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。     

超高压阻断多聚磷酸盐水解结合离子色谱法检测水产品中多聚磷酸盐

为寻找多聚磷酸盐水解酶的抑制方法,提高检测肌肉中多聚磷酸盐的准确度,建立了超高压阻断多聚磷酸盐水解结合免试剂离子色谱检测水产品中多聚磷酸盐的方法。采用单因素和正交试验法研究阻断多聚磷酸盐水解的最优超高压条件,试验结果表明,样本经400 MPa,保压时间10 min处理能有效阻断多聚磷酸盐水解。此条件下多聚磷酸盐标准缓冲溶液稳定,不发生分解,样品中的水分含量没有变化。超高压阻断多聚磷酸盐水解,后续用三氟乙酸为蛋白沉淀剂结合免试剂离子色谱法准确检测水产品中残留的焦磷酸盐、三聚磷酸盐含量,回收率在64%~100%之间,相对标准偏差小于10%。本方法在样品处理阶段可有效阻断多聚磷酸水解,提高分析的灵敏度,回收率和重复性好,操作简单,可满足分析测定的要求,为色谱分析的样本前处理以及水产品中多聚磷酸盐的检测提供了新的思路与试验数据。     

磷酸盐对肉制品持水力影响的研究

肉制品中添加磷酸盐可以提高肉制品的持水力。选择常用的磷酸三钠、六偏磷酸盐、焦磷酸盐为样品,通过混料试验设计对多聚磷酸盐对肉制品持水力的影响进行了研究,建立了测量肉制品持水力的方法和不同多聚磷酸盐对肉制品持水力影响的数学模型。结果表明:不同的磷酸盐单体对肉制品持水力的影响差别是比较大的,大小顺序为焦磷酸盐>磷酸三钠>六偏磷酸盐。     

磷酸盐对肉制品质构影响的研究

肉制品中添加磷酸盐可以改善肉制品的质构。选择常用的磷酸三钠、六偏磷酸盐、焦磷酸盐为样品,通过混料试验设计对多聚磷酸盐对肉制品质构的影响进行了研究,建立了评价肉制品质构的方法和不同多聚磷酸盐对肉制品质构影响的数学模型。结果表明:不同的磷酸盐单体对肉制品质构的影响差别是比较大的,大小顺序为;焦磷酸盐>磷酸三钠>六偏磷酸盐。     

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.     

离子色谱法研究多聚磷酸盐在肌肉中的动态水解变化

采用免试剂离子色谱法同时检测焦磷酸四钠（tetrasodium pyrophosphate,TSPP）、三聚磷酸钠（sodiumtripolyphosphate,STPP）和混合磷酸盐（m（TSPP）∶m（STPP）∶m（六偏磷酸钠）=3∶4∶3）在猪背最长肌、鱼背侧肌以及鸡胸大肌中的水解情况。结果表明,多聚磷酸盐在肌肉中的水解情况存在着差异。单一的TSPP在鸡胸大肌中的水解速率最快,TSPP在猪背最长肌中水解量比在鱼背侧肌中多。将STPP或混合磷酸盐加入到肌肉中,均在猪背最长肌中的水解速率最快,在鸡胸大肌中次之,在鱼背侧肌中最慢。本研究探索多聚磷酸盐在不同物种肌肉中的动态变化,为调控多聚磷酸盐的水解进程,指导多聚磷酸盐在不同物种肌肉中的合理添加提供了理论依据。     

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。     

复合磷酸盐对鸭肉饼嫩度的影响

研究焦磷酸盐与三聚磷酸盐的复合磷酸盐添加量和冰水添加量对鸭肉饼嫩度的影响.结果表明鸭肉饼较好嫩化的条件为:焦磷酸盐:三聚磷酸盐为1∶2,复合磷酸盐添加量为0.4％,冰水添加量为25％.其中,在3个因素中复合磷酸盐添加量对鸭肉饼嫩度的影响最大,其次为焦磷酸盐:三聚磷酸盐,水分影响最小.     

水产品中添加剂多聚磷酸盐抑菌效果的研究

目的：分析多聚磷酸盐中主要抑菌成分,并找出临界抑菌浓度。方法：利用微生物法,用pH 值分别为6.0、7.2、8.0 的检测琼脂研究正磷酸盐、三聚磷酸盐、焦磷酸盐和三偏磷酸盐对枯草芽孢杆菌和滕黄微球菌的抑菌作用。结果：三聚磷酸盐和焦磷酸盐是影响抑菌效果的主要因素,其引起抑菌剂阳性的临界质量浓度分别为0.2g/100mL 和0.2g/100mL,用P2O5 计分别为1157.56mg/kg 和1601.43mg/kg。通过对三聚磷酸盐和焦磷酸盐进行两因素三水平正交试验结果分析,发现两者互存时,只要有一种质量浓度达到临界值就会产生抑菌阳性效果(抑菌圈宽度≥ 2mm)。结论：通过控制焦磷酸盐和三聚磷酸盐使用量,可降低由多聚磷酸盐引起的抑菌剂阳性风险。     

碱液提取离子色谱法测定水产品中多聚磷酸盐的研究

建立了碱液提取水产品中多聚磷酸盐并同时测定焦磷酸盐、三聚磷酸盐和六偏磷酸盐的离子色谱法。以3mol/L NaOH溶液为提取液,回收率达90%以上,有效阻断了多聚磷酸盐的水解。在AS11-HC阴离子色谱柱上,焦磷酸盐、三聚磷酸盐和六偏磷酸盐分离度良好,在质量浓度为1.0～100.0mg/mL的范围内,其浓度与峰面积成良好的线性关系。在优化的色谱条件下,三种多聚磷酸盐的测定低限分别为：焦磷酸3.0mg/kg,三聚磷酸盐为3.0mg/kg,六偏磷酸盐为10.0mg/kg。以鲢鱼为空白样,添加三个浓度（1.0、10.0、50.0mg/mL）进行精密度和回收率实验,RSD在4.0%以下,回收率在95%～100%。     

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.     

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。     

Verhalten von Polyphosphaten bei der Herstellung und Lagerung von Dauermilcherzeugnissen

Zusammenfassung Als Stabilisatoren zugesetzte Polyphosphate werden während der Herstellung von flüssigen, sterilisierten Milchprodukten vollständig zu Mono- und Diphosphaten hydrolysiert. Während der Lagerung der Produkte erfolgt eine weitere Hydrolyse des Diphosphates. Der Umfang der Hydrolyse des Diphosphates ist von den Herstellungsbedingungen abhängig und kann von Produktion zu Produktion unterschiedlich groß sein. Bei der Sprühtrocknung von Milch werden zugesetzte Polyphosphate nur zum Teil hydrolysiert, ein weiterer Abbau der Polyphosphate erfolgt während der Lagerung.

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The behaviour of polyphosphates during production and storage of long keeping milk products

Summary Polyphosphates added as stabilizers in the production process if liquid sterilized milk products are completely hydrolyzed to mono- and diphosphates. The diphosphate is further hydrolyzed during storage of the products. The extent of hydrolysis of diphosphate depends upon the processing conditions and may vary from production to production. During spray-drying of milk, the polyphosphates added are only partially hydrolyzed; further degradation of the polyphosphates takes place during storage.

     

Purification and characterization of pyrophosphatase from bighead carp (Aristichthys nobilis)

Pyrophosphatase (PPase, EC 3.6.1.1) responsible to the hydrolysis of pyrophosphate (PPi) in muscle was purified from bighead carp (Aristichthys nobilis), and characterized in detail herein for the first time. PPase was extracted with 20 mmol/L Tris-HCl buffer (pH 7.0) containing 0.05 mol/L KCl, followed by heat treatment and ammonium sulfate precipitation. Then it was purified by deithylaminoethyl-cellulose (DE52) and Sephacryl S-300 chromatography, subsequently resulted in a 114.5-fold purification. The molecular mass of the PPase was defined to be 50 kDa with two subunits. The optimum pH of the purified PPase was around 8.0, and its optimum temperature was confirmed to be 50 °C. Magnesium ion was necessary to the activity of PPase. An excess of PPi over Mg²⁺ resulted in inhibition of PPase. When the Mg²⁺/PPi molar ratio was 1:1, the maximal enzyme activity was obtained. In addition, PPase converted PPi to orthophosphate (Pi) stoichiometrically with a K_m of 1.98 mmol/L under the condition of 5 mmol/L Mg²⁺. Ethylene diamine tetraacetate (EDTA) activated the activity of PPase at low concentration, however, it consumingly did inhibit the enzyme activity at high concentration.     

Tripolyphosphate hydrolysis by bovine fast and slow myosin subfragment 1 isoforms

Polyphosphates are used in the meat industry to increase the water holding capacity of meat products. Tripolyphosphate (TPP) is a commonly used polyphosphate and it is metabolized into pyrophosphate and monophosphate in meat. The enzymes responsible for its metabolism have not been fully characterized. The motor domain of myosin (subfragment 1 or S1) is a likely candidate. The objectives of this study were to determine if bovine S1 hydrolyzes TPP, to characterize the TPPase activity of the fast (cutaneous trunci) and slow (masseter) isoforms, and to determine the influence of pH on S1 TPPase activity. S1 hydrolyzed TPP and in comparison with ATP as substrate, it hydrolyzed TPP 16–32% more slowly. Fast S1 hydrolyzed both substrates faster compared to slow S1 and the difference between the isoforms was greater with TPP as the substrate. The V_max was 0.94 and 5.0 nmol Pi/mg S1 protein/min while the K_m was 0.38 and 0.90 mM TPP for slow and fast S1, respectively. Pyrophosphate was a strong inhibitor of TPPase activity with a K_i of 88 and 8.3 μM PPi for fast and slow S1 isoforms, respectively. Both ATPase and TPPase activities were influenced by pH with the activity being higher at low pH for both fast and slow S1 isoforms. The activity at pH 5.4 was 1.5 to 4-fold higher than that at pH 7.6 for the different isoforms and substrates. These data show that myosin S1 readily hydrolyzes TPP and suggest that it is a major TPPase in meat.     

Morphology and structural characterization of high-amylose rice starch residues hydrolyzed by porcine pancreatic α-amylase

High-amylose starches are attracting considerable attention because of their potential health benefits and industrial uses. Enzyme hydrolysis of starch is involved in many biological and industrial processes. In this paper, starches were isolated from mature grains of high-amylose transgenic rice line (TRS) and its wild type rice cultivar Te-qing (TQ). The morphological and structural changes of starch residues following porcine pancreatic α-amylase (PPA) hydrolysis were characterized by SEM, DSC, XRD, ¹³C CP/MAS NMR, and ATR-FTIR. TQ starch was hydrolyzed faster than TRS starch. PPA pitted the starch granule surface first, then penetrated into the interior and hydrolyzed the granule from the inside out. The peripheral region of subgranule and the surrounding band of TRS starch were more resistant to PPA hydrolysis than the external region of TQ starch. Both amorphous and crystalline (the long- and short-range ordered) structures were simultaneously hydrolyzed in TQ starch. A-type polymorph of TRS C-type starch was hydrolyzed faster than B-type polymorph. The long-range ordered structure was hydrolyzed faster than the amorphous structure, whereas the short-range ordered structure was hydrolyzed slower than the amorphous structure in TRS starch in the initial hydrolysis stage. The above results indicated that B-type crystallinity and short-range ordered structure in the peripheral region of subgranule and the surrounding band of TRS starch increased the resistance of TRS starch to PPA hydrolysis.     

响应面法优化元宝枫籽粕酶解工艺及多肽功能特性研究

本文以元宝枫籽粕为原料,采用碱性蛋白酶法对元宝枫籽粕进行酶解,以酶解时间、加酶量、pH、酶解温度、料液比为考察因素,酶解多肽得率为评价指标,在单因素实验的基础上,根据Box-Behnken中心组合实验设计对元宝枫籽粕碱性蛋白酶酶解多肽制备工艺进行优化,并对优化工艺获得的酶解多肽进行了氨基酸组成、吸水性、吸油性、起泡性质、乳化性质和表面疏水性等功能特性表征。结果表明:最优的酶解制备工艺为:酶解时间3.3 h,pH为10,加酶量为3%,酶解温度为55 ℃。在最优制备工艺条件下元宝枫籽粕碱性蛋白酶酶解多肽得率为40.13%±0.15%。氨基酸组成分析表明酶解多肽所含八种必需氨基酸量高达20.3%,远高于国际粮农组织所建议成人所需必需氨基酸量。此外,酶解多肽的吸油性（4.553 g/g）高于大豆蛋白（2.61 g/g）,其表面疏水性（1365.3）与大豆7S球蛋白的表面疏水性相似,乳化性和乳化稳定性略低于大豆分离蛋白。本研究所获得的元宝枫籽粕碱性蛋白酶酶解多肽具有较好的功能特性,这也表明它可作为一种潜在的功能成分应用于食品中,为元宝枫籽粕的新应用开发提供数据和理论支撑。     

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。     

酶水解大宗副产物蛋白质的技术研究

研究了不同水解条件(不同酶、酶用量、水解时间和温度)对啤酒废酵母、大豆粕、花生粕的水解的影响。通过研究发现，木瓜蛋白酶和中性蛋白酶能较好地水解啤酒废酵母；而菠萝蛋白酶和中性蛋白酶能较好地水解大豆粕和花生粕。不同的酶的水解条件有所区别。