摘要:

The formation and properties of Formed‐In‐Place (FIP) membranes upon which enzymes had been immobilized were investigated to examine the potential of these reactive membranes in food processing applications. Enzymes were immobilized on two types of FIP membranes and their activities in appropriate fluids investigated. Flux was increased in the microfiltration of pectin solutions by immobilizing pectinase on titanium dioxide microfiltration membranes. A flux increase of 15% was obtained without permeate recycle and 112% with permeate recycle using a 0.1% solution of citrus pectin. Glucose production from dextrin was performed using glucoamylase (GA) immobilized on a zirconium hydrous oxide‐polyacrylate nanofiltration membrane. Optimum activity occurred at pH 4.0 and 50C for the immobilized GA. the dextrose equivalent (DE) value of the membrane permeate was approximately ten times higher than the product obtained with free GA during the same time int

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1994.tb00344.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Shallow beds (3–9 mm) of two commercial agglomerated spray dried instant coffees were compressed using a Universal testing machine. the stress‐stress relationships had the sigmoid shape characteristic of cellular solids and could be described by a four parameter model originally developed for solid foams. the magnitude of the model parameters was less sensitive to the relative humidity level at storage in the range of 11–65% than to the bed's thickness. the jaggedness of the stress‐strain relationship is a manifestation of the particles brittleness and crumbliness and it is considerably reduced when they are plasticized, as a result of moisture uptake, for example. the degree of jaggedness, determined in the normalized (dimensionless) stress‐strain relationships, could be qualified and compared in terms of an apparent (“natural”) fractal dimension. It was calculated from the linear region of the corresponding Richardson plots using the “blanket” algorithm. This apparent fractal dimension, however, was only a relative measure of jaggedness, since both the scales and resolution of the mechanical signatures were arbitrarily selected. the jaggedness of the individual agglomerates signatures could not be directly inferred from those of their assemblies, primarily because the effects of averaging and the bed's cushioning could

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1994.tb00345.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Hall effect sensors were used to determine residence time distributions for diced carrot particles in 4% Colflo 67 carrier fluid. Four sensors at either end of a 3.2 m long 2 in. IDF tube viscometer allowed residence times to be measured for carrot particles incorporating a ceramic magnet. Mean particle residence times were greater than mean bulk residence time for 8 mm diced carrots, whereas 15 mm carrots showed trials in which particles travelled faster than the bulk fluid. Increasing concentration of 15 mm diced carrots from 3.25, 6.30, 9.16 to 11.85% w/w resulted in decreasing mean particle residence times from 17.6, 17.0, 15.9 to 14.3 s, with minimum residence times of 16.4, 16.2, 14.8 and 13.4 s, respectively. This sensing technique operates through stainless steel, providing applications for UHT foods containing particles. In addition, the technique was not affected by high particle concentration, and will operate for any distribution of particle size, shape or type.

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1994.tb00346.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Two dimensional temperature maps of a potato during heating were obtained using magnetic resonance imaging (MRI) techniques. the molecular pseudo self‐diffusion coefficient of the water in the potato was used as a temperature indicator. Two dimensional half Fourier transform spin‐echo and Generalized Series reconstruction techniques were used to reduce data acquisition time to about 10 s/image and to improve temperature mapping resolution. Thermocouples were implanted into the sample so that temperature and MRI data were acquired simultaneously. the error in MRI measurements caused by noise and the time delay required to collect each data set was less than 0.84C with 0.75 mm2resolution. the average variation between MRI and thermocouple measurements was less than 0.5C. This is a promising new technique to noninvasively study heat transfer and to measure thermal properties of food materi

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1994.tb00347.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Matrix Data Structure (MDS) and the Gozinto Procedure (GP) can be the basis for resource tracking and for costing systems used in the food industry. These methods have enjoyed great success and broad application among fabricators, but they have not been used much in process industries, including the food industry. While the main data entry requirement for such a system is to build accurate bills of material (BOM) for the intermediate and finished products, this is not sufficient to make a useful application in the food industry. Food and other process industries need such a system to convert between purchase units, batch units and sales units. This conversion problem and the existence of unit operations that are separation processes have prevented the application of these methods in the industry. These two problems have led to many ad hoc methods for calculating costs and tracking resource use. the unit conversion problem (purchasing in pounds, kilograms or gallons of input materials, processing batches of intermediate products, and selling containers or cases of finished product) is solved by introducing a unit conversion matrix to the system. the problem of multiple counting the input material going into a separation process is solved by using dummy input material names for the BOM of the products coming out of the separation process. the solution to these problems have provided access to the structural power of MDS as an organizational tool and the application of GP to the matrix structure to obtain integrated, consistently computed information to support managers in the production planning and control activities.

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1994.tb00348.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

A laboratory study was conducted to assess the efficiency of using a combination of flocculating substances to remove organic constituents from poultry chiller water. Rice bran in combination with commercial flocculant AP‐273 (polyelectrolyte) removed 60% and 72% of chemical oxygen demand (COD) from low and high COD samples, respectively. Addition of granular activated carbon to the flocculant mixture increased COD removal to about 75%, respectively, from the same samples. Turbidity (suspended particles) of the chiller water was reduced by more than 90% using flocculant AP‐273 plus rice bran. Chlorine demands were also greatly reduced. Soluble inorganic mineral content was not reduced by the combined flocculating substances. the residues collected after flocculation could be used as a feed ingredient, or as an organic fertilizer. Flocculation of chiller water would be a beneficial pretreatment to further recycling processes or to microfiltration of chiller water for re

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1994.tb00349.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

With equivalent electrical energy input, inactivation of microorganisms by pulsed electric fields depends on pulse waveform. Exponential‐decay and square‐wave pulsed electric fields were selected to treatSaccharomyces cerevisiaesuspended in apple juice. A parallel‐plate static treatment chamber with 25 ml volume and 0.95 cm electrode gap was used. Peak electric field and pulse electric energy input were 12 kV/cm and 260 Joules per pulse for both waveforms. Both waveforms were found effective in the microbial inactivation. However, inactivation ofS. cerevisiaetreated with square‐wave pulses was greater than yeast treated with exponential‐decay pulses. For the purpose of food pasteurization, square‐wave pulsed electric fields may result in significant energy savings compared to exponential

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1994.tb00350.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY