Seaweed Polysaccharides (Laminarin and Fucoidan) as Functional Ingredients in Pork Meat: An Evaluation of Anti-Oxidative Potential,Thermal Stability and Bioaccessibility

The anti-oxidative potential of laminarin (L), fucoidan (F) and an L/F seaweed extract was measured using the DPPH free radical scavenging assay, in 25% pork (longissimus thoracis et lumborum (LTL)) homogenates (TBARS) (3 and 6 mg/mL) and in horse heart oxymyoglobin (OxyMb) (0.1 and 1 mg/mL). The DPPH activity of fresh and cooked minced LTL containing L (100 mg/g; L₁₀₀), F₁₀₀ and L/F_100,300, and bioaccessibility post in vitro digestion (L/F₃₀₀), was assessed. Theoretical cellular uptake of antioxidant compounds was measured in a transwell Caco-2 cell model. Laminarin displayed no activity and fucoidan reduced lipid oxidation but catalysed OxyMb oxidation. Fucoidan activity was lowered by cooking while the L/F extract displayed moderate thermal stability. A decrease in DPPH antioxidant activity of 44.15% and 36.63%, after 4 and 20 h respectively, indicated theoretical uptake of L/F antioxidant compounds. Results highlight the potential use of seaweed extracts as functional ingredients in pork.     

采用热重红外联用技术研究猪肉的热解特征

为了了解病害牲畜在回转窑内的热解失重过程,以猪肉为代表,采用TG-FTIR技术来研究猪肉的热解特性。结果表明,猪肉热解过程中,水分在蒸发的同时伴随有少量的小分子多肽、脂肪酸与酯类的挥发。蛋白质的热解活化能为80.8 k J·mol~(-1),其热解过程开始于180℃左右,并主导了热解过程的低温阶段(180~300℃)。而脂肪的热解活化能为206 k J·mol~(-1),其热解过程开始于280℃左右,主要处于热解过程的高温阶段(300~500℃)。两者的热解产物存在显著差异,蛋白质主要生成无机气体,包括CO_2、NH3和HCN,还会生成一些酰胺、羧酸和芳香烃。而脂肪主要生成有机气体,包括烃类、醛类、脂肪酸和芳香烃。另外,脂肪与蛋白质之间会产生相互反应,生成酰胺类物质,并加速热解进程。通过该研究,能够帮助病害牲畜回转窑热解焚烧炉的设计,并为随后利用该焚烧炉实现病害牲畜尸体的大规模处理提供理论依据。     

Dietary inclusion of tomato pomace improves meat oxidative stability of young pigs

The aim of this study was to assess the nutritional effect of tomato pomace, in combination with two distinct fat sources (lard or soya bean oil), on longissimus lumborum muscle, subcutaneous fat and liver of young pigs. Forty male pigs of 4 weeks old were randomly assigned to four dietary treatments using two fibre sources (wheat bran or 5.0% tomato pomace) and two fat sources (lard or soya bean oil), in a 2 × 2 factorial design for a 5‐week trial. Tomato pomace did not improve colour, fatty acid profile, cholesterol content or lipid oxidation, nor did it yield detectable levels in lycopene or β‐carotene in the meat (p > 0.05). However, a positive increase in α‐tocopherol content of meat and liver was observed in pigs fed tomato pomace (p < 0.05). Compared with lard, soya bean oil increased MUFA and PUFA proportions and decreased the percentage of SFA (p < 0.05). Our results indicate that 5.0% of tomato pomace increases pork oxidative stability and that 5.0% of soya bean oil, compared with lard, improves its nutritional quality.     

日粮添加氧化鱼油及硒和维生素E对育肥猪生产性能的影响

试验旨在研究氧化鱼油对育肥猪后期生产性能和冷藏生猪肉肉质的影响以及硒和维生素E的抗氧化作用。将40头DLY杂交猪(59.4kg)分为4个处理,对照组和3个添加剂组(0.3mg/kg硒,100mg/kg维生素E,0.3mg/kg硒+100mg/kg维生素E)。试猪平均体重为81.3kg时,将每个处理的10头猪各分为2组,分别在日粮中添加5%新鲜和氧化鱼油,试猪于平均体重109.8kg时屠宰取样。结果表明:①各处理组血清乳酸脱氢酶(LDH)和冷藏0~6d肉样的TVB-N、pH、L*无显著差异。②氧化鱼油显著提高肌肉丙二醛(MDA)含量,肉色b*值和血清尿素氮(BUN)、丙二醛(MDA)(P0.05);③油脂和添加剂在日增重(ADG)、滴水损失、肉色a*值、血清超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GPx)活性上表现显著的互作效应(P0.05)。本试验结果表明育肥后期添加5%氧化鱼油5周,对冷藏2d肉样b*值和2、4d肉样MDA含量有显著影响,硒和维生素E表现显著的抗氧化效应和与氧化鱼油的互作效应,硒+维生素E的添加在氧化鱼油组的作用效应大于新鲜鱼油组。     

SNP discovery, expression and association analysis for the SDHD gene in pigs

The SDHD gene was examined for single nucleotide polymorphisms (SNP) as well as for expression changes in the Longissimus dorsi muscle of commercial pigs with different potential for growth. Three SNPs, including one previously described in the coding region and two new ones in the 3′‐UTR, were found. The normalized expression of SDHD was correlated with growth, meat quality and sensory traits (p < 0.05). For the commercial pigs used in this study, as well as a Berkshire × Yorkshire resource population, the SNPs have been associated (p < 0.05) with: growth, carcass composition, meat quality and sensory traits. Despite the fact that the described SNPs were not significantly associated with the normalized expression values, the SDHD SNPs and expression were associated with growth and meat quality traits in pigs.     

Investigation of the effect of pork compositions on freezing points in different pork cuts by measuring thermal properties and water mobility and distribution

This work was to compare the difference of freezing point in the four pork cuts (chuck roll, picnic shoulder, loin, and topside) and evaluate the effect of pork compositions on the freezing points. Loin exhibited lower freezing points and accompanied by higher content of unfreezable water, lower relaxation times, and higher proportions of bound water, compared with other pork cuts. Low freezing points of pork may be attributed to high sarcoplasmic protein solubility, due to high sarcoplasmic protein solubility related to increase of bound water proportion and decrease of NMR T₂ relaxometry. In addition, correlation analysis revealed that sarcoplasmic protein solubility and ash content were negatively related to the freezing point, which was verified by a quadratic polynomial correlation between the sarcoplasmic protein solubility and the freezing point in vitro. These results could help to better understand the freezing point of pork and provide more theories for improving superchilled storage.     

广州市农贸市场猪肉源伦敦沙门菌的流行情况及耐药性分析

本研究旨在探究广州市2016年5-10月农贸市场猪肉源伦敦沙门菌的流行和耐药情况.从广州市农贸市场采集样品198份,分离得到28株猪肉源伦敦沙门菌,用K-B法测定其对18种抗菌药物的耐药性,用PCR方法鉴定其所携带的耐药基因.结果表明,市场猪肉样品中沙门菌的阳性率为74.2％(147/198),伦敦沙门菌的分离率为19...     

Effects of bacterial strains on the development of the ripening flavor of cured pork loins

To determine the effect of bacteria on the development of the ripening flavor of cured meat, pork loins were cured with pickles containing 8 or 16% sodium chloride at 0 and 8°C. The bacterial flora, total free amino acid content and total free fatty acid content in the cured loins, sensory properties of cooked pork loins and the relationships between the proteolytic and lipolytic activities of isolates and curing conditions were investigated. Desirable bacteria, including salt‐tolerant bacteria and lactic acid bacteria, were predominant under the condition of 8% sodium chloride in the pickles and a curing temperature of 8°C. The total free amino acid content and total free fatty acid content at a curing temperature of 8°C were higher than those at 0°C. Cooked pork loins cured in pickles containing 8% sodium chloride at a temperature of 8°C for more than 7 days were preferred in terms of color, flavor and taste. Before the curing procedure, gram‐negative bacteria (Vibrio, Acinetobacter, Pseudomonas and Enterobacteriaceae) were predominant in the pork loins. During the curing period, the numbers of viable gram‐positive bacteria (Micrococcus, Staphylococcus and Pediococcus) increased and the numbers of viable gram‐negative bacteria decreased. Strains of Micrococcus and Staphylococcus with proteolytic and/or lipolytic activities in cured meat also increased during the curing period and were more predominant in the pork loins cured in pickles containing 8% sodium chloride and at a curing temperature of 8°C than in pork loins cured in pickles containing 16% sodium chloride and at a curing temperature of 0°C. The actions of these bacteria were thought to be important factors affecting the flavor of the cured pork. Micrococcus and Staphylococcus with proteolytic activity might contribute to the development of the ripening flavor of ham. The results of the present study together with the results of further investigations on the relationships of the enzyme activities of Micrococcus and Staphylococcus in cured meat with a preferable flavor would be useful for establishing a novel effective method for using bacteria to produce ham of a high quality.     

基于乳酸-LDH的牦牛肉NADH线粒体介导再生研究

为了研究乳酸-乳酸脱氢酶(LDH)体系对牦牛肉线粒体在电子传递链中烟酰胺腺嘌呤二核苷酸(NADH)再生的影响,建立了体外孵化模型,研究乳酸盐对线粒体膜通透性、膜电位的影响和乳酸-LDH体系在NADH再生和高铁肌红蛋白(MetMb)还原中的作用。结果表明:乳酸盐处理组线粒体膜通透性增大、线粒体膜电位下降;在所有试验组中,乳酸钙(CaL)+LDH+NAD体系组的样品氧消耗速率和MetMb还原最高(P<0.05),当抗霉素A存在时,由CaL-LDH-NAD处理生成的NADH不能进行氧消耗。当MetMb只和线粒体孵育时,体系内的Mb氧化还原状态几乎未发生改变(P>0.05),由LDH形成的NADH不能在没有还原酶或电子载体的情况下还原MetMb。添加LDH抑制剂草氨酸钠处理组虽然降低了CaL-LDH-NAD组合对MetMb的还原(P<0.05),但并未完全抑制MetMb的还原,说明除了电子传递链介导的非酶促还原外,CaL-LDH-NAD体系产生的NADH也可用于线粒体内的酶促MetMb还原。作为线粒体内三羧酸循环中间代谢物,乳酸盐与宰后牦牛肉肉色有关,乳酸盐的氧化过程是导致MetMb还原的原因,线粒体的还原能力可以影响氧消耗、MetMb还原以及肌红蛋白(Mb)氧化还原状态,进而影响牛肉色泽的稳定性。