Long wavelength infrared 128×128 AlxGa1-xAs/GaAs quantum well infrared camera and imaging system

The authors discuss the development of a long-wavelength (8-14-μm) 128×128 Al_xGa_1-xAs/GaAs multiquantum well infrared (MQW IR) imaging system. Highly uniform, high-yield GaAs focal plane arrays, incorporating an integral grating structure for efficient optical coupling, were hybridized to CMOS multiplexers. Excellent imagery, with low noise, a noise equivalent differential temperature (NEΔT) of less than 10 mK, and a high image contrast signal-to-noise ratio, has been achieved. It is shown that figures of merit concerning array uniformity, such as yield, NEΔT, and maximum deliverable charge to the CMOS multiplexer are much more relevant variables that affect image quality than D*     

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.     

Physical Properties of Pecans Relating to Shelling Efficiency

Inshell pecans of 21 cultivars and numbered trial selections were evaluated for selected physical properties and for their adaptability to be efficiently shelled by existing commercial technology. Processing efficiency was based on yield of unbroken half kernels during shelling. There were highly significant differences among varieties in both selected physical properties and shelling efficiency. Correlations between shelling efficiency and physical properties were determined. Results showed that percent total kernel, inshell length/diameter ratio and shell thickness were the physical properties that appeared to have the greatest effect on shelling efficiency.     

Cotyledon Structure of Resting Peanut (Arachis Hypogaea L. cv. Florunner) Seed Before and After Hydraulic Pressing

The cotyledon structure of resting peanut (Arachis hypogaea L. cv. Florunner) seed before and after hydraulic pressing was investigated with light and scanning electron microscopy. Observations were made of the appearance of cell walls and the major subcellular components: spherosomes (oil reserve bodies), aleurone grains and starch grains. Major findings include previously unreported cell wall damage and surface fissures that may be important to processors who express the oil from peanuts.     

Polyphenol Oxidase System in Red Delicious Apples

The polyphenol oxidase system (E.C. 1.14.18.1) in‘Red Delicious’apples (Malus domestica) was investigated. Polyacrylamide gel electrophoresis (PAGE) revealed two active isoenzymes as detected with pyrocatechol substrate. The crude enzyme extract (acetone powder) was found to have one optimum pH of 6.2 and one optimum temperature for the browning reaction of 30°C with the experimental conditions described. The Michaelis constant (Km) as an average of the two active enzyme forms was 2.2 × 10^?lM pyrocatechol and the average maximum velocity (Vmax) was 4.8 × 10^?l AA390 per minute.     

KINETIC ANALYLSIS OF THE FORMATION OF NITROSYLMYOGLOBIN

The formation of nitric oxide myoglobin (nitrosylmyoglobin) was followed in buffered solutions in which the concentrations of ascorbate, nitrite, chloride, myoglobin and hydrogen ion were varied systematically to determine their effect on the rate constants. The rate of formation of nitrosylmyoglobin was zero order with respect to the pigment. The orders for the other reactants were determined by plotting the zero order rate constants as functions of varying orders of each reagent to determine which order gave a linear plot. The results were used to develop a mechanism and a mathematical expression for the reaction. Two reaction sequences involving different nitrosating species were involved; 1, direct action of nitrous acid and 2, the formation of nitrosyl chloride. Both species then nitrosated ascorbate and ascorbic acid, by different mechanisms. The nitric oxide for nitrosylmyoglobin formation came from the nitrosated ascorbate.     

Physical-Chemical Characteristics of Partially Clarified Guava Juice and Concentrate

Partially clarified guava juice concentrate was prepared from single strength guava puree (5.5°Brix) by treatment with pectinase (2 hr at 50°C), extraction of juice with a rack-and-cloth press, and vacuum concentration to 23°Brix. The concentrate had the following characteristics: density, 1.10; pH, 3.16; total acids, 4.67%; ash, 1.51%; moisture, 72.4%; ascorbic acid, 867 mg%; viscosity, 4.4 cp; and CIE L* 39.2, CIE a* 10.33, CIE b* 27.11.     

Effects of Heat Treatments on the Head Yields of High Moisture Rough Rice

The influence of high temperature heat treatments on the head yields of rough rice having moisture in the range 18–30% wet basis was investigated using an experimental rotary conduction heating unit with constant agitation. Based on the time-temperature history of bulk grain, reaction kinetic parameters (F_c and z_c values) were determined for specified changes in head rice yields for general application. The estimated isothermal heating times (F_c values) were related to the reference bulk grain temperatures (T_ref) and initial moisture of rice samples (IMC). The plots of F_c value and T_ref led to the determination of z_c value and its dependence on the IMC of rough rice.     

Short-Time Breadmaking Systems. Effect on Oxidation

A spread test was used to study the effects of fermentation time and various agents on dough. Short fermentation times (15–30 min) greatly improved spread ratio. Yeast also improved spread ratio, particularly in combination with time. A combination of 60 ppm KBrO₃ and 100 ppm ascorbic acid was the most effective oxidant system. There was an obvious interaction between yeast and oxidants. Loaf volume was not affected by the timing of addition of yeast or ascorbic acid to dough. Potassium bromate was more effective when added at the premix. A 60 min rest between premix and remix consistently gave higher loaf volume when yeast was added, but not when both yeast and oxidants were present.     

N-Nitrosamine Analysis in Beer Using Thermal Desorption Injection Coupled with GC-TEA

A fast and sensitive method is described for determining a mixture of volatile N-nitrosamines in beer and other malt products. It consists of direct extraction of the sample with dichloromethane, volume reduction, cleanup by trapping volatiles onto Tenax-TA, and thermal desorption injection into a capillary gas chromatograph-thermal energy analyzer. Average recovery of N-nitrosodimethylamine added to beer ranged from 70 to 81%. N-Nitrosodimethylamine and N-nitrosopyrrolidine were detected in 10 samples of various domestic and imported beers analyzed. Total volatile N-nitrosamine concentrations ranged from 0.03 to 1.10 ppb in beer. Minimum detection limit of the method was 0.01 ppb for N-nitrosodimethylamine, a 10-fold increase in sensitivity compared to other similar methods.