In-vivo magnetic resonance imaging studies of mammogenesis in non-pregnant goats treated with exogenous steroids.

Mammogenesis and lactation were induced in five multiparous, non-pregnant goats by treatment with oestrogen and progesterone for 11 d, followed by dexamethasone for 3 d. Reserpine was administered during the last 5 d. All five goats lactated, although milk yield was less than had been achieved in previous natural lactations. Mammary development was assessed in vivo, using magnetic resonance imaging. Although parenchyma volume increased by more than 6-fold overall, only 25% of this increase occurred during steroid treatment. Most development took place after the cessation of treatment, when milking commenced. Maximum size was not achieved until week 8 of the induced lactation, and was only 70% of normal parenchyma volume. After 18 weeks lactation the activities of three key milk synthetic enzymes were very similar to values previously found in natural lactations, and secretion efficiency (milk production per unit volume of parenchyma) was also similar to that of natural lactations. We conclude that the lower than normal milk yields were associated with incomplete proliferation of mammary tissue, rather than inadequate differentiation of individual secretory cells.     

The effect of freezing and thawing on the magnetic resonance imaging parameters of water in beef, lamb and pork meat

A new multisample magnetic resonance imaging (MRI) technique has been used to measure the values of T ₁, T ₂, magnetization transfer (MT) rate and liquid proton density ratio ( M ₀%) for water in fresh and frozen–thawed beef, lamb and pork; four samples from the longissimus dorsi muscle of 25 different individuals per species were studied. The effect of two different chilling regimes, standard and tenderloin, were also studied. Standard chilled pork and lamb had a significantly higher M ₀% than tenderloin chilled samples, but there was no correlation between M ₀% and fresh weight; the differences in M ₀% are thought to be due to differences in MR (magnetic resonance)-visible water. There was a significant decrease in water content, T ₁ relaxation time, and a significant increase in MT rate in the frozen–thawed samples when all the data were pooled for each species. However, individual animals differed in the magnitude and direction of the change; this means that because of interanimal variation, measurements of MR parameters from a single sample of meat cannot be used at present to authenticate it.     

NMR对水分的研究及其在食品科学中的应用

近年来,核磁共振技术(NuclearMagneticResonance,简称NMR)引起了科研人员的极大兴趣。核磁共振有很多优点,使得它在有机化学、分析化学、表面活性剂、涂料食品、医学等不同的化学分析领域都得到了广泛的应用本文首先简单介绍NMR技术及其应用的价值,主要叙述NMR用来研究水分的情况及其在食品科学中的应用,并在水分含量的测定、持水力、玻璃化温度、分子扩散、食品结块、质构研究等方面作了详细的阐述,同时列举了丰富的实例。      

Electron spin resonance (ESR) spectroscopy study of dry-cured ham treated with electron-beam

The generation, accumulation and decay of free radicals in muscle and fat fractions from three varieties of Spanish dry-cured ham treated (0–4 kGy) in an electron accelerator have been studied by electron spin resonance (ESR) spectroscopy. In the ESR spectra from fat fractions, a well-resolved triplet signal corresponding to an alkyl radical was found only in treated samples. Linear regression models (P < 0.05) were obtained for ESR signal intensity estimation using the absorbed dose and storage time at 4 °C (from 0 to 28 days). Several ESR signals were observed in the spectra from muscle fractions related to the presence of metalloprotein complexes. However, no significant (P > 0.05) differences were found between ESR spectra from untreated (0 kGy) and treated (0–4 kGy) samples. Results suggest that the analysis of ESR spectrum in fat samples can be used to evaluate the E-beam treatment of dry-cured ham.     

Diffusion of NaCl in meat studied by (1)H and (23)Na magnetic resonance imaging

The effect of sodium chloride (NaCl) diffusion into meat was investigated. Proton and sodium magnetic resonance imaging were used to determine the diffusion behaviour of brine (NaCl) in porcine Longissimus dorsi and semitendinosus. NaCl diffusion was visualized through images and diffusion coefficients were determined to be in the range 3-7×10(-10)m(2)s(-1), which is in agreement with values reported in the literature. The diffusion coefficient was found to increase during curing, suggesting microstructural changes in the meat. A supplementary experiment proved that the diffusion behaviour of sodium chloride in regions of meat with connective tissue/fat is distinctive from regions with pure myofilament tissue, as anticipated. Apparent diffusion coefficient (ADC) maps showed that meat microstructures shrunk when cured with 20% (w/w) NaCl brine. ADC across (⊥) the main muscle fiber direction decreased more than ADC along (‖) the main muscle fiber direction. The greater shrinkage in the direction across muscle fibers suggests that the curing induced shrinkage of the transverse structures rather than reduction in longitudinal structures.     

Estimation of rubber content of guayule (Parthenium argentatum) using low-resolution proton magnetic resonance

Low-resolution proton magnetic resonance (p.m.r.) has been investigated as a rapid screening method for the determination of rubber in guayule. Regression equations have been derived relating p.m.r. measurements to rubber content in the original material and in acetone extracted material, and to the amount of rubber extracted. Linear relationships have been established for all three variables with r² values of 0.92, 0.94 and 0.92 (P < 0.001) respectively. Sample pretreatment was found to be important, with grinding and heating resulting in a loss of rubber, as determined by both p.m.r. and extraction.     

Determination of fat and water content in vitro and in vivo by proton nuclear magnetic resonance

Proton NMR spectroscopy was performed on a series of pork samples containing varying proportions of fat and muscle and on a series of control and obese mice. Initial measurements were made using a 0.5 T (21 MHz) whole body imaging system and the results were expressed as the ratio of water and lipid hydrogen peak areas. With pork samples the NMR results correlated well with per cent water or lipid in the tissue (r = 0.99 for 20- and 50-g samples). For the mice the correlation between per cent water or lipid in the body and the NMR measurement was 0.92. Subsequent measurements were made using a 4.7 T (200 MHz) imaging/spectrometer from which separate integral values were obtained for the water and lipid hydrogen peaks. The separation of the water and lipid peaks was 3.5 ppm. For pork samples measured with the 4.7 T system the correlation between the peak area and the amount of water or lipid in the sample was 0.997 with the standard error of the estimate being ±0.72 g for water and ±1.00g for lipid. NMR imaging was used to determine the relative amount of fat and muscle in a cross-section of a control and an obese rat.     

Microstructure and water distribution of commercial pasta studied by microscopy and 3D magnetic resonance imaging

Manufacturing pasta is a rather well known process, but it is still challenging to tailor pasta products with new raw materials. In this study, we evaluated the effects of raw materials on the microstructure and water distribution in cooked pasta using ¹H magnetic resonance imaging (MRI) as well as bright field and polarized light microscopy. The MRI parameters initial intensity (I₀) and transverse dephasing time (T₂^⁎) serve as indicators of the local water concentration and water–macromolecule interactions through chemical exchange, respectively. These parameters were mapped throughout the whole pasta volume with a spatial resolution of 78 μm in all three dimensions. MRI was combined with light microscopy to link I₀ and T₂^⁎ to microstructure components such as fiber particles and the extent of starch gelatinization. Four commercial spaghetti samples were analyzed which were made of durum wheat flour, both plain and enriched with wheat fiber, as well as with wholegrain and soft wheat flour. Although all pasta samples showed similar macroscopic water absorption as measured by weight increase, the sample structures differed at the microscopic scale. Compared to durum wheat spaghetti, the presence of fiber particles decreased T₂^⁎, while spaghetti enriched with soft wheat flour increased T₂^⁎. In addition, light microscopy showed that large fiber particles partly acted as barriers against water migration and protected starch granules from swelling. Smaller wheat fiber particles did not affect local starch swelling. Thus, the combination of light microscopy and MRI is a powerful tool to study the microstructure and water distribution in pasta.     

Characterization of water distribution in xanthan-curdlan hydrogel complex using magnetic resonance imaging, nuclear magnetic resonance relaxometry, rheology, and scanning electron microscopy

Abstract: Xanthan‐curdlan hydrogel complex (XCHC) has been shown capable of retaining moisture up to 5 freeze‐thaw cycles (FTCs); however, moisture distribution in the complex in relation to the hydrogel composition and structure remains uncharacterized. In the present study, magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) relaxometry, rheology, and scanning electron microscopy (SEM) were used to examine the effect of water distribution and interaction with 2.0% aqueous solutions of xanthan, curdlan, and XCHC consisting of equal amounts of both polysaccharides. A gel structure with an indication of syneresis was clearly seen in the MR image of curdlan alone, whereas the distribution of protons throughout xanthan and XCHC samples remained homogeneous and showed no detectable syneresis. The three‐dimensional network, indicated by frequency sweeps, of curdlan was responsible for curdlan's gel structure. The frequency sweep and slope of the storage modulus (G′) of XCHC was significantly closer to curdlan with higher elasticity and less dependency upon angular frequency than xanthan alone. The reduction in XCHC dynamic moduli (G′ and G″) compared to curdlan could be attributed to the formation of wavy layers instead of a fully cured three‐dimensional structure. Addition of xanthan to curdlan restricted XCHC spin–spin relaxation time (T₂) to intermediate and slower exchange regimes, namely approximately 110 and 342 ms, respectively, promoting the polymer's interaction with water while inhibiting interpolymer interactions found in curdlan. A 3rd proton pool with the slowest T₂ seen in curdlan was not found in XCHC, correlating to the absence of syneresis. Practical Application: The combination of texture measurements and discrete noninvasive techniques was found capable of providing insightful understanding of water distribution in a gel system. These techniques may be applied to other hydrogel complexes. The XCHC system investigated has the potential to enhance freeze‐thaw stability in frozen food products by minimizing syneresis due to undesirable temperature fluctuations during distribution and consumer application.     

近红外光谱技术快速测定木材抽出物含量的研究

探讨了近红外光谱法快速预测木材冷水、热水、1.0%NaOH和苯醇抽出物含量的可行性。四个模型的决定系数（R2）高,分别为0.9804、0.9800、0.9823和0.9648;交叉验证均方根偏差（RMSECV）低,分别为0.21%、0.29%、0.48%和0.24%;冷水、热水、1.0%NaOH抽出物模型的残留预测偏差（RPD）值分别为7.14、7.07和7.51,而苯醇抽出物模型的RPD值仅5.33。采用不同校正模型分别对样品进行预测,四个模型的预测偏差分别为-0.19%～0.20%、-0.29%～0.28%、-0.36%～0.42%和-0.25%～0.14%,基本符合标准方法的误差要求。结果说明可以利用近红外光谱分析技术对木材抽出物进行快速、准确地测定。     

Influence of salt content on eye growth in semi-hard cheeses studied using magnetic resonance imaging and CO2 production measurements

Eye growth in semi-hard cheeses was previously found to be subject to a strong spatial-dependency between the periphery and the core zone, and salt appeared to be a key factor to be studied to better understand the phenomenon of eye growth. An experiment was therefore designed to study salted and unsalted cheeses, by combining magnetic resonance imaging and a method for determining CO₂ production based on gas pressure measurements. Chemical and rheological tests were also performed to make sure that only the salt content was modified between the two types of cheeses. It appeared that the presence of salt induced a delay in both bacterial development and CO₂ production. The eyes in salted cheeses were found to be six times smaller, and their growth kinetics were slower. The combination of these two techniques thus made it possible to decorrelate factors and to quantify the influence of salt on eye development.     

Simultaneous determination of oil and water content in olive husk by pulsed low resolution nuclear magnetic resonance

A pulsed low-resolution NMR method for the oil and water determination in olive husk samples is reported. It is based on the determination of the solid to liquid ratio of the sample and on the detection of the spin-echo decay curve. This method is very fast and can be fully self-contained, as it does not require either to weigh and dry the sample or any correlation curve. It seems suitable for other oil containing samples, such as seeds. The way to simplify and speed up the procedure is also discussed.     

Nuclear magnetic resonance study of water mobility in pasta filata and non-pasta filata mozzarella

Changes in molecular mobility of water in pasta filata and non-pasta filata Mozzarella cheeses were investigated during the first 10 d of storage using nuclear magnetic resonance (NMR) relaxation techniques. Water in pasta filata Mozzarella was classified into two fractions by spin-spin relaxation times, T21 and T22, and corresponding proton intensities, A1 and A2, representing low and high molecular mobility, respectively. Increase in A1 (and decrease in A2) suggested that, there was a redistribution of water from more- to less-mobile fraction (from T22 to T21 fraction) during the first 10 d of storage. The NMR data did not indicate the two-state behavior of water molecules in non-pasta filata Mozzarella. However, the T2 values of non-pasta filata Mozzarella were comparable to the T21 values of pasta filata Mozzarella indicating that the molecular mobility of water in non-pasta filata Mozzarella is comparable to that of the less mobile water fraction in pasta filata Mozzarella. Generally, T2 and T1 values of pasta filata and non-pasta filata Mozzarella cheeses increased during the 10-d storage. This is believed to be due to structural changes in the protein matrix.     

Weathering of uncoated and coated wood treated with methylated 1,3-dimethylol-4,5-dihydroxyethyleneurea (mDMDHEU)

Scots pine (Pinus silvestris L.) sapwood panels were treated with a methylated 1,3-dimethylol-4,5-dihydroxyethyleneurea (mDMDHEU) causing weight gains of approx. 25% and were exposed to weathering for 18 months. Compared to untreated panels, treatment with mDMDHEUreduced surface discoloration mainly caused by staining fungi. Panels treated with mDMDHEU clearly exhibited lower moisture content throughout the exposure time and lower water uptake in periodical submersion tests. The treatment also reduced deformation (cupping) and crack formation of the panels due to weathering (assessed as waviness and surface roughness). When coated panels were compared, a pre-treatment with mDMDHEU resulted in lower water uptake in periodical submersion tests, less discoloration, minor deformation (cupping) and less crack formation (assessed as waviness and surface roughness). Oil-based coatings did not peel off the mDMDHEU treated panel surfaces as observed for the untreated panel surfaces.     

Magnetic resonance imaging (MRI) and relaxation spectrum analysis as methods to investigate swelling in whey protein gels

Effective means for controlled delivery of nutrients and nutraceuticals are needed. Whey protein-based gels, as a model system and as a potential delivery system, exhibit pH-dependent swelling when placed in aqueous solutions. Understanding the physics that govern gel swelling is thus important when designing gel-based delivery platforms. The extent of swelling over time was monitored gravimetrically. In addition to gravimetric measurements, magnetic resonance imaging (MRI) a real-time noninvasive imaging technique that quantified changes in geometry and water content of these gels was utilized. Heat-set whey protein gels were prepared at pH 7 and swelling was monitored in aqueous solutions with pH values of 2.5, 7, and 10. Changes in dimension over time, as characterized by the number of voxels in an image, were correlated to gravimetric measurements. Excellent correlations between mass uptake and volume change (R(2)= 0.99) were obtained for the gels in aqueous solutions at pH 7 and 10, but not for gels in the aqueous solution at pH 2.5. To provide insight into the mechanisms for water uptake, nuclear magnetic resonance (NMR) relaxation times were measured in independent experiments. The relaxation spectrum for the spin-spin relaxation time (T(2)) showed the presence of 3 proton pools for pH 7 and 10 trials and 4 proton pools for pH 2.5 trials. Results demonstrate that MRI and NMR relaxation measurements provided information about swelling in whey protein gels that can constitute a new means for investigating and developing effective delivery systems for foods.     

Moisture content in a wheat germ diet and its effect on the growth of Plodia interpunctella (Hübner)

The growth rate of Plodia interpunctella larvae feeding on wheat germ was highly dependent upon the water content in the diet. The water content in a cereal diet is established by the hygroscopicity of the dietary components and the relative humidity (r.h.) in the equilibrating atmosphere. The larval growth rates on wheat germ increased with corresponding increases in r.h. over the range of 40-85%. Similar changes in r.h. had a measurable, albeit minimal, impact on the time required for embryonic development and egg hatch. The water content of wheat germ was further increased by supplementing the germ with the humectant, glycerol. The larval growth rate increased with each incremental increase in dietary water content irrespective of whether it resulted from increases in r.h. or glycerol. However, glycerol supplementation provided an additional boost to the growth rate that was in addition to and distinct from the dietary water increase.     

Moisture content detection of maize seed based on visible/near-infrared and near-infrared hyperspectral imaging technology

To realise accurate and nondestructive detection on moisture content of maize seed based on visible/near-infrared (Vis/NIR) and near-infrared (NIR) hyperspectral imaging technology, the hyperspectral images on two sides (embryo and endosperm sides) of each maize seed of four varieties were collected. The effects of average spectra extraction regions, that is centroid region and whole seed region, and different spectral preprocessing methods, were investigated. Uninformative variable elimination (UVE) was used to extract the feature wavelengths, and the partial least squares regression (PLSR) prediction models were established. The results showed that extracting the average spectra from the centroid region did better than from the whole seed region, and S-G smoothing was prior to other preprocessing methods. The PLSR models established with NIR spectra had better performance than that with Vis/NIR spectra. The model developed for a single variety was superior to that for all varieties together.     

Impact of surface water conditions on preservative leaching and aquatic toxicity from treated wood products

New alternative wood preservatives contain higher levels of copper (Cu) which can promote aquatic toxicity in natural water systems. Earlier work focused on evaluating toxicity using laboratory generated leaching solutions. In this study, the impact on preservative leaching and aquatic toxicity from treated wood products was evaluated using natural surface waters including waters from two rivers, three lakes, two wetlands, and one seawater, in addition to synthetic moderate hard water and deionized water. Blocks of wood treated with Cu based alternatives such as alkaline copper quaternary (ACQ) and copper boron azole (CBA), along with chromated copper arsenate (CCA)-treated wood, were leached under quiescent conditions, and total Cu, labile Cu, and heavy metal toxicity were measured. Results show that ACQ- and CBA-treated wood leach approximately 10 and 20 times more total Cu relative to CCA-treated wood and that the presence of organic and inorganic ligands in natural waters lowered the labile fraction of Cu relative to that from laboratory generated leaching solutions. Aquatic toxicity was found to correlate with the labile Cu fraction, and hence, the aquatic toxicity of the treated wood leachates was lower in natural waters in comparison to laboratory leaching solutions. The results of the present study suggest that studies designed to evaluate the impacts of treated wood should therefore consider the role of complexation in reducing the labile Cu fraction and its potential role in decreasing toxicity.     

基于低场核磁共振技术的大米水分含量及活度快速预测

以直接干燥法和水分活度仪测定的结果作为参考值,采用低场核磁共振仪对大米样品进行测量,获取样品的横向弛豫数据,结合化学计量学算法建立多元校正模型,实现对大米水分含量及活度的快速测定。采用偏最小二乘方法(PLS)和误差反向传播人工神经网络方法(BP-ANN)对160个校正集样品进行训练后,建立多元校正模型,并对90个预测集样本进行预测。结果显示,PLS与BP-ANN 2种方法中预测集样品的水分含量预测值和参考值之间的相关系数分别为0.937 6和0.955 5,预测均方根偏差分别为0.005 8和0.004 6,水分活度预测值和参考值之间的相关系数分别为0.983 0和0.993 4,预测均方根偏差分别为0.009 2和0.006 2,表明2种方法能够快速而准确地对大米的水分含量及活度进行预测。