Sex Pheromone Components in Defense of Melon Fly, Bactrocera cucurbitae Against Asian House Gecko, Hemidactylus frenatus

The Asian house gecko, Hemidactylus frenatus, after being acclimatized to feeding on the melon fly, Bactrocera cucurbitae, consumed fewer numbers of 15-day-old (DO) and older male melon flies compared to sexually immature flies 10 DO and younger. The first male melon fly that performed mating did so on the 10th day after eclosion (DAE), but >80% of the males performed their first mating between 10 and 15 DAE. This confirmed that between 10 and 15 DAE most male melon flies are already sexually mature and producing sex pheromone. Synthetic 1,3-nonanediol, a component of male melon fly sex pheromone produced endogenously, when topically applied onto the thorax of housefly Musca domestica at ca. 80 or 320 ng/fly, reduced consumption by geckos compared with untreated flies in subsequent days after the first day in a four-day feeding test. Raspberry ketone (RK) is consumed and sequestered into the pheromonal gland and later released as a pheromonal component of male melon fly. Houseflies topically treated with 2.6 g RK/fly did not deter predation by geckos. However, houseflies treated with 5.1 g RK/fly caused geckos to consume fewer flies, especially on the third and fourth days during a four-day feeding test, compared with the period when they were offered untreated flies.     

红树莓叶片中黄酮类物质提取及抗氧化性的研究

以小浆果果树红树毒叶片为实验材料，利用分光光度法测定其总黄酮含量，并采用烘箱贮存法研究了不同添加量红树毒叶片提取物粗黄酮在猪油中的抗氧化性。结果表明：鲜样中红树毒叶片总黄酮含量是278．73mg／100g，干样中是533．71mg／100g；红树毒叶片提取物粗黄酮对猪油有一定的抗氧化作用，并随添加量的增加而增强；增效剂以(柠檬酸)对红树毒叶片提取物粗黄酮无增效作用，而Vc具有一定的增效作用。抗氧化活性顺序为：0．02％槲皮素＞0．02％PG＞0．02％BHT＞0．4％粗黄酮＞0．05％粗黄酮 0．05％Vc＞0．2％粗黄酮＞0.1％粗黄酮＞0．05％粗黄酮＞0．02％粗黄酮＞0．05％粗黄酮 0．05％CA＞对照。     

红树莓色素的定性鉴定及提取工艺研究

采用定性鉴别的方法判断红树莓色素的主要成分,并通过单因素试验确定提取红树莓色素的条件。溶解性和颜色反应结果表明,红树莓色素的主要成分为花色苷。提取红树莓色素的适宜条件为:红树莓匀浆液以3%的盐酸水溶液为提取溶剂,以1∶15(g/mL)的料液比在60℃水浴中浸提60 min,提取2次,在此条件下,每克鲜果中红树莓花色苷的提取量可达0.718 mg。     

Effect of raspberry pomace extracts isolated by high pressure extraction on the quality and shelf‐life of beef burgers

Raspberry pomace extracts isolated with supercritical carbon dioxide (SCE) and pressurised ethanol/water (ETE) were tested in beef burgers. Only ETE additives effectively inhibited lipid oxidation and the growth of microorganisms, as it was observed by measuring the changes of thiobarbituric acid reactive substances, bacterial counts and the content of O₂ and CO₂ during storage in the modified atmosphere package. ETE additives also demonstrated some meat colour preservation effects, which were assessed by the intensity of hamburger colour and metmyoglobin concentration. However, ETE additives did not alter burger's taste at the applied concentrations (up to 1%). It may be concluded that the most effective extracts possessing strong antioxidant and antimicrobial activity may be isolated from raspberry pomace by the pressurised liquid extraction with a hydroethanolic solvent; such extracts may be considered as promising additives in meat products for improving their stability and enriching with beneficial to health phytochemicals.     

红莓果中花青素的提取工艺研究

以HCl-乙醇为溶剂,研究了红莓果中花青素的最佳提取工艺。在单因素试验中,选择了单次提取和2次提取,分别测定了不同提取级数下各因素(物料比、提取时间、提取温度)的最佳水平值。同时,以果实中花色苷的绝对含量作为提取效率的评价标准,提高了单纯采用吸光度值测定法作为评定指标的精确性与可靠性。通过响应面试验确定了最佳的提取工艺参数为:浓度为1.5 mol/L的HCl和体积分数95%的乙醇(体积比15∶85)为溶剂,提取料液比为5 g∶1 mL,提取时间为53 min,提取温度为71℃,提取2次。依此工艺,红莓花青素的提取得率为36.39 mg/100 g(鲜果)。     

树莓汁中键合态香气物质提取方法及糖基组成的研究

本文采用Amberlite XAD-2树脂吸附洗脱分离的方法和甲醇直接提取法对树莓汁中的键合态香气物质进行了分离,对得到的键合态香气物质进行了酶水解释放,采用GC-MS分析方法对水解得到的键合态香气物质进行了分析鉴定,重点比较了这两种方法的提取效果,并对酶水解后的糖基部分进行了分析研究。结果显示,甲醇直接提取法只提取得到4种键合态香气物质,总含量为77.1μg/kg,包括2种苯系物和2种脂肪醇类物质;Amberlite XAD-2树脂吸附洗脱提取法共提取得到20种键合态香气物质,包括11种苯系物,6种醇类物质及3种萜烯类物质,总含量达3042μg/L。两种方法提取得到的键合态香气物质在种类和含量上存在很大的差异,Amberlite XAD-2树脂吸附提取法提取得到的键合态香气物质种类丰富。树莓汁中糖苷键合态香气物质的糖基部分含有甘露糖和葡萄糖两种单糖。     

使用树莓派实现主机远程断电重启

针对运行维护中出现的一些嵌入设备因系统故障无法远程维护的情况,文中提出了采用树莓派GPIO和web编程方式控制设备电源的解决方案,实现设备远程断电重启;详细介绍了树莓派web服务器的配置方法、利用python编程语言进行GPIO和web编程的要点。该方案与采用智能PDU的方案相比具有成本低,后续扩展能力强的特点。     

高压脉冲电场(PEF)处理对红莓花色苷提取过程的影响

研究了3.0 kV/cm高压脉冲电场(PEF)处理对红莓花色苷提取过程的影响。结果表明:3.0 kV/cmPEF处理对红莓果实液泡细胞膜的损伤比冷冻-解冻过程的机械损伤更显著,60~420个脉冲数的PEF处理能使甘露醇等渗溶液的电导率由65μs/cm增加至490μs/cm,明显加快花色苷的传质速率;用3.0 kV/cm PEF处理420个脉冲后,用酸化甲醇提取15 min,可使花色苷的提取率达到54.24%,较未处理样品增加41.29%,较直接冷冻-解冻样品的提取率增加25.16%。     

Biochemical monitoring of black raspberry (Rubus coreanus Miquel) fruits according to maturation stage by H NMR using multiple solvent systems

Nuclear magnetic resonance (NMR) techniques coupled with multivariate data analysis were used to conduct monitoring of biochemical changes of black raspberry fruits at different stages of maturation and under various extraction and NMR dissolution solvent conditions: extraction with 50% methanol and D₂O as an NMR dissolution solvent, extraction with 50% methanol and 50% methanol-d₄ as an NMR dissolution solvent, and extraction with 100% ethyl acetate and 100% methanol-d₄ as an NMR dissolution solvent. Partial least-squares discriminant analysis reliably distinguished black raspberry fruits according to the maturation stage, whereby the relative levels of various compounds such as amino acids, organic acids, sugars and phenolic compounds were compared using analysis of variance. Sucrose and most of the amino acids, and organic acids decreased, whereas fructose, glucose, and cyanidins increased in relative concentration according to maturation of black raspberry fruits. The total number and kinds of assigned compounds of the three solvent systems were also compared. This research demonstrates that the metabolic profile of black raspberry fruits changes during maturation, and provides objective criteria for determining the stage of black raspberry fruit maturation via a ¹H NMR-based metabolomics technique using multiple solvent systems.     

Energy consumption during Refractance Window® evaporation of selected berry juices

The Refractance Window^® evaporator represents a novel concept in the design of evaporation systems for small food processing plants. In this system thermal energy from circulating hot water is transmitted through a plastic sheet to evaporate water from a liquid product flowing concurrently on the top surface of the plastic. The objectives of this study were to investigate the heat transfer characteristics of this evaporator, determine its energy consumption, and capacity at different tilt angles and product flow rates. The system performance was evaluated with tap water, raspberry juice, and blueberry juice and puree as feed. With a direct steam injection heating method, the steam economy ranged from 0.64 to 0.84, while the overall heat transfer coefficient (U) was 666 W m^?2 °C^?1. Under this condition, the highest evaporation capacity was 27.1 kg h^?1 m^?2 for blueberry juice and 31.8 kg h^?1 m^?2 for blueberry puree. The energy consumption was 2492–2719 kJ kg^?1 of water evaporated. Installation of a shell and tube heat exchanger with better temperature control minimized incidences of boiling and frequent discharge of condensate. The steam economy, highest evaporation rate and overall heat transfer coefficient increased to 0.99, 36.0 kg h^?1 m^?2 and 733 W m^?2 °C^?1, respectively. Copyright © 2004 John Wiley & Sons, Ltd.