Volatiles in Skin of Low Dose Irradiated Fresh Chicken

Fresh chickens were irradiated with up to 1200 krad at 0–5°C. Volatile compounds from the skin and subcutaneous fat of these chickens, and from unirradiated controls, were analyzed by gas chromatography. Acceptability of the odor of the chickens was also evaluated. Other samples (0 and 300 krad) were evaluated by chemical and sensory analysis after storage at 4°C. Analysis of volatiles indicated that levels of octane, l-octene, hexanal, and nonane increased regularly with radiation dose. Amount of total volatiles was greater in unstored irradiated samples than in controls, but this was reversed after storage. After 14 days, the irradiated sample still had acceptable odor, while the control ahd severely deteriorated.     

A Model System for Curd Formation and Melting Properties of Calcium Caseinates

A lipid-free model system was developed to aid in the study of melting and other functional properties of calcium caseinates in their application to imitation processed cheese. The model system was formed by the controlled addition of water to an alcohol suspension of the protein. At a critical water concentration, a curd was formed spontaneously. The recovered curd was melted and the area of the melt determined (melt area index). The amount of water added, rate of water addition and the source of caseinate affected the melt area index. A protein fraction, recovered from the supernatant, was rich in γ-casein and also contained minor amounts of β-, α_s- and k-caseins.     

THE β-N-ACETYLGLUCOSAMINIDASE ACTIVITY OF EGG WHITE. 1. Kinetics of the Reaction and Determination of the Factors Affecting the Stability of the Enzyme in Egg White

SUMMARY– Enzymatic activity of β-N-acetylglucosaminidase, which occurs naturally in chicken egg white, was characterized to establish conditions suitable for routine assay for this enzyme in egg products. A variation in enzyme content of approximately 3-fold was observed in individual fresh eggs. The enzyme has a pH optimum between 3.0 and 3.4, and a K_m of approximately 0.6 mM for the substrate p-nitrophenyl-N-acetyl-β-D-glucosaminide. Activation energy for hydrolysis of this substrate is 10.7±0.8 kcal/mole. The enzyme is stable for at least several hours at ambient temperature from pH 6.8 to approximately 8.8. Above pH 8.8, inactivation is first order with respect to time. Enzyme activity in shell eggs decreases fairly rapidly at ambient temperature; loss of activity probably results from increase in pH of egg white, which occurs normally upon loss of carbon dioxide. Eggs held at 4°C retain activity much longer.     

LIPIDS OF CURED CENTENNIAL SWEET POTATOES

SUMMARY –Lipids isolated from cured Centennial sweet potatoes were identified and quantitated by a combination of column and thin layer chromatography. These lipids were shown to consist of 42.1% neutral lipids, 30.8% glycolipids and 27.1% phospholipids. Triglycerides and steryl esters were the major lipids of the neutral fraction. Among the phospholipids, phosphatidyl ethanolamine, phosphatidyl choline and phosphatidyl inositol were the most abundant. Galactolipids and the steryl glucosides were also present. The predominant fatty acids were stearic, palmitic, oleic, linoleic and linolenic.     

Effect of Storage Temperature on the Stability of Aseptically Packaged Concentrated Orange Juice and Concentrated Orange Drink

Commercial orange drink concentrate and two orange juice concentrates were aseptically packed in flexible bags and stored at 4°, 15°, 22°, and 30°C for 6 months. Ascorbic acid, nonenzymatic browning and sensory quality were measured monthly. Sensory characteristics for drink concentrate deteriorated after 3 and 4 months at 30°C and 22°C, respectively. Juice concentrates were unacceptable after 2 and 5 months at 30°C and 22°C, respectively. Drink concentrate ascorbic acid loss was greater than juice concentrates at 4°, 15°, and 22°C. Changes in nonenzymatic browning as measured by Hunter color and by absorbance at 420 nm were similar to changes in other containers. The quality of refrigerated aseptic drink (15°C) and juice (4°C) was similar to frozen concentrates (?18°C).     

Effect of Low-Dose Irradiation and Post-Irradiation Cooking and Storage on the Thiamin Content of Fresh Pork

Low-dose gamma irradiation of vacuum-packaged, ground fresh pork resulted in a dose-dependent, first-order rate of thiamin destruction (R²= 0.99). Thiamin losses for raw pork irradiated at 0.57, 1.91, 3.76, 5.52 and 7.25 kGy were 7.7, 23.5, 38.1, 49.8 and 57.6%, respectively, of the nonirradiated sample. Post-irradiation cooking resulted in additional thiamin losses of 11.3, 11.5, 13.0, 13.6, 13.5 and 15.0% for respective treatment samples irradiated at doses of 0, 0.57, 1.91, 3.76, 5.52 and 7.25 kGy. Time of storage had little effect on the thiamin content of raw irradiated and nonirradiated pork.