Influence of keeping system on the fatty acid composition in the <Emphasis Type="Italic">longissimus</Emphasis> muscle of bulls and odorants formed after pressure-cooking

German Simmental bulls were kept either in a stable (group 1) or on a pasture (group 2). For both groups the intramuscular fat content of the longissimus muscle and the fatty acid composition in phospholipids and triacylglycerols were investigated. Significant influences of feeding were shown in most fatty acids measured in both lipid classes. In concentrate-fed bulls a higher content of linoleic acid (C18:2n-6) was detected, corresponding to the large amount of linoleic acid found in concentrate used as feed. In contrast, bulls fed grass proved to have a higher linolenic acid (C18:3n-3) content, also correlating well with the larger amount of linolenic acid found in grass. Pressure-cooking of the beef followed by an analysis of eight important meat odorants revealed that, in line with the higher concentrations of the precursor fatty acids C18:3n-3 and C18:1 in muscle of group 2, (E,Z)-2,6-nonadienal (from C18:3n-3) as well as nonanal and octanal (from C18:1) were much higher in the processed meat of animals fed grass. On the other hand, the much higher amounts of C18:2n-6 in bulls fed concentrate were well-reflected by higher concentrations of five aroma compounds known to be formed by a thermal degradation of this acid, e.g. (E,E)-2,4-decadienal.     

A novel analysis and design of a neural network assisted nonlinear controller for a bioreactor

A novel approach is presented for the analysis and the design of a controller for a bioreactor. It is based on the model reference control theory, assisted by a neural network identifier. The control objectives specified in the paper require the controller to be a nonlinear one, however, it is shown that it is stable in the sense of bounded input bounded output and locally stabilizing in the sense of Lyapunov. The feasibility and the efficacy of the proposed approach are tested on the benchmark problem. Copyright © 1999 John Wiley & Sons, Ltd.     

N‐3 fatty acids and conjugated linoleic acids of longissimus muscle in beef cattle

The objective of the experiment with cattle was to produce high quality beef under different feeding conditions and to increase the concentration of essential fatty acids in muscle. In total 10 German Simmental (GS) bulls and 9 German Holstein (GH) steers were kept either on pasture (grass feeding) or in stable (concentrate feeding). Despite biohydrogenation in the rumen, linolenic acid (C18:3n‐3) contained in grass was absorbed and deposited into the lipids of muscle. This led to a significantly (p ≤ 0.05) higher content of n‐3 fatty acids in the muscle lipids of grazing cattle. The relative amount of total n‐3 fatty acids increased from 1.4 g/100 g fatty acid methyl ester (%FAME) in the intensively fed Simmental bulls to 5.5 %FAME in grass fed cattle. The n‐6/n‐3 ratio of pasture grazing GS bulls was 1.3 in contrast to 13.7 of the animals kept in the byre. The total n‐3 fatty acid concentration in beef muscle increased from 24.6 mg (concentrate) to 108.6 mg/100 g wet weight (grazing). In GH steers the total n‐3 fatty acid concentration was significantly (p ≤ 0.05) increased up to 86.3 mg/100 g wet weight in pasture grazing steers compared to 28.8 mg/100 g wet weight in animals fed the concentrate. The relative content (%FAME) of CLAcis‐9, trans‐11 (0.6 vs 0.56 %FAME in GS; 0.55 vs 0.52 %FAME in GH) in muscle was not significantly increased by grazing on pasture in comparison to concentrate feeding neither in GS bulls nor in GH steers, respectively.     

Effect of Porcine Somatotropin (pST) on Fat Quality of Growing-Finishing Pigs

Long-term application of recombinat porcine somatotropin to pigs induced a decrease in fat deposition and a reduction in percentage fat in backfat and intramuscular fat. The proportion of poly-unsaturated fatty acids especially of C18:2 increased. Lower thickness and higher water content of backfat influenced the fat quality negatively. Growth of subcutaneous adipose tissue was affected substantially by pST administration with evidence of dose dependency. During withdrawal time until slaughter a marked compensatory fat deposition occurred.     

Einfluß von porcinem Somatotropin (pST) auf die Fettqualität von Schweinen unterschiedlichen Geschlechts

Influence of porcine Somatotropin (pST) on the Fat Quality in Pigs of Different Sex The longterm application of recombinant porcine somatotropin (pST) to Landrace pigs of serveral sexes markedly improved carcass quality, mainly due to an increase of meat percentage (7 – 14%) at the expense of fat content. Meat quality was not deteriorated by pST application. The fat percentage in subcutaneous and intramuscular fat decreased significantly. PST induced an increase of polyunsaturated fatty acids especially the concentration of linoleic acid (C18:2) in backfat. These aspects connected with lower thickness and consistency of backfat result in a decrease of fat quality.     

Measured and simulated flow downstream of the submerged sluice gate

In this study, turbulent flow downstream of the submerged sluice gate was investigated experimentally and numerically. Experimental studies were conducted in a laboratory flume to measure the flow velocities and turbulence characteristics. Three‐dimensional computational fluid dynamics (CFD) simulation was performed to investigate the flow structure downstream of the sluice gate. It is found that the flow downstream of the submerged sluice gate is highly three‐dimensional and unsteady in nature because of the interaction of mean flow and recirculation flow. The three‐dimensional simulation results indicate that the interacted flow triggers the formation of two corner vortices. Secondary velocities associated with the free surface vortices are found to be about 6% of the mean jet velocity at the inlet, which is significant for the river bank erosion. Vortex induced free surface fluctuations were also observed in the vicinity of the submerged gate.     

The effect of dietary magnesium oxide supplementation on postmortem (31)P NMR spectroscopy parameters, rate of Ca(2+) uptake and ATPase activity of M. longissimus dorsi and meat quality of heterozygous and normal on malignant hyperthermia pigs

Twenty four crossbred (Large White, White Meaty, Pietrain, Hampshire) pigs were tested by DNA probe for a mutation on the ryanodine receptor RYR1 (malignant hyperthermia-MH). An equal number of pigs heterozygote (monomutant-MON) and normal on MH (nonmutant-NON) were used in the experiment. The pigs were fed finisher feed (control group) or finisher feed supplemented with magnesium (3.6 g MgO per pig per day; MgO group) for 5 days prior to slaughter. Pigs fed the diet supplemented with MgO had higher plasma Mg concentrations. Phosphorus nuclear magnetic resonance ((31)P NMR) measurements on postmortem (15 min) muscle samples (longissimus muscle) showed the highest phosphocreatine levels in normal pigs fed MgO (P<0.05). The MgO supplementation caused increased Ca(2+) uptake and Ca(2+) ATPase activity only in normal (NON) pigs. ATPase activity was lowest (P<0.05) in heterozygote control pigs. Pigs fed MgO supplemented diet had higher pH (45 min postmortem). A significant lower pH (P<0.05) was obtained in heterozygous (MON) control pigs. Also pigs fed with MgO had lower percentage of drip losses and significant differences (P<0.05) were obtained between heterozygous (MON) pigs. The results indicate that dietary MgO supplementation can improve parameters of muscle energetic metabolism, Ca(2+) uptake and meat quality (pH, drip loss).     

Effects of cooking methods on chlorophylls, pheophytins and colour of selected green vegetables

The effect of microwave and conventional cooking methods on chlorophyll pigments and colour properties of squash, green beans, peas, leek, broccoli and spinach were studied, by HPLC and colorimetry, respectively. In five of six vegetables, chlorophyll a was found more heat resistant compared with chlorophyll b, except in peas. Chlorophylls in peas were retained to the 80–90%, the highest in all vegetables evaluated. Chlorophylls were retained to 19–100%, depending on the vegetable type and cooking method. Pheophytins increased in all vegetables after cooking. Highest chlorophyll a and chlorophyll b losses were observed in boiled leek while microwaved peas and boiled peas retained the most chlorophyll a and chlorophyll b, respectively. Pheophytin a and pheophytin b formation was highest at boiled squash and boiled green beans, which were fifty‐ninefold and twenty‐onefold compared with fresh ones, respectively. Most of the pheophytin formations occurred in boiled and the least in microwaved vegetables. Surface colour changed depending on the type of vegetable and cooking method.