Detection of irradiation in scampi tails — effects of sample preparation, irradiation dose and storage on ESR response in the cuticle

This paper describes the potential of using ESR spectroscopy for the identification of irradiated scampi (Norway lobster) using the signal induced in the cuticle at 349.5 mT. Freeze-drying the cuticle gave a larger signal than air-drying, and peak height was found to be a more reliable method of quantification than double integration of the peak. There was a linear response with increasing irradiation dose. Samples were stored intact at –20°C and +5°C and as dry shell at room temperature for up to 84 d and it was observed that signal intensity was reduced with increased storage time and higher temperature, especially at the higher doses. Thus ESR spectroscopy can be used to detect irradiation in scampi cuticle and has potential for the estimation of irradiation dose.     

Evaluation of a Water Jet Cutting System for Slicing Potatoes

A water jet cutting machine was used to slice potato tubers, and characteristics of the cut surfaces were studied. Irregularities on the cut face were visualized by staining with a nonspecific protein stain. The amount of protein extractable from the cut face was measured and used to quantitate the cellular damage resulting from different water jet operational conditions. Observations were confirmed with scanning electron microscopy. A wide range of water jet settings could be used to cut potato slices. French fries cut with the water jet set to cause intermediate subsurface damage had increased color irregularities but no extreme taste or textural differences compared to conventionally cut controls.     

Investigation into the Formation of N-Nitrosamines in Heated Chicken Frankfurters

Chicken frankfurters, prepared with various levels of sodium nitrite (0, 20, 40, 60, 100, and 156 ppm) were heated either in a microwave oven, boiled or broiled and then analyzed for N-nitrosamines. As expected, “apparent” N-nitrosamine levels increased with increasing concentrations of sodium nitrite. The effect of the various heating procedures on N-nitrosamine formation was inconclusive, due possibly to the low levels of “apparent” N-nitrosamines present. The two most common N-nitrosamines present appeared to be N-nitrosodimethylamine and N-nitrosomorpholine. However, only in the frankfurter samples prepared with 156 ppm nitrite was the presence of N-nitrosomorpholine confirmed by mass spectrometry.     

Effects of Cooking and/or Processing Upon Levels of Aflatoxins in Meat from Pigs Fed A Contaminated Diet

Pork loins, bellies and hams from pigs fed a diet containing 571 and 386 Mg of aflatoxins B₁ and B₂ per kg of feed, respectively, for 42 days were analyzed for aflatoxins in the fresh, fresh-cooked, cured smoked (hams only) and cured-smoked-cooked states. Although some destruction of aflatoxins B₁ and B₂ occurred during cooking and/or processing, the maximum amount of inactivation did not exceed 41% of the total, and was generally in the range of 15–30%. Thus, results suggest that aflatoxins are quite stable during cooking and/or processing.     

The effect of post-irradiation cooking on the ESR signal in irradiated chicken drumsticks

Groups of seventy-two, 6-week-old broiler chicken carcasses were either not irradiated and served as controls or were given 2.5 or 5.0 kGy doses of irradiation. Half of each group remained uncooked and half were cooked in a convection oven at 190°C. Pairs of drumsticks were taken from each carcass, the bones excised and the free radical content measured using electron spin resonance (ESR) spectroscopy. The ESR signal strength increased significantly as irradiation dose increased, the value at 5.0 kGy being 96% greater than that at 2.5 kGy. Cooking significantly reduced the free radical concentration of the irradiated bone by approximately 23%.     

The application of photo-conductors as voltage variable operational elements in iterative analogue computation†

This paper is concerned with the application of photo-conductors as variable operational resistor elements in iterative analogue computation. Suitable control circuits have been devised which achieve a linear relationship between a controlling voltage level and the resistance of the variable operational element. The use of crystal lumps in conjunction with silicon photo-detectors enables control circuit settling times of the order of 180 µsec to be achieved and results indicate that with the correct choice of detector, the speed of the controlled response is limited only by the performance of the operational amplifier in the control circuit.