Determination of phytic acid in feeds and faeces of pigs and poultry by capillary isotachophoresis

A method for phytic acid determination in the feeds and faeces of pigs and poultry has been developed on the basis of capillary isotachophoresis. Phytic acid was extracted by 0.95 M HCl and separated from interfering compounds by iron precipitation. Complete formation of ferric phytate required 7 mol FeCl₃ mol⁻¹ phytic acid. Residual Fe³⁺ was estimated colorimetrically by the tiron reagent, and ferric phytate was dissolved in 1.5 M NaOH at 9 mol NaOH mol⁻¹ Fe precipitated. Analyses were carried out using an electrolyte system with Cl⁻ as the leading anion, bis‐tris‐propane, and 2‐morpholinoethanesulphonic acid as the terminating anion. The recovery of phytic acid (added to hen faeces) using this procedure was 962 ± 24 g kg⁻¹. The limit of determination of phytic acid was 0.3 µmol ml⁻¹ extract. The amount of phytic acid in feeds ranged from 8.3 to 10.8 g kg⁻¹ on a dry matter basis. Phytic acid P represented 112 g kg⁻¹ total P in faeces of young pigs (40–60 kg) fed a feed with supplemental phytase (490 U kg⁻¹), 153 g kg⁻¹ total P in faeces of finishing pigs and 185 g kg⁻¹ total P in faeces of non‐lactating sows. Excreta of laying hens contained 23.7 g phytic acid kg⁻¹ dry matter (362 g kg⁻¹ total P). The isotachophoretic method is sufficiently simple and reproducible to be used for routine analyses of feeds and faeces. © 2000 Society of Chemical Industry     

生姜提取物对冷藏期间淘汰蛋鸡胸肉糜品质的影响

本试验以淘汰蛋鸡胸为研究对象,硫代巴比妥酸值(Thiobarbituric acid reactive substance,TBARS)、蒸煮损失、L^*值、a^*值、pH、质构、菌落总数及低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)为考察指标,以未添加生姜提取物组为对照组,研究4℃条件下不同浓度(0.05、0.2、0.4 mg/mL)生姜提取物对淘汰蛋鸡胸肉糜品质变化的影响,同时采用电子鼻技术对冷藏条件下各组淘汰蛋鸡胸肉糜的挥发性成分进行主成分分析。结果表明:三组处理组(0.05、0.2、0.4 mg/mL)在冷藏期12 d时TBARS值分别为2.0433、1.0100、0.8133 mg/kg,显著低于对照组(P<0.05)。随着冷藏时间的增加,生姜提取物能够显著延缓淘汰蛋鸡胸肉糜中的脂肪氧化,同时降低蒸煮损失、亮度、pH和菌落总数,改善质构特性,延缓肉糜因氧化而产生的气味变化,抑制肉糜中不易流动水向自由水的转化。生姜提取物浓度越高,对淘汰蛋鸡胸肉糜品质改善效果越明显。因此,添加适量的生姜提取物可在一定程度上改善冷藏期间淘汰蛋鸡胸肉糜的品质特性。     

超高效液相色谱-串联质谱法测定鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留

目的建立超高效液相色谱-串联质谱准确测定鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留的分析方法。方法鸡肉和鸡蛋样品加入D5-氯霉素内标,经氨化乙酸乙酯混合溶液超声离心提取,提取液减压蒸馏浓缩后,C18固相萃取柱净化处理,采用超高效液相色谱-串联质谱法对氟苯尼考和氟苯尼考胺同时进行检测。结果氟苯尼考线性范围为0.2～20μg/L,检出限为1.0μg/kg,定量限为3.0μg/kg,方法回收率为88.0%～108.0%,相对标准偏差为4.7%～6.4%;氟苯尼考胺线性范围为0.2～20μg/L,检出限为1.0μg/kg,定量限为3.0μg/kg,方法回收率为76.0%～93.1%,相对标准偏差为4.1%～7.2%。结论本方法精确、重现性好,适用于鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留量的测定。     

利用二次回归正交旋转组合设计优化鸡蛋壳膜唾液酸提取工艺

为研究水解鸡蛋壳膜制备唾液酸的工艺,在单因素试验的基础上,采用二次回归正交旋转组合设计,以水解温度、水解时间、pH值、料液比为考察因素,优选了水解鸡蛋壳膜制备唾液酸的最佳工艺。结果表明:各因素对提取率的影响由大到小依次为:水解温度、水解时间、pH值、料液比。最佳工艺条件为:水解温度为83℃,水解时间为2.1h,pH值为1.4,料液比为101mL/g。在该工艺条件下,唾液酸的得率为85%,工艺稳定,提取率较高,实验验证结果与模型预测值相符合。     

Myofibrillar protein extracts from spent hen meat to improve whole muscle processed meats

Myofibrillar protein (MP) from spent hen meat was used as an ingredient for chicken breasts and pork hams. Cooking loss (CL) and texture of both products were evaluated. Salt-soluble MP was extracted following centrifugation. A brine with 6% MP or a brine without MP were injected into meat to 20% of the original meat weight. CL was reduced in pork hams treated with 6% MP (P<0.05). Chicken breasts with 6% MP had greater hardness and gumminess than those without MP (P<0.05). Pork hams with 6% MP had greater hardness, gumminess and chewiness than those without MP (P<0.05). It was concluded MP from spent hen meat may be used to improve the functional properties of whole-muscle meat products.     

Study on the evolution of the microstructure,phase composition,three-dimensional morphology,and hardness in the solution treatment of Mg−7.80Gd−2.43Y−0.38Zr alloy

The evolution of the microstructure, phase composition, three-dimensional morphology, and hardness of Mg−7.80Gd−2.43Y−0.38Zr (wt.%) alloys during solution treatment at 480 °C is investigated using scanning electron microscopy (SEM), electron probe micro-analyzer, nanoindentation, and x-ray tomography. The as-cast alloy consists of an α-Mg matrix phase and divorced eutectics, including the secondary and the supersaturated magnesium phases. The chemical composition of the secondary phase is similar to that of Mg_7.22(Gd, Y), and the nanoindentation hardness of the secondary phase is significantly higher than that of the α-Mg matrix phase, according to the energy-dispersive spectroscopic and nanoindentation analyses. The three-dimensional morphology and quantitative information, such as the number and volume fraction of the secondary phases during the solution treatment, are discussed in detail. A large number of small acicular secondary phases are found near the large secondary phase after solution treatment at 480 °C for 1 h, while the acicular phase disappears completely after 2 h. The secondary phase dissolves into the α-Mg matrix after solution treatment for 8 h, and the solution-treated alloy primarily consists of an α-Mg matrix phase and a cuboid-shaped phase, which was identified as (Gd,Y)H₂.     

Microstructure and mechanical properties of hypereutectic aluminium‐silicon alloy annealing at liquid‐solid region

The microstructure and mechanical properties of hypereutectic Al?Si alloys containing 16 wt.%, 21 wt.% and 30 wt.% Si (AlSi16, AlSi21 and AlSi30) have been investigated in “as‐cast” and “annealed at the liquid‐solid region”. The results show that the morphologies of primary Silicon in AlSi30 changed hardly after being annealed at 587 °C for different time. The morphology of eutectic silicon in all Al?Si alloys changed from flake‐like to granular after being annealed at 587 °C for 5 min to 15 min. With the increase of silicon content, the average size of the granular eutectic silicon decreased. The spheroidized effect for the eutectic silicon in AlSi21 was the best. After being annealed for 15 min, the tensile strength of AlSi16, AlSi21 and AlSi30 alloys decreased by 10.4 %, 11.7 % and 11.5 %, respectively. Their elongation increased 61.1 %, 50.0 % and 33.3 %, respectively. The comprehensive mechanical properties of AlSi16 and AlSi21 alloys were improved markedly after being annealed at 587 °C for 15 min.     

Effect of solid solution state of zirconium and Al3Zr (L12) precipitates on the recrystallization behavior of Al-0.2 wt.%Zr alloy

Effect of homogenization annealing on the existence form of zirconium in Al-0.2wt.%Zr alloy and effect of various existence form of zirconium on the recrystallization behavior of Al-0.2wt.%Zr cold-rolled (total deformation is 92.8 %) sheet are studied. The results show that large numbers of nearly spherical Al₃Zr (L1₂) nanoparticles precipitated from aluminum matrix after homogenizing at 475 °C for 24 h. Moreover, due to the precipitation of Al₃Zr particles, the hardness and electrical conductivity of the as-cast Al-0.2wt.%Zr alloy is increased from 25.1±0.5 HV 3 and 54.0±0.2 %IACS to 28.6±0.7 HV 3 and 56.2±0.1 %IACS, respectively. Hence, zirconium exists as solid solution state in the as-cast Al-0.2wt.%Zr alloy and metastable Al₃Zr phase in the homogenized alloy. Moreover, the recrystallization temperature of the pure aluminum without addition of zirconium is 300 °C, while the recrystallization temperature of the Al-0.2wt.%Zr alloy without and with homogenization is about 350 °C and 400 °C, respectively. Obviously, the solid solution state of zirconium has certain effect on retarding the recrystallization of aluminum alloy, while the nanometer Al₃Zr particles can inhibit the recrystallization of aluminum alloy effectively and increase the recrystallization temperature remarkably.