连翘果实多酚提取及其复合涂膜保鲜剂在葡萄保鲜中的应用

为解决植物源防腐保鲜成分用于食品保鲜问题,以连翘果实为研究对象,采用恒温磁力搅拌水浴辅助乙醇浸提连翘果实多酚类物质,优化提取工艺使用L₉(3 ⁴)正交实验进行设计;将连翘多酚、植酸、氯化钙和柠檬酸与壳聚糖结合,对葡萄进行涂膜处理,研究其在常温贮藏条件下的保鲜效果。结果表明,在优化提取条件为料液比1:10、乙醇体积分数60%、提取温度60℃、提取时间2.5 h,连翘果实多酚的提取率可达7.21%;2%连翘多酚、1%氯化钙、0.15%植酸、2%柠檬酸与1%壳聚糖制成的保鲜剂,在葡萄贮藏中有一定防腐保鲜作用。研究结果可作为连翘果实多酚提取物用于果蔬类食品防腐保鲜的技术参考。     

乙醇法提取枇杷叶总黄酮的研究

对乙醇法提取枇杷叶黄酮的工艺进行研究,采用单因素试验法对影响枇杷叶中黄酮类物质提取率的主要因素进行了考察,利用正交试验优化了提取黄酮类物质的最佳工艺条件。确定了枇杷叶总黄酮的最佳提取工艺为∶料液比1∶50,提取温度80℃,提取时间3 h,乙醇浓度50%。在最佳提取工艺条件下测得解放钟枇杷叶中总黄酮含量为0.3805%,回收率98.37%。     

Cattle, ethanol, and biogas: Does closing the loop make economic sense?

The recent surge in US ethanol production has led to an increase in the amount of byproduct feed available to cattle producers. The impetus behind the increase in ethanol production is US policy to increase the production and use of renewable fuels. Manure from cattle production can also be used to produce a renewable fuel: methane. By co-locating a cattle feedlot with an existing ethanol plant, there may be synergies between ethanol, methane and cattle production. Byproduct from the ethanol plant can be fed to feeder cattle, manure from the cattle used in methane production, and the methane used as an energy source in the ethanol plant. Alternatively, methane can be used to generate electricity. We investigate the economic advisability of these systems. Using cost estimates for construction and operating a feedlot and anaerobic digester for methane production, we project revenues and costs over a 20-year time period. Our findings are consistent with studies that have considered just cattle production and methane production. The investment required to build a slatted-floor feedlot and concrete anaerobic digester cannot be justified under existing economic conditions. An increase in renewable fuel/electricity subsidies of at least $0.053 per kW h or $72 per 1000 m³ of methane are required to just break even when methane is used to produce electricity or is burned for thermal energy, respectively.     

乙醇、乙二醇二甲醚与柴油混合燃料排放特性研究

提出了将乙二醇二甲醚作为乙醇柴油燃料的一种组成成分,利用乙二醇二甲醚好的发火性来改善乙醇柴油燃料差的发火性。试验表明乙二醇二甲醚与乙醇、柴油互溶,具有较好的稳定性。对三种比例混合燃料测试了柴油机在主要工况下的性能与排放特性,得出乙二醇二甲醚加入量以E20为最佳,此时,烟度降低了约80%,NOx略有增加,燃油消耗率略有下降。此外考察了随着十六烷值的变化对混合燃料的排放特性的影响,得出随着十六烷值的增加,NOx排放逐渐增加,对烟度和经济性存在一个最佳值。     

Evaluating the potential of wine-making residues and corn cobs as support materials for cell immobilization for ethanol production

Three wine-making residues (grape seeds, skins and stems), and corn cobs were evaluated as support material for immobilization of Saccharomyces cerevisiae and the ethanol production by the immobilized cells was assessed. The main objective of this study was to find an abundant and low cost material suitable for the cells immobilization and able to be used in a next step of wine production by immobilized yeast cells. The four natural materials were used as support in two different forms: untreated, and treated by a sequence of acid and basic reactions. Untreated grape skin and corn cobs provided the highest cell immobilization results (25.1 and 22.2 mg cells/g support, respectively). The maximum ethanol production yield (about 0.50 g/g) was also obtained when the cells were immobilized in these untreated materials. It was also found that the support materials released nutrients to the medium, which favored the yeast development and the ethanol production. The use of immobilized cells systems under agitated conditions gave ethanol yields similar to those obtained by the static fermentations, but the immobilized cell concentration was significantly lower. In brief, static fermentation with cells immobilized on grape skins or corn cobs appear to be an interesting alternative for use on wine-making. The use of grape skins, particularly, which is a by-product of the wine elaboration, could be of larger interest to obtain an integrated wine production process with by-product reuse.     

Conversion of starch from dry common beans (Phaseolus vulgaris L.) to ethanol

Dry common beans (Phaseolus vulgaris L.) were evaluated for potential conversion of starch to ethanol. Eight varieties of beans with average starch content of 46% (db) were assayed in a laboratory-scaled process based upon the commercial corn dry grind fermentation process. Ethanol yield was 0.43-0.51 g ethanol/g glucose (0.19-0.23 g ethanol/g beans). The average ethanol yield for the eight bean types was 92% of maximum theoretical yield, demonstrating that starch from beans could be efficiently converted to ethanol. Ethanol concentration obtained from 20% (w/w) solids loading was 3.5-4.4% (w/v). The residual fermentation solids contained, on a dry basis, 37.1-43.6% crude protein, 10.8-15.1% acid detergent fiber and 19.1-31.3% neutral detergent fiber.     

金银花中绿原酸的提取和含量测定

[目的]研究金银花中绿原酸的不同提取方法并测定了不同花期金银花中绿原酸的含量。[方法]以金银花为材料,采用乙醇回流法和超声提取法提取金银花中的绿原酸,并以紫外分光光度法测定提取物中绿原酸的含量,探讨了不同开花时期金银花中绿原酸含量的差异。[结果]以乙醇回流法提取的金银花原液中绿原酸浓度为1.905 mg/ml,含量为3.81%,而以超声提取法提取的金银花原液中绿原酸浓度为1.306 mg/ml,含量为2.61%,故乙醇回流法比超声提取法提取率更高一些;以乙醇回流法提取的全开金银花原液中绿原酸浓度为0.167 7 mg/ml,含量为0.34%,而以乙醇回流法提取的花苞原液中绿原酸浓度为0.260 1 mg/ml,含量为0.52%,故花苞中的绿原酸含量要高一些。[结论]该方法操作简便迅捷,可用于金银花中绿原酸的提取和含量测定。     

不同产地鲜姜乙醇浸提物化学成分分析及6-姜酚含量的测定

[目的]分析比较不同产地鲜姜乙醇浸提物的化学成分并定量测定鲜姜中6-姜酚的含量。[方法]采用GC-MS分析不同产地鲜姜乙醇浸提物中的化学成分,采用HPLC法测定鲜姜中6-姜酚的含量。[结果]5个不同产地的鲜姜乙醇浸提物中分别鉴定出39、44、45、49、44种化合物,其主要成分为姜酚、姜烯酚类、姜酮酚类及姜油酮类等;由于产地不同,各产地鲜姜的乙醇浸提物组成成分及相对含量存在较大差异。姜酚类化合物在鲜姜中含量相对较高,约占总挥发油的30%左右。采用HPLC法测定鲜姜中6-姜酚的含量,结果显示,6-姜酚在0.024 8～0.124 mg/ml浓度范围内与峰面积呈良好线性关系（r=0.996 6,n=5）,平均加样回收率为99.20%,RSD为1.26%。[结论]GC-MS法能快速、简便、高效的检测鲜姜乙醇浸提物的化学成分,HPLC测定法简便可靠、重复性好,可用于鲜姜中6-姜酚的含量测定。     

Ethanol vapor and saprophytic yeast treatments reduce decay and maintain quality of intact and fresh-cut sweet cherries

The objective of this study was to evaluate the use of an ethanol vapor release pad and a saprophytic yeast Cryptococcus infirmo-miniatum (CIM) to reduce decay and maintain postharvest quality of intact or fresh-cut sweet cherries (Prunus avium) cv. Lapins and Bing. Intact or fresh-cut fruit were packed in perforated clamshells (capacity 454 g) and stored at 1, 10 or 20 °C for up to 21, 14 and 8 d, respectively. For ethanol treatment, a pad made with silica gel powder containing 10 g ethanol and covered with perforated film, which allows ethanol vapor to diffuse gradually, was attached to the upper lid of the clamshells. Ethanol treatment caused accumulation of ethanol in the packaging headspace, about 10 μL L⁻¹ with little change within 14 d at 1 °C, 23 μL L⁻¹ at d 1 and decreased to 15 μL L⁻¹ at d 10 at 10 °C, and 26 μL L⁻¹ at d 1 and decreased to 13 μL L⁻¹ at d 3 at 20 °C. Ethanol content in fruit was less than 9 mg kg⁻¹ in all the control fruit, and increased to 16, 34 and 43 mg kg⁻¹ in ethanol-treated fruit at 1, 10 and 20 °C, respectively. Nonetheless, a sensory taste panel did not perceive any flavor difference from the ethanol treatment. The ethanol treatment retarded softening, darkening, and acid decrease in fruit as well as discoloration of the stems, and extended shelf-life of intact cherries. Ethanol reduced brown rot (Monilinia fructicola) in fresh-cut cherries stored at 20 °C, but not at 1 and 10 °C. A pre-packaging dip in CIM completely controlled brown rot in inoculated fresh-cut cherries stored at 1 °C, and in naturally infected cherries at 20 °C.