Effects of Meat and Phosphate Level on Water-Holding Capacity and Texture of Emulsion-Type Sausage During Storage

This paper was designed to verify the influence of phosphate on water-holding capacity （WHC） and texture of emulsiontype sausage prepared with pre-rigor meat, ageing meat or frozen meat. Pre-rigor pork, ageing pork and frozen pork were pre-blended with five levels of phosphate and made into emulsion-type sausage. The yield, hardness and total expressible fluid （TEF） were measured with texture profile analysis machine and pressiometer when emulsion-type sausage was produced. Meanwhile, hardness and purge loss （PL） were measured during 30 d storage. As emusion-type sausage made by pre-rigor meat, higher yield and relatively stable hardness could be found. It indicated that increasing of phosphate level caused an alleviatable effects in increasing of hardness when emulsion-type sausage made by pre-rigor meat, but opposite effects made by ageing meat or frozen meat. The distribution of PL of emulsion-type sausage was found to be affected by phosphate addition. Significant decrease of PL could not be obtained by increasing of phosphate level during storage. Pre-rigor meat improved WHC and texture of emulsion-type sausage. Problem of WHC and texture of emulsiontype sausage during storage could not be resolved by single use of phosphate at relatively higher level （3%） of NaCl.

The Scavenging of Free Radical and Oxygen Species Activities and Hydration Capacity of Collagen Hydrolysates from Walleye Pollock(Theragra chalcogramma) Skin

Fish skin collagen hydrolysates （FSCH） were prepared from walleye pollock （Theragra chalcogramrna） using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of 〈1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical （DPPH）, superoxide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione （GSH）. FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scavenge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore FSCH may have potential applications in the medicine and food industries.

Study on Quantitative Model of Karst Drainage Basin Water-Holding Based on Principal Component Analysis: A Case Study of Guizhou, China

In Karst drainage basins, there are the ground water and underground water exchanging frequently, and the shortage of water resources due to having the special double aquifer mediums and unique surface and subsurface river systematic structure. This paper is to select 20 research sampling areas coming fromGuizhouProvince, and according to the spectral characteristics of the catchment water-holding mediums and vegetations, and using the remote sensing technique, extract the watershed vegetation index. According to the principle of principal component analysis, using the software of Spss and Matlab is to analyze the impacts of watershed vegetation type on the catchment water-holding ability, and establish the principal component analysis function. Studies have shown that: 1) the watershed vegetation coverage rate plays an important role in Karst basin water-holding ability;2) the catchment water-holding ability is the comprehensive reflection and manifestation of the Catchment Water-storing Capacity (CWC);3) it is much better effects and higher accuracy to monitor/forecast the catchment water-holding volume by using the vegetation indices.

Low-temperature combined with high-humidity thawing improves the water-holding capacity and biochemical properties of Portunus trituberculatus protein

This study compared the effects of conventional thawing methods(water immersion thawing(WIT,(25±1)℃),natural air thawing(AT,(25±1)℃,relative humidity(RH(65±2)per cent),refrigerator thawing(RT,4℃,RH(80±2)per cent)and low-temperature(LT)combined with high-humidity thawing LT,-1℃to 1℃(LT-1-1),2-4℃(LT2-4),5-7℃(LT5-7)and 8-10℃(LT8-10),RH>95 per cent)on the water-holding capacity,lipid oxidation and biochemical properties of Portunus trituberculatus(P.trituberculatus)myofibrillar protein.The results showed that WIT and AT significantly decreased the water-holding capacity while dramatically increasing lipid oxidation,protein oxidation and degeneration,resulting in serious P.trituberculatus quality deterioration.High humidity was beneficial for P.trituberculatus\.ha\A/\ng.The thawing time of P.trituberculatus under the conditions of LT2-4 was only 39.39 per cent of that of conventional air thawing at 4℃(RT),and the LT2-4 samples not only maintained better water-holding capacity but also had an obviously reduced degree of lipid oxidation,protein oxidation and denaturation.Thawed samples LT2-4 and LT5-7 provided better maintenance of P.trituberculatus quality than the LT-1-1 and LT8-10 samples.The best quality was exhibited after thawing at 2-4℃.The levels of thiobarbituric acid reacting substances,carbonyl content and surface hydrophobicity observably decreased in these samples,while the total sulfhydryl contents dramatically increased compared to those of conventionally thawed samples,indicating lower lipid oxidation and protein oxidation.Moreover,the Ca2+-ATPase activity of the sample thawed at 2-4℃(2.06 μmol Pi/mg prot/h)was markedly higher than that of samples subjected to WIT and AT.The product qualities observed after thawing at-1℃to 1℃,5-7℃and 8-10℃under LT were comparable to that observed by RT.Considering its thawing efficiency and product quality,LT is a suitable method for the thawing of P.trituberculatus,and the ideal thawing conditions were LT at 2-4℃.

低场NMR研究pH对肌原纤维蛋白热诱导凝胶的影响

【目的】探讨pH对猪肉肌原纤维蛋白热诱导凝胶保水性及水的移动性影响。【方法】从猪肉中提取肌原纤维蛋白,用低场NMR(nuclear magnetic resonance)研究pH对肌原纤维蛋白热诱导凝胶中水的T2弛豫性质的影响。同时用离心法测量pH对肌原纤维蛋白凝胶保水性(water holding capacity,WHC)影响。【结果】NMR结果拟合后得到水有4个组分,合并为对应水的3种状态即不可移动水、可移动水和自由水。随着pH升高,pH偏离肌原纤维蛋白的等电点(pI),代表可移动水的T2弛豫时间显著增加,其所占峰的面积和凝胶的WHC也随之增加。主成分分析结果发现,处于等电点附近的样品在样品评分图上与其它pH样品显著不同。【结论】凝胶保水性的增加主要是可移动水的增加,凝胶WHC增加的原因可能是肌原纤维凝胶后孔径增加,从而可以容纳更多的水。

不同解冻方式对秘鲁鱿鱼肌肉保水性和蛋白质氧化程度的影响

比较静水解冻、流水解冻、盐水解冻、空气解冻及冷藏解冻5种不同解冻方式及对秘鲁鱿鱼品质的影响。结果表明:流水解冻方式用时最短,其次是盐水解冻。5种不同解冻方式秘鲁鱿鱼的解冻损失率和蒸煮损失率差异极显著(P<0.01),经冷藏解冻和盐水解冻后秘鲁鱿鱼的持水能力较高,而静水解冻和空气解冻对鱿鱼的保水性影响较大。低场核磁共振实验结果也证实,经冷藏解冻和盐水解冻后秘鲁鱿鱼的持水能力较高。样品解冻过程中,5种不同解冻方式鱿鱼在不同温度条件下其羰基含量、巯基含量和二聚酪氨酸含量差异极显著(P<0.01)。综合蛋白质氧化指标,盐水解冻和冷藏解冻是最适宜的解冻方式。研究结果说明,解冻过程中肌肉保水性的下降和蛋白质氧化存在一定的关系。

硝、铵态氮肥对旱地土壤氧化亚氮排放的影响

用静态箱法在田间研究了黄土性土壤不同水分条件下施用硝态氮肥和铵态氮肥后土壤N2O的排放特点,并对包括温度、pH、水分等因子的影响进行了探讨。结果表明:在水分含量为田间持水量的90%和70%的条件下,铵态氮肥处理土壤的平均N2O排放量分别为233.6±165.4μg/(m2.h)和166.4±153.3μg/(m2.h);而施用硝态氮肥时则仅为75±40.2μg/(m2.h)和49.27±17.0μg/(m2.h)。施肥后短期内,铵态氮肥排放的N2O量显著高于硝态氮肥处理,由此可说明黄土性土壤表层土壤N2O的主要来源是土壤氮的硝化过程。在自然矿化条件下黄土性土壤N2O的排放量约为17.0μg/(m2.h)。如果把两个水分处理相比较,土壤水分对铵态氮肥处理土壤N2O的排放影响不明显,而对施用硝态氮肥的土壤有明显影响,高水分处理更利于土壤反硝化作用的进行从而增加了土壤N2O的排放量。施用不同肥料种类在施肥后短期内影响土壤的pH值和有效NO3--N、NH4+-N含量,而反过来土壤水分含量、土壤pH以及土壤温度均不同程度地影响着土壤N2O的产生和排放。

壳聚糖复合膜对冷却肉保水性的影响

以猪背最长肌为原料,以滴水损失、贮存损失、水分含量等为评价指标,研究贮藏温度为4℃时不同配方壳聚糖涂膜液对冷却肉保水性的影响.结果表明,各种配方壳聚糖涂膜液处理均可降低冷却肉的滴水损失和贮存损失,减缓水分含量下降速率.0.9%壳聚糖、0.6%山梨酸钾、0.25%N isin溶于0.5%醋酸制成的涂膜液显示了较好的保水性能,用其处理的冷却肉滴水损失为0.823%,贮存损失为5.885%,分别比对照组减少了46%和14%.

提取条件对鲨鱼肉盐溶蛋白热诱导凝胶特性的影响

以鲨鱼肉为材料,研究NaCl浓度、pH值、静置提取时间及加热时间对鱼肉盐溶蛋白热诱导凝胶保水性和质构特性的影响。结果表明:鲨鱼肉盐溶蛋白凝胶的保水性、硬度、弹性和黏聚性与NaCl溶液浓度呈正相关;在NaCl溶液浓度0.8mol/L、pH6.5～7.0、静置提取时间24h、40℃加热40～60min时形成的凝胶保水性及其质构指标较理想;40℃加热盐溶蛋白,有利于形成凝胶结构,但随着加热时间的延长,盐溶蛋白凝胶硬度增加,保水性降低。

Effect of Substituting Plantation Species for Native Shrubs on the Water-holding Characteristics of the Forest Floor on the Eastern Tibetan Plateau

Although the forest floor plays important roles in water-holding and nutrient cycling, there is not enough knowledge of the functional changes of the forest floor resulting from changes in vegetation. To evaluate the effect on the hydrological properties of forest floor by the substitution of plantation species for native coppice, we selected four species substituting plantations and one native coppice （secondary native broad-leaved forest, dominated by Quercus liaotungensis and Corylus heterophylla var. sutchuenensis） （QC） as a comparison forest. The substituting plantations were Cercidiphyllum japonicum （Cj）, Pinus tabulaeformis （Pt）, Pinus armandi （Pa）, Larix kaempferi （Lk）. These were established in 1987 with a stocking density of approximately 2500 stem ha -1 . Thickness and the amount of floor in coniferous plantations were significantly higher compared to secondary native broad-leaved forest and pure broad- leaved plantation. The maximal water-holding capacity of the floor showed the same trend as thickness and amount of litter. Main contributors to the difference in hydrological characteristics in the plantations were the quantity of forest floor and the maximal water holding capacity per unit weight of the floor. The relationships between water absorption processes, water absorption rate and the immersion time for litter, fitted to logarithmic and exponential regressions, respectively. Water absorption processes differed significantly between the various plantations and different decomposition floor horizons. Water absorption characteristics were influenced by leaf structure in various tree species and the degree of decomposed litter. Our results showed that litter amount in coniferous plantations were significantly higher than in deciduous broad-leaved plantation. This suggests that a large amount of nutrients are held in the litter horizon, delaying return to the soil and utilization by plants. At the same time, maximal water-holding capacity of the forest floor in F [fermentation] and H [hummus] horizons was significantly higher than that in L [fresh litter] horizon. Therefore, improving litter transformation from L horizon to F and H horizons by promoting forest floor environment would be one of the best methods for plantation management.

影响猪血浆蛋白热诱导凝胶质构特性及持水性因素的研究

本实验研究在一定的加热条件下猪血浆蛋白质量浓度、加热温度、加热时间、离子种类、离子强度和pH值对猪血浆蛋白热诱导凝胶的质构、持水性等性质的影响。利用质构仪测定猪血浆蛋白热诱导凝胶的硬度和黏附性,利用离心的方法测定凝胶的持水性。结果表明,在80℃下加热45min,猪血浆蛋白质量浓度超过6g/100mL可以形成凝胶,并且随蛋白质量浓度的增大,凝胶强度和持水性也增大;凝胶强度随pH值(3～9)增加而增大,pH5时凝胶的持水性最小,pH3时最大;NaCl浓度0.2mol/L,CaCl2浓度0.6mol/L时,凝胶硬度最大。实验得出,猪血浆蛋白热诱导凝胶的质构特性及持水性受许多因素影响,在实际生产中应该控制加热条件,以获得高质量的凝胶。

降低食盐添加量对火腿肠的感官、质构及保水特性的影响

为研制低钠盐火腿肠,研究降低食盐添加量对火腿肠质量的影响。设置6个不同的食盐添加量梯度(以原料猪肉质量为基准计):3%(对照)、2.5%、2.0%、1.5%、1.0%、0.5%,分别对产品的水分活度、保水性和质构进行测定,同时进行感官评分。结果表明:随着食盐添加量的降低,火腿肠的水分活度逐渐升高,而保水性逐渐下降;质构测定显示,产品的硬度、咀嚼度、黏聚性也随着食盐添加量的下降而降低,当食盐添加量极低时,这种下降趋势很明显,但弹性却变化不大;感官评定结果表明,随着食盐添加量的降低,火腿肠颜色变浅,切面粗糙,咸味下降,当食盐添加量降低到1.0%时不易被接受。因此,食盐对猪肉火腿肠的感官、质构和保水性等有着重要的作用,本研究为进一步调整配方开发低钠盐火腿肠提供了重要参考。

鸡胸肉盐溶蛋白热诱导凝胶保水性和超微结构的研究

本文以鸡胸肉为材料,采用L9(34)正交设计及混料回归分析研究了鸡胸肉盐溶蛋白热诱导凝胶保水性和凝胶超微结构。结果表明,鸡胸肉最佳提取条件为MgCl2浓度0.01mol/L、NaCl浓度0.6mol/L、提取液pH7.0,其凝胶的保水性为96.92%。扫描电镜观察显示,保水性不同的凝胶其超微结构表现出很大的差异,保水性为96.92%,其凝胶的网络结构比较均匀、细致,蛋白束平滑;保水性为52.19%其凝胶的网状结构粗糙、疏松、不均匀。磷酸盐的最佳组合为:DSPP0.04g、STPP0.05g、HMP0.03g。

响应面法优化双髻鲨(Sphyrna zygaena)肌肉盐溶蛋白的提取和凝胶形成条件

采用响应面分析法,以双髻鲨肉盐溶蛋白凝胶保水性为依据,对盐溶蛋白的提取和凝胶形成条件NaCl浓度、pH和低温加热时间进行优化。结果表明:(1)根据中心组合试验设计,采用三因素三水平的响应面分析法,建立了双髻鲨肉盐溶蛋白凝胶保水性与其提取条件的数学模型:保水性(%)=65.440+10.868X1+1.835X2-0.502X3-4.647X12+0.121X1X2-0.415X1X3-0.856X22+0.487X2X3-1.789X32,其中NaCl浓度和pH对双髻鲨肉盐溶蛋白凝胶的保水性影响极其显著,低温加热时间对保水性影响不显著;(2)在分析各因素显著性及其交互作用的基础上,得出盐溶蛋白提取和凝胶形成的适宜条件为:NaCl浓度为0.90mol/L,提取溶液的pH=7.0,低温加热时间为35min,此时盐溶蛋白凝胶的保水性达到72%,与模型预测值基本相符。

燕麦复合火腿肠的感官、质构及保水特性研究

为了探索燕麦粉添加量对燕麦复合火腿肠品质特性的影响,分别对复合火腿肠进行感官评定及质构测定(质构剖面分析),并对这两种评价测定方法的结果进行相关性分析,同时也对复合火腿肠的保水特性进行测定。感官和质构测定结果表明:燕麦粉添加量为14%时,复合火腿肠具有较理想的质构,感官总体接受性好;质构测定硬度与感官评定硬度呈显著相关性(r=0.898),质构测定黏聚性与感官评定硬度、弹性呈显著相关性(r分别为-0.863和-0.825)。保水性测定结果表明:随着燕麦粉添加量的增加,复合火腿肠保水能力逐渐上升(94.33%～94.83%),当添加量达到17%以后,保水能力变化不大,增加趋势平缓,可以看出,燕麦粉的添加可能有利于提高复合火腿肠的保水性。因此,将适量的燕麦粉与肉品复合可以制作出能被消费者接受、质构和保水性很好的燕麦复合火腿肠。

大豆皮低酯-高酯复合果胶凝胶的持水能力及力学、光学特性

研究蔗糖质量分数及大豆皮低酯与高酯果胶复配比例对复合凝胶体系的持水能力及力学、光学特性的影响。结果表明:蔗糖质量分数对复合凝胶的持水性、力学特性及光学特性均有较大影响,蔗糖质量分数越大,其持水性越高,破坏应力越大,凝胶的弹性和透明度均有提高。低酯与高酯果胶的配比同样对上述性质有较大影响,二者合适的配比可以诱导两种果胶分子之间的协同作用,使产品具有更好的持水能力和力学性质。

基于近红外光谱检测猪肉系水力的研究

为了快速无损无污染得测定猪眼肌的系水力,提出了用近红外漫反射光谱检测真空包装猪肉的系水力的新方法。采用常规的滴水损失法和压力法标定猪肉的系水力。利用光谱专用分析软件Unscrambler9.6,对采集的光谱进行平滑,二阶微分预处理,用偏最小二乘法(PLS)建立其定量检测模型。该实验的样本总数为106,将样品分为校正集和检验集。用校正集建立定标方程,用检验集检验定标方程的预测精度。常规方法与近红外光谱漫反射法的预测植的相关系数为0.73～0.79,结果明显要好于近红外透射法和反射光谱法。该研究验证了近红外光谱漫反射法对真空包装后鲜猪肉的系水力的无损检测的可行性。

热风干燥制备马铃薯颗粒全粉试验研究

采用两因素三水平的全面正交试验,研究热风干燥温度和切片厚度对马铃薯干燥特性及对马铃薯颗粒全粉堆积密度、水合能力的影响。结果表明:马铃薯片的干燥过程分为调整、等速和降速3个干燥阶段,其中等速和降速干燥阶段的速率明显受到干燥温度和切片厚度的影响。粒径为0.125mm～0.175mm之间的马铃薯颗粒全粉堆积密度为0.73g/mL～0.80g/mL、水合能力(WHC)为每克样品中含水2.98～6.01,复水后的马铃薯泥具有沙口性和浓郁的马铃薯香味。

氧化对鸡胸肉肌原纤维蛋白热诱导凝胶保水性及水分子T_2弛豫特性的影响

采用不同氧化程度的羟基自由基氧化体系(含0、0.05、0.1、0.5、1和5 mmol.L-1H2O2,10μmol.L-1FeCl3,0.1 mmol.L-1抗坏血酸)对鸡胸肉肌原纤维蛋白进行氧化(4℃24 h),测定蛋白质热诱导凝胶的保水性(WHC),观察凝胶微观结构的变化,并利用低场核磁共振(NMR)研究氧化对肌原纤维蛋白热诱导凝胶中水分子的T2弛豫特性的影响。结果表明:在小于0.5 mmol.L-1H2O2浓度范围内,凝胶形成致密均匀的网络结构,其保水性随H2O2浓度升高(即氧化程度增大)而逐渐增大;当H2O2浓度增至5 mmol.L-1时,凝胶网络孔径变大,并出现断裂,凝胶保水性显著降低(P<0.05);NMR结果拟合后得到的水有4个组分。随着H2O2浓度升高,T23弛豫时间由364.26 ms下降至316.82 ms,弛豫峰面积百分数由84.79%降低至78.38%。表明,适度氧化可以提高肌原纤维蛋白凝胶保水性;保水性改善与凝胶网络结构及水分子的弛豫特性有关。

高静压下添加酪朊酸钠鸡肉肠制品保水性与质构特性的相关性研究

在50～600MPa高静压和5～40min保压时间范围内单因素考察添加1.5%酪朊酸钠鸡肉肠制品保水性与质构特性的相互影响规律,并用电镜从微观结构上分析其机理。结果表明:与未受压的对照样比较,200～500MPa高静压和10～30min保压时间都能显著增强其保水特性(P<0.01),过低压力50MPa和过高压力600MPa有明显降低保水性现象(P<0.01);制品质构特性(硬度、咀嚼性)随着压力增大而先迅速后平缓增大;而保压时间对鸡肉肠制品的保水性、质构特性的影响不显著。与保压时间比较,不同压力水平处理下的制品保水性与质构特性有着更加显著的相关性(P<0.01),提高保水性同时能明显改善其质构特性。