Effects of breed and a concentrate or grass silage diet on beef quality in cattle of 3 ages. I: Animal performance, carcass quality and muscle fatty acid composition

An increase in the intake of the n-3 series polyunsaturated fatty acids (PUFA) is recommended by nutritionists for the human diet and beef is a significant source of these fatty acids. Enhancing the n-3 PUFA content of beef is important in view of the generally saturated nature of fatty acids in ruminant meats and the potentially negative effect this can have on human health. This study examined the effects of breed and diet on the fatty acid composition of beef M. longissimus. Ninety-six steers were used, 48 Aberdeen Angus cross (AA) and 48 Holstein-Friesian (HF). At 6months of age, 3 groups were identified, to be slaughtered at 14, 19 and 24months, respectively. Each group consisted of eight steers of each breed fed on a concentrate or a grass silage diet, rich in n-6 and n-3 PUFA, respectively. The intake of the concentrate diet was restricted so that steers of each breed grew at a similar rate on each diet. The early maturing AA produced heavier, fatter carcasses with better conformation. Animals fed grass silage had higher carcass fatness and conformation scores and higher levels of neutral lipid and total lipid in muscle than those fed concentrate. When all animals were pooled, a decline in PUFA% as total muscle lipid increased was evident. Feeding a grass silage diet rich in α-linolenic acid (18:3n-3) increased levels of this fatty acid in muscle neutral lipid by a factor of about 3.0 compared with the concentrate diet, as well as enhancing the synthesis of the n-3 series long-chain C20-22 PUFA in the phospholipid fraction, including docosahexaenoic acid (DHA, 22:6n-3). In contrast, both levels and proportions of linoleic acid (18:2n-6) and the n-6 series C20-22 PUFA were higher in animals fed the concentrate diet. The proportions of 18:1trans and conjugated linoleic acid (CLA) in muscle neutral lipid were higher in animals fed concentrate compared with silage in all 3 groups. This was partly due to increased consumption of 18:2n-6. The ratio of PUFA to saturated fatty acids (P:S) in muscle was reduced by feeding grass silage, partly as the result of increased fat deposition. However, the increase in levels of n-3 series fatty acids with silage-feeding resulted in beneficially low n-6:n-3 ratios in muscle in all age groups (approximately 1.2 compared with 12.0 in the concentrate diet). Subtle breed differences in PUFA amounts and proportions were noted. Holstein-Friesians had higher proportions of PUFA and higher P:S ratios compared with AA, partly due to a higher proportion of phospholipid in total lipid. In phospholipid itself, HF in the 19 and 24months groups had higher proportions of most n-3 PUFA. In all age groups the ratio of DHA to its precursor, 18:3n-3 was higher in HF.     

Occurrence, synthesis, and mammalian cell cytotoxicity and genotoxicity of haloacetamides: an emerging class of nitrogenous drinking water disinfection byproducts

The haloacetamides, a class of emerging nitrogenous drinking water disinfection byproduct (DBPs), were analyzed for their chronic cytotoxicity and for the induction of genomic DNA damage in Chinese hamster ovary cells. The rank order for cytotoxicity of 13 haloacetamides was DIAcAm > IAcAm > BAcAm > TBAcAm > BIAcAm > DBCAcAm > CIAcAm > BDCAcAm > DBAcAm > BCAcAm > CAcAm > DCAcAm > TCAcAm. The rank order of their genotoxicity was TBAcAm > DIAcAm approximately equal to IAcAm > BAcAm > DBCAcAm > BIAcAm > BDCAcAm > CIAcAm > BCAcAm > DBAcAm > CAcAm > TCAcAm. DCAcAm was not genotoxic. Cytotoxicity and genotoxicity were primarily determined by the leaving tendency of the halogens and followed the order I > Br > > Cl. With the exception of brominated trihaloacetamides, most of the toxicity rank order was consistent with structure-activity relationship expectations. For di- and trihaloacetamides, the presence of at least one good leaving halogen group (I or Br but not Cl) appears to be critical for significant toxic activity. Log P was not a factor for monohaloacetamides but may play a role in the genotoxicity of trihaloacetamides and possible activation of dihaloacetamides by intracellular GSH and -SH compounds.     

Fat deposition, fatty acid composition and meat quality: A review

This paper reviews the factors affecting the fatty acid composition of adipose tissue and muscle in pigs, sheep and cattle and shows that a major factor is the total amount of fat. The effects of fatty acid composition on meat quality are also reviewed. Pigs have high levels of polyunsaturated fatty acids (PUFA), including the long chain (C20-22) PUFA in adipose tissue and muscle. The full range of PUFA are also found in sheep adipose tissue and muscle whereas cattle ‘conserve’ long chain PUFA in muscle phospholipid. Linoleic acid (18:2n − 6) is a major ingredient of feeds for all species. Its incorporation into adipose tissue and muscle in relation to the amount in the diet is greater than for other fatty acids. It is deposited in muscle phospholipid at a high level where it and its long chain products eg aracidonic acid (20:4n − 6) compete well for insertion into phospholipid molecules. Its proportion in pig adipose tissue declines as fat deposition proceeds and is an index of fatness. The same inverse relationships are not seen in ruminant adipose tissue but in all species the proportion of 18:2n − 6 declines in muscle as fat deposition increases. The main reason is that phospholipid, where 18:2n − 6 is located, declines as a proportion of muscle lipid and the proportion of neutral lipid, with its higher content of saturated and monounsaturated fatty acids, increases. Oleic acid (18:1cis − 9), formed from stearic acid (18:0) by the enzyme stearoyl Co-A desaturase, is a major component of neutral lipid and in ruminants the same enzyme forms conjugated linoleic acid (CLA), an important nutrient in human nutrition. Like 18:2n − 6, -linolenic acid (18:3n − 3) is an essential fatty acid and is important to ruminants since it is the major fatty acid in grass. However it does not compete well for insertion into phospholipid compared with 18:2n − 6 and its incorporation into adipose tissue and muscle is less efficient. Greater biohydrogenation of 18:3n − 3 and a long rumen transit time for forage diets also limits the amount available for tissue uptake compared with 18:2n − 6 from concentrate diets. A positive feature of grass feeding is that levels of the nutritionally important long chain n − 3 PUFA are increased ie EPA (20:5n − 3) and DHA (22:6n − 3). Future research should focus on increasing n − 3 PUFA proportions in lean carcasses and the use of biodiverse pastures and conservation processes which retain the benefits of fresh leafy grass offer opportunities to achieve this. The varying fatty acid compositions of adipose tissue and muscle have profound effects on meat quality. Fatty acid composition determines the firmness/oiliness of adipose tissue and the oxidative stability of muscle, which in turn affects flavour and muscle colour. Vitamin E is an essential nutrient, which stabilises PUFA and has a central role in meat quality, particularly in ruminants.     

The perceived risk of the Line 5 Pipeline and spills under ice

Using the psychometric paradigm of risk in conjunction with surveys of the Michigan public (n = 638) and a regional planning organization (n = 65), we examine the perceived risk and concerns associated with underwater oil pipelines, the Enbridge Line 5 pipeline in particular, and oil spills under ice. The fate of Line 5 is heavily debated in Michigan, specifically the portion that traverses the Straits of Mackinac, which can be ice-covered for months. Scant literature examines how individuals perceive the risk associated with Line 5, its alternatives, or potential spills in open water or under ice. Here we identify considerable concern regarding both the pipeline and the potential for spills under ice on behalf of the public, and increased concern about spills under ice on behalf of the planning organization. Organization members' concerns are significantly predicted by beliefs about the difficulty in remediating spills, however not by beliefs about spills' likelihood, difficulty in detection, noticeability, or consequences. Our results identify the need to better examine and communicate the risks associated with underwater pipelines and spills, both in open water and under ice, as well as options for remediating oil captured under ice. Furthermore, we recommend the adoption of decision-making and risk governance processes that explicitly expand analysis of the social, economic and environmental tradeoffs of underwater pipelines such as Line 5.     

Factors affecting the composition and amount of 'white exudate' from cooked bacon

Bacon sometimes produces a white, unsightly fluid that exudes from the surfaces during cooking —a phenomenon that has resulted in frequent consumer complaints. The quantity of exudate from bacon of known history was assessed subjectively, by ranking photographs following ‘dry-frying’, and objectively, by collecting exudate in an ice cooled tray after grilling. Trained assessors ranked samples in order of visible exudate as follows: dry cured相似文献   

Dual-injection: The flexible,bi-fuel concept for spark-ignition engines fuelled with various gasoline and biofuel blends

Dual-injection strategies in spark-ignition engines allow the in-cylinder blending of two different fuels at any blend ratio, when simultaneously combining port fuel injection (PFI) and direct-injection (DI). Either fuel can be used as the main fuel, depending on the engine demand and the fuel availability. This paper presents the preliminary investigation of such a flexible, bi-fuel concept using a single cylinder spark-ignition research engine. Gasoline has been used as the PFI fuel, while various mass fractions of gasoline, ethanol and 2,5-dimethylfuran (DMF) have been used in DI. The control of the excess air ratio during the in-cylinder mixing of two different fuels was realized using the cross-over theory of the carbon monoxide and oxygen emissions concentrations. The dual-injection results showed how the volumetric air flow rate, total input energy and indicated mean effective pressure (IMEP) increases with deceasing PFI mass fraction, regardless of the DI fuel. The indicated efficiency increases when using any ethanol fraction in DI and results in higher combustion and fuel conversion efficiencies compared to gasoline. Increasing the DMF mass fraction in DI reduces the combustion duration more significantly than with increased fractions of ethanol or gasoline in DI. The hydrocarbon (HC), oxides of nitrogen (NO_x) and carbon dioxide (CO₂) emissions mostly reduce when using any gasoline or ethanol fraction in DI. When using DMF, the HC emissions reduce, but the NO_x and CO₂ emissions increase.     

Distribution and removal of added mercury in milk.

Distribution patterns of added mercury in raw whole milk after equilibration for 30 min and 2 h at 37 C showed a distribution among acid casein, whey proteins, fat globule membrane, and soluble fat globule membrane of 33, 28, 16, and 2%. On the basis of protein content, the fat globule membrane had the highest amount of mercury. Mercury added to milk as mercuric chloride was removed by treatment with thiolated aminoethyl celluloses and reduced human hair. In a 5 min treatment, 70, 43, and 41% of the mercury was removed by thiosuccinylated aminoethyl cellulose, thionitrocarboxyphenylated aminoethyl cellulose, and reduced human hair, respectively, from whole milk initially containing 1 ppm mercury and equilibrated for 2 h at 37 C prior to treatment. After treatment for 60 min, 82, 52, and 64% of the mercury was removed by thiosuccinilated aminoethyl cellulose, thionitrocarboxyphenylated aminoethyl cellulose, and reduced hair, respectively. However, increasing incubation temperature and time prior to treatment decreased the removal efficiencies. Thiosuccinilated aminoethyl cellulose and reduced human hair showed increasing efficiency directly with pH, while thionitrocarboxyphenylated aminoethyl cellulose showed the opposite effect and had higher affinity for mercury at pH 5.5 than at pH 7.5. Moreover, the rate of removal of mercury at 4 C compared to 37 C was much slower. The removal of mercury from soluble casein and soluble whey proteins was more efficient than from micellar casein. Protein, lactose content, and pH of milk were not changed by the polymer treatments.     

Tribromopyrrole,brominated acids,and other disinfection byproducts produced by disinfection of drinking water rich in bromide

Using gas chromatography/mass spectrometry (GC/MS), we investigated the formation of disinfection byproducts (DBPs) from high bromide waters (2 mg/L) treated with chlorine or chlorine dioxide used in combination with chlorine and chloramines. This study represents the first comprehensive investigation of DBPs formed by chlorine dioxide under high bromide conditions. Drinking water from full-scale treatment plants in Israel was studied, along with source water (Sea of Galilee) treated under carefully controlled laboratory conditions. Select DBPs (trihalomethanes, haloacetic acids, aldehydes, chlorite, chlorate, and bromate) were quantified. Many of the DBPs identified have not been previously reported, and several of the identifications were confirmed through the analysis of authentic standards. Elevated bromide levels in the source water caused a significant shift in speciation to bromine-containing DBPs; bromoform and dibromoacetic acid were the dominant DBPs observed, with very few chlorine-containing compounds found. Iodo-trihalomethanes were also identified, as well as a number of new brominated carboxylic acids and 2,3,5-tribromopyrrole, which represents the first time a halogenated pyrrole has been reported as a DBP. Most of the bromine-containing DBPs were formed during pre-chlorination at the initial reservoir, and were not formed by chlorine dioxide itself. An exception wasthe iodo-THMs, which appeared to be formed by a combination of chlorine dioxide with chloramines or chlorine (either added deliberately or as an impurity in the chlorine dioxide). A separate laboratory study was also conducted to quantitatively determine the contribution of fulvic acids and humic acids (from isolated natural organic matter in the Sea of Galilee) as precursor material to several of the DBPs identified. Results showed that fulvic acid plays a greater role in the formation of THMs, haloacetic acids, and aldehydes, but 2,3,5-tribromopyrrole was produced primarily from humic acid. Because this was the first time a halopyrrole has been identified as a DBP, 2,3,5-tribromopyrrole was tested for mammalian cell cytotoxicity and genotoxicity. In comparison to other DBPs, 2,3,5-tribromopyrrole was 8x, 4.5x, and 16x more cytotoxic than dibromoacetic acid, 3-chloro-4-(dichloromethyl)-5-hydroxy-2-[5H]-furanone [MX], and potassium bromate, respectively. 2,3,5-Tribromopyrrole also induced acute genomic damage, with a genotoxic potency (299 microM) similar to that of MX.     

Innovations in beef production systems that enhance the nutritional and health value of beef lipids and their relationship with meat quality

Consumers are becoming more aware of the relationships between diet and health and this has increased consumer interest in the nutritional value of foods. This is impacting on the demand for foods which contain functional components that play important roles in health maintenance and disease prevention. For beef, much attention has been given to lipids. This paper reviews strategies for increasing the content of beneficial omega-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid (CLA) and reducing saturated fatty acids (SFA) in beef. Particular attention is given to intramuscular fat (IMF) and the relationships between fatty acid composition and key meat quality parameters including colour shelf life and sensory attributes. Despite the high levels of ruminal biohydrogenation of dietary PUFA, nutrition is the major route for increasing the content of beneficial fatty acids in beef. Feeding grass or concentrates containing linseed (rich in α-linolenic acid, 18:3n-3) in the diet increases the content of 18:3n-3 and its longer chain derivative eicosapentaenoic acid (EPA, 20:5n-3) in beef muscle and adipose tissue, resulting in a lower n-6:n-3 ratio. Grass feeding also increases docasahexaenoic acid (DHA, 22:6n-3). Feeding PUFA rich lipids which are protected from ruminal biohydrogenation result in further enhancement of the PUFA in meat with concomitant beneficial improvements in the ratio of polyunsaturated:saturated fatty acids (P:S ratio) and n-6:n-3 ratio. The main CLA isomer in beef is CLA cis-9, trans-11 and it is mainly associated with the triacylglycerol lipid fraction and therefore is positively correlated with level of fatness. The level of CLA cis-9, trans-11 in beef is related to (1) the amount of this isomer produced in the rumen and (2) synthesis in the tissue, by delta-9 desaturase, from ruminally produced trans vaccenic acid (18:1 trans-11; TVA). Feeding PUFA-rich diets increases the content of CLA cis-9, trans-11 in beef. Trans-fatty acids in foods are of rising importance and knowledge of the differential effects of the individual trans isomers is increasing. TVA is the major trans 18:1 isomer in beef and as the precursor for tissue CLA in both animals and man should be considered as a neutral or beneficial trans-isomer. Increasing the content of n-3 PUFA in beef can influence colour shelf life and sensory attributes of the meat. As the content of n-3 PUFA increases then sensory attributes such as "greasy" and "fishy" score higher and colour shelf life may be reduced. Under these situations, high levels of vitamin E are necessary to help stabilise the effects of incorporating high levels of long chain PUFA into meat. However, grass feeding not only increases n-3 PUFA and CLA but, due to its high content of vitamin E, colour shelf life is improved. It is evident that opportunities exist to enhance the content of health promoting fatty acids in beef and beef products offering opportunities to add value and contribute to market differentiation. However, it is imperative that these approaches to deliver "functional" attributes do not compromise on the health value (lipoperoxidation) or the taste of beef products.