Food Microbiology Commons^™

Comparison Of Compatibility Of Streptococcus Starters In Reconstituted Nonfat Dry Milk And A Whey-Based Bacteriophage Inhibitory Medium, Clinton K. Searle

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Compatibility of mixed cultures of Streptococcus lactis and Streptococcus cremoris were studied by the phage tracer technique in 10% nonfat dry milk and a whey-based phage inhibitory medium. Methods of membrane dialysis and differential enumeration were tried and abandoned. Dominance occurred in nonfat dry milk and in the whey-based medium during a continuous fermentation period within a pH range 6.8 to 5.2. The dominance pattern of two-strain combinations in 10% nonfat dry milk was different from that in the whey-based media. Dominance varied from one strain to another in no consistent sequence in some combinations. Dominance patterns of combinations were …

Evaluation, Assay, Distribution, And Survey Of Staphylococcus Aureus Thermonuclease In Milk And Cheese Products, Gene Leong Hong

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The metachromatic agar-diffusion test of Lachica, Hoeprich, and Genigeorgis (1971) was modified by adding 17 ml of the agar medium to a 100 by 15 mm plastic petri dish, using 5 µl samples and 3 mm wells. The test detected 0.5 ng/ml of thermonuclease in 3 hr at 37 C. This was equivalent to 10⁶ to 10⁷ cells/ml of Staphylococcus aureus strains 196 E, 14458, and 19095 grown in Brain Heart Infusion (BHI) broth. The test sensitivity was decreased ten fold in raw and pasteurized milk.

One-half gram of cheese was dissolved in 4.5 ml of 0.1 M …

Milk Protein Analysis By Automated Ultraviolet Spectroscopy, R. Ford Wilkinson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An automated continuous flow analysis for milk protein utilizing ultraviolet spectroscopy resulted in a correlation coefficient of 0.972 and a standard estimate of error of 0.082 percent protein when 30 samples were compared with the acid orange 12 dye binding method. Milk was solubilized in 95-105 volumes of acetic acid using the Technicon Auto Analyzer II and measured for absorbance at 274 nanometers. No deviation from the standard method due to mastitis and varying milk fat concentration was observed. A theoretical model indicated a possible standard estimate of error 0.059 percent protein due to inter- and intra-breed variation in milk …

The Effects Of Gamma Irradiation, Color Mutation And Various Subatmospheric Pressures On The Growth And Patulin Production By Penicillium Expansum And Penicillium Patulum, Karl B. Adams

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To assess the effects of gamma radiation at low doses, spores of Penicillium expansum NRRL 971 and Penicillium patulum NRRL 989 were exposed to doses of 0, 50, 100, 150, and 200 krads. The amount of patulin for each culture was quantitatively determined and growth at each dose was evaluated. The results showed a 31% increase in the amount of patulin synthesis after a dose of 150 krads for Penicillium expansum. At 200 krads, both fungi showed low levels of patulin production and inhibited growth.

Eight color mutants of P. expansum and eight color mutants of P. patulum were produced …

Effect Of Processing On Aliphatic Aldehyde Content Of Turkey Meat, Carolyn G. Ponce

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nitrite at the level found in turkey frankfurter formulations vii did not interfere in the hydrazone test as developed by Andrews (1975). The aldehyde levels of frankfurters made principally from MD turkey meat were, on the average, twice as high as the levels in the raw meat. Aldehyde levels generally increased as the frozen storage time of the raw meat increased. There were some variations from this trend due to variation in the fat content of the raw meat. Sixty days was recommended as a maximum frozen storage time. However, because of variation in the fat content from sample to …

Formation And Anatomical Distribution Of Chlorophyll And Glycoalkaloids In Potato (Solanum Tuberosum L.) Tubers And Their Control By Physical And Chemical Treatments, Robert Bruce Jeppsen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Applications of growth regulators and modifications of light exposures were investigated regarding their abilities to curtail the normal development of chlorophyll and glycoalkaloids in potato tubers responding to light. Four growth regulators were sprayed on the foliage of potato plants 14 days prior to harvest, of which two (Ethephon and N⁶-Benzyladenine [N6BA]) successfully retarded chlorophyll and glycoalkaloids in the harvested tubers. When tubers were dipped in N6BA, lower concentrations of the chemical promoted glycoalkaloid formation, while larger amounts were more inhibitory. When fluorescent lights were directed through colored cellophane filters, tubers receiving yellow and orange illuminations were inhibited …

Development Of A Whey-Based Lactic Culture Medium Capable Of Bacteriophage Inhibition, Chao Tung Cheng

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A whey product has been formulated for use as a lactic starter medium. Phosphate-treated whey medium (PWM) has been shown to support growth of lactic cultures and prevent phage proliferation. Comparisons were made of a commercial phage inhibitory medium (PIM), reconstituted non-fat dry milk (NDM) and PWM. PWM inhibited all phages tested and stimulated starter growth. PWM was not as stimulating as PIM but was better than NDM. Good Cheddar cheese has been made using PWM. PWM is more economical than PIM but NDM is the most economical one if cheese yield is considered.

Thermal Degradation Of Pigments And Relative Biochemical Changes In Cherries And Apricots, K. B. Dalal

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The extent and nature of biochemical changes that take place in canned fruits during storage temperatures above freezing have been reviewed and discussed by Pederson, et al. (1947). These changes include loss in nutritive value, e.g. ascorbic acid, thiamine (Brenner, et al., 1948) and deterioration of color (Tressler, et al., 1955). Bauernfeind (1953) reported that canned peaches, apricots, and sweet cherries, after a few months of storage at 70°F, frequently undergo changes such as destruction of anthocyanin and carotenoid pigments with the subsequent formation of brown colored compounds. Darkening of fruit-color eventually results in their unacceptability at …