生鲜猪肉持水性的核磁共振研究

用低场核磁共振仪检测了宰后猪肉样品水分分布的变化情况。研究发现:肉中有三个明显的水分群,分别对应的横向弛豫时间是T21、T22、T23,其中T23积分面积与滴水损失之间的相关系数为-0.860。实验数据表明,LF-NMR的横向弛豫时间是研究持水性和水分分布的一种非常有效的方法。      

利用核磁共振技术研究添加剂对面团持水性的影响

本实验利用核磁共振技术探讨变性玉米淀粉、馒头改良剂和蔗糖脂肪酸酯(SE)对馒头面团形成过程的影响,并将核磁共振仪测定结果与TA质构仪测定结果相比较,确定三种面团改良剂的最优复配比例.通过正交试验得出,变性玉米淀粉:面粉为4:46,馒头改良剂添加量为0.5%,蔗糖脂肪酸酯添加量为0.5%时,面团的自旋-自旋弛豫时间较低,质子信号幅度较大,面团黏聚性好、硬度小、黏度适中,此时面团中的水分自由度较低,面团面筋充分形成,面团持水性和面团质构都达到最佳的状态.     

生鲜肉品持水性的核磁共振研究

低场核磁共振(LF-NMR)技术在地矿、石油及粮油食品等领域已得到了广泛的应用,但在肉品特别是宰后生鲜肉品水分研究中的应用国内还很少.本文主要介绍低场核磁共振的基本原理及近年来国外利用其在宰后生鲜肉品持水性方面的研究进展.     

利用核磁共振技术研究添加齐对面团持水性的影响

本实验利用核磁共振技术探讨变性玉米淀粉、馒头改良剂和蔗糖脂肪酸酯（SE）对馒头面团形成过程的影响,并将核磁共振仪测定结果与TA质构仪测定结果相比较,确定三种面团改良剂的最优复配比例。通过正交试验得出,变性玉米淀粉：面粉为4：46,馒头改良剂添加量为0．5％,蔗糖脂肪酸酯添加量为0．5％时,面团的自旋．自旋弛豫时间较低,质子信号幅度较大,面团黏聚性好、硬度小、黏度适中,此时面团中的水分自由度较低,面团面筋充分形成,面团持水性和面团质构都达到最佳的状态。     

生鲜肉品持水性的核磁共振研究

低场核磁共振（LF-NMR）技术在地矿、石油及粮油食品等领域已得到了广泛的应用,但在肉品特别是宰后生鲜肉品水分研究中的应用国内还很少。本文主要介绍低场核磁共振的基本原理及近年来国外利用其在宰后生鲜肉品持水性方面的研究进展。      

生鲜猪肉肌细胞内外间隙和水分状态与持水性的关系

为探究生鲜猪肉汁液流失通道形成的位置,补充完善汁液流失形成机理,本研究选择20条猪背最长肌,通过低场核磁共振技术测定了宰后12 h和24 h肌肉中结合水(P_2b)、不易流动水(P₂₁)和自由水(P₂₂)的相对含量,宰后45 min,3、9、12 h和24 h肌原纤维与肌细胞膜之间的距离(肌细胞内间隙)和肌细胞之间的距离(肌细胞外间隙)。结果显示:在宰后24 h,高汁液流失率组的P₂₁极显著低于低汁液流失率组(P<0.01),P₂₂极显著高于低汁液流失率组(P<0.01);高汁液流失率组宰后45 min的肌细胞内间隙和宰后9 h的肌细胞外间隙显著大于低汁液流失率组(P<0.05);宰后45 min的肌细胞内间隙与汁液流失率呈极显著正相关(P<0.01),解释了24 h P₂₂变异的24.8%和汁液流失率变异的45.3%;宰后24 h的P₂₂与汁液流失率呈极显著正相关(P<0.01),解释了汁液流失率变异的3...     

玉米胚芽蛋白粉持水性和持油性影响因素研究

以玉米胚芽蛋白为原料,研究温度、时间、pH值对其持水性,温度和浓度对其持油性的影响.结果表明:影响玉米胚芽蛋白粉持水性的主次因素分别为温度、时间和pH;浓度比温度对玉米胚芽蛋白粉持油性的影响大.在温度69℃,时间29 min,pH值为7时,玉米胚芽粉持水能力最高达4.88 g/g;玉米胚芽粉在温度70℃,浓度40％时,持油性最高达91.56％.     

花生蛋白持水性研究

花生蛋白的持水性决定了花生蛋白的应用品质，本文研究了时间、pH值及温度对花生蛋白持水性的影响，在时间2．5h、pH值8．0和95℃时的情况下花生蛋白的持水性最好。     

低场核磁共振分析仪研究添加剂对冷冻面团 持水性的影响

为提高面团的持水性以降低面团在冷冻过程中的水分迁移。利用低场核磁共振分析仪(NMR)研究34种面团常用添加剂的持水特性。对于发酵面团,提高面团持水性能力排在前5位的依次为双乙酰酒石酸单(双)甘油酯(DATEM)、瓜尔豆胶、硬脂酰乳酸钠(SSL)、抗坏血酸(VC)、三聚磷酸钠,它们能使深层结合水的比例从19.29%分别提高到28.66%、25.80%、25.10%、24.90%、23.86%。对于未发酵面团,提高面团持水性能力排在前5位的依次为三聚磷酸钠、羟甲基纤维素钠(CMC)、瓜尔豆胶、VC、六偏磷酸钠,它们能使深层结合水的比例从17.27%分别提高到23.80%、23.35%、23.16%、23.07%、22.84%。     

磷酸盐对獭兔肉持水性影响的研究

主要研究了六偏磷酸钠,三聚磷酸钠和焦磷酸钠以及由它们组成的混合磷酸盐对加工兔肉持水力的影响。通过单因素试验,分别确定了三聚磷酸钠,焦磷酸钠和六偏磷酸钠的最佳添加量分别为0.1%,0.12%,0.1%。同时采用4因素3水平的正交表做正交实验,得出复合磷酸盐的最佳配比为1.5∶1.7∶1(三聚磷酸钠∶焦磷酸钠∶六偏磷酸钠)。当该复合磷酸盐的添加量为3%时,獭兔肉持水性能最佳。     

复合变性淀粉提高鸡胸肉保水率的研究

报道了利用复合变性淀粉提高鸡胸肉保水率的研究。通过单因素实验，分别研究了磷酸酯玉米淀粉、磷酸酯木薯淀粉、交联马铃薯淀粉、交联木薯淀粉、醋酸酯玉米淀粉添加量对胸肉的吸水率和失水率的影响。根据单因素实验结果，进行了正交实验，验证得出最优配方为磷酸酯玉米淀粉为0．4％，磷酸酯木薯淀粉为0．8％，交联马铃薯淀粉为0．5％，交联木薯淀粉为0．6％及醋酸酯玉米淀粉为0．06％。经过验证实验所得到的吸水率和失水率的数据分别为7．9％和13．8％。     

Early prediction of water-holding capacity in meat by multivariate vibrational spectroscopy

This study had the dual purpose of (a) investigating the feasibility of measuring fundamental vibrational information in fresh porcine meat using infrared (IR) absorption and Raman scattering, and (b) investigating if the vibrational spectra obtained within 1 h after slaughter contained information about the water-holding capacity (WHC) of the meat. Preliminary studies performed at a research slaughterhouse revealed a high correlation between WHC and both IR (r=0.89) and Raman spectra using Partial Least Squares Regressions (PLSR). The good results were confirmed under industrial conditions using FT-IR at-line spectroscopy. However, the latter experiment yielded a somewhat lower correlation (r=0.79). This result is, however, promising for the purpose of finding a method for classification of carcasses with regard to WHC at the slaughter line. The IR region 1800-900 cm(-1) contains the best predictive information according to WHC of the porcine meat. This region covers functional group frequencies of water, protein, fat and glycogen, including the carbonyl and amide groups.     

Prediction of water-holding capacity and composition of porcine meat by comparative spectroscopy

Forty-one autumn-born Friesian bull calves were allocated to two production systems (Extensive='E' and Intensive='I'). In the E-system, animals were loose-housed and fed a roughage-based diet from October to May, followed by a grazing period from May to October. Ten animals were slaughtered directly from pasture (360 kg BW) and 11 after a 10-week finishing feeding in tie-stalls (460 kg). E-bulls were compared with intensively fed tie-stall housed young bulls (I) slaughtered at comparable weights (360 kg, n=11 and 460 kg, n=9). Semitendinosus (ST), longissimus dorsi (LD), and supraspinatus (SU) muscles were analysed histochemically, and the meat analysed for colour and pigmentation. In LD and SU, Type I % was higher in E- compared with I-bulls (P<0.05-0.006). In ST and LD, Type IIA % was higher in E- compared with I-bulls (P<0.01-0.009). As a result, Type IIB % was lower in all three muscles in E- compared with I-bulls (P<0.05-0.001). In E- compared with I-bulls, Type IIA and IIB fibre areas were larger in ST (P<0.05-0.03) and capillarization was higher in both ST and LD (P<0.001). In all three muscles, the activity of citrate synthase was higher (P<0.07-0.001) and that of lactate dehydrogenase lower (P<0.003-0.001) in E- compared with I-bulls. E-bulls had lower glycogen content than I-bulls in ST and LD at 360 kg, but higher at 460 kg following finishing feeding (P<0.008-0.001). Meat colour (lightness) was darker (P<0.001) and pigmentation was higher (P<0.001) in ST and LD of E- compared with I-bulls, with no effects in SU. In conclusion, histochemically different muscles respond differently to changes in the production system, and differences between the extensive and the intensive production system were narrowed after the finishing feeding.     

Non-destructive determination of water-holding capacity in fresh beef by using NIR hyperspectral imaging

This study was carried out for post-mortem non-destructive prediction of water holding capacity (WHC) in fresh beef using near infrared (NIR) hyperspectral imaging. Hyperspectral images were acquired for different beef samples originated from different breeds and different muscles and their spectral signatures were extracted. Both principal component analysis (PCA) and partial least squares regression (PLSR) models were developed to obtain an overview of the systematic spectral variations and to correlate spectral data of beef samples to its real WHC estimated by drip loss method. Partial least squares modeling resulted in a coefficient of determination (R_CV²) of 0.89 and standard error estimated by cross validation (SECV) of 0.26%. The PLSR loadings showed that there are some important absorption peaks throughout the whole spectral range that had the greatest influence on the predictive models. Six wavelengths (940, 997, 1144, 1214, 1342, and 1443 nm) were then chosen as important wavelengths to build a new PLS prediction model. The new model led to a coefficient of determination (R_CV²) of 0.87 and standard error estimated by cross validation (SECV) of 0.28%. Image processing algorithm was then developed to transfer the predicting model to each pixel in the image for visualizing drip loss in all portions of the sample. The results showed that hyperspectral imaging has the potential to predict drip loss non-destructively in a reasonable accuracy and the results could be visualised for identification and classification of beef muscles in a simple way. In addition to realize the difference in WHC within one sample, it was possible to accentuate the difference in samples having different drip loss values.     

提高肉制品保水性方法的研究进展

肉制品的保水性是衡量肉制品品质和经济价值的重要指标之一,如何提高肉制品的保水性具有重要意义。本文对影响肉制品保水性的因素和提高肉制品保水性的方法进行了综述,希望为肉制品的生产加工提供参考。      

添加含磷与非磷保水剂对牦牛肉肉糜保水性的影响

为了将不同水平的无磷保水剂海藻酸钠、柠檬酸三钠和乳酸钠分别加入牦牛肉肉糜中,研究其对牦牛肉肉糜持水力、蒸煮损失、离心损失和冻后失重率的影响,并与复合磷酸盐的保水效果做对比分析。结果表明:三种无磷保水剂都可以替代复合磷酸盐。柠檬酸三钠可以明显提高肉糜的持水力,当添加量为1.20%时,蒸煮损失和离心损失率最小;当海藻酸钠的添加量为0.20%时,离心损失和冻后失重率最小;当乳酸钠的添加量为0.20%时,持水力可提高约4%,蒸煮损失、离心损失和冻后失重率可降低约3%;复合磷酸盐的添加量为0.30%时,可产生良好的持水效果且肉糜的蒸煮损失也最小。      

The effect of simulated transport of fresh meats on their water-holding capacity as assessed by various methods

This study was designed to establish the effects of transport vibrations on the water-holding capacity of fresh non-stimulated veal and pork and electrically- and non-stimulated beef. Furthermore, drip production was followed during storage by various methods which were compared for their suitability in industrial practice and scientific research. During storage, the amount of drip increased, whilst the rate of drip formation decreased. Filter paper wetness measured at 1 day post mortem was positively correlated with drip lost over a period of 2 weeks of refrigerated storage in poly-ethylene bags (method 1) and poly-propylene containers (method 2). This suggests that the filter paper wetness test may be useful to predict drip loss of stored meat. Simulated transport did not result in higher drip losses, although a significant increase in filter paper wetness from the fresh cut surface of veal and pork was found, suggesting that transport affects the initial rate of drip production, but not the total amount of drip. In beef, transport simulation resulted in an increase in filter paper wetness from the surface of electrically-stimulated meat, stored for 1 or 2 weeks, indicating that fluid loss was elevated due to transport vibrations. However, this effect seemed to be related to the intrinsic water-holding capacity of the sample: meat with a low intrinsic water-holding capacity seemed to be more sensitive to transport vibrations than meat with a high intrinsic water-holding capacity.     

Theoretical aspects of water-holding in meat

As myofibrils consist of a three-dimensional network of long, solid protein particles with the shortest dimension of less than 20 nm, the theoretical foundations of water-holding in meat should be studied from a colloid or surface chemistry point of view. The classical hypotheses for water-holding in meat are based on electrostatic forces or osmotic forces, which cause the swelling of the myofibrils. The more recent research adds to those the structure of water, whether it is low density water induced by kosmotropic effects dominating in the system, or high density water induced by chaotropes, respectively. The phenomena in the one to three molecules thick water layers on protein surfaces do not, however, explain the bulk water-holding. The interactions of ions and non-polar kosmotropes with water and proteins have a relevant effect on water-holding. The chaotropic/kosmotropic effects of different ions will be of importance especially when reducing sodium contents in meat-based foods.     

The influence of mechanically deboned meat and pH on the water-holding capacity and texture of emulsion type meat products

The influence of the amount of mechanically deboned pork meat (MDM) on the quality of model 'Frankfurters' was studied, and the relationship between the pH of the blends versus the texture and water-holding capacity (WHC) of the finished products was investigated. In the experiments 2·9%, 5·8% and 11·6% pork loin were exchanged with MDM. It was found that addition of MDM increased the pH and the WHC, and that moderate addition of MDM resulted in greater yield stress and elasticity modulus, while higher concentrations of MDM resulted in very soft texture. The pH of the meat blends was very important for the functional properties of the pasteurized products. It made no difference whether pH was determined by the meat raw materials alone or adjusted through addition of NaOH or MDM.