A combined procedure to evaluate the global antioxidant response of bread

Baking is the most representative manufacturing process applied to bread, involving thermal and moisture conditions that facilitate the Maillard reaction (MR) and, at the same time, the destruction-formation of natural-labile and thermally-induced antioxidant compounds respectively. In the present paper, the use of a new approach to measure the Global Antioxidant Response (GAR) of cereal derivatives is proposed: a combination of in vitro digestion – which enables measurement of the bioaccessible fraction – and the QUENCHER, which makes it possible to determine the antioxidant activity of the insoluble fraction, since it is a simple and direct procedure for determining the total antioxidant capacity of solid products. After digestion, the results obtained by the antioxidant assays are up to 20-fold higher than those reported using the standard extraction methods. The non-extractable residue displayed significant antioxidant activity that accounted for up to 17% of the total antioxidant activity. Moreover, the GAR obtained in some of the assays developed was 10–40% higher than the antioxidant activity registered by the QUENCHER procedure in wheat bread, and the difference was even higher in wheat bran bread. Therefore, the use of the GAR approach could avoid underestimation of the antioxidant activity of cereal derivatives.     

Amylolysis of wheat starches. I. Digestion kinetics of starches with varying functional properties

The susceptibility of wheat (Triticum aestivum L.) starches to hydrolysis by pancreatic α-amylase in vitro was investigated using a series of 35 starches with slightly enriched amylose content within a narrow range (36–43%), but widely differing functional properties. After 2 h of incubation with α-amylase, native starch granules were digested to different extents, but there were no differences between any of the starches once they were gelatinized. Cooling the starch for 72 h at 4 °C after cooking reduced the susceptibility of all of the starches to enzymic digestion by a similar extent, whereas addition of monopalmitin decreased the digestibility of the starches that contained amylose, but did not affect the digestibility of waxy starches that were also included in the study. Amylopectin chain length distribution of partly digested starch granules displayed increased proportion of short and medium chains and decreased proportion of long chains in comparison to native granules. Separated large (A) and small (B) starch granules from three of the starches differed significantly in their susceptibility to in-vitro digestion. A predictive model of the susceptibility of starch in the different forms was developed from the physico-chemical and functional properties of the starches.     

测定小麦籽粒中全磷含量的2种消解方法比较

在小麦籽粒全磷含量测定中,比较了电炉法和消煮炉法消解样品的效果,结果表明:2种方法的消解效果一致,但消煮炉法比电炉法更方便。     

同时测定海产品中砷和汞方法的优化

建立微波消解—氢化物发生原子荧光光谱法同时测定海产品中砷、汞的方法,并对仪器工作参数及条件进行了优化和选择。砷和汞的质量浓度分别在0～10ng/mL和0～2.0ng/mL线性良好,相关系数分别为0.9995和0.9996;砷和汞的检出限分别为0.06ng/mL和0.05ng/mL,变异系数分别为0.58%和1.36%,砷和汞回收率分别为89.40%～103.3%和84.55%～93.01%。应用该方法分析海产品中砷和汞含量是可行的。     

小麦中重金属镉测定的分析与研究

石墨炉原子吸收光谱法由于灵敏度高,检出限低,自动化程度高,被广泛用于重金属元素的分析检测。利用干法灰化法对小麦样品进行前处理,石墨炉原子吸收光谱法检测,探讨仪器分析最佳试验条件。该方法检测结果表明,相对标准偏差为0.20%,加标回收率为82.0%～99.5%。     

蛋白水平对舍饲辽宁绒山羊产绒性能及消化代谢的影响

为探索舍饲辽宁绒山羊对蛋白质的营养需要,采用单因子试验方法,选取辽宁绒山羊2周岁母羊15只,随机分为3组,每组5只,研究日粮不同蛋白水平(9.26%、10.06%、11.02%)对辽宁绒山羊产绒性能及消化代谢的影响。结果表明:日粮蛋白水平对辽宁绒山羊产绒性能无显著影响(P0.05),日粮蛋白水平达到9.26%时,就能满足辽宁绒山羊山羊绒生长需要,日粮蛋白水平为10.06%,产绒量最高,为453.2 g,羊绒长度和绒层厚度也最高,羊绒细度最细,分别为5.72,5.31 cm和15.26μm,但各组间差异不显著(P0.05),可能是由于绒山羊个体间差异所致;日粮蛋白水平11.02%组,尿氮、可消化氮、沉积氮、氮表观沉积率均最大,分别为3.13,8.07,4.94 g/d和43.94%,均显著高于蛋白水平9.26%组和10.06%组(P0.05),粪氮最小,为3.17 g/d,显著低于其余2组。从氮平衡来看,3组均为正平衡,能够不同程度地促进山羊绒的生长;日粮蛋白水平对粗纤维消化率无显著影响(P0.05);日粮蛋白水平对能量消化代谢无显著影响(P0.05)。配制辽宁绒山羊日粮,粗蛋白水平以11.02%为宜。     

口服福尔马林对羔羊消化代谢与生长的影响

将8只30日龄、体重(6.9±1.0)kg的小尾寒羊×无角陶赛特母羔羊随机分为2组(每组4只),以研究口服福尔马林对羔羊自由采食、消化代谢、屠宰性能和甲醛残留的影响。结果表明,在55～80、95～120和125～150日龄3个日龄段,对照组羔羊的干物质采食量分别为(567.3±27.5)、(752.4±9.01)和(1044.1±30.8)g/(d.头),口服福尔马林组分别增加22.02%(P0.01)、28.75%(P0.01)和41.79%(P0.01);对照组羔羊的氮保留分别为(12.3±0.8)、(13.6±0.2)和(18.0±0.6)g/(d.头),口服福尔马林组分别增加25.20%(P0.01)、41.91%(P0.01)和46.11%(P0.01);对照组羔羊的日增重分别为(157.1±11.7)、(246.4±24.4)和(250.0±8.3)g/(d.头),口服福尔马林组分别增加18.20%(P0.05)、23.21%(P0.05)和27.16%(P0.01);而两组间的日粮消化率无显著差异。240日龄对照组和口服福尔马林组羔羊的胴体重分别为(20.37±1.78)和(24.55±1.14)kg/头(P0.01),屠宰率分别为48.59%±1.08%和50.46%±1.02%(P0.05),瘦肉率分别为65.22%±1.57%和64.84%±1.11%(P0.05)。羔羊血液、肌肉、肾脏、肝脏、瘤胃组织和小肠组织中的甲醛含量对照组分别为(1.84±0.44)mg/L、(0.35±0.26)mg/kg、(1.10±0.67)mg/kg、(0.74±0.34)mg/kg、(0.91±0.72)mg/kg和(0.79±0.41)mg/kg,在试验组分别为(1.47±0.61)mg/L、(0.54±0.34)mg/kg、(1.65±0.71)mg/kg、(0.91±0.38)mg/kg、(2.03±0.71)mg/L和(0.85±0.42)mg/L。因此,口服福尔马林可增加羔羊的自由采食量而不影响消化率,提高羔羊对日粮的消化量和羔羊日增重;以上这种作用随羔羊的日龄增加而增强;口服福尔马林提高羔羊的胴体重、屠宰率,但不影响胴体的瘦肉率;长期口服福尔马林羔羊的组织器官中甲醛的含量低于2.0 mg/kg。     

土壤中重金属元素统一制备液测试方法的研究

针对目前不能同时检测土壤中总镉、总铬、总铅、总汞、总砷、总铜、总锌和总镍等现状,本试验通过对样品前处理、消解方法及消解条件的选择及优化,探索出一套可以同时消解和测定8种重金属元素检测方法,此方法具有操作简便、快速、准确、干扰少等优点,适用于大批土壤样品的测定,可提高土壤中重金属检测效率。     

基于线粒体序列特征的茶树菇及杨柳田头菇分离物快速鉴定

此试验拟探寻特异的DNA序列,快速鉴定茶树菇（Agrocybe aegerita）及其形态上易混淆种,给种质资源收集及利用提供有效工具。本研究以云南采集到的18个菌株为材料,其中5株为A. aegerita,13个为A. salicacola,并对线粒体小亚基V9区进行序列分析。结果发现A. aegerita比A. salicacola多1个约50碱基的插入片段,而其他序列组成一致。根据此特点,在插入区筛选到1个特异DraⅠ酶切位点。通过对18个菌株V9区PCR产物进行酶切,发现A. aegeritaV9片段能完全被切开,而A. salicacola V9片段则为完整。根据此酶切方法,可以高效鉴定A. aegerita及A. salicacola 2个近似种,为食用菌遗传及育种研究提供了重要的基础。     

环境光色对工业化养殖豹纹鳃棘鲈幼鱼生长、肤色及生理指标的影响

为探究环境光色对工业化养殖豹纹鳃棘鲈(Plectropomus leopardus)幼鱼生长、肤色和生理指标的影响,本试验设计了红色光、蓝色光、黑暗和昼夜4种养殖光照环境处理,进行豹纹鳃棘鲈幼鱼(64.2g±1.1g)94 d动物实验及其相关指标检测。结果表明:1)试验鱼增重率,昼夜组较黑暗组和红光组分别显著和极显著提高28.6%和39.2%(P0.05,P0.01),与蓝光组差异不显著;而蓝光组比红光组显著提高31.2%(P0.05)。2)试验鱼皮肤胡萝卜素含量,昼夜组分别显著高于蓝光组和黑暗组45.7%和68.5%(P0.05),与红光组的差异不显著。同时新发现,各处理组试验鱼皮肤胡萝卜素和黑色素含量出现增减同时进行,但增减量前者较大后者较小的"同步异幅"现象。3)昼夜组试验鱼胃蛋白酶活性较其他组显著提高48.0%~88.5%(P0.05),血清SOD和LZM活力极显著提高20.4%~39.7%和140.4%~161.2%(P0.01);蓝光组试验鱼胰蛋白酶活力显著高于红光组和昼夜组(P0.05);红光组试验鱼Na~+,K~+-ATP酶活力极显著高于蓝光组和黑暗组(P0.01)。总之,豹纹鳃棘鲈幼鱼在昼夜组光照下,生长、肤色及生理等指标都表现出显著优势;蓝色光提高蛋白质消化能力、促进生长;红色光提高皮肤胡萝卜素含量和吸收能力;"同步异幅"新发现,对调控和优化鱼类肤色具有重要价值。