Quality of Green Beans, Bell Peppers and Spinach Stored in Polyethylene Bags

Quality attributes of packaged and unpackaged vegetables generally decreased nonlinearly during storage at 10°C or 20°C, and most of the decrease was greater at 20°C than at 10°C. Packaging reduced weight loss of green beans and spinach kept at 20°C; and reduced chlorophyll loss of green beans at 10°C and of spinach at 20°C. Ascorbic acid (vitamin C) benefited by packaging of green beans and spinach kept at 10°C. Packaging had an effect on thiamin (vitamin B₁) of only spinach held at 10°C and 20°C and had no effect on riboflavin (vitamin B₂). Loss of these quality attributes appears to be enhanced with water loss.     

Extrusion of Apple Pomace Facilitates Pectin Extraction

Twin-screw extruder was employed to disintegrate apple pomace (AP) to facilitate production of apple pectins by hot water extraction. AP was extruded under different conditions of screw speed, 250-350 rpm; feed rate, 30-40 kg/h; moisture, 20-30%. The yield of water soluble polysaccharides (WSP) increased with increasing specific mechanical energy (SME), but intrinsic viscosity decreased with increasing SME. Considering both the WSP yield (g/dL) and intrinsic viscosity (dL/g), a dimensionless term, product yield ∞ intrinsic viscosity (Y[]), was an objective function for optimizing conditions for the solubilization of AP polysaccharides. Y[] of pectins in extruded WSP ranged 0.59-1.34, while acid extracted WSP had Y[] of 1.12. Extruded WSP with Y[] comparable to acid extraction was obtained in the SME ranges of 110-170 kWh/h.     

EFFECTS OF VARIOUS FRESH MEAT STORAGE METHODS ON THE COLOR OF COOKED GROUND PORK

The effects of microbial growth in raw materials on cooked pork color were investigated. In two trials with sow meat held aerobically at 2C for 3 weeks, microbial load reached spoilage levels (10⁷ cfu/g), pH increased to 6.46, and samples cooked to 71C had red exudate, shown by absorption spectroscopy to contain myoglobin and cytochrome c. Samples cooked to 82C also received high panel ratings for red color, due to red, flocculent precipitate in the exudate, but undenatured myoglobin levels were low. In sow meat held frozen or vacuum-packaged at 2C, pH after 3 weeks was 6.03 and 6.18, and plate counts were 10⁴ and 10⁷, respectively, but exudates after cooking were much less red. In five trials with fresh pork legs, total plate counts also reached 10⁷ cfu/g by 3 weeks storage, and pH increased to 6.37, but cooked samples were not red. Higher myoglobin levels in sow meat probably accounted for the red color and level of undenatured myoglobin remaining after cooking of high pH, spoiled samples.     

Piezoelectric properties and equivalent circuits of ferroelectric relaxor single crystals

Temperature dependent piezoelectric properties of ferroelectric relaxor single crystals, particularly the cerium-doped strontium barium niobate compositions (SBN60: Ce), were investigated by resonance and anti-resonance technique. Characteristic resonant frequencies (f_r−f_a, f_s−f_p, and f_m−f_n) were studied using equivalent circuit simulation. Piezoelectric resonance in a relaxor resonator persists into temperatures much higher than Tm (the temperature at which dielectric constant, κ, has a maximum at 1 kHz) in comparison with the normal ferroelectrics such as TGS. The parameters in an equivalent circuit, however, are phenomenally different from a normal resonator like a TGS, near and above the transition temperature region. The significance and understanding of the piezoelectric resonance characteristics in ferroelectric relaxor are discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

The effects of initial sol parameters on the microstructure and optical transparency of TiO2–SiO2 binary aerogels

The effects of initial sol parameters on the pore structure and optical transparency of TiO2–SiO2 binary aerogels are investigated. Different silicon alkoxides, catalysts and water to alkoxide ratios were considered as initial sol parameters to control the hydrolysis and condensation reactions in each reaction stage. Strongly acidic conditions gave rise to the most transparent monolithic aerogels for both tetra-ethyl ortho silicate (TEOS) and tetra methyl ortho silicate (TMOS) based systems. In the TMOS-based system, due to a larger number of monosilicic acids acting as equivalent nucleation centres for further growth, smaller and uniformly distributed particles and interstitial pores were produced during the gellation and supercritical drying. Therefore, with the same catalyst and water content, better transparency was observed in the TMOS-based system than in the TEOS-based system.     

An optimal path of a moving vehicle on a sphere

We consider the problem of finding an optimal path of a moving vehicle, which during its journey provides a certain type of service to a group of existing facilities on a sphere. Service requests from each facility are assumed to follow a Poisson process and the conditional expected cost incurred by a service call is assumed to be proportional to the shortest arc distance between the facility and the vehicle's location at the time of the service request. This problem is formulated as a variational problem and solved by repeatedly applying a dynamic programming procedure to a sequence of staged networks that are constructed via perturbation.     

N-substituted copolyaniline for electrorheological material

Abstracts are not published in this journal