Predicting beef tenderness using color and multispectral image texture features

The objective of this study was to investigate the usefulness of raw meat surface characteristics (texture) in predicting cooked beef tenderness. Color and multispectral texture features, including 4 different wavelengths and 217 image texture features, were extracted from 2 laboratory-based multispectral camera imaging systems. Steaks were segregated into tough and tender classification groups based on Warner-Bratzler shear force. The texture features were submitted to STEPWISE multiple regression and support vector machine (SVM) analyses to establish prediction models for beef tenderness. A subsample (80%) of tender or tough classified steaks were used to train models which were then validated on the remaining (20%) test steaks. For color images, the SVM model correctly identified tender steaks with 100% accurately while the STEPWISE equation identified 94.9% of the tender steaks correctly. For multispectral images, the SVM model predicted 91% and STEPWISE predicted 87% average accuracy of beef tender.     

内切壳聚糖酶在食品级壳寡糖酶法生产中的应用

研究1株曲霉JXSD-01发酵液中内切壳聚糖酶(eCSN)的纯化与功能,以寻求一种清洁的生产不含单糖的壳寡糖的方法。经分析,不含外切酶活性的eCSN蛋白酶比活力＞50U/mg,分子质量为25kD,酶的最适温度为63℃,最适pH6.5。经N末端测序,内切壳聚糖酶的N端序列为YNLPNNLKQ。eCSN用于天然大分子壳聚糖的生物降解,可获得分子质量在1000～3500D的寡糖聚合物,其中无单糖污染,达到国际食品级壳寡糖质量标准。     

产L－乳酸的菌种的筛选及L－乳酸生产新途径

本实验以大豆秸秆酶解液为原料,发酵制备L- 乳酸。首先对产L- 乳酸的四株菌进行筛选,选出性能优良、糖利用率和乳酸产量均较高的干酪乳杆菌作为实验用菌种。然后对乳酸菌发酵大豆秸秆酶解液制备L- 乳酸的影响因素进行了研究,研究结果表明：干酪乳杆菌发酵的最佳接种量为10%,最适发酵温度为30℃,最佳pH 值为5.5;在发酵42h 时,大豆秸秆酶解液中残留糖浓度接近于零,此时,随底物浓度的增高,乳酸产量相应增加,并且酶解液浓度达到34.98g/L 时,乳酸生产没有受到抑制。     

Formation of acrylamide at temperatures lower than 100°C: the case of prunes and a model study

Acrylamide concentrations in prune products--baby strained prunes (range = 75-265 μg kg(-1)), baby apple/prune juice (33-61 μg kg(-1)), prune juice (186-916 μg kg(-1)) and prunes (58-332 μg kg(-1))--on the Canadian market were determined. The formation of acrylamide in a simulated plum juice was also investigated under 'drying conditions' in an open vessel at temperatures <100°C for 24 h and under 'wet conditions' in a closed vessel at a temperature of 120°C for 1 h. Acrylamide was produced in a simulated plum juice under 'drying conditions' in amounts comparable with those found in prunes and prune juices. Acrylamide was not produced in simulated plum juice under 'wet conditions' in a closed vessel at temperature of 120°C for 1 h, but under the same condition an authentic prune juice doubled its acrylamide concentration. Formation of acrylamide in prune products was attributed to the presence of asparagine and sugars in the starting materials.     

In vitro batch fecal fermentation comparison of gas and short-chain fatty acid production using "slowly fermentable" dietary fibers

Abstract: Sustained colonic fermentation supplies beneficial fermentative by‐products to the distal colon, which is particularly prone to intestinal ailments. Blunted/delayed initial fermentation may also lead to less bloating. Previously, we reported that starch‐entrapped alginate‐based microspheres act as a slowly fermenting dietary fiber. This material was used in the present study to provide a benchmark to compare to other “slowly fermentable” fibers. Dietary fibers with previous reports of slow fermentation, namely, long‐chain inulin, psyllium, alkali‐soluble corn bran arabinoxylan, and long‐chain β‐glucan, as well as starch‐entrapped microspheres were subjected to in vitro upper gastrointestinal digestion and human fecal fermentation and measured over 48 h for pH, gas, and short‐chain fatty acids (SCFA). The resistant fraction of cooked and cooled potato starch was used as another form of fermentable starch and fructooligosaccharides (FOS) served as a fast fermenting control. Corn bran arabinoxylan and long‐chain β‐glucan initially appeared slower fermenting with comparatively low gas and SCFA production, but later fermented rapidly with little remaining in the final half of the fermentation period. Long‐chain inulin and psyllium had slow and moderate, but incomplete, fermentation. The resistant fraction of cooked and cooled potato starch fermented rapidly and appeared similar to FOS. In conclusion, compared to the benchmark slowly fermentable starch‐entrapped microspheres, a number of the purported slowly fermentable fibers fermented fairly rapidly overall and, of this group, only the starch‐entrapped microspheres appreciably fermented in the second half of the fermentation period. Practical Application: Consumption of dietary fibers, particularly commercial prebiotics, leads to uncomfortable feelings of bloating and flatulence due to their rapid degradation in our large intestine. This article employs claimed potential slowly fermenting fibers and compares their fermentation rates with a benchmark slow fermenting fiber that we fabricated in an in vitro simulation of the human digestive system. Results show a variety of fermentation profiles only some of which have slow and extended rate of fermentation.     

基于Pro/E的不规则钣金展开件的优化排样

介绍了遗传算法以及基于Pro/E的不规则形状钣金展开件的计算机优化排样,研究了排样中如何建立遗传算法的目标函数,如何实现编码、排样等优化过程,找到了运用遗传算法实现不规则形状钣金展开件优化排样的方法.     

用于复合材料风力机叶片的端对端解决方案

随着叶片长度的增加,为避免疲劳载荷引起的裂纹和降低制造成本,叶片需要更高的刚度和更轻的重量。目前开发过程主要是以2D为基础,依靠各种类型的工具,它们不符合设计更大叶片的质量和刚度要求。此外,这些工具在制造工艺中未考虑最后的工程技术改变。在这种情况下,风力机制造商正在寻找创新的开发方案——尤其是针对叶片结构、设计、模拟和制造——这些方案将帮助他们满足这些要求,并在没有缺陷的情况下获得更长的使用寿命。     

2,4-二羟基-二苯甲酮改水性聚氨酯的 制备与性能

以异佛尔酮二异氰酸酯(IPDI)、聚己内酯二元醇(PCL1000)、三羟甲基丙烷(TMP)、二羟甲基丙酸(DMPA)和2,4-二羟基二苯甲酮(UV-0)为原料,采用阴离子自乳化法制备了一系列具有紫外吸收性能的水性聚氨酯乳液(UVWPU)。利用FTIR、UV-Vis、XRD、PSA、拉伸测试、TGA对聚合物的结构与性能进行了表征和测试。结果表明:2,4-二羟基二苯甲酮质量分数为2%时,乳液UVWPU2粒径为109.6 nm且分布均匀;与纯水性聚氨酯(WPU)乳液相比,UVWPU2乳液的紫外光吸光度提高了0.53。UVWPU2胶膜具有良好的热稳定性,最大分解温度达到318.27℃,拉伸强度达到48.1 MPa。     

CO2/N2在HP-MOF-74(ZnxNi1-x)上的吸附性能探究

以SDBS为模板剂,采用水热合成法制备了不同比例的双金属HP-MOF-74(Zn_xNi_1-x)材料,利用XRD、FT-IR、SEM等对其物化性能进行了研究;以烟道气CO₂和N₂为吸附质,使用静态容量法在273 K和298 K处测试了三种不同HP-MOF-74(Zn_xNi_1-x)材料上CO₂和N₂的等温线;根据理想吸附溶液理论(IAST)估算了CO₂/N₂二元混合物的吸附选择性;此外,使用克-克方程计算了等量吸附热(QST)。     

环氧复合材料模具材料

正德国巴德乌拉(Bad Urach)的Sika Deutschland GmbH公司推出了Biresin CR132 ST和Biresin CR136两种环氧树脂体系,可用于复合材料模具。Biresin CR132 ST是一种糊状环氧树脂体系,用于连接胶衣和铺层第一层,据报道它最少印透第一层织物。Biresin CR136是一种填充型环氧树脂体系,据报道用于对由蒸汽、油或其他液体加热的模具区域的热流进行疏