摘要:

ABSTRACTA methodology was developed for the evaluation of centerpoint nutrient degradation in conduction heating canned food subjected to thermal processing. the methodology involved sealing of 75μL aliquote of test solution in a leakproof pressure‐stable stainless steel capsule, placing the capsule at the geometric center of a can filled with a conduction heating simulated food prior to the closure, and recovering the capsule and analyzing the contents following a given thermal treatment. Experiments carried out using aqueous solutions of ascorbic acid and thiamine indicated good reproducibility of the results. Employing kinetic data for thermal destruction of the nutrients and center temperature‐time history of the food simulant obtained from several simultaneously processed cans, the centerpoint nutrient retention predicted by several models agreed favorably with the experimental res

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1990.tb00048.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTA mathematical model for a radial, continuous‐crossflow dryer was modified and used to simulate the drying process in a fixed bed dryer. the predictions of the adapted model were compared with experimental test results for canola drying at the following drying conditions: airflow rates of 0.4 and 0.6 kg/(m2s), inlet air humidity 0.098 and 0.0114 kg/kg of dry air, initial grain moisture content 0.221 and 0.251 kg/kg dry basis. In both tests the inlet drying air temperature was kept at an average of 67.5°C. At the end of canola drying, the mean drying air temperature predicted by our model was within 1°C of the measured temperature and the mean predicted moisture content was within 0.5% of the measured moisture content, dry basis. Also, our model was verified against experimental results for barley published by other authors and against predictions from a published model for barley. the predictions from our model were in good agreement with the published experimental and predicted data. Simulations results for canola and barley drying in the same thickness of a deep bed were compared. Simulations were conducted to investigate the effects of canola properties such as bulk density and dryinig conditions of air such as airflow rate and air humidity on drying in deep beds of can

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1990.tb00049.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTCommercial scale ceramic microfilters were used in plant tests to determine flux rate and operating parameters for waters from a poultry scalder, a poultry chiller, and brine from a delicatessen products chiller, under commercial conditions. Filtration produced clear permeate from all waters. Microorganism counts were essentially reduced to zero in scalder and chiller water permeates, with BOD reduced by about 70% in scalder water permeate and about 60% in chiller water permeate. Flux rates were in the range of 224‐204 L/m2h for scalder water at 54°C and 114‐81 L/m2h for chiller water at ambient temperature. Test results were used to project nonlabor operating savings and/or costs resulting from the use of microfiltration to recondition and reuse bath overflow. For a processing rate of 140 birds/min and bath size of 37,850 L (10,000 gal), an annual savings of $21,000‐$26,000 were estimated for scalder water filtration, while annual costs of $65,000‐$84,000 were estimated for chiller water filtration. For a deli brine bath size of 1,170 L (300 gal), annual costs of about $700 were estimated. Retentate heating and electrical usage associated with centrifugal filter pumps were projected as predominant cost factors. Besides costs, other factors such as nonchemical control of microbial growth, water savings, and reduced discharge levels may also be important reasons for considering microfi

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1990.tb00050.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThermal performance of thin film scraped surface heat exchanger was evaluated for concentration of milk to high solids with process variables such as mass flow rate, steam condensing, temperature, etc. Appropriate dimensionless groups were formulated and fitted in Cobb‐Douglas model to obtain a correlation. This relationship which is in the form of a Nusselt equation will be useful in predicting the scraped film coefficient during milk concentration to high solids. the effect of process variables on scraped film coefficient were discusse

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1990.tb00051.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTA procedure similar to the one commonly used with mixers has been utilized to develop a model for estimating the shear rate in co‐rotating twin screw extruders. Newtonian and non‐Newtonian fluids were used to estimate the average shear rate for three screw configurations of a Baker Perkins (MPF‐50D) twin screw extruder. As would be expected, the shear rate was highly correlated to the screw speed. At a given screw speed, 30 forwarding paddles generate the highest rate of shear, followed by feed screws and single lead screws. No data was found in the published literature to provide comparison with the results of this work. However, the model has performed well in heat transfer analysis of twin screw processes.The procedure is sensitive to screw configuration, accounts for the shearing effects in the different regions within the extruder barrel, and covers a range of screw speeds (100–400 RPM) typical of what is encountered in industrial pilot plants. Even though much more work remains to be done before the shear rate can be confidently characterized for composite screw configurations, this technique provides a sound fou

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1990.tb00052.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY