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1.
Rock crab (Cancer irroratus) is abundant in the southern Gulf of St. Lawrence and along coastlines of the Atlantic region of Canada. The objective of this work was to prepare a pasteurization schedule for Atlantic Canadian Rock Crab meat (claw, leg and body). Samples of 175 g of meat plus 52 g of 2% w/w brine or 125 g meat plus 102 g brine were placed in an 8 oz polypropylene container with an aluminum pull-top lid. The slowest heating spot for a conductively heating product was found to be 3.0 cm below the lid. Pasteurization was evaluated at 81C, 82C and 83C to a pasteurization lethality of 40 min at 85C (z = 8.89 C). The heat penetration parameters obtained were jh = 1.703, fh = 34.8 min, jc = 1.549 and fc = 51.0 min. The optimal process was found to be 83C for 130 min. The shear strength for unprocessed crab leg samples was, on average, 0.33 N/mm2 (±0.06) compared to 0.24 N/mm2 (+0.02) for processed samples. This represents 27.4% reduction in the shear stress that is largely attributed to the processing method. Thirty two free amino acids were determined including 9 essential amino acids, and their total amounts ranged between 24.8% and 30.0% of the sample, on dry basis. The total amounts of essential amino acids in the processed and unprocessed samples were, respectively, 15.3 and 17.8 mg/g sample. No significant losses in the amounts of essential amino acids was observed between processed and unprocessed samples, except for methionine, isoleucine and lysine, which were significantly reduced in the processed samples. 相似文献
2.
Harvesting experiments revealed that immature whole mushrooms with closed veils had higher 1-octen-3-0l levels than more mature whole mushrooms with open veils. The l-octen-3-01 content of the gills was higher in immature mushrooms with closed veils, gradually decreased with maturity as the veil opened, and finally increased after the gills were well exposed. Postharvest experiments demonstrated that storage temperature influenced the activity of lipoxygenase-hydroperoxide lyase, but no differences in 1-octen-3-01 content were observed. Enzyme activity as well as 1-octen-3-01 content decreased during storage. Addition of calcium chloride to irrigation water, employed to improve quality and shelf life of fresh mushrooms, increased the amount of l-octen-3-01 immediately after harvest. 相似文献
3.
L. ALBERTO MOSQUERA CHARLES A. SIMS ROBERT P. BATES SEAN F. O'KEEFE 《Journal of food science》1996,61(4):856-861
Horchata is a sweetened water extract of chufa tubers (Cyperus esculentus) which is very popular in Spain, and has potential in the U.S. The objectives of this research were to characterize horchatas from different types of chufa, and to monitor flavor and stability of unheated and pasteurized horchatas during storage (2°C). Trained panelists rated the following attributes: color, chalkiness, sweetness, vanilla-like, nutty, earthiness, bitterness, and off-flavor. Horchatas made with chufa grown in Spain and chufa from Spain but grown in Florida showed higher vanilla and nutty levels than horchata from the Florida type. During storage (2°C), vanilla, nutty, and sweetness decreased, and other attributes increased. Heating to 70 and 95°C for 1 min did not alter sensory attributes initially, prevented off-flavor development, and slowed changes in desirable attributes for 35 days. 相似文献
4.
The thermal decomposition of europium hydroxide in an air atmosphere was investigated by means of weight-loss measurements, infrared spectroscopy, X-ray diffraction analysis, and electron microscopy. These studies showed that EU(OH)° decomposed at temperatures between 225° and 300°C into EuOOH, which was stable up to about 425°C. Between 435° and 465°C this compound decomposed into cubic Eu2 O3 , which was stable until its inversion to the high-temperature monoclinic form. X-ray diffraction data were collected for Eu(OH)3 and EuOOH and showed that the trihydroxide has a hexagonal crystal structure and the oxyhydroxide is possibly orthorhombic. The Eu(OH)2 , EuOOH, and cubic EunOa powders contained particles up to several microns in size consisting of agglomerates of crystallites in the size range 200 to 400 A. The single monoclinic Eu2 O3 sample studied contained crystallites whose average size was greater than 2000 A. 相似文献
5.
IRWIN GORDON ROBERT L. HARVEY R. A. BRADEN 《Journal of the American Ceramic Society》1962,45(6):297-301
The preparation of nonoriented as well as magnetically oriented specimens of 2MeO · 2BaO·-6Fe2 O3 and 2MeO·3BaO·12Fe2 O3 is described. The MeO component is limited to NiO, ZnO, CoO, and CuO and mixtures of these in this discussion. The orienting apparatus and technique employed are briefly described. The magnetic permeability and loss as measured at 250 Mc is shown for many of these prepared compositions. The effect of the orienting magnetic field strength as well as firing temperature on the observed magnetic properties is discussed. 相似文献
6.
ROBERT C. LINARES 《Journal of the American Ceramic Society》1965,48(2):68-70
Single crystals of yttrium iron garnet with substitutions of aluminum and gallium were grown from lead oxide-fluoride, lead borate, and barium borate fluxes. Crystals were grown both by slow cooling and by the gradient technique. The aluminum and gallium contents of these crystals were measured; the amount of substitution and its distribution in one crystal and in the mass of crystals in a run were determined. Crystals grown by slow cooling were badly segregated with respect to aluminum and gallium content whereas gradient-grown crystals were very uniform. 相似文献
7.
High-density Si3 N4 +6% CeO2 composites with 5 to 50% BN were fabricated by hot-pressing. BN remained as a discrete phase. Dielectric constants were 4 to 8 and loss tangents were 0.0008 to 0.06 for the room temperature to 1100°C range for compositions with 10 to 50% BN. Thermal-expansion values perpendicular to the hot-pressing direction were somewhat less than those of hot-pressed Si3 N4 +6% CeO2 . Flexure strengths at room temperature were considerably lower than those of hot-pressed Si3 N4 +6% CeO2 but values at 1000°, 1250°, and 1400°C in air were only slightly lower. Young's modulus values were found to decrease with increasing BN content at all temperatures. Better thermal shock resistance was found than for commercial hot-pressed Si3 N4 . 相似文献
8.
9.
LINDA J. BRUECHERT YUANGANG ZHANG TZOU-CHI HUANG THOMAS G. HARTMAN ROBERT T. ROSEN CHI-TANG HO 《Journal of food science》1988,53(5):1444-1447
Volatile compounds generated by model systems of zein, corn amylopectin and corn oil extruded at barrel temperatures of 120°C and 165°C were analyzed by GC and GU/MS. The largest quantities of lipid oxidation products were detected in systems containing all three components. In each system, the quantity of 2,4-decadienal was low relative to the quantities of hexanal, heptanal, and benzaldehyde. Identification of the Maillard reaction products, 2-methyl-3(or 6)-pen-tylpyrazine, 2-methyl-3(or 6)-hexylpyrazine, and 2,5-dimethyl-3-pen-tylpyrazine, suggested that lipid-derived aldehydes might be involved in the formation of substituted pyrazines. 相似文献
10.