Protein Hydrolysates for Reducing Water Activity in Meat Products

Soy protein hydrolysates were assessed for their effectiveness as water activity (a_w) lowering agents. Four protein hydrolysates were prepared by the following treatments of soybean flour: 1N H₂SO₄ (7hr), 2.5% Alcalase (15hr), 2.5% bromelain (15hr), and combined acid-enzymatic (0.5N H₂SO₄, 7 hr - 1.25% Alcalase, 6 hr). Of all the soy protein hydrolysates in solution at a 20% solids level, the acid-enzyme (A-E) hydrolysate solution had the lowest a_w When 3.3 - 4.6% of this A-E hydrolysate was incorporated into raw and steamed beef sausages and broiled beef patties, a_w was reduced to a level equivalent to that for beef with 1% added NaCl. Sensory analysis of broiled ground beef supplemented with 2.5, 5.0 and 10.0% of A-E hydrolysate did not significantly alter the flavor. The A-E hydrolysate may be used as a substitute for sodium chloride in enhancing the shelf life of meat products.     

Production of Nonbitter, Desalted Milk Hydrolysate for Fortification of Soft Drinks and Fruit Juices

A simpler and less expensive process than the process of Helbig et al. (1980) for preparation of a nonbitter, desalted milk hydrolysate is presented. Skim milk was hydrolyzed with Alcalase (subtilisin Carlsberg) at 50°C in 3 hr. The resin in OH form was added to milk batchwise to simultaneously raise the pH to 8.5 for optimum proteolysis and exchange the anions in milk which contributed to saltiness. These modifications resulted in a shorter hydrolysis time and a more economical resin regeneration than those of the Helbig process. The dried milk hydrolysate was added to soft drinks and fruit juices at solids concentrations up to 10% (3% protein) without adverse effects on their taste, color, viscosity and clarity.     

ULTRAVIOLET SPECTROPHOTOMETRIC DETERMINATION OF PROTEIN IN SOME FOOD PRODUCTS

SUMMARY— The spectrophotometric method of estimating the protein content of whole milk at wavelength 280 nm (Nakai and Le, 1970) was modifed for corned beef, flour, bean and egg yolk. A clear solution was obtained by adding 50% sulfuric acid or 2N sodium hydroxide with and without 7–8M urea depending on solubility of the food products. The protein content was calculated from the absorbance at 280, 243 or 215 nm on o spectrophotometer. The correlation coefficient between the absorbance and the protein by Kjeldahl method was 0.99, 0.99, 0.99 and 0.99 with the coefficient of variability of Kjeldahl protein for absorbance of 1.8, 4.1, 3.8 and 4.1% for bean, corned beef, egg yolk and flour, respectively.     

Predicting Milk Shelf-life Based on Artificial Neural Networks and Headspace Gas Chromatographic Data

The usefulness of artificial neural networks (ANN) for milk shelf-life prediction by multivariate interpretation of gas chromatographic profiles and flavor-related shelf-life was evaluated and compared to principal components regression (PCR). The training set consisted of dynamic headspace gas chromatographic data collected during storage of pasteurized milk (input information for the neural network used to make a decision) and its corresponding shelflife (prediction or response). ANN had better predictability than PCR. A standard error of the estimate of 2 days in shelf-life resulting from regression analysis of experimental vs predicted values indicated a high predictability of ANN.     

Lysozyme Separation from Egg White by Cation Exchange Column Chromatography

Cation exchange column chromatography was investigated for simple and efficient separation of lysozyme from homogenized egg white. A macroporus weak acid type resin, Duolite C-464, was selected based on high lysozyme recovery in the90–95% range, retention of whipping and gelling properties in the lysozyme-separated egg white, and ease of column operation. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicated high purity of the recovered lysozyme and simultaneous recovery of avidin under the eluting conditions used. The process for lysozyme separation from egg white using Duolite C-464 is suitable for operation in an automated, continuous mode.     

Extended Shelf Life of Frankfurters and Fish Frankfurter-Analogs with Added Soy Protein Hydrolysates

Incorporation of a low salt protein hydrolysate into a sausage batter significantly extended the shelf life of the product stored at 25°C. This temperature was chosen for saving the energy costs for refrigeration. The supplemented frankfurters (a_w= 0.92) had CFU/g l/5000 and 1/ 1000 of that for the unsupplemented controls (a_w= 0.97) after a 10day aerobic and anaerobic storage at 25°C, respectively. However, bacterial counts of fish frankfurter-analogs treated similarly were reduced only slightly. Differences in flavor and texture between the supplemented and unsupplemented frankfurters were nonsignificant. Supplemented fish frankfurter-analogs were found to be significantly softer than the unsupplemented controls.     

Static Headspace Gas Chromatographic Method for Volatiles in Canned Salmon

Amount of fish placed in vials as well as incubation temperature and time were factors studied to improve a static headspace sampling method applied to analyze volatiles in canned salmon. A random-centroid optimization program (RCO) was used to simultaneously search for the optimal levels of other factors, namely, initial oven temperature, column headpressure, and total flowrate. RCO was an effective optimization program while allowing testing of several treatments at a time. The optimal conditions of operation permitted detection of 80 volatile compounds, 34 of which were identified including aldehydes, alkanes, aromatic compounds, sulfur-containing compounds, alkenes, ketones, several miscellaneous compounds plus an alcohol and an acid.     

Proposal and Feasibility Study of the Integrated Diode Synchronous Motor

This paper presents a new type of magnet‐free motor that has concentrated stator windings and rotor coils with a pair of diodes. The most important feature of this motor is that currents in the rotor coils can be generated by utilizing the changes in the spatial second harmonic of the magnetic fields due to the concentrated stator windings, which normally increase motor losses. A prototype of the motor was designed and fabricated, and its basic performance was evaluated. First, using simplified analytic models, we explain the mechanism of inducing currents in the rotor coils by the changes in the spatial second harmonic of the magnetic fields. Second, we compare the torque performance of the proposed motor and that of other types of motors including a magnet motor through finite‐element analyses. The analyzed data show that the proposed motor can possess greater torque/volume ratio than that of the other motors. Finally, using the measured data, we validate the mechanism of inducing currents in the rotor coils, and examine the torque and power characteristics of the motor.