Dynamics of Solidification in 2% Corn Starch-Water Mixtures: Effect of Variations in Freezing Rate on Product Homogeneity

Directional solidification studies of gelatinized corn starch-water mixtures were undertaken in order to examine, in situ, the freezing behavior of this food model. The solidification rate was controlled by varying sample cell velocity as it moved from a 25°C hot stage to a -25°C cold stage. While freezing at cell velocities ≤7.5 μm/sec, starch granules were alternately pushed or entrapped by the advancing solid-liquid interface producing a segregated structure consisting of alternating high-starch and low-starch bands. At a cell velocity of 10 μm/sec, the frozen product was homogeneous. The relationship between the solid-liquid interface velocity and segregation behavior was quantified and compared to an existing model of particle-interface interactions.     

EXTRUSION PROCESSING OF RICE OR CORN FLOUR WITH MECHANICALLY DEBONED TURKEY1

Rice flour and yellow or white corn flour were combined at 50, 60 and 70% levels with mechanically deboned turkey and extrusion processed at 104C and 121C. The texture of the extrudates was evaluated by Warner-Bratzler shear (WBS), and flour concentration had more effect on the WBS values than flour type; treatments with 70% flour had significantly greater WBS values. Corn flour treatments and low temperature extrusion resulted in greater TBA values. Proximate composition of extrudates confirmed moisture losses during extrusion and that high temperature processing had mixed results on ether-extractable compounds.     

Determination of Heat Transfer Coefficients for Continuous Belt Freezers

Air-product heat-transfer coefficients for belt freezers were determined experimentally. Measurements were performed for foods (beef hamburgers) and a model substance (copper disk) using a prototype tunnel. Air flow parallel, as well as perpendicular, to the belt, was employed; in the latter case moving upwards or downwards through the belt. From the measured temperatures, heat-transfer coefficients were calculated using appropriate mathematical methods. Values obtained for both types of materials were compared, and the usefulness of the test substance was discussed. From these data, simple and precise regressions were obtained, useful to predict the coefficient for the above mentioned types of air flow and valid over a wide range of operating conditions in belt freezers.     

生物医用Ti6Al4V/xTiN复合材料的腐蚀与腐蚀磨损行为

用固相烧结法制备Ti6Al4V/xTiN(x=0,5,10,15,体积分数,％)复合材料,研究材料的腐蚀与腐蚀磨损行为及其与显微组织和显微硬度的关系.采用37℃ 和模拟体液模拟人体环境.结果表明,当TiN含量为15％时,氮(N)固溶到钛(Ti)晶格中使α-Ti稳定化,该显微组织的改变使Ti64基体的硬化效应达到58％....     

Viability of probiotic micro-organisms (Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp. lactis Bb-12) in ice cream

The purpose of this research was to determine the survival of two probiotic micro-organisms in ice creams (4% fat). The micro-organisms were Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp . lactis Bb-12 . To meet this objective, an ice cream mixture was formulated and subjected to three treatments. Treatment 1 was inoculated with L. acidophilus , treatment 2 with B. lactis and the third treatment was inoculated with a mixture of both bacteria inoculated in 1 : 1 proportions. The inoculation was with 4% culture for each treatment. The final products were stored at −25°C for 60 days. The ice cream inoculated with L. acidophilus had a final concentration of 2 × 10 ⁶ cfu/g and the survival rate was 87%. The treatment inoculated with B. lactis had a final concentration of 9 × 10 ⁶ cfu/g, with a logarithmic decrease of 10%. When both micro-organisms were inoculated together, the survival rate was 86%.     

Flow Characteristics of Viscous, Non-Newtonian Fluids in Holding Tubes of HTST Pasteurizers

The type of flow and ratio of maximum to average velocity in the holding tube was studied for viscous, non-Newtonian fluids. Appropriateness of the salt test in water for holding time determinations was also studied. Sucrose and guar solutions were used to model rheological characteristics typical of ice cream mixes. Flow was observed using a dye stream and video photography. In straight-line flow, maximum velocity was 1.6 to 2 times faster than bulk-flow velocity for typical industrial settings (Re_g from 70 to 1900). When elbows were added, the dye stream was displaced from its centerline position and the ratio of dye stream to bulk-flow velocity decreased. No extrapolation could be made from salt tests in water to minimum holding time for viscous, non-Newtonian fluids.     

Study of the White Film Developed on the Cut Surface of Vacuum-packed Dry-cured Ham Slices

Scanning electron microscopy of the white film developed on the cut surface of some vacuum-packed dry-cured ham slices showed a fibrous structure composed of protein materials. Gradient SDS-PAGE revealed the main components in the film were proteins with molecular weight in the range 26000–87000, but especially 37000, 41000, 56000, and 65000. Free amino acids were also in the film in low proportions (250 μg total free amino acids per mg of protein). The main amino acids were proline methionine, isoleucine, leucine, phenylalanine, histidine and tyrosine. 11.7% of the total free amino acids was tyrosine, thus indicating its minor role in formation of white film.     

PHYSICAL,CHEMICAL, and THERMAL CHARACTERIZATION of WHEAT FLOUR MILLING COPRODUCTS1,2

Hard red winter (HRW) and hard red spring (HRS) wheat milling coproducts (bran, germ, shorts, and red dog) from three commercial flour mills and the Kansas State University pilot mill were evaluated for differences in physical, chemical, and thermal properties. the ranges of bulk density for bran, germ, and red dog determined at three moisture levels were 146.5 to 205.2 kgm^?3, 269.2 to 400.6 kgm^?3, and 298.9 to 398.1 kgm^?3, respectively. the true density ranking order was: red dog >shorts = germ >bran, independently of the moisture level. Red dog had the smallest geometrical mean diameter with the highest variation (coefficient of variation of 23.8%). There was a significant (P < 0.05) difference among wheat blends and milling flows in the thickness of bran and germ at the same particle separation size. the image analysis study determined that the equivalent projected area diameter of bran at the same separation size was significantly (P < 0.05) larger than that of germ. the ratio between the equivalent projected area diameter and the particle thickness were within ranges of 15.7 to 37.6 for bran and 15.5 to 32.2 for germ particles. the chemical composition (ash, protein, lipids and fiber) ranges were determined for each coproduct. Ranges of thermal conductivity for bran, germ, shorts, and red dog were 0.049 to 0.074, 0.054 to 0.0907, 0.057 to 0.076, and 0.063 to 0.080 W(mK)^?1, respectively. Specific heat of coproducts, measured with a differential scanning calorimeter, exhibited a wider range [1.08–1.94 kJ(kgK)^?1] than that observed in whole wheat kernels and wheat flour. the variability observed among the samples was due to the different wheat sources and characteristic milling flows for the flour mills.