Search Results - (Author, Cooperation:N. Webb)

2012-07-07

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Sex odor/flavor in pork was produced when fat, lean (with fat), and most organs from a boar were heated in a skillet or in boiling water. Odor seemed not to be entirely absent in boar fat at body temperature, although volatilization appeared to occur to a much greater extent at approx. 100–108° C. Sex odor was found to be water-insoluble, ether-soluble, and definitely associated with the fatty tissues of boars. It was absent in rehydrated moisture-free, fat-free lean. Distillation methods proved unsatisfactory for collecting the sex odor components in recognizable form, since no consistent and reproducible differences could be detected between boar and barrow fat when collected volatile compounds were analyzed by heat test and gas ehromatography. Cold saponification of boar fat yielded a small quantity of unsaponifiable matter that produced a concentrated, permeating sex odor on exposure to heat. Thus, the agent(s) responsible for sex odor in pork are located in the unsaponifiable material. Cholesterol and squalene were found in this fraction in both boar and barrow fat, but sex odor was not produced when these compounds were heated.

Electronic Resource

1365-2486

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Energy, Environment Protection, Nuclear Power Engineering

Geography

Hydrologists and ecologists studying tundra ecosystems have worked largely independently, with little cross-fertilization between disciplines. Their disciplines are, however, inextricably linked by a need to understand the dynamics and significance of the common substance water, in its liquid, solid and gaseous state within tundra environments. The impacts of predicted long-term changes in climate have particularly important consequences for the functioning of tundra systems and there is a pressing need to initiate studies that integrate hydrological and ecological methodologies and concepts. Our paper attempts to summarize existing information on the role of water within tundra ecosystems, to emphasize the fundamental links between the biotic and the physico/chemical environments and to suggest how a closer integration of ideas might be achieved. Given the breadth of the subject matter the paper is intended to be illustrative rather than comprehensive. The paper examines the physical impacts of water in its various states on the tundra environment, emphasizing in particular the causes of spatial variation in water availability to living organisms. The significance of water is discussed for a range of organism groups, including plants, invertebrates and microorganisms and its pivotal role in ecosystem function and disturbance stressed. The need to develop integrated hydological/ecological models for tundra systems on different spatial scales is emphasized.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Protein functionalities were studied in comminuted fish gels from mechanically deboned fish tissues of four species after storage at −29° C up to 12 months. Differences in gel textures, which were evaluated instrumentally and by a texture profile sensory panel, were evident among fish species and time in frozen storage. Fish gel texture was not significantly related to, protein solubility of raw tissues, but was closely related to water-holding capacity and protein solubility of cooked gels. Degradation of tropomyosin and myosin probably occurred in some of the fish gels during thermal processing.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Mechanically separated (MS) fish muscle tissue was compared with hand-separated (HS) tissue to determine their relative effects upon functional properties and final product texture. Proximate analyses revealed that HS muscle tissue was significantly higher in moisture content than MS tissue. MS tissue had significantly higher quantities of sarcoplasmic and nonprotein nitrogen than HS tissue. No significant difference was found between the level of myofibrillar protein for the two treatments, as determined by sodium dodecyl sulfate (SDS, 1%) extraction, although the HS tissue had a slightly higher level. A significantly higher amount of myofibrillar protein and a lower amount of stroma protein was extracted by SDS than by NaCl (0.58M) for both treatments. This difference was attributed to the development of an insoluble sol by the NaCl extraction method which was sedimented as a gel by centrifugation. Stroma protein was significantly higher in the HS tissue for both extraction methods. There was no significant difference between the two treatments for emulsifying capacity or cook stability and these were not related to final product texture evaluated by a sensory panel and instrumental shear force. The texture of the comminuted product prepared with HS tissue was significantly better than that prepared with MS fish tissue.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Special and claw meat products from the blue crab produced in the commercial processing plants in North Carolina had relatively poor shelf life. These products had high initial total anaerobe and psychrotroph counts. Many of the samples were positive for presumptive Vibrio parahaemolyticus, even though many samples did not have coliforms (in 0.2g sample). The presence of presumptive V. parahaemolyticus and high numbers of aerobic plate counts, total anaerobes and psycbrotrophs in these samples was probably from improper cooking of the raw crabs and post-heat-treatment contamination of the cooked crabs. The results suggested that coliforms may not be suitable to indicate proper plant sanitation and product contamination. Crab meat produced under sanitary conditions had lower numbers of total anaerobes and psychrotrophs; these products had relatively long shelf life. The results of these studies indicated that to produce products having longer shelf life the commercial plants will have to adopt proper sanitary practices. The main objective will be to prevent post-heat-treatment contamination to reduce the initial bacterial load in the products, especially with the anaerobes and psychrotrophs.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Biological and food materials can develop stress cracks under the influence of variable temperature and moisture gradients. Frankfurter sausages, from a molecular concept are a heterogenous system, but for engineering purposes the molecular structure may be disregarded and can be treated as a continuum. In the present investigation a continuous Maxwell model was assumed to represent the frankfurters subject to variable temperature and moisture conditions. Utilizing the techniques of linear viscoelasticity, an expression for the mechanical stiesses in a cylinder was obtained. Uniaxial modulus as a function of time and temperature was determined experimentally and the resulting data were analyzed to obtain time-temperature shift factors, relaxation time and a master curve for the modulus. The temperature as a function of radius and time was determined during cooking, and an algebraic expression for axial, tangential and radial stresses was developed. The maximum shearing stresses exceeded failure stress of the frankfurters, thus explaining the development of cracks.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

The Hobart FMP-1 Automatic Meat Analyzer has been developed for rapid (approximately 5 min), simultaneous determination of the fat, moisture and protein content of meat and meat products. Results were compared with those using official AOAC methods for raw beef and pork and cooked sausage samples. Analyses of the data indicated that, except for determination of fat content of raw pork and protein content of raw beef, the Hobart FMP-1 was not significantly different from the official AOAC methods within the sampling parameters studied. From a practical meat operations standpoint, these differences were not considered to be of major concern as the machine can be calibrated to adjust for bias.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Effects of rate of heating and final internal temperatures on the texture of fish gels were studied using mechanically deboned fish tissues of 2 species and 2 harvest locations. Generally, rapid heating to 85°C internal temperature (using 100°C steam) produced a firmer, more springy texture in fish gels in comparison with those heated slowly to 70°C internal temperature. However, these thermal effects on gel textures were species and harvest location dependent. Degradations of tropomyosin and myosin observed in cooked fish gels were highly related to gel textural properties. Results further suggested that changes in muscle proteins during heating were caused by proteolytic factor(s) in the sarcoplasmic fraction. The proteolytic crude fraction was isolated and partially characterized. Optimal temperature for proteolytic activity was 60°C; optimal pH was between pH 8.0 and pH 8.5; calcium ion activated the proteolytic activity and the optimal calcium ion concentration for activation was 1 mM; metal chelators, EDTA and EGTA, inhibited the proteolytic activity. A thorough understanding of these proteolytic factors and their subsequent control is important for the utilization of mechanically deboned fish tissues.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The effects of sublethal waterborne Zn (2·28 μmol l−1) on Zn binding kinetics to the apical gill surface were studied in juvenile rainbow trout (Oncorhynchus mykiss). Two separate radiotracer techniques were employed to ascertain this information. First, in vitro binding kinetic experiments were performed at extremely elevated zinc concentrations (up to 20 mmol l−1) to measure relatively low-affinity binding sites at the gill epithelium. There were no differences in Zn binding parameters (Km and Bmax) for fish sublethally exposed to Zn for 21 days and their simultaneous controls. Nevertheless, Ca did have an increased inhibitory effect on Zn binding in Zn-exposed fish suggesting that the anionic groups on the gill epithelium of these fish had been altered in some manner. Additionally, in vivo Zn binding kinetics were investigated using environmentally relevant waterborne Zn concentrations (low μmol l−1 range) to isolate high-affinity Zn binding sites (Ca transporters). No appreciable alterations in the Km and Bmax values for Zn binding were seen between the Zn-exposed group and its simultaneous control following 15 days of exposure. Furthermore, no significant differences in CC morphometry were observed between treatments. Despite these lack of treatment effects, there were temporal alterations in Km, Bmax and CC fractional surface area in both groups. It is proposed that these fluctuations are controlled by hormonal factors (such as stanniocalcin), believed to play a role in Ca influx.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

SUMMARY: Bay scallops (Aequipecten irradians), calico scallops (Aequipecten gibbus) and sea scallops (Placopecten magellanicus) were sampled from known locations and months of harvest for determination of proximate composition. A scallop sample (Chlamys hericius) was obtained from near Whidbey Island, Puget Sound, for comparative purposes. The adductor muscles were analyzed for total moisture, protein, fat, glycogen and ash content. The proximate composition varied widely among locations and months of harvesting. In general, coefficients of variation were relatively low for moisture and protein but high for fat, glycogen and ash. The range for each component was fairly similar among species studied. The percent ranges for bay and calico scallop meats, respectively, were: moisture 74.15–83.66, 76.12–81.86; protein 13.44–21.57, 13.28–17.53; fat 0.23–0.91, 0.23–1.13; glycogen 0.13–3.86, 0.35–3.71 and ash 1.09–2.24, 1.17–1.91. Sea scallop percent ranges were: moisture 74.63–80.97; protein 13.87–18.11; fat 0.31–0.96; glycogen 0.27–8.74 and ash 1.28–1.81.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

SUMMARY— A laboratory technique for the preparation of small batches of sausage emulsion was developed for a comparative study of the effectiveness of fresh and frozen beef in achieving emulsion stability. The technique consisted of three basic steps: (1) low speed chopping and blending of ingredients at −2° to +2°C; (2) low speed blending with the gradual addition of soybean oil at 2°−8°C; and (3) high speed chopping to a temperature of 15°-16°C. The preparation and evaluation of emulsions with widely varying compositions revealed that the lean and fat percentages could be varied over wide ranges without significantly affecting emulsion stability, but the range for percentage of water was narrow and critical to stability. The relative stability for fresh and frozen lean was influenced by the amount of added water. For example, at 30% fat level, there was a sharp drop in stability as the added water was reduced below 16% for fresh beef; whereas, an equivalent drop in stability was found as the added water was reduced below 21 % for frozen beef. The theory is proposed that emulsion instability is highly dependent upon the level of added water based on results of this investigation.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

—The tenderness of beef was improved by aging. Tenderness decreased with increasing maturity for the cattle evaluated in this investigation. During the early stages of aging, samples were more tender from control animals than from ante-mortem-stressed cattle, but this difference was eliminated by the end of the aging periods. Water-holding capacity and juiciness scores were increased by ante-mortem stress treatments. WHC and juiciness scores decreased during aging. Tenderness scores were correlated significantly with WHC values and juiciness scores at the termination of the low-temperature aging period. Transfer of moisture and mineral ions during aging appeared to be associated with the changes involved in the development and resolution of rigor mortis and improved tenderization of the meat. AS tenderness improved during aging, extractable sodium, magnesium, and calcium were released from the muscle proteins, while potassium, phosphate, and nitrogen were retained. These components changed radically during the early stages of aging, with movement and transfer more uniform during the latter stages.Magnesium was the only mineral component present in the exudate of the water-holding-capacity determination that appeared to be related to tenderness. A relationship existed between physiological cell maturity and the ability of the meat to transfer and bind cellular magnesium. Tenderness decreased as the quantity of magnesium decreased in the exudate from the water-holding-capacity determination.The pH of meat was increased by broiling, while the pH of the exudate decreased when meat samples were cooked in the water-holding-capacity tubes.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] We report here X-ray diffraction studies of a tRNATyr from E. coli. tRNATyr was purified by the combination of countercurrent distribution and benzoylated DEAE-cellulose column chromatography procedures and was fully active as judged by the extent of charging ability (〉 90 per cent). Fibres were ...

Electronic Resource

0022-2860

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Physics

Electronic Resource