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Nutrition, Dietetics, and Food Sciences Faculty Publications

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Full-Text Articles in Nutrition

Determination Of Wax Concentration In Sunflower-Seed Oil, Silvana Martini, M.C. Anon Oct 2000

Determination Of Wax Concentration In Sunflower-Seed Oil, Silvana Martini, M.C. Anon

Nutrition, Dietetics, and Food Sciences Faculty Publications

Isothermal crystallization of waxes was studied by using an optical setup. The induction time of crystallization was assessed as a function of wax concentration. The relationship was found to be a decreasing exponential curve. The wax content of some of the solutions prepared in the laboratory was determined by calculating the crystallization induction time. The values obtained were compared to those from different methods (cold test, microscopic, and turbidimetric methods). The results obtained with the optical setup method are similar to those obtained with other methods for concentrations greater than 100 ppm. An analysis of variance test was used to …

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Influence Of Capsular And Ropy Exopolysaccharide-Producing Strepococcus Thermophilus On Mozzarella Cheese And Cheese Whey, B. L. Peterson, R. I. Dave, Donald J. Mcmahon, C. J. Oberg, Jeff Broadbent Jan 1999

Influence Of Capsular And Ropy Exopolysaccharide-Producing Strepococcus Thermophilus On Mozzarella Cheese And Cheese Whey, B. L. Peterson, R. I. Dave, Donald J. Mcmahon, C. J. Oberg, Jeff Broadbent

Nutrition, Dietetics, and Food Sciences Faculty Publications

We investigated the effect of capsular and ropy exopolysaccharide-producing Streptococcus thermophilus starter bacteria on Mozzarella cheese functionality and whey viscosity. Mozzarella cheeses were manufactured with Lactobacillus helveticus LH100 paired with one of four S. thermophilus strains: MR-1C, a bacterium that produces a capsular exopolysaccharide; MTC360, a strain that secretes a ropy exopolysaccharide; TAO61, a nonexopolysaccharide-producing commercial cheese starter; and DM10, a nonencapsulated, exopolysaccharide-negative mutant of strain MR-1C. As expected, cheese moisture levels were significantly higher in Mozzarella cheeses made with exopolysaccharide-positive versus exopolysaccharide-negative streptococci, and melt properties were better in the higher moisture cheeses. Whey viscosity measurements showed that unconcentrated …

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Tryptophan Catabolism By Lactobacillus Casei Andlactobacillus Helveticus Cheese Flavor Adjuncts, S. Gummalla, Jeff Broadbent Jan 1999

Tryptophan Catabolism By Lactobacillus Casei Andlactobacillus Helveticus Cheese Flavor Adjuncts, S. Gummalla, Jeff Broadbent

Nutrition, Dietetics, and Food Sciences Faculty Publications

Microbial degradation of Trp is thought to promote the formation of aromatic compounds that impart putrid, fecal, or unclean flavors in cheese, but pathways for their production have not been established. This study investigated Trp catabolism by Lactobacillus casei and Lactobacillus helveticus cheese flavor adjuncts under carbohydrate starvation (pH 6.5, 30 or 37°C, no sugar) and near cheese-ripening (pH 5.2, 4% NaCl, 15°C, no sugar) conditions. Enzyme assays of cell-free extracts indicated that both species of Lactobacillus catabolized Trp to indole-3-lactic acid, and micellar electrokinetic capillary chromatography of culture supernatants showed this reaction occurred via successive transamination and dehydrogenation reactions. …

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Peptideaccumulation And Bitterness In Cheddar Cheese Made Using Single-Strain Lactococcus Lactis Starterswith Distinct Proteinase Specificities, Jeff Broadbent, M. Strickland, B. Weimer, M. E. Johnson, J. L. Steele Jan 1998

Peptideaccumulation And Bitterness In Cheddar Cheese Made Using Single-Strain Lactococcus Lactis Starterswith Distinct Proteinase Specificities, Jeff Broadbent, M. Strickland, B. Weimer, M. E. Johnson, J. L. Steele

Nutrition, Dietetics, and Food Sciences Faculty Publications

This study investigated peptide accumulation and bitterness in reduced- and full-fat Cheddar cheeses that were manufactured with single-strain Lactococcus lactis starters that had distinct cell envelope proteinase specificities. Micellar electrokinetic capillary electrophoresis of aqueous cheese extracts detected three large peaks, designated O, P, and Q, that eluted with peptide standards and increased in area during cheese maturation in a pattern that was distinct for each starter. Regression analysis of bitter flavor scores from trained sensory panels and individual OQ peak areas suggested that peaks P and Q had a negative and positive correlation, respectively, to this defect. Then, HPLC, capillary …

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Physical And Functional Characteristics Of Cellclumping In Lactose-Positive Transconjugants Of Lactococcus Lactis Ssp. Lactis Ml3, H. Wang, Jeff Broadbent, J. K. Kondo Jan 1994

Physical And Functional Characteristics Of Cellclumping In Lactose-Positive Transconjugants Of Lactococcus Lactis Ssp. Lactis Ml3, H. Wang, Jeff Broadbent, J. K. Kondo

Nutrition, Dietetics, and Food Sciences Faculty Publications

Transconjugants of Lactococcus lactis ssp. lactis ML3 that acquire the ability to utilize lactose often exhibit self-aggregation and become able to transfer the ability to utilize lactose at frequencies 102 to 105 times higher than strain ML3. Our laboratory investigated the physical and functional characteristics of cell aggregation in ML3 transconjugants. Results showed that donor cell auto-aggregation was dissociated when cells were suspended in buffers that contained EDTA or when they were briefly exposed to proteinase K or α-chymotrypsin. Conjugation studies revealed that disruption of donor cell aggregation substantially decreased the efficiency of lactose plasmid transfer. Dissociation by EDTA or …

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Thermophilic Starter Cultures: Another Set Of Problems, C. J. Oberg, Jeff Broadbent Jan 1993

Thermophilic Starter Cultures: Another Set Of Problems, C. J. Oberg, Jeff Broadbent

Nutrition, Dietetics, and Food Sciences Faculty Publications

Increased consumer demand for yogurt and Italian cheeses, particularly Mozzarella, over the past decade has intensified production demands on thermophilic starter cultures. Dramatically elevated production rates within existing facilities have created problems analogous to those experienced years ago by the dairy industry for mesophilic lactococci when Cheddar cheese production increased dramatically. In contrast to mesophilic lactococci, however, diversity among lactic genera that contain thermophilic species has impeded the progress of microbiological research required to meet these challenges. For example, the bacteriophages that attack these cultures are becoming an important commercial problem, yet little is known about them. Another unique characteristic …

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Nisin Inhibits Several Grampositivemastitis-Causing Pathogens, Jeff Broadbent, Y. C. Chou, K. Gillies, J. K. Kondo Jan 1989

Nisin Inhibits Several Grampositivemastitis-Causing Pathogens, Jeff Broadbent, Y. C. Chou, K. Gillies, J. K. Kondo

Nutrition, Dietetics, and Food Sciences Faculty Publications

Organisms known to cause bovine mastitis, Enterococcus faecalis ssp. liquefaciens ATCC 27959, Staphylococcus aureus ATCC 29740, Streptococcus agalactiae ATCC 27956, Streptococcus equinus ATCC 27960, Streptococcus dysgalactiae ATCC 27957, Streptococcus uberis ATCC 27958, and the neotype Staphylococcus epidermidis ATCC 14990 were examined for their susceptibility to die small peptide antibiotic, nisin. Using a disc assay, minimum inhibitory concentrations of nisin ranged from 10 to 250 μg/ml among the strains. Examination of die antimicrobial effect of 50 μg/ml nisin in milk showed nisin inhibited all gram-positive pathogens tested.

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