Gram Negative Bacteria Inhibition by Lactic Acid Culture and Food Preservatives on Catfish Fillets during Refrigerated Storage

Treating catfish fillets with sodium acetate (SA) and/or potassium sorbate (PS), with or without lactic culture (Lactococcus lactic spp. cremoris ATCC 19257 grown in 20% milk solids) was studied at 4°C. Gram negative bacterial (CVT) counts on crystal violet tetrazolium chloride agar, pH, and sensory evaluation of fillets were assessed over time. Treatment with the combination of 0.50% SA, 0.25% PS with 2.50% lactic acid culture (LC) and, also, 0.50 to 1.00% SA alone completely inhibited growth for 6 days at 4°C. After 12 days, counts with this treatment and the 1.00% SA increased ～1.3 and 1.2 log cycles, respectively. The antimicrobial effects did not appear to be due to pH values. The combination of 0.50% SA and 0.25% PS with 2.50% LC, or 1.00% SA, alone, improved catfish odor and appearance during 13 days storage.     

SURVIVAL OF VIBRIO VULNIFICUS AT REDUCED TEMPERATURES AND ELEVATED NUTRIENT

Studies were conducted on the survival of the human bacterial pathogen, Vibrio vulnificus, in heart infusion broth held at 5, 10 and 15°C. Culturability was monitored by plate counts on heart infusion agar, and viability by examination of electron transport activity. Whereas V. vulnificus demonstrated growth at 15°C, a rapid loss of culturability for cells held at the lower temperatures was observed. At all temperatures, however, a significant portion of the population was found to remain viable over the 28 day study period. The ability of V. vulnificus cells to metabolize exogenously supplied nutrient at reduced temperatures was also examined as an indicator of viability. Cells were able to rapidly take up and respire mixed amino acids at 9 and 13°C, whereas cells incubated at 2°C showed relatively little metabolism of the labeled substrates. Like the growth and viability study, the radiotracer study indicates survival of V. vulnificus at reduced temperatures, although with reduced rates of activity. The possible implications of these findings for the transport and storage of shellfish is discussed.     

Electronic Sensing of Aromatic Volatiles for Quality Sorting of Blueberries

An electronic sniffer using semi-conductor gas sensors that nondestructively measured aromatic volatile gas emissions from fruit was developed to assess blueberry quality. The sniffer detected soft and damaged fruit in packaged containers at a 5% level of damage and distinguished four of five fruit ripeness classes: (1) mature-green and green-pink; (2) blue-pink; (3) blue; and (4) ripe fruit. Sniffer response increased as fruit ripened, as did total concentration of aromatic volatiles. Sniffer response correlated with berry firmness, pH, titratable acidity, and color, and detected differences among 10 cultivars, as did impact response analysis. The electronic sniffer is rapid, nondestructive and may be used to sort and quality check for presence of unripe or damaged fruit in closed packs of fresh berries.     

ANTIMICROBIAL ACTIVITY OF SOME FOOD FLAVORING COMPOUNDS

Of 21 food flavoring compounds tested against 39–40 organisms, 10 were ineffective at 1,000 ppm or 10 mM either at pH 6 or 8 and by either surface plating or in broth. The 11 effective compounds were d- and l-carvone, diacetyl, ethyl vanillin, eugenol, maltol, menthol, phenylacetic acid, phenylacetal-dehyde, 2,3-pentanedione and vanillin; with diacetyl and eugenol being the most effective. All were more effective at pH 6 than at pH 8. With the exception of maltol and phenylacetic acid, each was generally more effective against fungi than bacteria with the lactic acid bacteria being the most resistant. At pH 5.5 and 5°C, diacetyl was inhibitory to Pseudomonas fluorescens and P. geniculata at < 10 ppm. The findings suggest that compounds used in acid foods, ostensibly as flavoring agents, may exert antimicrobial effects when considered in context with all parameters of growth.     

INTERSTATE SHIPMENT AND STORAGE OF FRESH MUSCADINE GRAPES

Muscadine grapes (Vitis rotundifolia michx.) are highly perishable, with a short harvest season. The objective of this study was to enhance the commercial viability of muscadine grapes by developing harvesting and handling systems through interstate shipment studies, using sulfur dioxide and/or polyethylene overwrap treatments. Cultivars Fry, Summit and Granny Val from Florida, Arkansas and Mississippi, respectively, were shipped from each region to the other in refrigerated trucks for subsequent storage at OC and evaluation at 0, 2, 4 and 6 weeks. Biochemical properties: pH, titratable acidity and degrees Brix, remained fairly constant with time for all cultivars, under all treatments. The cultivar, Granny Val, which was shipped, wrinkled after 2 weeks' storage, but maintained 6 weeks' shelf-life in the in-house study. ‘Summit’ shelf-life was increased to 4 weeks with SO₂ treatment at all test sites while ‘Fry’ became bleached by SO₂. The shelf-life of ‘Fry’ was 6 weeks in the in-house study using     

RHEOLOGICAL MODELING of POTATO FLOUR DURING EXTRUSION COOKING

A generalized model for predicting the effects of shear rate, temperature, moisture content, time-temperature history and strain history on viscosity has been evaluated for extruded potato flour doughs. an Instron Capillary Rheometer and a 50 mm Baker Perkins co-rotating twin screw extruder were used to evaluate all effects incorporated in the model, except strain history. the power law model was used to describe shear rate effects in the range 10–10000 s^?1. the generalized model fit observed data for temperatures of 25–95°C and moisture contents ranging from 22 to 50%, wet basis. Since potato flour by its manufacturing process is pregelatinized, it was unnecessary to evaluate the effects of time-temperature history. Strain history was found to have an insignificant influence on the viscosity.     

ORIFICE DISCHARGE COEFFICIENTS FOR POWER-LAW FLUIDS

Orifice discharge coefficients for non-Newtonian (power-law) fluids (5, 7.5 and 10% corn starch solutions) were measured using a closed end pipe with different orifice diameters. Results indicate that orifice discharge coefficients, found to be in the range of 0 – 0.7, are a function of the orifice diameter, fluid velocity in the orifice and the fluid rheological properties (consistency coefficient and flow behavior index). They increase with the fluid velocity, tend to be constant at high velocities and decrease when the consistency coefficient of the solution is increasing. Orifice discharge coefficients are presented as a function of the generalized Reynolds number.     

Kinetic Processes Involved in the Sintering and Crystallization of Glass Powders

Viscometry, crystal growth kinetics, and glass powder sintering were used to determine the activation energies of viscous flow, crystal growth, and sintering behavior of a standard NBS 710 glass and two crystallizable glass powders in the calciaaluminosilicate system. In a system which sintered successfully to zero porosity, the activation energy for sintering was comparable to the activation energy of viscous flow. When the apparent activation energy for the sintering process was lower than that of viscous flow, sintering was found to proceed at a slower rate because the precipitated crystalline phase retarded viscous flow and the shrinkage of the pores. Initial crystallization appeared to occur on the surfaces of coalesced particles. A chemical treatment was partially successful in suppressing the onset of surface nucleation of the precursor powder.     

COMMUNITY DEVELOPMENT BLOCKS GRANTS IN URBAN COUNTIES: THE CASE OF HAMILTON COUNTY,OHIO

Urban counties must struggle with metropolitan expansion in order to deliver vital urban services. With the passage of the Housing and Community Development Act, urban counties throughout the nation found it necessary to develop the administrative capacity and the intergovernmental network sufficient to implement the Act. Hamilton County, Ohio, offers a typical example of how an urban county implemented CDBG. The result was a small county community development staff that look a pragmatic approach and relied heavily on the recommendations of participating municipalities and townships. The funded projects were primarily oriented toward transportation and public works. These projects, widely dispersed throughout the county, rewarded diverse political interests, generated few political conflicts, and required minimal county staff resources.