ECONOMIC ANALYSIS OF ALTERNATIVES TO MANUAL SORTING USING SELECTED ELECTRONIC GRADERS IN ASPARAGUS FRESH PACKING

Supplying quality fresh asparagus to the consumer begins with rapid handling at the fresh packing shed, which in turn requires a significant amount of labor. This study analyzed the effects of reducing the required labor by using selected electronic graders in the grading and sorting process of fresh asparagus packing firms. Four alternative electronic graders were considered by using two throughput scenarios of 680 and 880 kg/h with 25 people. The electronic graders generated labor savings in all cases. In the first scenario, substituting technology for labor produced modified internal rates of return (MIRR) of between 30 and 39%. All four graders in the second scenario had positive returns, with an MIRR range of 8 to 21%. The electronic graders have the potential to increase the profitability of fresh asparagus packing firms.     

Physicochemical Properties of Ovalbumin and Lysozyme Treated with Oleic Acid

Results from polyacrylamide gel electrophoresis confirmed that proteins were more negatively charged in the presence of oleic acid. The electrophoretic mobility of unmodified and modified lysozyme was of opposite but similar magnitude. Critical micelle concentration (50.0 μ M) of oleic acid suggested that association between the fatty acid and proteins was mostly hydrophobic. Muramidase activity of modified lysozyme and difference spectra of modified ovalbumin suggested that oleic acid was partially or totally surrounding the proteins. Improved freeze-thaw characteristics of treated egg white were attributed to greater negative charge and instability of proteins produced by oleic acid.     

Thermally Induced Gelation of Native and Modified Egg White-Rheological Changes During Processing; Final Strengths and Microstructures

The heat-induced gelation of native egg white (EW) and egg white modified with succinic anhydride (SEW) or oleic acid (OEW), by addition of 15 moles of reagent/50000g protein, was evaluated. Rigidity modulus (G) and mechanical energy damping were continuously monitored during heating of the samples from 5 - 95°C in a nondestructive temperature-controlled thermal scanning rigidity monitor (TSRM). A measurable increase in G and decrease in energy damping were observed at lower temperatures for OEW than for EW. In SEW the measurable rheological transitions occurred at the highest temperature ranges. Failure strength of the cooked products (gels) evaluated using torsion and uniaxial compression tests revealed large differences due to treatments. Micrographs of gels showed apparent structural differences among treatments.     

A Chemical and Biological Study of Acylated Egg White

Egg white treated with acetic and succinic anhydride was evaluated chemically and biologically. Lyophilized albumen contained 4.9% moisture and 82.0–85.8% protein. Acetylation blocked 64 and 68% total and epsilon amino groups while sucdnylatkm blocked 52% total and 55% epsilon amino groups, respectively. The in vitro multi-enzyme technique for evaluating protein digestibility indicated that untreated and treated egg white both were about 80% digestible. Weight gain of chicks fed acylated egg white as the sole source of dietary protein was significantly less than that of chicks fed the control. Chick mortaility observed during the bioassays was attributed to a sodium and chloride imbalance in the diets.     

Influence of Poultry Species, Muscle Groups, and NaCl Level on Strength, Deformability, and Water Retention in Heat-Set Muscle Gels

The effects of poultry species (chicken and turkey), muscle groups (breast, thigh, and drum) and NaCl concentration (1% and 2%) on a low fat gel system were compared using measurements of shear stress (strength), shear strain (deformability), and two water retention measurements. Results showed doubling NaCl tended to double stress for all species and muscle groups and increased strain by 30–50%. Cross species differences showed higher stress in turkey gels than in chicken gels with 2% NaCl. For both species, stress, strain and water retention were lowest in breast gels with both NaCl concentrations, and strain was greater in thigh gels than in drum gels with 2% NaCl.     

Concentration of Liquid Egg White by Vacuum Evaporation and Reverse Osmosis

Egg-white was concentrated by vacuum evaporation (VE) and reverse osmosis (RO). The treatments consisted of a control, RO process, VE process using 50°C water-jacket temperature and 60-min processing time (5060VE), and a VE process using 60°C water-jacket temperature and 45-minute processing time (6045VE). Solids contents for the concentrates were 17.82% for the RO. 17.41% for the 6045VE. and 18.98% for 5060VE. The VE product had better foaming properties and comparable gel qualities to that of the RO product. Foam enhancing and stabilizing additives improved the quality of all concentrates. Electrophoretic studies indicated a significant decrease in globulins A1 and A2 in the VE treatments.