用~(31)P NMR研究猪背最长肌中3种多聚磷酸钠的水解

试验利用31P核磁共振(NMR)技术研究了焦磷酸四钠(TSPP)、三聚磷酸钠(STPP)和六偏磷酸钠(HMP)在猪背最长肌中的水解变化。研究结果表明,TSPP和STPP的最终水解产物为正磷酸盐(Pi),TSPP在猪肉背最长肌中12h后还未完全水解,STPP在12h时已经完全水解为焦磷酸盐和正磷酸盐,派生的焦磷酸盐继续水解;HMP在肉中是稳定的,只有少量支链多聚磷酸盐能逐渐分解为Pi。     

四种多聚磷酸钠在鸡胸肉中水解的^31P核磁共振研究

本文利用^31P核磁共振技术（NMR）研究厂添加到鸡胸肉（CB）中的焦磷酸四钠（TSPP）、焦磷酸二氢二钠（DSPP）、三聚磷酸钠（STPP）和六偏磷酸纳（HMP）所发生的水解。研究结果表明，TSPP、DSPP、STPP和HMP在鸡胸肉中均发生水解。TSPP在10h内完全水解为正磷酸盐。DSPP水解较慢，10h后仍占核磁共振总可测磷的40％。STPP在10h时已经完全水解为焦磷酸盐和正磷酸盐，10h之后由三聚磷酸钠产生的焦磷酸盐继续水解。在HMP腌制液处理的鸡胸肉匀浆物中，没有焦磷酸盐存在，两端的磷原子到10h时的相对含量为零，内部磷原子的相对含量在10h内基本保持不变。     

多聚磷酸盐在鸡腿肉中水解的~(31)P核磁共振研究

利用31P核磁共振(NMR)对添加到鸡腿肉中的焦磷酸四钠(TSPP)和三聚磷酸钠(STPP)所发生的水解进行了研究。三组新鲜鸡腿肉样品,按照200ml腌制液/kg的比例分别注入新配制的腌制液5%NaCl、5%NaCl+6%TSPP、5%NaCl+6%STPP。结果表明,TSPP和STPP在肉中均发生水解。TSPP水解成正磷酸钠,STPP水解成焦磷酸钠和正磷酸钠,生成的焦磷酸钠随即水解成正磷酸钠。STPP水解速率大于TSPP。     

3种磷酸盐对白鲢鱼肌原纤维蛋白磷酸化的影响

为改善低盐（1g/100mLNaCl）环境中肌原纤维蛋白的功能特性,研究不同添加量的焦磷酸钠（tetrasodium pyrophosphate,TSPP）、三聚磷酸钠（sodium tripolyphosphate,STPP）、六偏磷酸钠（sodium hexametaphosphate,SHMP）对白鲢鱼肌原纤维蛋白结构和功能特性的影响。结果表明：低盐条件下,随着磷酸盐添加量的增加,肌原纤维蛋白的溶解度、表面疏水性、乳化性均呈上升趋势;3种磷酸盐均使肌原纤维蛋白引入磷酸基团;添加0.2～0.5 g/100 mL STPP能够降低肌原纤维蛋白热解速率,提升蛋白质热稳定性,其中0.4 g/100 mL STPP修饰的蛋白质磷酸化程度最大,此时大量的磷酸根基团与肌原纤维蛋白结合;TSPP和STPP更有利于蛋白质的聚集,而SHMP磷酸化的蛋白质更稳定。综上,0.4 g/100 mL STPP对低盐条件下肌原纤维蛋白功能特性具有更好的改善作用。     

低场NMR结合响应面法优化复合磷酸盐保水剂配比

采用低场核磁共振技术研究焦磷酸钠(TSPP)、三聚磷酸钠(STPP)、六偏磷酸钠(HMP)对鲈鱼肌肉持水特性的影响.以可移动水的积分峰面积为指标,在单因素试验基础上,采用响应曲面法(response surface methodology,RSM)优化复合磷酸盐的配比.经多聚磷酸盐溶液浸渍,继而蒸煮处理后的鲈鱼肌肉的低场NMR谱拟合后得到的水有4个峰,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,这3种水分别对应的横向驰豫时间是T21、T22、T23.影响鱼肉保水性因素的主次顺序为TSPP＞STPP＞HMP,且TSPP对鱼肉保水效果具有显著影响,复合磷酸盐(焦磷酸钠-多聚磷酸钠-六偏磷酸钠)的优化配方为:焦磷酸钠溶液1.74%、三聚磷酸钠溶液3.03%、六偏磷酸钠溶液0.92%.低场核磁共振谱能很好地表征肌内组织内部水分的状态以及复合磷酸盐配比对鲈鱼肌肉保水性的影响,可用于对复合磷酸盐配比的筛选.本研究结果可为磷酸盐在水产品中的加工与应用提供一定的理论依据.     

多聚磷酸盐在冷冻罗非鱼肉中的降解及其对鱼肉品质的影响

利用离子色谱检测冷冻罗非鱼肉中多聚磷酸盐的降解.并通过研究鱼肉保水性、Ca2 ATPase活性、巯基含量的变化,考察了多聚磷酸盐的降解对冷冻鱼肉品质的影响.结果表明:三聚磷酸盐(STPP)在冷冻鱼肉中随着时间的延长会被不断降解;焦磷酸盐(TSPP)则随着冻藏时间的延长逐渐被降解为单磷酸盐.多聚磷酸盐的降解最终影响了冷冻鱼肉的品质参数,提高了鱼肉的持水力.随冻藏时间的延长和多聚磷酸盐的水解,蛋白质结合水的能力下降,内部的水分又逐渐形成冰晶,导致蛋白质逐步变性,Ca2 -ATPase活性丧失.添加多聚磷酸盐可以增强蛋白质的抗冻性,因而延缓了活性巯基的氧化或二硫键的形成;但是多聚磷酸盐一旦发生水解,蛋白质的变性程度升高,将导致活性巯基的含量下降.     

不同磷酸盐对猪肌肉嫩度及保水性的影响

以猪背最长肌为原料,选择不同浓度多聚磷酸盐、六偏磷酸盐和焦磷酸盐对样品进行盐水注射和滚揉处理,采用正交试验设计,测定肌肉嫩度、滴水损失率、离心损失率、蒸煮损失率,研究磷酸盐对肌肉嫩度及保水特性的影响。结果表明：不同磷酸盐对肌肉嫩度及保水性的不同指标影响不同,其中多聚磷酸钠对肌肉嫩度有显著影响(P ＜ 0.05)。当焦磷酸钠:多聚磷酸钠:六偏磷酸钠为0.3%:0.3%:0.2% 时,其嫩化效果最明显。多聚磷酸盐对滴水损失率、蒸煮损失率有影响显著(P ＜ 0.05)。依据蒸煮损失率确定的磷酸盐最佳组合为0.2% 焦磷酸钠-0.3%多聚磷酸钠-0.2% 六偏磷酸钠。     

肌肉中多聚磷酸盐水解的研究进展

该文主要阐述了添加到肌肉中的多聚磷酸盐的水解及其影响因素的研究现状。三聚磷酸盐首先水解成焦磷酸盐和单磷酸盐,生成的焦磷酸盐进一步水解成单磷酸盐,添加的焦磷酸盐则直接水解成单磷酸盐。多聚磷酸盐在肌肉中主要是通过相应的水解酶水解,受到较多物理化学因素影响。     

荣昌猪和杜洛克猪肉质及营养价值的比较分析

以脂肪型的荣昌猪和瘦肉型的杜洛克猪为研究对象,比较分析2 个品种之间背最长肌的肉质、氨基酸、脂肪酸和微量元素含量差异。结果显示：荣昌猪的肌内脂肪含量、肉色和大理石纹显著高于杜洛克猪（P＜0.05）,剪切力显著低于杜洛克猪（P＜0.05）;荣昌猪背最长肌中丝氨酸、丙氨酸、精氨酸、异亮氨酸、酪氨酸、总氨基酸含量和呈味氨基酸总量显著高于杜洛克猪（P＜0.05）;荣昌猪背最长肌的饱和脂肪酸含量显著低于杜洛克猪（P＜0.05）;单不饱和脂肪酸含量显著高于杜洛克猪（P＜0.05）;荣昌猪背最长肌中微量元素Co、Mn、Cr、Se和Zn含量均显著高于杜洛克猪（P＜0.05）,微量元素As和Mo含量显著低于杜洛克猪（P＜0.05）。结果表明,脂肪型的荣昌猪在肉质及营养价值方面总体优于瘦肉型的杜洛克猪,为中国地方猪种遗传资源的保护及开发利用提供了理论依据。     

肉中添加多聚磷酸盐的研究进展

多聚磷酸盐是世界各国广泛应用的食品添加剂,是肉制品加工中不可缺少的添加物,如焦磷酸盐、聚磷酸盐和偏磷酸盐等。磷酸盐的在改善肉品的品质中的作用很多。利用先进的31PNMR技术可以对添加到肉中的多聚磷酸盐水解过程进行动态监测,为弄清多聚磷酸盐在肉中的作用原理提供依据。另外本文还介绍了多聚磷酸盐与肌肉蛋白质的相互作用。     

Mechanism of Polyphosphates Hydrolysis by Purified Polyphosphatases from the Dorsal Muscle of Silver Carp (Hypophthalmichthys Molitrix) as Detected by 31P NMR

The dynamic hydrolysis of tetrasodium pyrophosphate (TSPP), sodium tripolyphosphate (STPP) and polyphosphate compound, which was catalyzed by purified pyrophosphatase (PPase) and myosin‐ tripolyphosphatase (TPPase) from the silver carp dorsal muscle, was studied using ³¹P NMR spectroscopy. In the PPase + TSPP system, the pyrophosphate (PP) was hydrolyzed quickly and completely within 8 h and the hydrolysis rate of PP was 12.51%/h. In the TPPase + STPP system, the first‐order hydrolysis of tripolyphosphate (TPP) was not yet complete after 48 h, and the derived PP accumulated progressively. Given the coexistence of PPase and TPPase, only 1.20% of TPP in STPP alone remained after 48 h. However, the generation rate of Pi in the polyphosphate compound (TSPP: STPP: sodium hexametaphosphate = 1: 8: 1) was 0.76%/h, which was less than 0.88%/h in STPP alone. In the presence of polyphosphatases, the decrease of PP or TPP content in the polyphosphate compound was not as rapid as that in TSPP or STPP alone due to the inhibitory effect of PP on TPPase and the effect of low system pH on PPase. The understanding of polyphosphates hydrolysis mechanism was capable of developing the advanced polyphosphate mixture in order to reduce the phosphate residue in fish products.     

THE INFLUENCE OF POLYPHOSPHATE MARINATION ON SIMMENTAL BEEF SHEAR VALUE AND ULTRASTRUCTURE

The beef semitendinosus muscles were marinated for 1, 2 or 3 days with every polyphosphate at concentration of 1, 3 and 5%. Disodium dihydrogen pyrophosphate significantly increased ( P <  0.01) soluble collagen content compared with the other polyphosphates; tetrosodium pyrophosphate (TSPP) and sodium hexametaphosphate (SHMP) disrupted myofibrillar structure completely; Z-disks disappeared under transmission electron microscope (TEM); and myofibril bundles collapsed together. Sodium tripolyphosphate (STPP) disrupted myofibrillar structure as well, but Z-disks were still perceptible under TEM. TSPP dissolved perimysium into collagen fibers and collagen fibrils, which arranged loosely and looked like dispersed silk. Perimysium was separated into collagen fibers and collagen fibrils by STPP and SHMP, but collagen fibrils were in close contact with each other. Polyphosphates all decreased shear force significantly compared with controls ( P <  0.05).

PRACTICAL APPLICATIONS

The tenderness and juiciness of meat are the most important focus of consumers. Food additives, especially polyphosphates, are generally added into fresh retail cuts as well as further processed products to improve water-holding capacity and tenderness by meat industries. The article compared the different effects of polyphosphates and the effect of concentration on the ultrastructure and shear force of meat samples, thereby offering a theoretic guidance for the practical application of polyphosphates.     

31P NMR analysis of chicken breast meat vacuum tumbled with NaCl and various phosphates

The hydrolysis of several commercially used phosphates was studied in chicken breast meat marinated and tumbled in 70 g kg^?1 NaCl and 12 g kg^?1 of either disodium pyrophosphate (DSPP), tetrasodium pyrophosphate (TSPP), tetrapotassium pyrophosphate (TKPP), sodium tripolyphosphate (STPP) or glass phosphate. After treatment, intact muscle was ground in the presence of EDTA‐Na₂ to prevent further enzymatic breakdown of phosphates. TSPP and TKPP were fully hydrolysed within 1.25 h, STPP within 3.25 h, DSPP within 6 h and glass phosphate within 24 h. DSPP lowered the muscle pH from 5.97 to 5.60, while TSPP and TKPP increased the pH to 6.10 and 6.19 respectively. Based on PP chemical shifts, the pH was found to increase with time. No evidence of tripolyphosphate (TPP) in the STPP‐treated samples was found, suggesting that it had already been hydrolysed to pyrophosphate (PP) or monophosphate (Pi) during treatment. PP hydrolysis occurred at about the same rate as Pi production in STPP‐treated samples. Pi production in meat treated with glass phosphate was relatively slow, indicating a lack of muscle enzymes capable of breaking down long‐chain phosphates. Late production of Pi after depletion of oligophosphate was attributed to hydrolysis of cellular phosphates. © 2001 Society of Chemical Industry     

宰后高温诱导制备类PSE兔肉

研究了类苍白、松软、表面汁液渗出（pale soft exudative,PSE）兔肉的制备方法,以保证PSE兔肉科学研究用实验材料品质的一致性。以新鲜的兔背最长肌和后腿肉为实验材料,参照猪、家禽PSE肉的制备方法,研究37 ℃水浴条件下兔背最长肌和腿肌肉感官品质、pH值、色泽、失水率、弹性、肌原纤维蛋白溶解度及弹性储能模量（G′）的变化。结果表明：随着处理时间的延长,兔背肌和腿肌的感官品质下降;pH值、a*值、弹性、蛋白质的溶解度及凝胶G′值均显著下降（P＜0.05）;L*值和失水率显著增加（P＜0.05）。水浴2 h时,兔背肌肉的极限pH＜5.74,L*＞63.40,汁液损失率＞25.36%;3 h时,兔腿肌肉的极限pH＜5.84,L*＞56.82,汁液损失率＞17.85%。在37 ℃保温2 h,兔背肌肉表现出了PSE肉的特征;在37 ℃保温3 h,兔腿肌肉表现出了PSE肉的特征。     

磷酸盐混合物对鸡胸肉盐溶蛋白凝胶特性的影响

本试验以艾维茵肉鸡鸡胸肉为试材,采用混料回归试验设计,在特定的条件下加入不同配比的磷酸盐TSPP、STPP、HMP,提取盐溶蛋白,制备热诱导凝胶。通过蛋白含量及其组分、凝胶保水性、流变性的测定,筛选最适磷酸盐混合物。结果表明,不同磷酸盐混合物改善凝胶特性的程度不同。在0.01mol/LMgCl2、0.6mol/LNaCl和pH7.0条件下,改善鸡胸肉盐溶蛋白凝胶特性的最佳磷酸盐配比为TSPP:STPP:HMP=1/3:5/12:1/4。当这种磷酸盐混合物的添加量为3g/kg时,可使鸡胸肉盐溶蛋白凝胶保水性和流变特性保持较高水平。     

Comparison of flavor changes in cooked-refrigerated beef, pork and chicken meat patties

Beef and pork longissimus dorsi (LD) and semimembranosus (SM) and chicken breast (B) and thigh (T) muscles excised 24 h postmortem were ground by muscle/species group, formed into patties, pan-fried, refrigerated for 0, 3 or 6 days, and evaluated by a trained sensory panel for intensity of specific flavors. The rate of decline in species-specific natural meat flavor intensity and the rate of increase in "cardboard" (CBD) flavor intensity during the first half of the 6-day storage were fastest for beef, while such decline and increase during the entire storage period were slowest for chicken B. Overall trends of natural meat flavor and CBD intensity changes for chicken T appeared more like those for the red meats than chicken B. It was concluded that, while flavor deterioration can occur in cooked-stored meats from all the species, quantitative or the magnitude of differences between species would depend on muscle types and sensory terms/method used.     

注射水和氯化钙溶液对宰后猪肉肉色及其稳定性的影响

目的：探讨注射水和氯化钙溶液对宰后冷藏期间猪背最长肌肉色及其稳定性的影响。方法：猪背最长肌于宰后1.5h注射肉质量分数5%的水和200mmol/L氯化钙溶液,分别测定其冷藏期间肉色a*值、总色素含量、高铁肌红蛋白(MetMb)相对百分含量、MetMb还原酶活性等指标。结果：注射氯化钙溶液能降低肉中a*值、总色素含量、MetMb还原酶活性和乳酸脱氢酶-B(LDH-B)活性,增加MetMb相对百分含量和丙二醛(MDA)含量。注水能降低肉中总色素含量和MetMb还原酶活性,增加MetMb相对百分含量。结论：注射水和氯化钙溶液均能降低宰后冷藏期间猪背最长肌中总色素含量,增加MetMb相对百分含量,从而加快猪背最长肌的褪色,不利于其冷藏期间新鲜肉色的维持。