超声提取羊胎盘水溶性活性蛋白

以淋巴细胞增殖率为主要指标,在单因素的基础上,采用响应面法优化了超声提取羊胎盘中水溶性活性蛋白质的工艺,建立了二次多项模型,研究超声功率、固液比、超声时间3个因素及其交互作用对提取工艺的影响。试验结果表明,对蛋白质提取率的影响次序为超声功率>固液比>超声时间;最优工艺参数是:超声功率为300W,固液比为1:30,超声时间25min,淋巴细胞增殖率达53.17%。     

Immunoglobulin G content and colostrum composition of different goat and sheep breeds in Switzerland and Germany

Colostrum represents the sole source to acquire humoral immunity and is an important energy source for newborn lambs and goat kids. However, colostrum composition (i.e., the contents of IgG, fat, protein, and lactose) is affected by various factors such as parity and litter size and, potentially, by breed. In the present study, we examined the colostrum composition of different goat and sheep breeds raised for milk and meat production in Switzerland and Germany. Ten goat breeds (Anglo-Nubian, Appenzell, Boer, Bunte Deutsche Edelziege, Chamois-colored, Grisons Striped, Peacock, Saanen, Toggenburg, and Valais Blackneck) and 10 sheep breeds (Brown-Headed Meat, East Friesian Milk, German Blackheaded Mutton, Gray Horned Heath, Lacaune Dairy, Merino Land, Swiss Black-Brown Mountain, Swiss Charollais, Swiss White Alpine, and Valais Blacknose) were involved in this study. First colostrum samples were obtained from ewes (n = 100) and goats (n = 116) between 10 and 390 min after parturition and analyzed for total IgG, fat, protein, and lactose contents. Colostral IgG concentrations varied between 4.8 and 75.0 mg/mL in goats, and between 6.2 and 65.4 mg/mL in ewes, and the time interval between milking and parturition did not affect colostral IgG concentrations. In goats, the highest IgG concentrations were found in Boer (meat-type; 61.0 ± 10.3 mg/mL; mean ± SD) and the lowest concentrations were observed in Bunte Deutsche Edelziege (milk-type; 26.5 ± 12.5 mg/mL). In sheep, East Friesian Milk and Lacaune Dairy showed the lowest colostral IgG concentrations (17.9 ± 7.3 and 20.2 ± 8.0 mg/mL, respectively), and the highest values were observed in the Merino Land breed (44.2 ± 15.7 mg/mL). The lowest fat and protein concentrations and concomitantly highest lactose concentrations were observed in colostrum of East Friesian Milk and Lacaune Dairy sheep. Parity number did not affect colostrum composition in sheep or goats. In contrast, colostral fat content was higher in ewes bearing twins and triplets than in those carrying singletons. Increasing litter size tended to be associated with higher protein and lower lactose concentrations in ovine (i.e., singletons vs. twins vs. triplets) and caprine colostrum (i.e., singletons vs. twins), whereas colostral IgG concentrations were not affected by litter size. In conclusion, IgG and concentrations of other colostrum constituents showed a wide range in goats and ewes and were mainly affected by the type of breed.     

羊血肠配方优化研究

锡林郭勒羊血肠一直是当地人们喜爱的蒙餐食品,味道鲜美,营养价值高。试验以新鲜的东乌珠穆沁羊血为原料,通过对羊血肠中添加的辅料调整,进行单因素和正交试验对羊血肠的配方进行了优化。结果表明：在白菜的添加量为2．5％,面粉的添加量为2％,韭菜花的添加量为1％时,羊血肠的品质最佳,产品质地细嫩,既不松散也不坚硬,富有弹性,颜色鲜艳,融合了菜和血特有的香气。     

基于ADAMS的倾斜式羊扯皮机运动仿真分析

基于运动学仿真软件ADAMS,对倾斜式羊扯皮机进行了虚拟建模并进行运动仿真分析,得到了主要部件的位移曲线和角速度曲线等。通过对两种扯皮机水平方向运动分别与羊胴体运行曲线进行比较,得出倾斜式扯皮机水平方向运动与羊胴体运动曲线接近程度更高一些,相对运动曲线更接近于零线;从而得出倾斜式扯皮机更适合用于连续羊屠宰生产线上。     

焙烤对宁夏滩羊羊脂水分分布和关键性香气成分的影响

以宁夏盐池滩羊肉羊脂作为研究对象,运用低场-核磁共振技术研究烤制过程中羊脂水分分布及迁移规律。采用顶空固相微萃取提取不同烤制过程中羊脂挥发性成分,并结合气相色谱-质谱、电子鼻进行分析。结果表明：羊脂L*随着烤制时间的延长而下降,a*、b*随烤制时间的延长呈上升趋势。羊脂烤制过程中弱结合水的相对含量呈增加趋势,而不易流动水相对含量呈下降趋势。T23随烤制时间的延长呈明显减小趋势,说明随烤制进行水分子与大分子物质结合更紧密。在10?个烤羊脂样品中共检出78?种挥发性成分,其中醛类12?种、醇类11?种、酮类9?种、烯烃类4?种、酸类10?种、酯类12?种、杂环类12?种、其他物质8?种。己醛、壬醛、1-辛烯-3-醇、3-羟基-2-丁酮、7-甲基-3-亚甲基-1,6-辛二烯和甲苯普遍含量较高。酯类物质主要存在于羊脂烤制初期,而杂环类化合物,特别是吡嗪类化合物主要存在于烤制后期。电子鼻数据的主成分分析结果表明,烤制过程对羊脂中的氮氧化物、芳香族化合物、有机硫化合物、醇类有显著影响,对烷烃、氢化物和氨类化合物影响不大。     

Seasonal variation in conjugated linoleic acid and vaccenic acid in milk fat of sheep and its transfer to cheese and ricotta

The seasonal variation in conjugated linoleic acid (CLA) and vaccenic acid (VA) concentrations in sheep dairy products and the extent of their transfer from milk fat to cheese and ricotta fat were investigated. Samples were collected from 2 sheep milk processing plants in North Sardinia (Italy) every 2 wk from March through June. Concentrations of fatty acids (FA) in fresh cheese and ricotta fat were primarily dependent on the fatty acid content of the unprocessed raw milk. The content of c9,t11-CLA averaged 1.73, 1.69, and 1.75 mg/100 mg of FA methyl esters (FAME), respectively, for milk, cheese, and ricotta, and differed significantly between cheese and ricotta. The content of VA averaged 3.40, 3.33, and 3.43 mg/100 mg of FAME, respectively for milk, cheese, and ricotta. The FA composition of dairy products was markedly affected by period of sampling: the mean c9,t11-CLA and VA concentration decreased from March (2.20 and 4.52 mg/100 mg of FAME) to June (1.14 and 1.76 mg/100 mg of FAME) in all dairy products. No differences in c9,t11-CLA and VA concentration of dairy products were observed between the 2 dairy companies obtaining milk from the same geographical origin. The seasonal changes in CLA and VA in milk fat were probably related to changes in pasture quality.     

Evaluation of confirmatory stains used for direct microscopic somatic cell counting of sheep milk

Current FDA regulatory screening and confirmatory methods, electronic cell counting and the direct microscopic somatic cell count (DMSCC), differ for the detection of abnormal milk in sheep and goats. The DNA-specific electronic SCC screening methods such as Fossomatic (Foss, Hillerød, Denmark) can be used for both sheep and goat milk; however, the nonspecific methylene blue-based stains used for DMSCC in sheep cannot be used for goats as they nonspecifically stain cytoplasmic particles naturally present in goat milk. The DNA-specific stain pyronin Y-methyl green (PMG) is currently used for DMSCC in goats. Sheep also shed cytoplasmic particles during the milk secretory process, but in fewer numbers than goats. The objective of this study was to determine whether the nonspecific, methylene blue-based Levowitz-Weber (L-W) stain is the appropriate regulatory stain to use for DMSCC in sheep milk. Composite milk samples from 42 commercial dairy ewes were collected every 4 wk for the duration of each ewe's lactation for a total of 10 sample days. Milk samples were subjected to 3 methods of SCC determination: automated Fossomatic counting, DMSCC with L-W stain, and DMSCC with PMG stain conducted according to FDA regulatory procedures (2400 series forms). The DMSCC from milk smears stained with L-W were greater than those from smears stained with PMG and those from the Fossomatic analysis on 6 of the 10 sampling days. Milk smears stained with PMG did not differ from Fossomatic analysis at any sampling. The average milk SCC for L-W, PMG, and Fossomatic were (mean ± SE) 275 ± 36 × 10³, 174 ± 24 × 10³, and 164 ± 24 × 10³ cells/mL, respectively. The DMSCC for milk stained with L-W was 58% greater than that with PMG and 68% greater than that obtained with the Fossomatic analysis. In conclusion, DMSCC of sheep milk stained with the nonspecific, methylene blue L-W stain resulted in a marked increase in SCC over that of the DNA-specific stain PMG and Fossomatic SCC analysis. The findings of this study support the continued use of Fossomatic SCC but recommend the replacement of the methylene blue-based stains with DNA-specific PMG for determination of DMSCC in sheep milk.     

滩羊肌肉在煮制过程中可挥发性化合物的变化

以盐池滩羊肌肉为原料,采用吹扫捕集法结合气相色谱-质谱联用技术和气相色谱-嗅闻技术,研究盐池滩羊肌肉在煮制过程中挥发性化合物的变化.实验共检测出42种挥发性物质,其中醛类16种、酮类6种、醇类5种、酸类3种、杂环化合物12种.经分析后,煮制温度由50℃上升到80℃时,醛类、酮类、醇类等相对含量较大,90℃后相对含量下降...     

酶法水解鲜羊骨骼的研究

以新鲜羊骨骼为原料,首先对不同种类的蛋白酶对羊骨酶解的效果进行了筛选,结果表明:中性蛋白酶水解度及三氯乙酸氮溶解指数相对较高,水解效果较理想。然后采用五因子二次正交设计对中性蛋白酶酶解羊骨的条件作进一步研究,确定其作用的最佳参数值为底物质量浓度为47kg/L,酶用量230U/g骨,酶解温度50.5℃、酶解时间为6.2h、pH值为7.0实验发现底物质量浓度、酶用量、酶解温度对羊骨酶解的水解度有极显著的影响,而作用时间和pH对水解度的影响不显著。     

Effect of forage type,season, and ripening time on selected quality properties of sheep milk cheese

The aim of this research was to study changes in the microbial populations, free AA profile, biogenic amine content, and sensory characteristics of ripened cheeses (100 and 180 d) produced in different seasons (summer, autumn, winter, and spring) from pasteurized sheep milk from 8 commercial flocks fed hay or silage diets. Twenty-one individual AA and 6 biogenic amines were determined by ultra-high performance liquid chromatography. Type of conserved forage for sheep feeding did not affect the variables studied, which is of great interest because hay and silage are low-cost ingredients for sheep feeding. Proteolysis led total free AA concentrations ranging between 35,179.26 and 138,063.71 mg/kg of cheese at 180 d of ripening. γ-Aminobutyric acid, which has been associated with beneficial effects on human health, was the second most abundant AA in all cheese samples, accounting for 15% of total free AA. Spring cheeses showed 2-fold higher concentrations of γ-aminobutyric acid than summer and autumn cheeses at the end of ripening. Overall, spring, winter, and autumn cheeses had lower average concentration of biogenic amines (431.99 mg/kg of cheese) than summer cheeses (825.70 mg/kg of cheese) as well as better sensory characteristics. Therefore, this study could provide the dairy industry with useful information for producing cheeses with valuable nutritional and sensory quality for consumers.