摘要:

ABSTRACTIn the selection of concentration processes the net added value of the concentrate with respect to the capital invested should be maximized. The net added value expressed per unit weight of feed is the difference between the gross added valve, being the increase in product value due to concentration, and the costs of concentration. The main factors affecting the gross added value and the concentration costs are treated systematically.The main factors influencing the gross added value are: thermal quality degradation by chemical reactions; loss of volatile aromas; and the concentration that is obtained in the process. The first two factors generally affect the gross added value negatively. The thermal effects of the various processes are shortly summarized. In revaporative concentration and reverse osmosis, aromas can usually be recovered by steam stripping and distillation if the aromas in the food are at least a factor of three more volatile than water. For liquids containing aromas with a relative volatility close to or smaller than unity only freeze concentration can be used, if the quality is to be fully retained.The approximate costs of concentration are given for dewatering capacities in the range of 1 to 50 tons per hour and 2000 to 7000 operational hr per year. As energy costs increase further, only concentration processes with a relatively low energy consumption will, at least for higher capacities, remain economically justified. The energy consumptions expressed in steam equivalents vary widely, viz. evaporation 0.16–1.3, freeze concentration 0.25–0.5, and membrane processes 0.01

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1977.tb00182.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe suitability of various carton materials for the nonrefrigerated storage of sterilized milk was investigated. One quart paperboard cartons were fabricated from the same base sheet of stock but varied in the type of sizing used to make them resistant to penetration by liquids and whether or not they were aluminum foil‐lined. They were preformed and sterilized with ethylene oxide. The four types of paperboard were: (a) rosin (sizing) paperboard (R); (b) rosin paperboard with foil lining (RF); (c) cyanasize (sizing) juice paperboard (CJ); and (d) cyanasizejuice paperboard with foil lining (CJF). Each carton was aseptically filled and sealed, in a glovebox. Incubation was carried out at 20°C for up to nine weeks. Every week five cartons of each type were randomly selected and the milk tested for microbial stability and flavor. The candidate cartons were also tested for degradation of the physical characteristics of static bulge, wicking, tensile strength, and stiffness. Of these, it appears as if selection of carton type will be determined mostly by wicking resistance. The most acceptable carton type is CJF, which had minimal wicking, acceptable bulge, acceptable stiffness, and acceptable tensile strength during the testing peri

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1977.tb00183.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTFirmness and thermal conductivity of “Detroit Dark Red, Ferry's Strain” and “Ruby Queen” beets were determined after storage at: 0°C, 95% relative humidity (RH); 12.8°C, 24% RH, and 1.7°C, uncontrolled humidity. Firmness at fixed temperature and humidity conditions decreased with storage; it could be described by a first order rate equation. At a fixed temperature (1.7°C) and uncontrolled humidity, magnitudes of firmness varied as the humidity varied; in contrast, thermal conductivity was influenced very little. At 0°C and 95% rel. humidity, thermal conductivity remained essentially constant for four weeks. The magnitude of thermal conductivity, at room temperature and on the day of harvest, was about the same for four different varieties of beets; “King Red,”“Detroit Dark Red, Ferry's Strain,”“Ruby Queen,” and “Detroit Dark Red, Morse's Strain;” it ranged be

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1977.tb00184.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTMass transfer characteristics and the applicability of theoretical transport models in ultrafilitration were evaluated in a pilot‐scale hollow fiber system processing soybean water extracts. Permeate flux was found to increase linearly with transmembrane pressure and then reach an asymptotic value. Substantial deviations from the pure water permeation line and marked hysteresis effects were also observed, indicative of concentration polarization and additional hydrodynamic resistance at the membrane surface. Pressure‐independence occurred at lower pressures with lower Reynolds Numbers (Re) and higher Schmidt Numbers (Sc). Flow rate and temperature significantly affected flux in the totally polarized region. The exponent in the flux‐Reα relationship varied from 0.6 at 20°C to 0.32 at 50°C. Theoretical laminar flow mass transfer models were found to predict Sherwood Numbers (Sh) and flux lower than experimental values. The correlation that fit the data best was Sh = 0.181 (Re).

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1977.tb00185.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1977.tb00186.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1977.tb00180.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY