Liquid Whole Egg Research Articles

Effect of Ultrapasteurization With and Without Homogenization on the Electrophoretic Patterns of Aseptically Processed Liquid Whole Egg

Polyacrylamide gel electrophoresis was performed on ultrapasteurized liquid whole egg (LWE), which was either homogenized or unhomogenized and heated at 64, 68, or 72 C each for 30, 60, or 95 s. Native PAGE was used to determine the effect of ultrapasteurization in combination with homogenization on LWE protein. The α-livetin band was absent at 72 C for 60 and 95 s processing times but remained present at the 30-s treatment time at 72 C and for all processing times at 64 and 68 C. Protein bands of the globulin/β-livetin and ovotransferrin/γ-livetin fractions appear to have faded in all heat-treated samples in comparison with the unheated samples, reflecting their heat instability. Homogenization had no effect on the presence of protein bands identified by PAGE.

Functional Properties and Composition of Liquid Whole Egg Proteins as Influenced by Pasteurization and Frozen Storage

Effects of pasteurization temperature and frozen storage on the functionality and soluble protein composition of liquid whole egg (LWE) were studied. Homogenized LWE control and LWE heated at 60, 64, or 68 C for 3.5 min were evaluated during 80 days of storage at −24 C. Protein solubility decreased by 11% when LWE was heated to 68 C. Protein solubility decreased 17 and 11% in LWE control and LWE heated to 68 C, respectively, during frozen storage. Polyacrylamide gel electrophoresis was used to monitor changes in soluble protein composition. Percentages of soluble ovotransferrin and globulin proteins decreased during pasteurization and frozen storage. Quality attributes of a pie filling were influenced by pasteurization and frozen storage of LWE.

Listeria Species in Commercially Broken Raw Liquid Whole Egg

Commercially broken raw liquid whole egg (LWE) was obtained from 11 processing establishments across the United States on 3 or 4 occasions over an eight-month period. The samples were evaluated for the presence of Listeria species by the FDA, USDA, and cold enrichment procedures. Forty-five Listeria isolates were obtained from 15 of 42 (36%) egg samples. Both the USDA and FDA methods were useful for isolation of Listeria species, resulting in 12 and 8 positive samples, respectively. Six samples were positive by both procedures. Listeria was isolated from one sample by cold enrichment. The most frequently isolated species was L. innocua, which was found in all (15) of the listeriae-positive samples. L. monocytogenes was the only other species isolated and was obtained from 5% (2) of the egg samples. The USDA and FDA procedures each yielded one L. monocytogenes-positive sample. The two L. monocytogenes-positive samples contained estimated populations of 1 and 8 CFU L. monocytogenes/ml and were obtained from the same plant during the spring and early summer sampling times. Twelve (80%) of the 15 Listeria-positive samples were solids-adjusted LWE. Thus, Listeria species, including the psychrotrophic pathogen L. monocytogenes, are present in commercially broken raw LWE.

Salmonella Inactivation in Liquid Whole Egg by Thermoradiation

ABSTRACT Salmonella enteritidis in liquid whole egg (LWE) was inactivated using heat, radiation and thermoradiation (combined heat and radiation). Rates of Salmonella inactivation were determined as a function of radiation dose, temperature, initial cell number and pH. Thermoradiation caused a greater reduction in viable cell number than either heat or radiation alone. This effect was more pronounced at pH 6.5 than at pH 7.0, and more so at 60°C than at 50°C. The lower the initial cell number, the faster the rate of Salmonella inactivation. Physical denaturation of LWE was not apparent after thermoradiation below 60°C, and endogenous egg white lysozyme was not affected by thermoradiation (19.5 krad, 60°C) treatment.

Rheological Properties of Pasteurized Liquid Whole Egg During Frozen Storage

ABSTRACTEffects of pasteurization and frozen storage on the rheological behavior of liquid whole egg (LWE) were studied using a cone and plate viscometer. Homogenized LWE control and LWE heated at 60°C, 64°C or 68°C for 3.5 min were evaluated during 80 days storage at −24°C. Thixotropic behavior was observed in all frozen samples. Apparent viscosity increased with pasteurization and frozen storage. Unpasteurized LWE exhibited Newtonian behavior throughout storage. Pasteurized LWE flow properties changed from Newtonian to Bingham Plastic during storage. Identification of rheological parameters will help understand the molecular changes that occur during the processing and storage of LWE and help processors monitor LWE quality.

MAXIMUM CHANGE IN PHYSICAL AND QUALITY PARAMETERS OF FLUID FOODS DURING CONTINUOUS FLOW HEATING. APPLICATION TO LIQUID WHOLE EGG

A fluid in continuous flow heating approaches maximum thermal treatment as the viscosity profile becomes plug flow. This effect is examined for physical and quality changes in tubular heating of fluid foods. Arrhenius mathematical forms of constituent change are incorporated into the thermal profile models for the general case. Application to soluble protein loss (SPL) and viscosity change in liquid whole egg (LWE) are used as examples. Time and temperature schedules are suggested for pasteurization of LWE at elevated temperatures and shorter times, relative to standard schedules, based on the plug flow velocity profile assumption.

Flow Behavior of Liquid Whole Egg During Thermal Treatments

Costs of handling and loss of functional properties of frozen liquid whole egg (LWE) has stimulated interest in a refrigerated product. To maintain adequate shelf life at refrigeration temperatures a heat treatment more severe than normal pasteurization may be needed. To establish limits for the thermal treatment and to prevent possible damage to the pasteurization system due to coagulation of the product, flow properties of LWE during pasteurization were investigated. Utilizing a cone and plate viscometer, egg viscosity was determined at shear rates between 1.15 and 450 sec−1. Test temperatures varied from 20-75°C and heat treatment durations ranged from 0.5-10 min. Percent protein denaturation for each treatment was also determined and correlated to the flow properties. Above 60°C viscosities were shear rate dependent while below this temperature flow properties were approximately Newtonian. Mathematical expressions were developed for viscosity as a function of time, temperature and shear rate.