Food Science Commons^™

Food Quality And Energy Usage In Foodservice Systems: Convective Thermal Processing Of Turkey Rolls, M. E. Matthews, M. E. Zabik, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

This study evaluated sensory and nutritional qualities, microbioloqical and chemical safety of turkey rolls and enerqy use durinq convective thermal processing. Turkey rolls were heat processed in home or institutional convection ovens to an internal temperature of 77 to 80°C in the geometric center of the roll. Treatment combinations included three heat-processing temperatures (105, 135, and 165°C) and two holding treatments (not chilled and chilled for 24 hr) and three hot-holding times (0, 60 and 120 min). Sensory studies of white turkey meat roasted at 165°C and reheated showed that juiciness decreased significantly (p<0.05), compared to roasting at 105 or 135°C without reheating. Juiciness was also decreased significantly (p<0.05) as hot-holding progressed (0 to 120 min).

Coagglutination And Enzyme Capture Tests For Detection Of Escherichia Coli Β-Galactosidase, Β-Glucuronidase, And Glutamate Decarboxylase, Charles W. Kaspar, Paul A. Hartman, Andrew K. Benson

Department of Food Science and Technology: Faculty Publications

Polyclonal antibodies to Escherichia coli β-galactosidase, β-glucuronidase, and glutamate decarboxylase were used in coagglutination tests for identification of these three enzymes in cell lysates. Enzyme capture assays were also developed for the detection of E. coli β-galactosidase and β-glucuronidase. The enzymes were released by using a gentle lysis procedure that did not interfere with antibody-enzyme interactions. All three enzymes were detected in 93% (51 of 55) of the E. coli strains tested by coagglutination; two of the three enzymes were identified in the remaining 7%. Of 42 non-E. coli tested by coagglutination, only four nonspecifically agglutinated either two or …

Prevalence Of Sensitivity To Sulfiting Agents In Asthmatic Patients, Robert K. Bush, Steve L. Taylor, Karen Holden, Julie A. Nordlee, William S. Busse

Department of Food Science and Technology: Faculty Publications

Ingestion of sulfiting agents can induce wheezing in some asthmatic patients. However, neither the prevalence of sulfite sensitivity nor the clinical characteristics of the affected asthmatic population are known. In a prospective single-blind screening study, 120 non-steroid-dependent and 83 steroid-dependent asthmatic patients underwent challenge with oral capsules of potassium metabisulfite. Five non-steroid-dependent and 16 steroid-dependent asthmatic patients experienced a greater than 20 percent reduction in their one-second forced expiratory volume within 30 minutes following the oral challenge. Twelve of these sulfite reactors were rechallenged with metabisulfite capsules in a double-blind protocol. Under these conditions, only three of seven steroid-dependent patients …

Phosphotransferase Activity In Clostridium Acetobutylicum From Acidogenic And Solventogenic Phases Of Growth, Robert W. Hutkins, Eva R. Kashket

Department of Food Science and Technology: Faculty Publications

Clostridium acetobutylicum cells, when energized with fructose, transported and phosphorylated the glucose analog 2-deoxyglucose by a phosphoenolpyruvate-dependent phosphotransferase (PT) system. Butanol up to 2% did not inhibit PT activity, although its chaotropic effect on the cell membrane caused cellular phosphoenolpyruvate and the 2-deoxyglucose-6-phosphate to leak out. Cells harvested from the solventogenic phase of batch growth had a significantly lower PT activity than did cells from the acidogenic phase.

Use Of Galactose-Fermenting Streptococcus Thermophilus In The Manufacture Of Swiss, Mozzarella, And Short-Method Cheddar Cheese, Robert W. Hutkins, S.M. Halambeck, H.A. Morris

Department of Food Science and Technology: Faculty Publications

Galactose-fermenting (galactose-posirive) strains of Streptococcus tbermopbilus, alone and combined with galactosepositive and galactose-negative strains of Lactobacillus bulgaricus, were used as starter cultures in the manufacture of Swiss and Mozzarella cheese and were paired with Streptococcus lactis (also galactose-positive) in short-method Cheddar cheese manufacture. Experimental Swiss cheese made with the galactosepositive Streptococcus tbermopbilus starter alone contained a large amount of galactose (ca. 26 to 28 /amol/g of curd) 28 h after hooping compared with control Swiss (< 2/amol/g) made with a nongalactose fermenting strain of Streptococcus tbermopbilus and a galactosepositive strain of Lactobacillus bulgaricus. Mozzarella and short-method Cheddar made with only galactose-positive Streptococcus tbermopbilus also contained …

Simple Method To Demonstrate Radiation-Inducible Radiation Resistance In Microbial Cells, S. T. Tan, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

A simple method for detection of radiation-inducible radiation resistance was developed by irradiating aliquots (0.01 ml) of cell suspension on agar plates. Part of each experimental plate was subjected to an induction treatment, and subsequent radiation resistance was compared with that of untreated cells on the same plate. The UV radiation resistance of a Micrococcus sp. was increased approximately 1.6 times by an induction treatment. This simple procedure of irradiating cells in a "fixed" position on agar avoided washing, centrifugation, and cell enumeration required in traditional methods.

Galactokinase Activity In Streptococcus Thermophilus, Robert W. Hutkins, Howard A. Morris, Larry L. Mckay

Department of Food Science and Technology: Faculty Publications

ATP-dependent phosphorylation of [¹⁴Cigalactose by 11 strains of Streptococcus thermophilus indicated that these organisms possessed the Leloir enzyme, galactokinase (galK). Activities were 10 times higher in fully induced, galactose-fermenting (Gal⁺) strains than in galactose-nonfermenting (Gal-) strains. Lactose-grown, Gal^- cells released free galactose into the medium and were unable to utilize residual galactose or to induce galK above basal levels. Gal⁺ S. thermophilus 19258 also released galactose into the medium, but when lactose was depleted growth on galactose commenced, and galK increased from 0.025 to 0.22 μmol of galactose phosphorylated per min per mg of …

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 …

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 …

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 …

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 …

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, …

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.

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 …

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 …

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.

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 …

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 …

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. …

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 …

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 …

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 …

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 …

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) …

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 …

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 …

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 …

The Biology And Ecology Of Trogoderma Glabrum (Herbst) In Stored Grains, Benjamin H. Kantack, Robert Staples

Nebraska Agricultural Experiment Station: Historical Research Bulletins

These investigations were undertaken to determine the distribution and importance of Trogoderma glabrum (Herbst) in stored grain in Nebraska, the ecological factors favoring population increase in stored wheat, corn, and sorghum, and the role T. glabrum might play in disseminating internally the Aspergillus molds commonly encountered in stored grain.

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 …

Factors Affecting The B-Vitamin Content Of Cottage Cheese, Gary Dean Reif

Department of Food Science and Technology: Dissertations, Theses, and Student Research

The purpose of this study was to investigate the vitamin content of Cottage cheese and to study the factors which may alter the content of certain B-vitamins. The specific objectives were as follows:

1. To determine the niacin, B₆, B₁₂ and folic acid content of skimmilk and Cottage cheese and the retention of those vitamins in the curd from the milk.
2. To study the synthesis of niacin, B₆, B₁₂ and folic acid during the 16-hr setting period used in making Cottage cheese, and to determine whether the vitamin synthesis by the starter was partly responsible …