55°C to 1.79 min at 62.5°C. D-values determined by a logistic model ranged from 43.18 min (D1, the D-value of a major population of surviving cells) and 89.84 min (D2, the D-value of a minor subpopulation) at 55°C to 1.77 (D1) and 0.78 min (D2) at 62.5°C. The thermal death times suggested that to achieve a 4-D reduction, contaminated processed ground beef should be heated to an internal temperature of 60°C for at least 30.32 min. Significantly increased sensitivity to heat (P < 0.05) was observed with the addition and/or increasing levels of carvacrol or cinnamaldehyde from 0.5 to 1.0%. The observed thermal death times may facilitate the design of acceptance limits at critical control points for ground beef at lower times and temperatures of heating.
Standardized Inspections of Food Premises during the 2004 Athens Olympic Games: Descriptive Analysis and Risk Factors for Unsatisfactory Results
Authors: HADJICHRISTODOULOU CHRISTOS , MOUCHTOURI VARVARA , VARZAKAS THEODOROS , ARVANITOYANNIS IOANNIS , KREMASTINOU JENNY
Published: December 2016

Standardized inspections of food premises are part of environmental health systems implemented worldwide. The food safety strategy for the 2004 Olympic Games included standardized inspections to ensure uniformity and consistency of procedures and effective electronic management of data. Inspections were carried out by 196 inspectors in the five Olympic cities: Athens, Thessalonica, Volos, Iraklio, and Patra. From January 2003 to September 2004, a total of 1,249 food premises were inspected. An unsatisfactory inspection result (C grade) was received by 347 (27.8%) food premises, a relatively satisfactory result (B grade) was received by 332 (26.6%), and a satisfactory result (A grade) was received by 570 (45.6%). About 16% of inspected premises did not hold a valid permit. Unsatisfactory inspection results were more frequent for premises located in the two largest Greek cities in comparison with the other smaller cities (relative risk = 1.95, 95% confidence interval [CI] = 1.36 to 2.80). Based on logistic regression analysis, unsatisfactory inspection results were positively associated with food premises that were not located on a ground floor (odds ratio [OR] = 2.56, 95% CI = 1.39 to 4.73) and negatively associated with application of hazard analysis critical control point (HACCP) principles (OR = 0.27, 95% CI = 0.10 to 0.71). Food hygiene education through formal training programs should be encouraged to improve compliance of food premises. Food premises located on hotel floors and serving buffet meals are at higher risk for unsatisfactory conditions. Businesses that implemented a HACCP system within their operations to ensure food safety operated under more hygienic conditions. Future inspections by Public Health Authorities should involve elements of audit after the legislation for the application of HACCP principles.