NMR-based metabonomics reveals relationship between pre-slaughter exercise stress, the plasma metabolite profile at time of slaughter, and water-holding capacity in pigs

Nuclear magnetic resonance (NMR)-based metabonomics was applied to investigate the effects of pre-slaughter exercise stress on the plasma metabolite profile at time of slaughter. The study included a total of 40 slaughter pigs, which were exposed to one of the following treatments: No pre-slaughter stress (control treatment), pre-slaughter exercise on a treadmill and subsequently 0, 1, or 3 h rest prior to slaughter. NMR-based metabonomics revealed a clear difference in the plasma metabolite profile at time of slaughter between control pigs and pigs exercised without rest, which mainly could be ascribed to increased plasma lactate due to exercise. A resting period of 1 or 3 h prior to slaughter reversed the stress-induced perturbations in the plasma metabolite profile. The plasma metabolite profile at time of slaughter was highly correlated with muscle temperature 1 min post-mortem, and a correlation to WHC was also demonstrated. Lactate was found to be the metabolite of importance for the association between the plasma metabolome and pH, temperature and WHC.     

Prediction of pork quality with near infrared spectroscopy (NIRS): 1. Feasibility and robustness of NIRS measurements at laboratory scale

The objective was to study prediction of pork quality by near infrared spectroscopy (NIRS) technology in the laboratory. A total of 131 commercial pork loin samples were measured with NIRS. Predictive equations were developed for drip loss %, colour L*, a*, b* and pH ultimate (pHu). Equations with R(2)>0.70 and residual prediction deviation (RPD)≥1.9 were considered as applicable to predict pork quality. For drip loss% the prediction equation was developed (R(2) 0.73, RPD 1.9) and 76% of those grouped superior and inferior samples were predicted within the groups. For colour L*, test-set samples were predicted with R(2) 0.75, RPD 2.0, colour a* R(2) 0.51, RPD 1.4, colour b* R(2) 0.55, RPD 1.5 and pHu R(2) 0.36, RPD 1.3. It is concluded that NIRS prediction equations could be developed to predict drip loss% and L*, of pork samples. NIRS equations for colour a*, b* and pHu were not applicable for the prediction of pork quality on commercially slaughtered pigs.     

Alternating frequency to increase the response to stimulation from medium voltage electrical stimulation and the effect on objective meat quality

The use of alternating frequencies during stimulation can increase stimulation response of a medium voltage electrical stimulation unit (MVS) by increasing the rate of pH decline. Various combinations of frequency modulation were tested in experiment 1 to determine the treatment resulting in the greatest stimulation response; the lowest initial pH, fastest rate of pH decline, highest temperature at pH 6 and the highest number of carcasses with a pH of 6 by 25(o)C and the treatment achieving the highest number of carcasses in the pH temp window (temperature at pH 6 between 18-25(o)C). The objective meat quality of these treatments compared to an unstimulated treatment was tested in experiment 2. Modulating the frequency (Hz) across the 6 segmented electrodes of the MVS by 10, 15, 25, 10, 15, 25Hz (Treatment 6, using a pulse width: 2.5ms, current: 1A) resulted in the greatest stimulation response. This treatment may be suitable for abattoirs that hot bone sheepmeat and require fast pH declines to ensure minimal cold shortening of meat. However, this treatment did not result in the tenderer meat despite the higher stimulation response. This treatment may have induced a greater number of contractions overall and therefore a greater pH decline response but resulted in less myofibrillar disruption compared to the other treatments due to a concomitant decreased force of contraction thus reducing potential tenderisation. Maintaining a constant frequency of 15Hz (Treatment 1; pulse width: 2.5ms, current: 1A) resulted in a higher number of carcasses in the pH temp window required (temperature at pH 6 between 18-25(o)C) in part A (P<0.05) and in addition to the higher tenderness levels this treatment may be more appropriate to satisfy the overall demands of abattoirs using these systems. This paper has also demonstrated electrical stimulation results in tenderer meat compared to unstimulated meat even after 30d of ageing (2.53±0.4 compared to 2.85±0.1 for the loin (M. longissimus thoracis et lumborum) (P<0.01) possibly due to a protective benefit of stimulation on meat tenderness. Overall, no detrimental effects of modulating frequency were observed on drip loss or retail colour display despite a greater rate of colour change observed with the modulated frequency treatment and the longer aged product.     

Simplified Procedure to Evaluate Head Losses in Drip Irrigation Laterals

The lateral lines of a drip irrigation system consist of pressurized pipelines with inline or online emitters. Proper hydraulic design of drip laterals usually requires the accurate evaluation of the total head losses, represented by friction losses along the pipe and the emitters, and local losses due to the emitter connections. This paper extends the local loss evaluation procedure, previously obtained for coextruded laterals, on the basis of new experiments. In addition, a simplified procedure was proposed based on the constant outlet discharge assumption for a quick evaluation of total head losses in drip irrigation lines, taking into account the total local loss due to the emitter connections. Total head loss values measured on 15 commercially available coextruded laterals were then compared with those obtained by using the nowly proposed methodology. Relative errors on the pressure head estimation for the examined cases were always ±2.4%, and therefore the proposed methodology could serve for a quick, approximate evaluation of the total head losses along the laterals.     

秸秆还田对膜下滴灌条件下日光温室西红柿产量的影响

西红柿是我国主要的设施农业蔬菜种类之一,目前日光温室内西红柿普遍采用膜下滴灌方式灌溉。秸秆还田可以改善土壤的理化性质,提高作物产量,因此针对膜下滴灌条件下的日光温室西红柿进行秸秆还田研究,结果表明秸秆还田虽然会提高西红柿的需水量,但可以显著提高产量和水分生产效率,增产效益显著。     

FTO镀膜玻璃滴落物的产生机理与解决方案

FTO镀膜玻璃在生产过程中产生的滴落物,会对FTO镀膜玻璃的外观、均匀性、稳定性、激光刻蚀等性能造成严重的影响,本文阐述了滴落物带来的影响,采用电镜分析的方法对其产生机理进行了研究,给出了可行的解决方案。     

The influence of superchilling storage methods on the location/distribution of ice crystals during storage of Atlantic salmon (Salmo salar)

The objective of this work was to study the influence of superchilling storage methods, shell freezing and non-shell freezing on the location/distribution of ice crystals during the superchilled storage of salmon. Physical measurements, water holding capacity and drip loss were also studied. Non-shell frozen samples resulted in extracellular ice crystals. Shell frozen samples showed both intracellular and extracellular ice crystals with a uniform distribution. Liquid loss (LL) decreased with storage time in both superchilling storage methods. There was no significant difference (p > 0.05) in LL between shell and non-shell frozen samples. There was significant difference (p < 0.05) in the drip loss between shell frozen samples (1.62% as maximum) and non-shell frozen samples (1.4% as maximum). The information on the characteristics of ice crystals (location/distribution), which has a strong influence on the quality of the final superchilled food, is a factor key for the manufacturing of products with desired quality and shelf life.     

Quality changes during superchilled storage of pork roast

Quality parameters (sensory, physical, biochemical and microbiological) of superchilled vacuum packed boneless pork roasts were studied during storage for 16 weeks. Superchilling of vacuum packed pork roast at a temperature of −2.0 °C improved shelf life significantly compared to traditional chilled storage at +3.5 °C. Superchilled pork roasts maintained good sensory quality and low microbiological counts during the whole storage period. The drip loss in superchilled samples was lower and showed less variation than in the references and the temperature abused roasts. The consequences of an interrupted cold chain during storage were also investigated. Superchilled samples with temperature abuse resembled chilled samples with respect to drip loss and microbial levels. To take advantage of all the benefits of superchilling and successfully implement the process in the food industry a stable, controlled temperature during storage is critical.     

Meat quality characteristics of springbok (Antidorcas marsupialis). 1: Physical meat attributes as influenced by age, gender and production region

Springbok is the most extensively cropped game species in South Africa. The effects of age (adult, sub-adult, lamb), gender and production region on the physical attributes (pH₂₄, cooking and drip loss, Warner Bratzler shear force and colour) were determined using samples of the M. longissimus dorsi (LD) muscles of 166 springbok. Stressed animals had a higher (P < 0.05) pH₂₄ (6.3 ± 0.07), as observed in the meat originating from the Caledon region. This meat had lower (P < 0.05) cooking loss (27.2 ± 0.62%) and drip loss (1.8 ± 0.08%) values in comparison to meat originating from the other regions. Inverse correlations were noted between pH₂₄ and drip loss (r = −0.26, P < 0.01) and cooking loss (r = −0.42, P < 0.001). Shear force values (kg/1.27 cm diameter) correlated positively (r = 0.25, P < 0.01) with pH₂₄. Age-related effects on tenderness were small in comparison with pH₂₄ effects. CIELab colorimetric values were typical of game meat and venison (L^* < 40, high a^* and low b^* values). It was noted that pH₂₄ correlated negatively (r = −0.51, P < 0.001) and positively (r = 0.33, P < 0.001) with the hue-angle and the chroma value of colour, respectively. Springbok originating from Caledon had a significantly (P < 0.05) higher a^* value, indicating meat to be more red with higher colour saturation.     

烤烟节水灌溉试验与示范

进行了不同灌水方式对烟田土壤性状、烤烟农艺性状和经济性状影响的试验。结果表明 ,滴灌、喷灌对烟田的土壤结构、烤烟的生长发育和产、质等有显著影响。采用滴灌和喷灌节水效果显著 ,灌水产出分别达 82 .19元 m3 、6 7.95元 m3 ;灌溉投入产出比分别为 6 8.5和 5 6 .6 ,而沟灌为 8.9。因此 ,烟田应采用滴灌和喷灌方式而不宜再采用沟灌