1,721,013 research outputs found
Postmortem changes in meat quality and myofibrillar protein degradation in turkey breast muscle
Get PDFThe purpose of this research was to evaluate the effect of elevated carcass temperature in combination with rapidly declining pH or with postrigor muscle on turkey breast meat quality. Two groups of twelve turkey carcasses with similar ultimate pH values were selected based on 15 min postmortem (PM) breast muscle pH (rapid-glycolyzing (RG), pH 6.0). One side of each carcass was held near 40°C and immersion chilling was delayed until 110 min PM (DC), while the other side was chilled at 20 min PM (IC). Raw breast meat quality was assessed using measurements of colour and protein extractability, while quality characteristics of cooked product were assessed using cook yield and torsion gelometry. The extractability and degradation of 10 specific proteins was monitored using SDS-PAGE and Western blotting. Additionally, holding postrigor turkey breast meat at 40°C was evaluated as a model for mimicking changes due to rapid PM glycolysis. Sarcoplasmic and myofibrillar protein extractability was reduced for breast samples from RG and DC carcasses as well as for postrigor meat held at 40°C (P < 0.05). All colour values ('L*a*b*') increased for DC ground breast meat. Strain at fracture for breast meat gels was lower for RG samples. Both stress and strain at fracture and cook yield were reduced for DC breast meat gels. The reduction in meat quality measurements was additive for RG samples that were delay-chilled. Densitometry of Western blot analyses revealed that the extractability of glycogen phosphorylase, creatine kinase, and M-protein was reduced for RG or DC samples. Increased myosin degradation was observed for samples from either RG or DC carcasses with up to 20% of myosin degraded in RG/DC samples. Nebulin degradation was also more extensive in RG samples than for controls. Heating postrigor breast increased myosin degradation, however, differences in the banding pattern of myosin fragments compared to samples from RG carcasses were observed. These results provide conclusive evidence that rapid PM glycolysis and delayed chilling have detrimental effects on turkey breast meat quality. The association of postmortem protein degradation with meat of reduced quality merits further investigations into the relationship between postmortem proteolytic activity and meat quality
Oxytetracycline degradation in model meat processing systems
Get PDFA RP-HPLC method was developed that successfully quantified mixtures of oxytetracycline (OTC), 4-epiOTC, á- and â-apoOTC down to 40, 20, 50 and 140 ng/ml at ambient temperature in less than 35 minutes. A 0.1M ammonium acetate buffer (pH 3.0)-acetonitrile-tetrahydrofuran (72.5:12.5:15, v/v/v) mobile phase was found by means of the statistical simplex method of solvent optimization to give excellent separation of compounds. Quantitative and reproducible isolation of OTC from aqueous and tissue matrices using solid-phase extraction (SPE) C18 cartridges was successful, whereas isolation of the degradation compounds, particularly á- and â-apoOTC from tissue, was not. Using this method, the degradation kinetics of OTC upon exposure to various meat processing parameters (heat, water activity, and the presence of certain additives) in aqueous and tissue matrices were studied. Regression analysis of ln-linear data revealed that pseudo-first order kinetics were observed for all matrices and parameters. Between 60 and 80°C, the rate of OTC degradation (kobs) increased several-fold. Glycerol-adjusted water activities (0.6 to 1.0) had only a minimal effect upon kobs (p > 0.05), although changes in the secondary kinetic parameters (enthalpy and entropy) were evident. Monomeric phosphate increased kobs in aqueous solution in accordance with a base-catalyzed reaction mechanism. Polymeric phosphates significantly decreased (p < 0.05) kobs in aqueous solutions, whereas in tissue matrices, kobs significantly increased, due in part to cation chelation. Calcium decreased both kobs (p < 0.05) and entropy, due to the formation of a thermally stable OTC-Ca2+ complex. Ionic strength and sodium nitrite per se did not alter the lability of OTC (p > 0.05), although their secondary effects on the matrix altered the apparent stability of OTC. Binding studies provided evidence that OTC binding to tissue was due in part to complexing protein-bound cations. Experimental evidence indicated that mineral content was the primary factor affecting OTC degradation. Parameter manipulation did not appear to alter the rate-limiting mechanism (E2 elimination) by which OTC breakdown occurred, as was evidenced by the occurrence of enthalpy/entropy compensation. This research has provided a detailed database for the degradation of OTC. Enthalpy/entropy compensation was shown to be a potentially useful tool for studying OTC degradation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Effect of feeding various dried distillers grains plus solubles on beef meat quality
Get PDFTwo studies were designed to investigate the effect of feeding crossbred beef steers a standard barley-based control diet or substituting wheat, corn, or wheat/corn (40% dry matter basis) dried distillers grains plus solubles (DDGS) on the resulting meat quality. The first study investigated the effect of diet on the quality of the longissimus muscle. It was observed that diet did not have an effect on meat composition, pH, drip loss or shear values; however, diet did have an effect on colour attributes, with steaks obtained from steers fed a DDGS diet losing redness faster over time and having a less desirable retail appearance than steaks obtained from steers fed the control diet (P<0.001). Differences (P<0.05) were also observed in both the subcutaneous and intramuscular fatty acid profiles, with steers fed corn DDGS having elevated levels of trans-monounsaturated fatty acids, and steers fed a DDGS diet having elevated levels of branched-chain fatty acids and conjugated linoleic acid. The fatty acid composition of cattle fed a DDGS diet also had higher (P<0.05) concentrations of polyunsaturated fatty acids, which resulted in a less desirable n-6 to n-3 ratio. Despite the fact that fat obtained from steers fed a DDGS diet had elevated levels of total unsaturated fatty acids when compared to steers fed the control diet, no differences were observed in regards to the oxidative stability of raw or cooked meat as determined by thiobarbituric acid reactive substances.
The second study investigated the effect of diet on the quality of raw and pre-cooked semimembranosus roasts injected with a salt/phosphate brine. No dietary effects were observed in meat quality, processing attributes, or shear values of the non-injected SM roasts, while roasts prepared from the semimembranosus of animals fed corn DDGS had the lowest brine pickup and the highest shear values. Raw non-injected meat from steers fed a DDGS diet was less oxidatively stable than meat obtained from steers fed a control diet. Oxidative changes due to diet were mitigated in the cooked injected roasts due to the chelating effect of phosphate, which improved overall oxidative stability. Similarly, oxidation levels in the pre-cooked SM roasts remained below levels where rancidity is normally detected over 56 days of refrigerated storage at 4°C. Overall, replacing barley grain with 40% wheat, corn, or wheat/corn DDGS did not have a profound impact on meat quality attributes of raw or cooked meat
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Physicochemical properties and phenolic composition of selected Saskatchewan fruits : buffaloberry, chokecherry and sea buckthorn
Get PDFThere is increasing interest in the commericalization of native fruits for utilization as foods and medicinal extracts. This study was undertaken to determine the physicochemical properties and phenolic composition of selected Saskatchewan native fruits, including buffaloberry (Shepherdia argentea Nutt.), chokecherry (Prunus virginiana L.) and sea buckthorn (Hippophae rhamnoides L.). The physicochemical analyses included carbohydrate content, CIELAB colour values, organic acid composition, phenolic content, % seed, soluble solids, pH, total solids, total titratable acidity and proximate composition. Fruit samples were collected and analyzed over four crop years. The proanthocyanidin content was also determined photometrically after acid depolymerization in acid-butanol. Buffaloberry contained a proanthocyanidin concentration of 505 ± 32 mg/100 g fresh fruit and this level was 10 fold higher than that of chokecherry and sea buckthorn. Chokecherry was found to contain an anthocyanin concentration of 255 ± 35 mg/100 g fresh fruit, as determined using the pH differential method.
Two high performance liquid chromatography (HPLC) methods were developed for simultaneous determination of seven phenolic classes, including anthocyanins, hydroxybenzoic acids, hydroxycinnamic acids, flavanols, flavanones, flavones and flavonols in aqueous methanol extracts. Based on the semi-quantitative analysis of the total phenolic chromatographic index (TPCI), chokecherry contained the highest levels of phenolic compounds with a concentration of 3,327 ± 469 µg/g fresh fruit followed by buffaloberry (578 ± 73 µg/g fresh fruit) and sea buckthorn (477 ± µg/g fresh fruit).
The antioxdant activity of the fruit extracts was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2´-azinobis-3-ethylbenzthiazoline-sulphonic acid (ABTS) radical scavenging assays. Buffaloberry and chokecherry produced the highest radical scavenging activity and were at least five fold greater than that of sea buckthorn. The major radical scavenging compounds in buffaloberry were ascorbic acid and proanthocyanidins. Radical scavenging activity of chokecherry fruit was largely attributable to its anthocyanins, flavonols and hydroxycinnamic acids. Prominent antioxidants in sea buckthorn included ascorbic acid, proanthocyanidins and flavonols.
Certain individual compounds in the phenolic extracts were identified by HPLC-photodiode array and HPLC-mass spectrometry. Rutin was found in all of the extracts. Other phenolic compounds identified included catechin in sea buckthorn, and chlorogenic acid and quercetin in chokecherry. The chokecherry fruit pigments were comprised of two major anthocyanins and these were identified as cyanidin 3-glucoside and cyanidin 3-rutinoside. A preparative scale purification method for these anthocyanins using centrifugal partition chromatography (CPC) was determined. Under the CPC conditions employed, cyanidin 3-glucoside and cyanidin 3-rutinoside were purified to concentrations of 84 and 90%, respectively
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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