Sabine M. Harrison

Turnover of carbon, nitrogen, and sulfur in bovine longissimus dorsi and psoas major muscles: Implications for isotopic authentication of meat

Stable isotope ratio analysis of light elements (including C, N, and S) is a powerful tool for inferring the production and geographic origins of animals. The objectives of this research were to quantify experimentally the isotopic turnover of C, N, and S in bovine skeletal muscle (LM and psoas major) and to assess the implications of the turnover for meat authentication. The diets of groups (n = 10 each) of beef cattle were switched from a control diet containing barley and unlabelled urea to an experimental diet containing maize, (15)N-labeled urea, and seaweed for periods of up to 168 d preslaughter. The feeding of the experimental diet was clearly reflected by the delta(13)C, delta(15)N, and delta(34)S values of the LM and psoas major muscles, but isotopic equilibrium was not reached in either muscle for C, N, or S after 168 d of feeding the experimental diet. The slow turnover in skeletal muscle was reflected by the C and N half-lives of 151 and 157 d for LM and 134 and 145 d for psoas major, respectively, and by an S half-life of 219 d in LM. It is concluded that the turnover of light elements (C, N, and S) in bovine skeletal muscles is a slow process; therefore, skeletal muscles contain isotopic information on dietary inputs integrated over a long period of time (months to years).

Nanoparticle passage through porcine jejunal mucus: Microfluidics and rheology

A micro-slide chamber was used to screen and rank sixteen functionalized fluorescent silica nanoparticles (SiNP) of different sizes (10, 50, 100 and 200 nm) and surface coatings (aminated, carboxylated, methyl-PEG1000ylated, and methyl-PEG2000ylated) according to their capacity to permeate porcine jejunal mucus. Variables investigated were influence of particle size, surface charge and methyl-PEGylation. The anionic SiNP showed higher transport through mucus whereas the cationic SiNP exhibited higher binding with lower transport. A size-dependence in transport was identified - 10 and 50 nm anionic (uncoated or methyl-PEGylated) SiNP showed higher transport compared to the larger 100 and 200 nm SiNP. The cationic SiNP of all sizes interacted with the mucus, making it more viscous and less capable of swelling. In contrast, the anionic SiNP (uncoated or methyl-PEGylated) caused minimal changes in the viscoelasticity of mucus. The data provide insights into mucus-NP interactions and suggest a rationale for designing oral nanomedicines with improved mucopermeability.

Quality of deli-style turkey enriched with plant sterols

Low-fat meat products could be excellent carriers for plant sterols, known for their cholesterol-lowering properties. In this study, we developed a protocol for the manufacture of a deli-style turkey enriched with plant sterols (S) at a level sufficient to deliver the maximum plant sterols amount recommended for cholesterol reduction by the European Food Safety Authority (3 g of plant sterols per day) in a 70 g portion. We investigated the stability of the plant sterols and the effects of their addition on the product quality. Plant sterols remained stable during the seven-day storage period. The addition of plant sterols significantly affected some texture parameters, shear force, lipid oxidation, L values and water-holding capacity compared with control (C). Sensory analysis was carried out by an untrained panel (32) using the difference-from-control test between C and S samples to evaluate first the extent of the overall sensory difference and then the extent of sensory difference on colour, texture and flavour. Results indicated that panellists considered the intensity of the difference between C and S samples to be ‘small’. Plant sterols could be used as a potential health-promoting meat ingredient with no effect on plant sterol stability but with some effects on texture and sensory characteristics.

Isotopic turnover of carbon and nitrogen in bovine blood fractions and inner organs

RATIONALE Isotope ratio analysis of bovine tissues is a tool for inferring aspects of the dietary history of cattle. The objective of this experiment was to quantify the carbon (C) and nitrogen (N) isotopic turnover in blood (serum and residue) and inner organs (liver, kidney, heart and brain) of beef cattle. METHODS Growing beef cattle (n = 70 in total) were either switched from a control diet containing barley and urea to an experimental diet containing maize and (15)N-enriched urea, for various intervals prior to slaughter or maintained on the control diet for 168 days pre-slaughter. Samples of blood, liver, kidney, heart and brain were collected at 0, 14, 28, 56, 112 and 168 days and analysed using Isotope Ratio Mass Spectrometry. RESULTS After 168 days, C- and N-isotopic equilibrium was reached in the blood serum, liver and kidney, approached in the heart and brain, but not reached in the non-serum component of blood. The estimated C and N half-lives were 16.5 and 20.7 days for liver, 19.2 and 25.5 days for kidney, 29.2 and 35.6 days for blood serum, 37.6 and 49.9 days for heart, 53.3 and 52.2 days for brain and 113.3 and 115.0 days for the non-serum blood residue, respectively. Modelling the C and N turnover in the different tissue combinations revealed that a combined analysis of liver and heart as well as brain and kidney can provide the most accurate estimation of the timing of the diet switch. CONCLUSIONS Based on the difference in turnover rates, bovine soft tissues can provide isotopic information on short- and long-term dietary changes, which in turn may be linked to the geographic or production origin of beef cattle. This study also provides basic biological data on organ C and N turnover in a large herbivorous mammal.

Effect of castration and carcass suspension method on the quality and fatty acid profile of beef from male dairy cattle: Quality of dairy beef affected by castration and carcass suspension method

BACKGROUND The use of bulls rather than steers for beef production offers some considerable advantages; however, the eating quality of bull beef is an issue of marketing concern. This study assessed the physicochemical characteristics of young Holstein-Friesian (HF) bull and steer beef. Steer carcasses were suspended by the Achilles tendon (AS) and by pelvic suspension (PS). RESULTS HF steer beef had higher redness, yellowness and chroma values, whereas bulls had higher ultimate pH and darker muscle. Warner-Bratzler shear force, cook loss at different ageing times, moisture, and insoluble and total collagen were higher for HF bull beef, whereas intramuscular fat, soluble collagen and collagen solubility were higher for steer beef. HF steer beef had a higher proportion of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA), whereas bull beef had higher proportions of polyunsaturated fatty acids (PUFA), PUFA/SFA and n-6/n-3 PUFA ratios. In comparison to AS, PS increased redness and chroma after 24 h blooming; PS improved tenderness up to 7 days of ageing and accelerated the ageing process. CONCLUSION For young dairy cattle, steer beef would likely have superior eating quality but a relatively less favourable nutritional fatty acid profile to bull beef. Suspension method affected the tenderness and colour intensity of dairy steer beef at different ageing times.

Volatile Profile of Grilled Lamb as Affected by Castration and Age at Slaughter in Two Breeds: Volatile profile of grilled lamb…

The aim of this study was to assess the effect of castration and slaughter age on the volatile profile of cooked meat from Scottish Blackface (SB) and Texel × Scottish Blackface (T × SB) lambs. M. longissimus thoracis et lumborum was sampled at slaughter and subjected to volatile analysis by SPME-GC-MS. Rams had higher relative proportions, expressed as relative abundance (RA), in lipid oxidation products while castrates had higher RA in pyrazines and benzenoid compounds. There was no consistent age effect on the RA of volatiles, although rams in November and January had a different volatile profile to castrates. There were higher proportions of free branched-chain fatty acids in muscle from SB compared to T × SB lambs. Overall, the results showed that production factors affected the volatile profile of cooked lamb meat which may explain differences in lamb flavor. PRACTICAL APPLICATION Lamb meat has a characteristic flavor which, according to the evidence to date, may be influenced by farm production factors like gender or slaughter age. Our results showed variations in the proportions of some flavor compounds in cooked lamb between rams and castrated lambs while an increase in slaughter age did not have a consistent effect on proportions of compounds.

The effect of plant sterol-enriched turkey meat on cholesterol bio-accessibility during in vitro digestion and Caco-2 cell uptake.

Abstract This study evaluated the effect of a plant sterol-enriched turkey product on cholesterol bio-accessibility during in vitro digestion and cholesterol uptake by Caco-2 monolayers. Turkey products, one plant sterol-enriched (PS) and one plant sterol-free (C), were produced in an industrial pilot plant. Before simulated digestion, matrices were spiked with cholesterol (1:5 weight ratio of cholesterol to plant sterol). Plant sterols were included at a concentration equivalent to the minimum daily intake recommended by the European Food Safety Authority (EFSA) for cholesterol lowering. After simulated digestion, the percentage of cholesterol micellarization and uptake by Caco-2 cells in the presence of PS meat were measured. Compared to C meat, PS meat significantly inhibited cholesterol micellarization on average by 24% and Caco-2 cell accumulation by 10%. This study suggests that plant sterols in meat can reduce cholesterol uptake by intestinal epithelia and it encourages efforts to make new PS-based functional foods.