2-取代-1，3-硫杂环戊烷香料的合成和香气评价

以醛／酮与1，2-乙二硫醇或1，2-丙二硫醇在对甲苯磺酸催化下反应，合成了10种2-取代-1，3-二硫杂环戊烷，产率62．8％～87．8％；其中，2-正丙基-1，3-二硫杂环戊烷产率达87．8％，纯度99．5％。经元素分析、FTIR、GC-MS和’HNMR确定了10种产物的结构。香气评价结果表明：合成的2-正丙基-1，3-二硫杂环戊烷具有花香、肉汤香气，可用于食品香精和调味料中；其余9种2-取代-1，3-二硫杂环戊烷具有肉香、葱蒜香和萝卜香。     

2-甲基-1,3-二硫环庚烷的合成及香气研究

以硫代硫酸钠、1，4-二氯丁烷和乙醛为原料，用BunteSalts法，经过一步操作合成了2-甲基-1，3-二硫环庚烷，其收率为42％。实验表明，当1，4-二氯丁烷与硫代硫酸钠以等摩尔投料时，可减少盐酸用量，并能避免单质硫的析出而影响分离提纯。用IR、1HNMR、MS证实了目标化合物结构，并对2-甲基-1，3-二硫环庚烷的香气进行了鉴定，结果表明2-甲基-1，3-二硫环庚烷具有浓郁的葱蒜气味，其阚值在水中为0．19ppm，在植物油中为12．90ppm。     

低含量3-氯-1,2-丙二醇的水解植物蛋白生产工艺优化

本文研究了在低酸、低温条件下植物蛋白的优化水解工艺，此工艺旨在降低水解蛋白中的氯丙醇类物质。研究确定：在98℃左右、固液比1：5、盐酸浓度4mol／L、水解18h所得水解蛋白中3-氯-1，2．丙二醇含量为1．25mg/kg，仅是常规酸法的5％。进一步进行碱中和与减压浓缩处理，可使3-氯-丙二醇残留大幅降低。     

1-萘胺和2-萘胺的快速分析

在现行检测标准条件下，2-萘胺和1-萘胺的气相色谱保留时间相近，且质谱图完全相同，所以，1-萘胺会对2-萘胺的检测造成干扰。将氨基完全甲基化后，虽然质谱图仍然相同，但色谱保留时间明显不同，可以利用保留时间定性。以萘为内标，GC-FID定量检测，1-萘胺转化率为85．3％，2-萘胺转化率为76．1％，甲基化后响应值和稳定性都增加，还可以进行外标法定量。     

超高效液相色谱法快速测定纺织品中的1-萘胺和2-萘胺

采用超高效液相色谱技术对纺织品中1-萘胺和2-萘胺进行了分离测定,建立了纺织品中1-萘胺和2-萘胺的高效液相色谱测定方法。试验结果表明,该方法线性范围为0．1～50mg／L,回收率为93．53％～101．95％,精密度为1．10％～2．50％,在5／N=3的条件下,检出限为0．01mg／L。该方法能解决禁用偶氮染料测试中2-萘胺的假阳性结果问题。     

4-甲基-4-烷硫基-2-戊酮类化合物的合成研究

对4-甲基-4-烷硫基-2-戊酮类化合物的合成与香气特征进行了研究。具体方法是:在四氢呋喃溶剂中,4-甲基-3-戊烯-2-酮与各种硫醇在哌啶的催化作用下回流反应20h,得到5种4-甲基-4-烷硫基-2-戊酮类新型食用香料化合物,产率40.3%～65.1%,其中烷硫基分别为乙硫基、丙硫基、丁硫基、己硫基、糠硫基。4-甲基-3-戊烯-2-酮是通过丙酮醇在碘催化剂作用下加热脱水制取的。采用IR、GC-MS、1HNMR分析并确证了上述合成化合物的结构,并对其香气特征进行了描述,它们可能是潜在的食用香料。     

废水中S^2-含量的间接光度法测定

在弱酸性(醋酸-醋酸钠缓冲溶液，pH值4．0)介质中，Cu^2 与废水中的S^2-发生完全定量化学反应，过量的Cu^2 与1-(2-吡啶偶氮)-2-萘酚形成稳定的配合物，用光度法检出，从而实现工业废水中S^2-的间接测定。该配合物在λmax-552m处有最大吸收。用于测定废水中的S^2-含量，回收率为98．7％～101.0％，灵敏度和选择性都能达到要求。     

2-萘胺和1-萘胺的鉴别

为实现2萘胺和1-萘胺的完全分离，采用气相色谱-质谱联用方法，通过改进色谱条件取得了理想的结果。试验结果表明，采用气-质联用方法可以将2-萘胺和1-萘胺的完全分离。     

2-氯-1-氟-4-硝基苯的相转移催化合成研究

采用重结晶方法制备了高活性的KF.在相转移催化剂十六烷基三甲基溴化铵(CTAB)存在条件下,以1,2-二氯-4-硝基苯(DCNB)为原料,氟氯置换法合成2-氯-1-氟-4-硝基苯(FCNB).正交试验确定的最佳相转移催化氟化工艺条件为:n(KF):n(DCNB)=1.20～1.25;n(CTAB):n(DCNB)=0.06～0.07;温度140 ℃～150 ℃;搅拌速度900 r/min～950 r/min;时间12 h.在此条件下,FCNB收率可达92.23%.     

面包酵母催化溶剂相不对称还原合成(R)-2-羟基-4-苯基丁酸乙酯

研究有机溶剂中面包酵母催化2-氧代-4-苯基丁酸乙酯（OPBE）不对称还原合成（R）-2-羟基-4-苯基丁酸乙酯（（R）-HPBE），分别考察有机溶剂种类、初始水含量、初始底物浓度、缓冲液pH值和添加剂等因素对OPBE转化率（COPBE）、HPBE产率（YHPBE）及（R）-HPBE的光学纯度（ee％）的影响。实验结果表明，乙醚为适宜反应介质，适宜pH为中性；反应初始水含量和初始底物浓度分别以ω（H2O）=30g／L、c（OPBE）=5mmol／L为佳。添加α-氯代苯乙酮（α—PC）对酵母预处理2h后，（R）-HPBE的PP从35．52％提高为82．25％，COPBE和YHPBE分别从75．29％和46．02％提高到98．51％和75．82％。     

Practical production of (S)-1,2-propanediol and its derivative through baker's yeast-mediated reduction

The enantiomeric excess (ee) of (S)-1,2-propanediol produced by baker's yeast-mediated reduction of 1-acetoxy-2-propanone was improved to 96% ee by a fed-batch operation of the substrate. A similar reduction of 1-benzoyloxy-2-propanone stopped because of the inhibition toward the enzymes for NADPH regeneration by the reduction product. The inhibition was prevented using resin that adsorbs the product from the reaction mixture, and 70 g/l substrate was reduced yielding (S)-1-benzoyloxy-2-propanol at > 99% ee.     

烤羊腿挥发性香成分分析

同时蒸馏萃取/气-质联机从烤羊腿中分析鉴定出33种香成分。含量较高成分依次为:糠醛、5-甲基糠醛、丁香酚、己醛、糠醇、糠硫醇、2,5,6-三甲基-1,3-氧硫杂环己烷、3-甲基丁醛、2-乙酰基-5-甲基-呋喃、壬醛、1-羟基-2-丙酮、2,5-二甲基苯酚、乙基麦芽酚。总结归纳所鉴定香成分,发现烤羊腿的香气主要由具有肉香香气成分、油脂香香气成分、烤香香气成分、烟熏香香气成分、酸败气、奶酪香气成分和茴香香气成分构成。     

硅胶负载硫酸铁催化合成2-庚基-1,3-二噁戊烷

以正辛醛和乙二醇为原料,以硅胶负载硫酸铁[Fe2(SO4)3/SiO2]为催化剂,合成了2-庚基-1,3-二噁戊烷,考察了醛醇摩尔配比、反应时间、催化剂用量及其稳定性对产率的影响。实验表明,硅胶负载硫酸铁是合成2-庚基-1,3-二噁戊烷的理想催化剂,较优反应条件为正辛醛0.1mol、n(正辛醛)/n(乙二醇)=1.0/1.2(mol/mol)、催化剂的用量为反应物总质量的2.0%、带水剂环己烷12mL、回流反应4.0h,2-庚基-1,3-二噁戊烷的产率可达92.0%以上。     

云南6种食用菌中维生素B1和B2的含量调查

目的 调查分析云南省6种食用菌中维生素B1和B2的含量。方法 定点采集云南省6种常见新鲜食用菌, 按GB 5009.84-2016《食品安全国家标准 食品中维生素B1的测定》和GB 5009.85-2016《食品安全国家标准 食品中维生素B2的测定》, 用高效液相色谱法测定样品中的维生素B1和B2的含量。结果 6种常见新鲜食用菌中维生素B1的含量平均值最高的是虎掌菌0.0812 mg/100 g, 最低的是干巴菌为0.0298 mg/100 g; 维生素B2含量平均值最高的是干巴菌为0.587 mg/100 g, 平均值最低的是人工种植的羊肚菌为0.0510 mg/100 g。 结论 人工种植和野生的食用菌均含有一定量的维生素B1和B2, 具有一定的营养价值。     

Purification and characterization of 2-aminoacetophenone reductase of newly isolated Burkholderia sp. YT

We found that a newly isolated Burkholderia sp. produced (R)-2-amino-1-phenylethanol from 2-aminoacetophenone, showing the high stereospecificity. NADPH-dependent 2-aminoacetophenone reductase purified to homogeneity was a dimer with a molecular mass of 65,000. The purified enzyme did not reduce acetophenone and 1-phenyl-1-propanone. The purified enzyme converted 2-aminoacetophenone to only (R)-2-amino-1-phenylethanol.     

Production and physicochemical properties of 2-octen-1-ylsuccinic derivatives from waxy corn starch

Waxy corn starch was esterified with 2-octen-1-ylsuccinic anhydride (OSA) using response surface methodology. The molecular structure and paste properties were also investigated. Results indicated that the optimum parameters for esterification were as follows: reaction period 4 h, temperature 36.7 °C, pH of reaction system 8.3, concentration of starch slurry 36.9%, and amount of OSA 3%. The degree of substitution was 0.0187 and the reaction efficiency was 80.6%. The ester carbonyl group in OSA starch was characterized by Fourier Transform Infrared Spectroscopy at 1723 cm(-1). Compared with native starch, OSA derivative had higher peak viscosity, better freeze-thaw stability, and decreased gelatinization temperature and digestibility by porcine pancreatic alpha-amylase. Scanning electron microscopy showed that the gels from OSA starch had less and smaller pores; however, the native starch gels changed to sponge-like structure after 4 freezing/thawing cycles. The OSA modified waxy corn starch offered a potential to be used in frozen foods. PRACTICAL APPLICATION: (a) To optimize operating conditions to achieve OSA modified waxy corn starch with a high degree of substitution; (b) to give a deeper insight into the physicochemical properties of OSA modified waxy corn starch, which offered a potential to be used in frozen foods.     

Yeast PIG Genes: PIG1 Encodes a Putative Type 1 Phosphatase Subunit that Interacts with the Yeast Glycogen Synthase Gsy2p

The biosynthesis of glycogen involves multiple proteins that associate with each other and the glycogen macromolecule. In efforts to understand the nature of these proteins, a two-hybrid screen was undertaken to detect proteins able to interact with Gsy2p, a major form of glycogen synthase in Saccharomyces cerevisiae. Two positives expressed proteins derived from genes designated PIG1 and PIG2, on chromosomes XIIR and IXL respectively. PIG1 codes for a protein with 38% identity over a 230 residue segment to Gac1p, a protein thought to be a type 1 protein phosphatase targeting subunit whose loss impairs glycogen synthesis. Pig2p has 30% identity to the protein corresponding to an open reading frame, YER054, on chromosome V. Deletion of PIG1 on its own had little effect on glycogen storage but, in combination with loss of GAC1, caused a more severe glycogen-deficient phenotype than seen in gac1 mutants. This result is consistent with Pig1p being functionally related to Gac1p and we propose that Pig1p may be a type 1 phosphatase regulatory subunit. Delection of PIG2, YER054, or both genes together caused no detectable change in glycogen metabolism under the conditions tested. Gac1p, Pig1p, Pig2p and the YER054p are the only four proteins coded by the yeast genome that share a conserved segment of ∼25 residues, designated the GVNK motif, that is identifiable also in R_GI, the mammalian type 1 phosphatase targeting subunit. © 1997 by John Wiley & Sons, Ltd.     

Development of a 1-Methylcyclopropene (1-MCP) Sachet Release System

ABSTRACT The partitioning of 1‐methylcyclopropene (1‐MCP) between the gas/polymer matrix was determined for 2 adsorbing agents and 4 sachet materials to estimate the adsorption potential of 1‐MCP at 23°C. The release study was performed using a closed system under 2 different environmental conditions, dry air (0% RH) and 90% RH. Sachets made from Tyvek®, paper, low‐density polyethylene (LDPE), and polyvinyl acetate (PVA) materials were fabricated to contain silica gel and activated carbon. Activated carbon sachets did not release 1‐MCP at either testing condition. Activated carbon had a very strong affinity for 1‐MCP. The permeability coefficients of 1‐MCP and water in polyethylene and polyvinyl acetate films were determined using a quasi‐isostatic method. LDPE sachets containing silica gel had similar 1‐MCP release rates at both 0% and 90% RH. PVA sachets containing silica gel had slow release of 1‐MCP. The amount of 1‐MCP released from PVA sachets containing silica gel at 90% RH was larger than the amount of 1‐MCP released at 0% RH. Release of 1‐MCP from paper and Tyvek sachets was largely dependent on the sorbate‐absorbing ability of the adsorbing agents.     

Plasma concentrations of glucagon-like peptide 1 and 2 in calves fed calf starters containing lactose

The objective of this study was to evaluate the effects of lactose inclusion in calf starters on plasma glucagon-like peptide (GLP)-1 and GLP-2 concentrations and gastrointestinal tract development in calves. Holstein bull calves (n = 45) were raised on an intensified nursing program using milk replacer containing 28.0% CP and 15.0% fat, and were fed a texturized calf starter containing 0 (control), 5.0 (LAC5), or 10.0% (LAC10; n = 15 for each treatment) lactose on a DM basis. Lactose was included in the starter by partially replacing dry ground corn in pelleted portion of the starter. All calf starters were formulated with 23.1% CP. The ethanol-soluble carbohydrate concentrations of the control, LAC5, and LAC10 starters were 7.3, 12.3, and 16.8% on a DM basis, respectively. Starch concentrations of the control, LAC5, and LAC10 starters were 29.7, 27.0, and 21.4% on a DM basis, respectively. All calves were fed treatment calf starters ad libitum. Blood samples were obtained weekly from 1 to 11 wk of age, and used to measure plasma GLP-1, GLP-2, and insulin concentrations, serum β-hydroxybutyrate (BHB) concentration, and blood glucose concentration. At 80 d of age, calves were euthanized, and weights of the reticulorumen, omasum, abomasum, small intestine, and large intestine tissue were measured. Serum BHB concentration was higher for calves fed the LAC10 (171 μmol/L) starter than for those fed the control (151 μmol/L) and LAC5 (145 μmol/L) starters. Plasma GLP-1 and GLP-2 concentrations did not differ between treatments. However, relative to the baseline (1 wk of age), the plasma GLP-1 concentration was higher for the LAC10 (125.9%) than for the LAC5 (68.2%) and control (36.8%), and for the LAC5 than for the control (36.8%). Moreover, similar differences between treatments were observed for GLP-2 concentration relative to the baseline (88.2, 76.9, and 74.9% for LAC10, LAC5, and control treatments, respectively). The serum BHB concentration was positively correlated with the plasma GLP-1 concentration (r = 0.428). Furthermore, the plasma GLP-1 concentration was positively correlated with the insulin concentration (r = 0.793). The weights of the reticulorumen, omasum, abomasum, small intestine, and large intestine were not affected by the treatments. In conclusion, inclusion of lactose in calf starters resulted in higher plasma GLP-1 and GLP-2 concentrations, and BHB might be associated with higher plasma GLP-1 concentration.     

Occurrence of fumonisin B1 and B2 in beer

A total of 29 nationally distributed brands of beer, representing 25 domestic US and four imported brands, were purchased in retail outlets in Lincoln, Nebraska and analysed for concentrations of fumonisin B₁ (FB₁) and B₂(FB₂). Immunoaffinity column extraction and cleanup of fumonisins from the beer samples, coupled with detection and analysis by gradient high performance liquid chromatography (HPLC), provided a limit of quantitation for each toxin of 0.3ng/ml. Of the brands of beer sampled, 86% were positive for FB and 41% were positive for FB2. No beer contained a detectable quantity of FB without a detectable quantity of FB1. The total fumonisin (FB₁ + FB₂) content of positive samples ranged from 0.3 to 12.7ng/ml, with a mean concentration for all positive samples of 4.0 ± 3.4ng/ml (n = 25). Considering that the level of fumonisin contamination of corn in recent harvest years has been minimal, the results of this limited survey could represent levels associated with current agricultural and brewing practices.