Drip loss,peroxidase and sensory changes in kiwi fruit slices during frozen storage

The biochemical, sensory and drip loss changes that occur during processing and prolonged frozen storage of kiwi fruit slices (cvs Abbott and Hayward) were studied. Fruit slices were frozen at ?40°C, packed in polyethylene bags and stored at ?18°C for 11 months. Maturity characteristics (pH, acidity, dry matter, soluble solids) were determined on raw fruit. Objective (proteins, peroxidase (EC 1.11.1.7) activity, drip loss) and subjective (sensory tests) analyses were carried out during processing and storage, and indicated a good quality of the frozen kiwi fruit slices after 11 months of storage. There were significant differences (P < 0.05) between the studied varieties with respect to drip loss during frozen storage and colour after 11 months. Best results were obtained with cv Hayward. This variety showed less drip loss after thawing and after 11 months storage presented the same green colour as after freezing, while cv Abbott became yellowish-green.     

水果内部品质近红外动态在线检测研究进展

近红外光谱技术具有无损检测、分析效率高、速度快、重现性好,适于现场检测和在线分析等特点,并已渗入到各个领域,在提高生产技术水平和改善产品质量方面发挥着重要作用。本文简述了水果近红外光谱在线检测原理和方式及动态在线检测装置的组成,并介绍了在线检测的控制过程及在线检测分析软件。总结了国内外近红外光谱技术在水果内部品质在线检测与分级方面的应用情况,并分析水果内部品质在线检测与分级中存在的问题,指出了水果内部品质近红外光谱在线检测的进一步研究方向。     

Vacuum Infiltration of Polyamines Increases Firmness of Strawberry Slices Under Various Storage Conditions

Strawberry slices were vacuum infiltrated with polyamines and changes in firmness during storage were determined. Spermine and spermidine at 10 mM or 100 mM significantly increased firmness, whereas pu-trescine was not as effective at increasing firmness of slices stored at 1°C. The firming effect of the polyamines was similar to that of calcium chloride, and may have been due to their ability to bind to cell walls and membranes. In ripe receptacles of various cultivars which differed in firmness, putrescine (12–38 nmol/g fresh weight) and spermidine (19–33 nmoI/g fresh weight) were the predominant polyamines, while only low levels of spermine (<10 nmol/g fresh weight) were present. There was no discernible relationship between endogenous polyamine levels and fresh fruit firmness for the cultivars studied.     

油砂沥青减压渣油超临界萃取分馏窄馏分黏温规律的分析

为了研究渣油馏分的黏温规律,在60～120℃范围内,考察了温度对窄馏分黏度的影响,窄馏分由加拿大油砂沥青减压渣油通过超临界萃取分馏制得。结果表明:①随着馏分的分子量增大,其黏度快速增大;②随着温度的升高,重馏分的黏度下降速度比轻馏分快;③Arrhenius方程能描述窄馏分的黏温关系,流动活化能为61.06～98.42 kJ/mol,活化能随分子量增大而呈现上升趋势;④Andrade、Vogel和Walther黏温经验式佐证了Arrhenius模型的正确性。本研究对渣油的黏温规律和模型的理解具有一定的指导意义。     

煤油共炼残渣性质分析

采用元素分析、工业分析、热重、X射线衍射、扫描电镜、红外光谱等手段对煤油共炼残渣的组成、微观结构、官能团进行分析表征，并通过红外谱图的分峰拟合对官能团含量进行半定量计算。结果表明：残渣的有机物由具有片层堆积结构碳质颗粒组成，无机物由煤油共炼催化剂和煤中的无机矿物质组成；残渣颗粒粒径呈10 μm和2 μm的两级分布，颗粒呈整体无序、局部有序的分布状态。分别采用工业分析和热重分析得到挥发分、固定碳和灰分的含量，两组数据一致：残渣的氢键中羟基自缔合结构占到了47.95%；脂肪氢中亚甲基结构占64%左右；含氧官能团主要以碳氧键和羰基形式存在，含有微量的硅氧键，没有羧基；芳香结构中烷基侧链取代基较多，五取代氢的芳香结构只占约4.5%。     

工业装置渣油加氢失活催化剂上的金属赋存状态研究

以工业固定床渣油加氢失活催化剂（失活剂）为研究对象,依次采用正庚烷、甲苯对其进行索氏抽提,通过对失活催化剂上金属含量、形态及分布进行分析表征,发现金属沉积量沿着物流方向呈现降低趋势。通过Raman光谱、XPS分析表征发现,渣油加氢失活剂表面沥青质类物质含量很低。渣油加氢处理催化剂的活性相主要有3种：MoS2相、NiMoS相或CoMoS相。沉积的焦炭和金属使得催化剂暴露在外表面的活性相数量非常少。     

沥青质在渣油加氢催化剂中的扩散行为

以甲苯为溶剂,在自制的扩散实验装置中,研究了不同初始质量分数下沥青质在渣油加氢催化剂中的扩散行为。结果表明:当沥青质初始质量分数由0.002%增加到0.030%时,随着前者的增加,沥青质聚集体的体积、单元体积分数和动力学直径增加,平移扩散系数减小,聚集效应明显,阻碍了沥青质在催化剂微孔中的扩散,有效扩散系数降低。另外,随着初始质量分数增加,沥青质聚集体的Langmuir动力学系数及其在催化剂中的饱和浓度增加,即聚集效应增强了沥青质的吸附能力。聚集效应对扩散和吸附的影响具有互补性,使扩散系数随沥青质初始质量分数增加的变化幅度减小。     

塔河渣油高温催化临氢热转化技术研究

以塔河减压渣油（简称塔河减渣）为原料,在实验室小型试验装置和中型连续试验装置上,对在较高温度条件下催化临氢热转化加工塔河减渣的工艺操作条件及改质效果进行了系统研究。采用高分散的油溶性催化剂,在高压釜反应器中考察了反应温度、反应压力、催化剂添加量、溶剂油添加量、反应时间以及助剂添加量对塔河减渣催化临氢热转化反应的转化率和缩合率的影响,优化了操作参数。在优化的操作条件下,进行了塔河减渣催化临氢热转化中型试验,得到初馏点大于524 ℃组分的裂化率为85.2%,馏分油收率为80%,金属（Ni+V）和沥青质脱除率均大于90%。     

Biology of pheromone release by male caribbean fruit flies,Anastrepha suspensa (Diptera: Tephritidae)

Males of the Caribbean fruit fly,Anastrepha suspensa (Loew), typically form leks and attract females by releasing a multicomponent volatile pheromone. Previous reports have identified two nine-carbon alcohols, three lactones, a sesquiterpene, and a monoterpene in the volatiles. The present report is a study of the physiology of male pheromone release and of ecological and social interactions that influence pheromone release by laboratoryreared flies. Volatiles released by males were trapped on Tenax, eluted, separated, and quantitatively measured by gas chromatography. Experiments showed that the volatiles were primarily released from mouth and anus. Sealing the anal opening or the mouth with melted beeswax resulted in up to 40% or greater reduction in most components, and sealing both mouth and anus further reduced release of volatiles, but some volatiles are possibly still released directly from the cuticle. An anal pouch of everted tissue played a major role as a large evaporative surface for release of some of the volatile components. Male flies entrained to a 1410 light-dark cycle showed a peak release of volatiles at 11–12 hr into the photophase, but smaller quantities of the same volatiles were released over a broad period during the daylight hours. Laboratory-reared males peaked in pheromone release at 7–10 days and production and release continued through 35 days of age. Single males released significantly more of all components measured than did groups of males. The reduction by aggregations of males may be related to lekking behavior in this fruit fly. The pheromone probably serves to attract females to a lek site, but additional parameters are likely to enter into the choice of male made by the arriving female.This is University of Florida Agricultural Experiment Station Journal Series No. 9589.     

A novel attractant for Mexican fruit fly,Anastrepha ludens,from fermented host fruit

Chemicals from fermented chapote fruit were identified and evaluated as attractants for hungry adult Mexican fruit flies in laboratory and greenhouse bioassays. Twenty-eight chemicals identified from an attractive gas-chromatography fraction were as attractive as a chapote volatiles extract (CV) when mixed in the same amounts found in CV. Sixteen of the chemicals were slightly attractive to flies when tested individually. A mixture containing 15 of the chemicals by design and the 16th as an impurity, in arbitrary concentrations, was at least as attractive as the original CV. In a series of experiments, the number of chemicals was reduced to three by elimination of unnecessary components. The three-component mixture retained the attractiveness of the 15-component mixture. The three chemicals were 1,8-cineole, ethyl hexanoate, and hexanol (CEH). Attractiveness of the three-chemical mixture was equal to the sum of the attractiveness of the three individual components, suggesting that each chemical binds to a different receptor type that independently elicits partial attraction behavior. Optimal ratios were 1011 of the three chemicals, respectively. Optimal test quantities ranged between 0.4–4g of 1,8-cineole and 40–400 ng each of ethyl hexanoate and hexanol applied to filter paper in the laboratory bioassays. A neat 1011 mixture of the chemicals was 1.8 times more attractive than aqueous solutions ofTorula dried yeast and borax to starved 2-day-old flies when the lures were tested in competing McPhail traps in a large greenhouse cage.Diptera: Tephritidae.