猪肉脂肪氧化酶在高压结合热处理过程中失活动力学模型

为了解猪肉高压加工过程中脂肪氧化酶(lipoxygenase,LOX)活性的变化规律,以猪背最长肌为原料,经不同压力(200~700 MPa)、温度(20~60℃)结合处理后,研究LOX失活常数的变化规律,并分别用Arrhenius和Eyring方程为基础来建立LOX失活的动力学模型。结果表明,当处理温度不变时,失活常数随压力的增加而增加;同样,当处理压力不变时,失活常数随温度升高而增加。Arrhenius和Eyring方程分别适用于整个研究的温度区间和压力区间,分别以两者为基础可以建立LOX失活的动力学方程,两个方程的拟合程度均较高,决定系数分别达到0.989和0.965。因此在一定的处理温度(20~60℃)和压力(200~700 MPa)范围内,猪肉高压结合热处理过程中LOX活性的变化可以用以Arrhenius和Eyring方程为基础建立的数学模型进行预测。     

SNP标记用于猪肉产品DNA溯源

采用基于个体基因组DNA序列的差异而进行个体识别的DNA溯源技术,建立DNA溯源系统对肉产品的质量安全进行控制。在实验群体中(10个品种,233个个体)检测了33个新单核苷酸多态性(single nucleotide polymorphism,SNP)标记的遗传多样性,通过杂合度计算筛选出6个SNP标记可用于猪肉产品DNA溯源。进一步在屠宰场采样进行溯源模拟实验,结果表明筛选的18个SNP标记(6个新SNP标记结合已有的12个SNP标记)能有效区分100头猪个体,随机抽取的10个个体的组织样品都能通过基因型比对找到对应的个体。本研究可为早日建立猪肉产品的DNA溯源系统提供一定的技术参考。     

基于LPC2132与MTD2009的步进电动机驱动器设计

阐述了微步距步进电动机驱动器的组成及设计方法，提出了实现方案。在具体设计中，充分利用LPC2132单片机强大的控制和处理能力，采用了8通道的高速串行DA转换器，实现4路两相步进电动机驱动控制，并已成功运用于医疗仪器自动控制系统中。     

Modelling the cross‐contamination of Listeria monocytogenes in pork during bowl chopping

This study has developed a predictive model for the cross‐contamination of pork by Listeria monocytogenes during bowl chopping. The transfer rates of L. monocytogenes were measured in sixteen chopping scenarios based on practical work. Meanwhile, contaminated bowl chopper was cleaned with either a dry rag (DR), warm water (WW) or 70% ethanol + water (EW), respectively. It was showed that significant differences (P < 0.05) were observed among the three cleaning methods on the reduction of L. monocytogenes, the greatest log reduction being achieved by EW. Moreover, the model introduced by a previous study, predicting cross‐contamination of L. monocytogenes during meat slicing, was improved and validated in this study. Verification results showed that the improved model was acceptable for predicting L. monocytogenes cross‐contamination during pork chopping with coefficients of determination (R² > 0.82), accuracy factors (A_f < 1.44), bias factors (B_f < 1.42), and root mean square error (RMSE < 0.99). Furthermore, the modified model might provide an effective tool for assessing the risk of the cross‐contamination of meat products.     

Effects of onion on physicochemical properties,lipid oxidation and microbial growth of fresh pork patties

Onions with or without heating (100 °C, 30 min) were extracted with water or methanol, and antioxidant and antimicrobial activities of onion extracts were evaluated. Product characteristics of fresh pork patties containing various onion extracts were measured during refrigerated storage. Water extracts of onions showed higher extraction yield and iron chelating ability than methanol extracts (P < 0.05), whereas, the latter was more effective than the former in phenolic compounds and reducing power (P < 0.05). The addition of onion extracts [water extract from fresh onion (WEFO), methanol extract from heated onion (MEHO) and their combinations (WEFMEHO)] to pork patties decreased redness, increased yellowness, and inhibited lipid peroxidation (P < 0.05). One per cent of WEFMEHO in pork patties had antioxidant activities as effective as butylated hydroxyl toluene (BHT, 0.01%). Redness and yellowness decreased and increased with the addition of onion extract, respectively (P < 0.05).     

Effects of Eubacterium coprostanoligenes and Lactobacillus on pH, Lipid Content, and Cholesterol of Fermented Pork and Mutton Sausage-Type Mixes

Pork and mutton sausage-type mixes produced using Eubacterium coprostanoligenes with or without Lactobacillus as starter culture showed changes in pH, cholesterol and lipid content. Viability of E. coprostanoligenes was assessed by culturing samples from each treatment and analyzing for coprostanol, a cholesterol metabolite. The pH and/or cholesterol decreased (P < 0.05) in the sausage-type mixes inoculated with E. coprostanoligenes or Lactobacillus or their combinations. Variability in lipid content was observed among and within treatments. Very low (6.2 μg/g dry matter) concentrations of coprostanol were produced in sausage-mixes and cultures except when inoculated with 2.0 g of E. coprostanoligenes (from 8.2 to 130.6 μg/g dry matter).     

斩盘产生的中子脉冲特性

为更好地设计转盘式中子斩波器,建立了单斩盘和异向旋转双斩盘的结构模型.采用国际上常用的Mcstas模拟计算软件,分别对单斩盘和异向双斩盘产生的中子束流脉冲的形成特性进行了模拟计算,获得了相关物理参数对斩盘产生中子束流脉冲的影响曲线,讨论了单斩盘与双斩盘脉冲形成的束流特性的差别与优缺点.分别对单斩盘和异向旋转双斩盘模型产生的中子束流脉冲可能产生的误差进行了理论分析,讨论了各客观物理因素对误差的影响.结果表明,考虑实际应用条件,在特定物理参数下,异向旋转双斩盘的第二斩盘窗口宽度应在不超过34 mm的范围内综合选择.计算结果可用于中子斩波器的理论设计及其相关物理参数的选择.     

笋干菜糯米营养保健香肠的开发研究

研究了笋干菜营养香肠的生产工艺,探讨了影响其质量的因素:笋干菜的添加量、糯米的添加量、糯米的颗粒度及肥、瘦肉的比例。并在此基础上采用正交实验得出了最佳工艺条件和配比,结果表明:五花猪肉79%,糯米用量15%,笋干菜用量6%,肥、瘦肉比例2:8,糯米颗粒度30目时香肠质量最佳。     

Thermal Inactivation of Salmonella spp. in Chicken Broth, Beef, Pork, Turkey, and Chicken: Determination of D- and Z-values

ABSTRACT: The heat resistance of 35 Salmonella strains was determined at 55 to 65°C. No correlation between the heat resistance and the origin of the Salmonella spp. could be established. D-values in chicken broth, using a linear regression, of an 8 Salmonella serotype cocktail were 4.87, 2.72, 1.30, and 0.41 min at 55, 58, 60 and 62°C, respectively. Using a linear model, the D-values ranged from 4.86 min at 55°C to 0.38 min at 62°C. When the 8 Salmonella serotype cocktail was heated in meat, D-values at the common test temperatures of 58 and 60°C calculated by both approaches were significantly higher (p < 0.05) than those observed in chicken broth.     

Effect of the combination of various NaCl levels and soy protein isolate on the quality characteristics of smoked pork loins

The objectives of this study were to evaluate the physicochemical, textural and sensory properties of smoked pork loins (PL) containing various levels of NaCl (0.0–2.0%) alone or in combination with soy protein isolates (SPI; 1.0%). The pH values, moisture, fat, and protein contents (%) of smoked PL were 5.97–6.17, 63.3–69.1%, 2.64–4.26%, and 20.2–26.6%, respectively. Increased NaCl levels increased moisture contents (%) and sensory scores, as well as reduced Hunter redness and yellowness and cooking loss (CL, %) (P < 0.05). A NaCl level of 1.0% had resulted in a CL (%) level similar to those at regular‐salt levels (1.5% and 2.0% NaCl). When 1.0% SPI was incorporated with smoked PL, the NaCl level of 0.5% was also similar to the CL (%) at higher NaCl levels and improved sensory scores. Thus, a NaCl level of at least 1.0% was required for the manufacture of smoked PL; however, smoked PL could be manufactured with 0.5% salt when 1.0% SPI was included as part of the manufacture of smoked PL to effect quality characteristics similar to those achieved with regular‐salt (1.5% and 2.0% NaCl) smoked PL.