粮油食品防霉微生物筛选及其活性物质初步研究

为开发新型防霉剂,降低粮油食品储藏、运输、流通等过程中霉变对其品质和食用安全的影响,研究筛选获得具有强防霉活性的微生物。采用抑菌圈法,以禾谷镰刀菌（Fusarium graminearum）为指示菌筛选具有防霉活性的菌株。利用形态学观察、生化特征鉴定和16S rDNA基因序列比对进行菌株鉴定;通过不同温度、pH和蛋白酶K处理对防霉活性物质进行初步分析。结果显示：通过初筛获得33株对禾谷镰刀菌具有强抑制活性的菌株,复筛后选择的7株菌归属为芽孢杆菌属（Bacillus）;活性物质分析发现7株菌的活性物质均不耐高温和强酸碱,同时蛋白酶K处理对其防霉效果没有明显影响,初步推断为肽类;通过抑菌谱测定发现菌株ASAG 62对常见霉菌（产黄青霉Penicillium flavum、黑曲霉Aspergillus Niger、赭曲霉Aspergillus ochre、黄曲霉Aspergillus flavus、禾谷镰刀菌F. graminearum）均具有良好的抑制效果。     

Osteogenic effects of the peptide fraction derived from pepsin-hydrolyzed bovine lactoferrin

Osteoporosis is a common disease that frequently occurs in the older population, particularly in postmenopausal women. It severely compromises the health of the older population, and the drugs commonly used to treat osteoporosis have a variety of adverse effects. Lactoferrin (LF) is a protein present in milk that has recently been found to exhibit osteogenic activity. Lactoferrin is nontoxic and harmless, suggesting that it may have excellent biocompatibility and tolerability after human consumption. Oral consumption of LF in an ovariectomized rat model has been found to ameliorate osteoporosis. However, the mechanism underlying this effect remains to be clarified. In this study, bovine LF (bLF) was first hydrolyzed by pepsin for 1 h, and the hydrolyzed mixture was freeze-dried and collected. The hydrolyzed mixture was then separated into 5 components (E1–E5), of which E3 had the greatest effect in promoting proliferation of osteoblasts (MC3T3-E1). Component E3 was further isolated into 21 components with preparative reversed phase HPLC, and the E3-15 component had maximal bioactivity. With HPLC-mass spectrometry and peptide sequencing, E3-15 was identified to contain amino acids 97 to 208 from the bLF N terminus. Then, E3-15 was divided into 6 different peptide segments (P1–P6), and the corresponding segments were generated by solid-phase synthesis. Only the P1 peptide (amino acids 97–122 from the N terminus of bLF) significantly promoted osteoblast proliferation. The bioactivity of P1 toward osteoblast cells and alkaline phosphatase activity were tested as a function of P1 concentration, and a nonlinear effect was observed.     

Kefir peptides exhibit antidepressant-like activity in mice through the BDNF/TrkB pathway

Depression is a prevalent, stress-related mental disorder that can lead to serious psychiatric diseases with morbidity and high mortality. Although some functional fermented dairy drinks have promising anxiolytic and antidepressant effects, the mechanism is still not clear. To determine the antidepressant-like effect and the potential molecule mechanism of kefir peptides (KP), various behavioral tests, including the elevated plus maze test, open field test, forced swimming test, and tail suspension test, were used. Administration of 150 mg/kg KP in mice reduced the duration of immobility in the forced swimming test and tail suspension test, elevated the time spent in the open arm and center zone in the elevated plus maze test, and increased the total distance traveled, average speed, and time spent in the center zone in the open field test compared with the mock group. These results indicated that KP dramatically ameliorated the depression-like behaviors. Kefir peptides were further isolated and identified using high-performance liquid chromatography and liquid chromatography–tandem mass spectrometry, from which 3 peptides were identified and designated KFP-1, KFP-3, and KFP-5. Among these peptides, administration of KFP-3 (15 AA residues) remarkably decreased immobility time in the forced swimming test and increased mobility time in the tail suspension test. Therefore, KFP-3 may be the major active peptide with antidepressant activity in KP. Overexpression of brain-derived neurotrophic factor, phosphorylated tropomyosin receptor kinase B, and phosphorylated ERK1/2 protein levels could be detected in the hippocampus under KP administration. Therefore, we suggest that KP improves depressive-like behaviors by activating the brain-derived neurotrophic factor–phosphorylated tropomyosin receptor kinase B signaling pathway. Kefir peptides may serve as a new type of antidepressant dairy product and may provide potent antidepressant effects for clinical use.     

牛肉酶解工艺及其产物的研究进展

常用于水解牛肉的酶有木瓜蛋白酶、动物蛋白水解复合酶、风味复合酶等,本文总结了蛋白酶水解牛肉的工艺以及酶法水解牛肉的研究现状,归纳了牛肉酶解的3种工艺方法:单酶水解、多酶复合水解和多酶分步水解。结果表明:牛肉经过酶解释放出氨基酸或形成多肽,更利于人体消化吸收,并且具有一定的生物活性,牛肉酶解工艺在肉制品行业中有广阔的发展前景。     

发酵芝麻粕小肽体内抗氧化和免疫活性

研究从发酵芝麻粕中提取分离出的小肽体内抗氧化和免疫活性。将56 只4 周龄健康昆明小鼠随机分成7 组,分别灌胃生理盐水,低、中、高3 个剂量的小肽（三肽和四肽）,连续灌胃28 d后取血,测定肝脏、脾脏、胸腺系数,血清中丙二醛含量,肝匀浆中的丙二醛含量、超氧化物歧化酶与谷胱甘肽过氧化物酶的活性,脾脏中T淋巴细胞CD3＋、CD4＋和CD8＋数量。灌胃发酵芝麻粕三肽和四肽后,血清和肝脏中丙二醛含量显著下降（P＜0.05）,肝脏中超氧化物歧化酶和谷胱甘肽过氧化物酶活性显著升高（P＜0.05）,四肽高剂量组小鼠的CD4＋/CD8＋值显著升高（P＜0.05）。结果表明发酵芝麻粕三肽和四肽均具有体内抗氧化能力,四肽在本实验设定中的高剂量条件下能在一定程度上增强机体的免疫活性。     

酶法制备小分子大豆肽的蛋白酶筛选以及酶解条件优化

本研究对制备小分子大豆肽的蛋白酶进行筛选,并对酶解条件进行优化。综合考虑酶量对产物的水解度、平均分子量及游离氨基酸的影响,确定酶解的最佳条件为:温度55℃,pH值8.5,底物浓度为10%,分别加入1.5%的木瓜蛋白酶、菠萝蛋白酶、无花果蛋白酶和3942中性蛋白酶,调pH值至4.5,再分别加入2.5%的Fromase真菌蛋白酶和537酸性蛋白酶。结果显示,多酶复合水解可提高蛋白质降解率,并尽可能降低多肽的相对分子质量。     

安徽省SMV株系的鉴定及其抗源筛选

为明确安徽省大豆花叶病毒（soybean mosaic virus,SMV）株系的最新组成、分布及消长动态,以及筛选对流行株系的抗性种质,2009-2010年广泛采集安徽省各大豆主产区疑似SMV病样461份,采用生物学及血清学方法鉴定得到83个SMV分离物。用全国统一的10个鉴别寄主对这些分离物进行鉴定,共鉴定出14个SMV株系,如SC3~SC9、SC11、SC13~SC15、SC17、SC19和SC22,其中SC5、SC11、SC14、SC15、SC17、SC19和SC22是本研究在大豆主产区新发现的。进一步比较分析发现,SMV株系SC3和SC7仍为目前安徽省大豆产区的流行株系,分别占分离物总数的16.9%和25.3%;其次为新发现的强毒株系SC15,在安徽省也有较为广泛的分布,比率为12.1%。针对流行株系SC3和SC7的抗源筛选结果表明,来自参加安徽省区试的149份资源中有中作J8023、中黄45、L85-2308、中涡47号和濉科13等5份材料对SC3表现高抗,中黄45、宿03-4-1-4和鲁06-7等9份材料对SC7表现高抗;参加我国南方区试的95份种质资源中有13份对强毒株系SC15表现抗病,占鉴定品种的13.7%。本研究明确了安徽省大豆产区的流行株系及变化趋势,筛选出针对SMV流行株系的抗源,为培育抗病品种和抗病品种布局提供了依据。     

多环境大豆种子维生素E含量遗传分析

利用高效液相色谱测定了三个地点的大豆品种合丰25与Bayfield及其衍生的144个重组自交系种子中的维生素E含量,运用主基因＋多基因混合遗传模型,对三个地点的大豆种子的维生素E进行了遗传分析。结果表明：在哈尔滨地区α-生育酚为2对主基因＋多基因遗传模型;γ-生育酚为1对主基因＋多基因遗传模型;δ-生育酚为2对主基因＋多基因遗传模型;在呼兰地区α-生育酚为3对主基因＋多基因遗传模型;γ-生育酚为2对主基因＋多基因遗传模型;δ-生育酚为2对主基因＋多基因遗传模型;在绥化地区α-生育酚为无主基因＋多基因遗传模型;γ-生育酚为3对主基因＋多基因遗传模型;δ-生育酚为2对主基因＋多基因遗传模型。     

大豆粗脂肪酸值检测方法的改进

以大豆粗脂肪酸值检测方法为研究对象,对GB/T 14488.1-2008《植物油料含油量测定》与GB/T 5530-2005的标准测定方法进行改进,减少称量步骤、缩短抽提时间,以提高检测效率。试验结果表明:改进后的大豆粗脂肪酸值检测方法在保证检测结果准确性的前提下,可大幅缩短检测时间,提升检测效率。