Influence of High-Pressure Treatment at 25°C and 80°C on Folates in Orange Juice and Model Media

ABSTRACT: The influence of high-pressure treatment on the 3 main folate species present in orange juice was assessed under conditions similar to those used in high-pressure pasteurization and sterilization using freshly squeezed orange juice and different model orange juices. The latter were used also to determine the influence of matrix components, pH, and excess ascorbic acid. Excess ascorbate strongly protected folates against pressure and heat. Pressurization at 600 MPa and 80°C affected model juice folates synergistically, and pressure increased the formation of 5,10-methenylfolate. In fresh orange juice, components other than ascorbate additionally stabilized folates, thus pressure preservation and pressure sterilization appeared very feasible.     

OPTIMUM ECONOMIC PIPE DIAMETER FOR PUMPING HERSCHEL-BULKLEY FLUIDS IN LAMINAR FLOW1

A method for determining optimum pipe diameter, for which total pumping system cost is minimum, has been derived for the transport of Herschel-Bulkley (H-B) fluids (power-law fluids with a yield stress) in laminar flow. the method accounts for pipe system cost as a function of diameter, and pump station and operating costs as a function of power requirements. the optimum diameter can be estimated given rheological properties, fluid density, mass flow rate and economic parameters. Optimum diameter does not depend on system elevation or pressure energy difference when a linear relationship is used for pump station cost. Friction loss in fittings and valves can be ignored when the pipe length is much greater than the pipe diameter. Pump station cost has less influence than operating cost in determining the optimum diameter.     

AUTHOR'S CLOSURE

A dilatometric technique was used to obtain kinetic data for UV-photoinitiated polymerization of acrylamide and methacrylamide. In this study, benzoinmethylether was the initiator. Two mixed-solvent systems, 30% acetic acid in water (for both monomers) and 40% methanol in water (for acrylamide only) were examined. In all three systems the rate of polymerization varies with the monomer concentration to the 1.4 to 1.5 power and to the initiator concentration to the 0.4 to 0.8 power. Energies of activation are very low, less than 1.5 kcal/mol. Molecular weights estimated from viscosity measurements support the idea that chain transfer to monomer is important in the case of methacrylamide.     

Physico—chemical modifications of liposome structures through interaction with surfactantsy‡

The liposome-surfactant interaction has been studied in this paper through the disrupting effect caused by surfactant molecules on large unilamellar vesicles prepared by reverse-phase evaporation. This process leads, in the end, to the rupture of such structures and to the solubilization of the phospholipidic components, via mixed surfactant-phospholipid micelle formation. This phenomenon is described by a three-stage model and characterized by two parameters: the highest surfactant/phospholipid ratio that can exist in a vesicle (R_{e sat}) and the lowest surfactant/phospholipid ratio required to keep the lipid and surfactant in the form of mixed micelles (R_{e sat}). These parameters have been determined by spectrophotometry and ³¹P NMR spectroscopy, obtaining results in a good agreement with both techniques. The surfactants tested have been: sodium dodecyl sulfate (SDS), sodium laurylether sulfate (SLES), N-hexadecyl-trimethylammonium bromide (HTAB), octylphenol series (8–20 EO) and alkylbetaines(C-10, C-12 and C-14). Different R_{e sat} and R_{e sol} values have been obtained for each of the surfactants. This has permitted a study of the solubilizing capacity versus the phospholipidic bilayer of the different surfactants as a function of their structure.     

Utilization of Surimi-like Products from Pork with Sex-odor in Restructured, Precooked Pork Roast

Surimi-like materials from boar and sow muscle and Alaskan pollack fish surimi were evaluated as binders for sow muscle chunks in restructured roasts. Boar surimi-like material tended to have lower mi-crobial counts and less lipid oxidation than unwashed counterparts. Increasing salt content increased lipid oxidation (P<0.05), degraded color and improved (P<0.05) textural integrity. The surimi-like boar material had equal or better binding properties than fish surimi at a 5% level and did not consistently result in detectable boar odor. Roasts without binder were comparable or better in textural and microbial characteristics than those with binders. Restructured, precooked, pork roasts were successfully produced with 0.2% NaCI.     

Pilot Study of Cucumber Fermentation: Diffusing Gases and Bloater Damage

A pilot study was made of the effect of temperature (17 and 26°C) and purging, with nitrogen (5-20 L/hr applied continuously and intermittently) or air (20 L/hr for 7 hr/day), o n the development of fermentation and on the incidence of bloater damage in cucumbers. Temperature affected the rate of fermentation and both temperature and purging strongly affected the incidence of bloater damage. At 17°C purging was not necessary, and at 26°C 10 L/hr was sufficient, applied for 7 hr/day for 7 days.     

Sensory Properties of Rib and Round Muscle Roasts from Two Beef Breed-Types on Two Feeding Regimes

Roasts from the rib and three round muscles obtained from Angus and Simmental Angus (SA) steers on two feeding regimes, high concentrate (HC) and pasture followed by short term HC, were roasted to an internal temperature of 65–68°C. Time of roasting, cooking losses, shear values, and pressed juice were determined. A trained sensory panel evaluated flavor, tenderness, juiciness, and overall acceptability. Sensory panelists scored flavor acceptability higher in SA roasts (P < 0.05) than in roasts from Angus steers. Flavor acceptability, overall acceptability, and tenderness were found to be higher in round muscle roasts from the HC feeding regime (P < 0.05) than in round roasts from the cattle fed pasture followed by short term HC.     

Fat Concentration Affects Sweetness and Sensory Profiles of Sucrose, Sucralose, and Aspartame

The sensory characteristics of sucralose, aspartame, and sucrose were studied in an unflavored lipid model system varying in fat levels. One study investigated the effects of fat on the potencies (vs. sucrose) of sucralose and aspartame. We also examined absolute changes in all three sweeteners in taste, temporal, and mouthfeel properties at fiied concentrations across a wide fat range. Results indicated a modest decrease in the potencies of sucralose and aspartame across fat concentrations, especially at lower sweetness levels. All sweeteners responded similarly to changes in fat concentration. Independent of fat level, sucralose was perceived more similar to aspartame in onset, bitterness, and aftertaste, than to sucrose.