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Department of Food Science and Technology: Faculty Publications

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Articles 511 - 536 of 536

Full-Text Articles in Food Science

Galactose Transport In Streptococcus Thermophilus, Robert W. Hutkins, Howard A. Morris, Larry L. Mckay Oct 1985

Galactose Transport In Streptococcus Thermophilus, Robert W. Hutkins, Howard A. Morris, Larry L. Mckay

Department of Food Science and Technology: Faculty Publications

Although Streptococcus thermophilus accumulated [14C]lactose in the absence of an endogenous energy source, galactose-fermenting (Gal+) cells were unable to accumulate [14C]galactose unless an additional energy source was added to the test system. Both Gal+ and galactose-nonfermenting (Gal-) strains transported galactose when preincubated with sucrose. Accumulation was inhibited 50 or 95% when 10 niM sodium fluoride or 1.0 mM iodoacetic acid, respectively, was added to sucrose-treated cells, indicating that ATP was required for galactose transport activity. Proton-conducting ionophores also inhibited galactose uptake, although N,N'-dicyclohexyl carbodiimide had no effect. The results suggest …

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Soybean Oil Is Not Allergenic To Soybean-Sensitive Individuals, Robert K. Bush, Steve L. Taylor, Julie A. Nordlee, William W. Busse Aug 1985

Soybean Oil Is Not Allergenic To Soybean-Sensitive Individuals, Robert K. Bush, Steve L. Taylor, Julie A. Nordlee, William W. Busse

Department of Food Science and Technology: Faculty Publications

We have previously demonstrated that peanut oil is not allergenic to peanut-sensitive individuals. Seven soybean-sensitive patients were enrolled in a double-blind crossover study to determine whether ingestion of soybean oil can induce adverse reactions in such patients. All subjects had histories of systemic allergic reactions (urticaria, angioedema, wheezing, dyspnea, and/or vomiting) after soybean ingestion and had positive puncture skin tests with a 1:20 w/v glycerinated-saline whole soybean extract. Sera from six of the seven subjects were tested by RAST assay for the presence of specific IgE antibodies to soybean allergens. All patients had elevated levels of serum IgE antibodies to …

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Potential For Development Of Tolerance By Penicillium Digitatum And Penicillium Italicum After Repeated Exposure To Potassium Sorbate, Lisa L. Schroeder, Lloyd B. Bullerman Jan 1985

Potential For Development Of Tolerance By Penicillium Digitatum And Penicillium Italicum After Repeated Exposure To Potassium Sorbate, Lisa L. Schroeder, Lloyd B. Bullerman

Department of Food Science and Technology: Faculty Publications

Two strains of Penicillium digitatum and one strain of Penicillium italicum were exposed to various levels of sorbic acid and potassium sorbate, and the MICs were determined. Selected strains of the molds were then repeatedly exposed to subinhibitory levels of the compounds to determine whether increased tolerance might develop. The MIC of sorbic acid (pH 4.75) to P. digitatum was between 0.02 and 0.025%. The MIC of sorbate (pH 5.5) to two strains of P. digitatum and P. italicum was found to be between 0.06 and 0.08%. Increasing levels of sorbate resulted in increasing growth suppression of the molds. Populations …

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Sulfite Residues In Maraschino Cherries, Julie A. Nordlee, Laura B. Martin, Steve L. Taylor Jan 1985

Sulfite Residues In Maraschino Cherries, Julie A. Nordlee, Laura B. Martin, Steve L. Taylor

Department of Food Science and Technology: Faculty Publications

A survey of 53 samples of maraschino cherries from 14 different processors revealed that total sulfite residues averaged 52.3 ± 44.7 ppm. However, 58.5% of the samples had less than 40 ppm total SO2, while only 7.6% had greater than 120 ppm total SO2 indicating that the distribution was skewed in the direction of lower residue levels. Free sulfite residues in the 53 samples were considerably lower, averaging 14.2 ± 7.1 ppm. With free SO2 levels, 35.8% of the samples had less than 10 ppm free SO2, while only 5.7% had greater than 30 …

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Effect Of Physiological Age On Radiation Resistance Of Some Bacteria That Are Highly Radiation Resistant, Lewis Keller, R. Burt Maxcy May 1984

Effect Of Physiological Age On Radiation Resistance Of Some Bacteria That Are Highly Radiation Resistant, Lewis Keller, R. Burt Maxcy

Department of Food Science and Technology: Faculty Publications

Physiological age-dependent variation in radiation resistance was studied for three bacteria that are highly radiation resistant: Micrococcus radiodurans, Micrococcus sp. isolate C-3, and Moraxella sp. isolate 4. Stationary-phase cultures of M. radiodurans and isolate C-3 were much more resistant to gamma radiation than were log-phase cultures. This pattern of relative resistance was reversed for isolate 4. Resistance of isolate 4 to UV light was also greater during log phase, although heat resistance and NaCl tolerance after heat stress were greater during stationary phase. Radiation-induced injury of isolate 4 compared with injury of Escherichia coli B suggested that the injury process, …

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Paper Replication Method For Isolation Of Radiation-Sensitive Mutants, S. T. Tan, R. B. Maxcy, T. L. Thompson Jul 1983

Paper Replication Method For Isolation Of Radiation-Sensitive Mutants, S. T. Tan, R. B. Maxcy, T. L. Thompson

Department of Food Science and Technology: Faculty Publications

A filter paper replication system particularly useful for isolation of radiation-sensitive mutants of pigmented bacteria was devised. The fidelity of replication was high. Adhesion between a paper disk and a properly dried master plate provided adequate contact pressure. The replicas arising from this technique constitute a convenient apparatus for general application in isolation of clones sensitive to a discriminating treatment.

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Significance Of Residual Organisms In Foods After Substerilizing Doses Of Gamma Radiation: A Review, R. B. Maxcy Jan 1983

Significance Of Residual Organisms In Foods After Substerilizing Doses Of Gamma Radiation: A Review, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

The nature of the flora surviving substerilizing irradiation of foods is dependent on the dose applied and the conditions of applications as well as the microenvi¬ronment of the food. At a dose level low enough to preserve acceptable sensory properties of fresh food, few if any of the common contaminants of public health significance survive irradiation. Survivors are weakened and present no unique problem of acquired resistance through recycling. Those bacteria surviving a low dose treatment of a relatively contaminated product like ground beef can grow under normal storage conditions and cause obvious sensory spoilage. Thus, low dose irradiation extends …

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Uv Light-Induced Survival Response In A Highly Radiation-Resistant Isolate Of The Moraxella-Acinetobacter Group, Lewis Keller, Thomas Thompson, R. Burt Maxcy Feb 1982

Uv Light-Induced Survival Response In A Highly Radiation-Resistant Isolate Of The Moraxella-Acinetobacter Group, Lewis Keller, Thomas Thompson, R. Burt Maxcy

Department of Food Science and Technology: Faculty Publications

A highly radiation-resistant member of the Moraxella-Acinetobacter group, isolate 4, obtained from meat, was studied to determine the effect of preexposure to UV radiation on subsequent UV light resistance. Cultures that were preexposed to UV light and incubated for a short time in plate count broth exhibited increased survival of a UV light challenge dose. This response was inhibited in the presence of chloramphenicol. Frequencies of mutation to streptomycin, trimethoprim, and sulfanilamide resistance remained the same after the induction of this survival response and were not altered by treatment with mutagens, with the exception of mutation to streptomycin resistance after …

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Allergenicity Of Various Peanut Products As Determined By Rast Inhibition, Julie A. Nordlee, Steve L. Taylor, R. T. Jones, John W. Yunginger Jan 1981

Allergenicity Of Various Peanut Products As Determined By Rast Inhibition, Julie A. Nordlee, Steve L. Taylor, R. T. Jones, John W. Yunginger

Department of Food Science and Technology: Faculty Publications

Extracts of 19 different peanut products and peanut oil were tested for their allergenicity by the radioallergosorbent test inhibition assay using a crude peanut extract from raw peanuts as the standard for comparison. Seventeen of the extracts were able to competitively inhibit the binding of serum IgE from peanut-sensitive patients with the solid-phase raw peanut extract. Peanut oil and the extract from hydrolyzed peanut protein did not inhibit binding, which suggests that these products are not allergenic. The peanut hull flour extract showed a slight ability to inhibit binding, suggesting that this product contains minor amounts of the peanut allergen.

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Significance Of Hemolytic Activity Of Some Radiation- Resistant Micrococci In Food, Ardyce Welch, R. Burt Maxcy Nov 1979

Significance Of Hemolytic Activity Of Some Radiation- Resistant Micrococci In Food, Ardyce Welch, R. Burt Maxcy

Department of Food Science and Technology: Faculty Publications

Micrococci resistant to 1 Mrad ofgamma radiation were isolated from irradiated chicken. Three isolates were hemolytic on blood agar plates and were selected for further study.Two other radiation-resistant micrococci, Micrococcus radiodurans and Micrococcus radiophilus, were included in the study because there is only a very limited amount of information regarding hemolytic activity of these organisms and their potential role of public health importance. Tests to determine hemolytic patterns, hemolytic activity of extracellular substances, leukocytic activity, presence of enzymes commonly associated with pathogenicity (coagulase, deoxyribonuclease, phosphatase), and pathogenicity for laboratory animals all suggested that the organisms would not be of …

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Isolation Of Radiation-Resistant Bacteria Without Exposure To Irradiation, Scott Sanders, R. Burt Maxcy Sep 1979

Isolation Of Radiation-Resistant Bacteria Without Exposure To Irradiation, Scott Sanders, R. Burt Maxcy

Department of Food Science and Technology: Faculty Publications

Resistance to desiccation was utilized in the selection of highly radiation-resistant asporogenous bacteria from non-irradiated sources. A bacterial suspension in phosphate buffer was dried in a thin film at 25°C and 33% relative humidity. Storage under these conditions for 15 days or more reduced the number of radiation-sensitive bacteria. Further selection for radiation-resistant bacteria was obtained by irradiation of bacteria on velveteen in the replication process, thereby avoiding the toxic effect of irradiated media. The similarity of radiation resistance and identifying characteristics in irradiated and non-irradiated isolates should allay some concerns that highly radiation-resistant bacteria have been permanently altered by …

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Patterns Of Cell Division, Dna Base Compositions, And Fine Structures Of Some Radiation-Resistant Vegetative Bacteria Found In Food, S. W. Sanders, R. Burt Maxcy Jan 1979

Patterns Of Cell Division, Dna Base Compositions, And Fine Structures Of Some Radiation-Resistant Vegetative Bacteria Found In Food, S. W. Sanders, R. Burt Maxcy

Department of Food Science and Technology: Faculty Publications

Representative highly radiation-resistant Moraxella-Acinetobacter (M-A), Pseudomonas radiora, Micrococcus radiodurans, and Micrococcus radiophilus exhibited a wide variety of division systems and cell wall characteristics. However, the most resistant M-A possessed unusually thick cell walls, indicating a possible role of the cell wall in radiation resistance in the M-A. Thick septation was present in most of the bacteria studied, but was absent in P. radiora, thus excluding this as a necessity for high resistance. Reliable determination of the number of division planes of the M-A for use as a taxonomic criterion was achieved by the direct observation of dividing cells. …

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Quantitation Of Proteinaceous Soil Removal From Clean-In-Place Systems, L. M. Rasmussen, R. B. Maxcy Jan 1979

Quantitation Of Proteinaceous Soil Removal From Clean-In-Place Systems, L. M. Rasmussen, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

The protein of milk residue can be quantitated to evaluate a cleaning process by monitoring the accumulation of protein in a test-wash solution. The test for protein is based on precipitation of hard water cations with orthophosphate and flocculation with a coagulant for rapid sedimentation of the protein. The sediment is collected on filter paper and stained with xylene brilliant cyanin G. Color reaction on the filter paper is proportional to protein content of the original test solution and is estimated visually. For more precise quantitation, the stain is released into a solution for optical measurements. The lower limit of …

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Characterization Of Radiation-Resistant Vegetative Bacteria In Beef, Ardyce Welch, R. B. Maxcy Jan 1975

Characterization Of Radiation-Resistant Vegetative Bacteria In Beef, Ardyce Welch, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

Ground beef contains numerous microorganisms of various types. The commonly recognized bacteria are associated with current problems of spoilage. Irradiation, however, contributes a new factor through selective destruction of the microflora. The residual microorganisms surviving a nonsterilizing dose are predominantly gram-negative coccobacilli. Various classifications have been given, e.g., Moraxella, Acinetobacter, Achromobacter, etc. For a more detailed study of these radiation-resistant bacteria occurring in ground beef, an enrichment procedure was used for isolation. By means of morphological and biochemical tests, most of the isolates were found to be Moraxella, based on current classifications. The range of growth temperatures was …

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Reuse Limits And Regeneration Of Solutions For Cleaning Dairy Equipment, S. M. Kulkarni, R. G. Arnold, R. B. Maxcy Jan 1975

Reuse Limits And Regeneration Of Solutions For Cleaning Dairy Equipment, S. M. Kulkarni, R. G. Arnold, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

Usable life of cleaning solutions in a model heat processing unit was studied by evaluation of the nature and quantity of residue remaining on the surface of the equipment after cleaning. Lipoidal residue was recovered from equipment surfaces by ether rinsing. A surface displacement technique was used to quantify the lipoidal material, which was characterized by gas-liquid chromatographic analyses of triglycerides and fatty acid methyl esters. Effects of factors, such as water hardness, rinse water temperature, cleaning solution additives and acid versus alkaline cleaners also were investigated in relation to overall cleaning efficiency. After evaluating limits of reuse of cleaning …

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Evaluation Of Soil Deposition And Removal Processes: An Interpretive Review, S. M. Kulkarni, R. B. Maxcy, R. G. Arnold Jan 1974

Evaluation Of Soil Deposition And Removal Processes: An Interpretive Review, S. M. Kulkarni, R. B. Maxcy, R. G. Arnold

Department of Food Science and Technology: Faculty Publications

In each food processing plant, soil deposition and removal constitute unique processes influenced by the food, water supply, processing equipment, and cleaning regimen. Since there are so many complex as well as unique processes, the scientific literature represents many varied approaches to problems related to deposition and removal of soil. This paper considers the role of various constituents in soil residue. Likewise, the various factors contributing to the cleaning process are reviewed. Cleaning processes have changed considerably during recent years because of technological advances in food processing equipment as well as development of specialized cleaning equipment. Generally speaking, better sanitation …

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Nature And Cause Of Yellow Film Occurring On Dairy Equipment, R. B. Maxcy Jan 1973

Nature And Cause Of Yellow Film Occurring On Dairy Equipment, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

A yellow film of milkstone developed on a laboratory system that simulated unclean stainless steel surfaces. Cursory washing or presoiling with phospholipids and subsequent growth of Pseudomonas sp. in a milk film produced the yellow color in 1 to 2 days. Sequence of treatments, microenvironmental conditions, and microbial growth contributing to the formation of the yellow film were determined, Pseudomonas sp. was isolated from laboratory developed yellow films and from milk soil deposits on farm equipment. The overall requirements for the production of yellow films were: a) inadequate cleaning or a presoil of phospholipids, b) growth of Pseudomonas sp., c) …

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Changes In Escherichia Coli Associated With Acquired Tolerance For Quaternary Ammonium Compounds, R. B. Maxcy, N. P. Tiwari, P. R. Soprey Jan 1971

Changes In Escherichia Coli Associated With Acquired Tolerance For Quaternary Ammonium Compounds, R. B. Maxcy, N. P. Tiwari, P. R. Soprey

Department of Food Science and Technology: Faculty Publications

Acquired tolerance for a quaternary ammonium compound produced a tolerance for a similar compound. Tolerance was associated with the structure and the extent of adsorption of the compound. Morphological changes and resistance to disruption by pressure and by sonic treatment accompanied the development of tolerance. An otherwise weakened culture evolved with the acquisition of tolerance. The maximum obtainable viable population density of tolerant cells in growth medium was approximately 5 %, of that obtained in the parent culture. Tolerant cultures died off more rapidly in the original growth medium as well as when washed cell suspensions were stored at 5 …

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Study Of Control Of Public Health Problems Using Irradiation, R. B. Maxcy, N . P. Tiwari, C. C. Anagnostis Jan 1971

Study Of Control Of Public Health Problems Using Irradiation, R. B. Maxcy, N . P. Tiwari, C. C. Anagnostis

Department of Food Science and Technology: Faculty Publications

Red meat, as exemplified by ground beef and pork, is subject to numerous opportunities for contamination and harborage of pathogenic organisms with the present commercial system of processing and distribution. An exploration was undertaken therefore to determine the usefulness of gamma irradiation for public health protection when applied to red meat. This work indicated that retail products are commonly heavily contaminated. The contamination can be reduced somewhat through central processing as shown by the data obtained from ground beef. Considerable numbers of the contaminants can be destroyed by irradiation at a 68 Krad level.
This work indicates that commercial ground …

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Evaluating Circulation Cleaning By Analysis Of Soil Depletion From Surfaces, R. G. Arnold, R.B. Maxcy Jan 1970

Evaluating Circulation Cleaning By Analysis Of Soil Depletion From Surfaces, R. G. Arnold, R.B. Maxcy

Department of Food Science and Technology: Faculty Publications

The rate of soil removal and its nature were studied with a small commercial high-temperature short-time pasteurizer. The commercial recirculation system was altered to provide a single pass of cleaning solution through the equipment to observe progress of cleaning. A composite of the first 38 liters was taken after 1.5 minutes. Subsequent samples were taken after 3, 6, 22 and 21 to 22 minutes. Cleaning solutions were analyzed by centrifugal fractionation, solvent extraction, gas liquid chromatography, thin layer chromatography and infrared spectroscopy to determine the composition of residue and rate of its depletion.
Results showed both the nature of the …

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Adsorption Of Free Fatty Acids On Cells Of Certain Microorganisms, R. B. Maxcy, C. W. Dill Jan 1967

Adsorption Of Free Fatty Acids On Cells Of Certain Microorganisms, R. B. Maxcy, C. W. Dill

Department of Food Science and Technology: Faculty Publications

Information on the inhibitory effect of free fatty acids was sought by growing lactic streptococci in the presence of labeled fatty acids and collecting the cells on membrane filters. The distribution of the radioactivity indicated adsorption by the bacteria. As the number of cells in the growth medium increased, accumulation of radioactivity with the cells on the filter increased. The cells accumulated less than one-tenth as much radioactivity from sodium butyrate as from lauric acid. Washing the cells on the filter with water decreased radioactivity. More complete elution of the radioactivity was obtained by filtering the mixture after it was …

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Influence Of Surface Active Agents On Some Lactic Streptococci, R. B. Maxcy Jan 1964

Influence Of Surface Active Agents On Some Lactic Streptococci, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

Fatty acids and other surface active agents were used to clarify the relationship of surface activity to the inhibition of lactic streptococci. There was complete inhibition of lactic streptococci in media where surface activity exceeded a critical level. The effectiveness of inhibition by fatty acids, nonionic surface active agents, anionic surface active agents, decyl alcohol, growth medium, and temperature variation was directly related to the surface activity. The surface active agents created an unfavorable environment at most concentrations, rather than acting as a specific inhibitory substance to which the organisms were capable of adapting and thereafter resuming normal growth. The …

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Improving Curd-Forming Properties Of Homogenized Milk, R. B. Maxcy, W. V. Price, D. M. Irvine Jan 1955

Improving Curd-Forming Properties Of Homogenized Milk, R. B. Maxcy, W. V. Price, D. M. Irvine

Department of Food Science and Technology: Faculty Publications

Homogenizing milk for cheese reduces fat losses in the whey (6, 9, 12) and decreases leakage of fat from cheese stored at high temperatures (6, 11). Homogenization of milk influences its curd-forming properties with rennet. Trout (10) has reviewed this subject thoroughly. Gel strength is reduced and rate of coagulation is increased. Reduction in gel strength is directly related to the effectiveness of homogenizing.
Apparently no single explanation of the mechanism responsible for the lowering of gel strength by homogenization of the milk has been commonly accepted. One possibility is the adsorption of proteins on the newly created fat surfaces. …

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Fat Separation In Evaporated Milk. Iii. Gravity Separation And Heat Stability, R. B. Maxcy, H. H. Sommer Jan 1954

Fat Separation In Evaporated Milk. Iii. Gravity Separation And Heat Stability, R. B. Maxcy, H. H. Sommer

Department of Food Science and Technology: Faculty Publications

Fat separation is a continuous problem in the production, handling, and storage of evaporated milk. This defect becomes most objectionable during prolonged quiescent storage at high temperatures. The butterfat rises to the upper surface forming a viscous, leathery layer, which may prevent pouring of the milk from a relatively small opening.
To retard fat separation, the manufacturer attempts to obtain effective homogenization and sufficient coagulation of the proteins during sterilization to give the product a high viscosity or "heavy body" (1, 12, 14). These practical applications are aimed at three fundamental considerations: a reduction in the size of the fat …

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Fat Separation In Evaporated Milk Ii. Age-Thinning Of Concentrated, Sterilized Milk, R. B. Maxcy, H. H. Sommer Jan 1954

Fat Separation In Evaporated Milk Ii. Age-Thinning Of Concentrated, Sterilized Milk, R. B. Maxcy, H. H. Sommer

Department of Food Science and Technology: Faculty Publications

During the process of sterilization of evaporated milk there is a gradual increase in the viscosity, or the body of the product. However, there is a reduction in the viscosity especially during the early phase of storage. This loss in viscosity, referred to as age-thinning, continues for a number of months.

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Fat Separation In Evaporated Milk I. Homogenization, Separation, And Viscosity Tests, R. B. Maxcy, H. H. Sommer Jan 1954

Fat Separation In Evaporated Milk I. Homogenization, Separation, And Viscosity Tests, R. B. Maxcy, H. H. Sommer

Department of Food Science and Technology: Faculty Publications

The rising of fat in evaporated milk on prolonged storage will inevitably occur since the density of the fat particles is lower than that of the concentrated milk plasma in which they are suspended. It has been shown that the velocity of rise of individual fat globules in milk plasma is in good agreement with the velocity as predicated by Stokes' law (5). Troy and Sharp (7) also found the velocity of rise of globule clusters in general agreement with this law. Their observations on clusters were less precise, however, because of inherent complications arising from the irregularities in the …

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