The use of magnetic resonance (MR) imaging is growing exponentially, in part because of the excellent anatomic and pathologic detail provided by the modality and because of recent technologic advances that have led to faster acquisition times. Radiology residents now are introduced in their 1st year of training to the MR pulse sequences routinely used in clinical imaging, including various spin-echo, gradient-echo, inversion-recovery, echo-planar imaging, and MR angiographic sequences. However, to make optimal use of these techniques, radiologists also need a basic knowledge of the physics of MR imaging, including T1 recovery, T2 and T2* decay, repetition time, echo time, and chemical shift effects. In addition, an understanding of contrast weighting is very helpful to obtain better depiction of specific tissues for the diagnosis of various pathologic processes.

A beverage consisting of water, whole soybeans (including hulls), sugar and flavor has been developed. Preparation includes soaking and then blanching the whole soybeans in 0.5% sodium bicarbonate, grinding with water in a hammermih, heating the slurry to 200"F, homogenizing, neutralizing, dilution, addition of sugar and flavor, pasteurizing and rohomogenizing. Enzyme inactivation by blanching prior to grinding of soaked beans was found to completely prevent formation of painty (oxidized) flavor and result in a bland flavored product. Trypsin inhibitors were also inactivated by blanching. A sufficient degree of tenderization of soybean tissue during the soak and blanch treatments was necessary to obtain good mouth feel and colloidal stability. Homogenizing conditions such as temperature and pressure were also important; when the soybeans had been blanched to a LEE-Kramer Tenderometer reading of 300 lb or below and homogenization was done at 200°F and 3500 psi, the resulting beverage showed zero separation after 2 months refrigerated storage. Dilution to below 1% protein had no effect on colloidal stability. Coulter Counter measurements of the beverage indicated that 81% of the particles fell between 3.4-7.3 microns which is larger than the defined colloidal particle range. Recoveries of protein and total solids based on the raw soybean were 99% and 90%, respeo tively.

A new concept is described for mechanical extraction of oil from soybeans, using dry extrusion as a pretreatment. It was found that coarsely ground whole soybeans at 10 to 14% moisture could be extrusion cooked so that the extrudate emerges from the die in a semi‐fluid state. The dwell time within the extruder was less than 30 seconds, and the temperature was raised to about 135 C. The semi‐fluid extrudate was immediately pressed in a continuous screw press to obtain high quality oil and press cake. Extrusion prior to expelling greatly increased the throughput of the expeller over the rated capacity. An oil recovery of 70% was obtained in single pass expelling using pilot model expellers. Higher recovery rates can be expected with commercial scale expellers. The high temperature‐short time extrusion cooking process eliminates the prolonged heating and holding of raw material in conventional expelling. Under the experimental conditions, press cake with 50% protein, 6% residual oil and 90% inactivation of trypsin inhibitors was obtained. The low fat cake was easily ground in a hammer mill without the usual problems associated with milling of whole beans. The expelled oil was remarkably stable with an AOM stability of 15 hr, which is comparable to refined deodorized oil according to NSPA specifications. The new procedure offers potential for producing natural soybean oil and food grade low fat soy flour by a relatively low cost operation. It may be adopted as an improvement to existing conventional expelling operations in less developed countries or as a commercial or on‐farm operation for producing value added products from soybeans within the U.S.

No abstract

The objective of this work was to determine the processing conditions responsible for suspension stability of Illinois soybean beverage and to elucidate the role of lipid in this stability. Stability was determined by visual and objective means after 5 days quiescent storage at 1°C. Pressure and temperature of first and second homogenization, formulation, lipid component and accelerated settling were studied. Homogenization pressure must be such that the sum of the two pressures must be at least 5000 psi and the minimum temperature of one of the two homogenizations must be 82°C. Free and, especially, bound lipid are necessary for stability. The hypothesis that stability is promoted by formation of a lipid-protein complex was further demonstrated by centrifugation and film formation studies. Formulation plays a minor role in stability.

Chalkiness is a defect used to describe a food which coats the mouth and throat with fine, grainy particles. This study evaluates the processing and formulation variables which affect chalkiness of Illinois process soymilk produced from dehulled soybeans. Alkalinity of the blanch solution, homogenization conditions, soymilk pH, and solids concentration had the most pronounced effects on chalkiness. Increasing blanch alkalinity decreased chalkiness; beverages adjusted to higher final pH were less chalky. Homogenization at higher temperatures or pressures also significantly reduced chalkiness. Chalkiness increased with soy solids concentration. Beverages produced using conditions to effect optimal quality were compared to low quality products. Centrifugal desludging reduced chalkiness to an imperceptible level. Particles retained by 150 mesh were primarily responsible for chalkiness. The process conditions leading to minimum chalkiness were: direct blanch of cotyledons in 0.25% NaHCO, ; homogenization at 180°F and 3500 psi; formulation with 6% soy solids; beverage pH of 7.5.

SUMMARY A kinetic procedure employing D values was used instead of the usual end‐point method to study heat inactivation of peroxidase in whole‐kernel sweet corn. Results at 150–200°F indicated that a heat‐labile fraction and a heat‐stable fraction were being inactivated. The resistant fraction represented 5% of total enzyme activity, and was concentrated in the pericarp. Increasing the blanch time at 200°F from 2 to 5 min decreased residual enzyme activity from 3.3% to 1.7%. Inactivation of the heat‐resistant fraction at 210–290°F also followed a first‐order reaction. The phantom inactivation‐time curve showed that an HTST process based on microbial destruction could leave residual enzyme activity.

This study was done to characterize the changes that occur during refrigerated storage of six salad vegetables individually and in a mixture.Salad-cut and intact lettuce, carrot, celery, radish, green onion and endive, and a salad mixture were stored at 4.4"C in packages made from a film having low gas permeability. Respiration of individual vegetables during storage showed two patterns: carrot and celery respired throughout the storage time while respirations by the others was halted after a few days. Respiration of cut vegetables exceeded that of intact. Total plate counts (TPC) for intact vegetables in storage increased slower than for cut vegetables; lettuce and endive showed higher TPC than the others. The cut vegetables were invariably poorer in organoleptic quality. Mixed vegetable salads were sealed with either air or an atmosphere containing 10.5% CO,, 2.25% 0,. After 2-wk storage, organoleptic evaluation indicated that the chemical treatments were generally of no value and in some cases were even detrimental but the modified initial headspace was beneficial.