腰果油提取工艺及其理化性质研究

采用水代法研究腰果油的最佳提取工艺,分别以料液比、提取温度、提取时间和离心力为单因素研究其对提油率的影响,并通过正交设计实验确定腰果油的最佳提取工艺条件为料液比1︰1 g/mL、提取时间4 h、离心力4800 r/min,最佳条件下获得的提油率为74.39%。采用水代法得到的腰果油色泽浅黄澄清透明,具有腰果固有的清香味。理化指标测定结果表明,油的酸价为0.65mg/g,碘值为14.25g/100g,皂化值为186mg/g,符合国家标准,过氧化值未检出。水代法提取腰果油的脂肪酸分析表明腰果种仁中含有的脂肪酸主要有棕榈酸,含量10.32%,油酸62.87%,和亚油酸25.36%。     

Speciation of Se in Bertholletia excelsa (Brazil nut): A hard nut to crack?

A separation method based on ion-pairing liquid chromatography was combined with both elemental (inductively coupled plasma mass spectrometry (ICP-MS)) and molecular (electrospray tandem mass spectrometry (ES-MS-MS)) mass spectrometry in order to unravel the identity of the Se-species present in the complex matrix of Brazil nuts rich in Se. Via enzymatic digestion, Se-species were released from the matrix. Subsequently the species were separated and the Se was monitored on-line by ICP-MS. By HPLC–ES-MS-MS, the species were identified based on their molecular mass and their specific product ions. The main compound was identified as Se-Methionine. Another compound was identified as Se-Cystine, partly on the basis of the isotopic pattern of Se. This research was further extended to the analyses of in vitro gastrointestinal digests of the Brazil nuts. These digests were analyzed for their Se-content and screened for the presence of the different Se-species by HPLC–ICP-MS. In both the gastric and the intestinal digests, we were able to identify the Se-species as Se-Methionine and Se-Cystine by HPLC–ES-MS-MS. By coupling HPLC to both elemental and molecular mass spectrometry, the species present in Brazil nuts and supposedly extractable by our body were fully characterized.     

Chemical characteristics of canarium salomonense oil

Canarium salomonense (ngali nuts) had an oil content of 736 g kg^?1 dry weight. The major fatty acids present were oleic (41–6%), palmitic (34–9%) and stearic (12–6% of the total fatty acids). The nuts produced a yellow oil which had a low free fatty acid content. The fatty acid composition of C salomonense is similar to palm oil and could be used as a general purpose cooking oil.     

土遗址锚固用烧料礓石拌合遗址土浆液龄期性能

为寻求与土遗址更为兼容的锚固灌浆材料,选择烧料礓石与民勤县明长城红沙堡遗址土以1∶1比例拌合的浆液材料,对其结石体进行了不同龄期收缩率、含水率、波速、渗透系数、密度、抗折强度和抗压强度的测定及微观结构变化观测。试验结果表明,结石体在龄期28天的收缩率、波速及含水量基本趋于稳定,而抗折强度和抗压强度28天后仍持续发展,直到龄期90天时保持稳定。微观结构观察结果较好地证明了以上规律。烧料礓石前期水化及后期碳化反应保证浆液早期及后期强度。同时渗透系数及密度与遗址土的相近,保证了结石体与遗址土体的兼容性。研究初步表明,该浆液适宜于土遗址锚固工程中使用。     

Macadamia Nut Consumption Modulates Favourably Risk Factors for Coronary Artery Disease in Hypercholesterolemic Subjects

Macadamia nuts are rich source of monounsaturated fats (oleic and palmitoleic acids) and contain polyphenol compounds, therefore, their consumption can be expected to impart health benefits to humans. This study was conducted to examine the effects of consuming macadamia nuts in hypercholesterolemic male individuals on plasma biomarkers of oxidative stress, coagulation and inflammation. Seventeen hypercholesterolemic male subjects were given macadamia nuts (40–90 g/day), equivalent to 15% energy intake, for a period of 4 weeks. As expected, monounsaturated fatty acids (16:1n-7, 18:1n-9 and 20:1n-9) were elevated in the plasma lipids of all volunteers following intervention with macadamia nuts. Plasma markers of inflammation (leukotriene, LTB₄) and oxidative stress (8-isoprostane) were significantly lower (1,353 ± 225 vs. 1,030 ± 129 pg/mL and 876 ± 97 vs. 679 ± 116 pg/mL, respectively) within 4 weeks following macadamia nut intervention. There was a non-significant (23.6%) reduction in the plasma TXB₂/PGI₂ ratio following macadamia nut consumption. This study demonstrates, for the first time, that short-term macadamia nut consumption modifies favourably the biomarkers of oxidative stress, thrombosis and inflammation, the risk factors for coronary artery disease, despite an increase in dietary fat intake. These data, combined with our previous results on cholesterol-lowering effects of macadamia nuts, suggest that regular consumption of macadamia nuts may play a role in the prevention of coronary artery disease.     

Evaluating a Solar Dryer for In-Shell Drying of Split Pistachio Nuts

Abstract

A thin-layer forced air solar dryer was designed to study the feasibility of drying pistachio nuts. The dryer was tested during the 2001 and 2002 drying seasons. The maximum temperature in the solar collector reached 56°C, which was 20°C above the ambient temperature. The required drying time was 36 h. During the first day of drying (0800 to 1700 h) the moisture content dropped to about 21% (wb). The final moisture content of the dried nuts was 6% wb, which was 1% below the recommended storage moisture. The drying constant of the pistachio nuts during solar drying was determined using two mathematical models, a one-term series solution of Fick's diffusion equation and an exponential decaying model. There was no significant difference between the two models (α = 0.05). In general, the quality of solar dried nuts was better than the conventional heated air due to slower drying rates.     

基于巴西果效应的颗粒床振动再生研究

为了探索一种低成本的、环境友好的颗粒床含尘滤料再生方式,采用垂直振动后拍照的方法,研究了滤料/粉尘的平均粒径比、体积比以及振动频率、加速度、振幅等对基于巴西果效应的滤料/粉尘的垂直振动分离的影响。结果表明,矿渣/滑石粉、矿渣/粉煤灰的平均粒径比不低于75,石英砂/滑石粉、石英砂/粉煤灰的平均粒径比分别不低于65, 15.3时,能形成巴西果。在20～100 Hz的振动频率下,矿渣/粉尘的振动加速度和振幅超过临界值时,矿渣/粉尘将从混合态转变为巴西果态。矿渣/粉尘体系形成巴西果的最优振动频率是45 Hz,该频率不受矿渣粒径、粉尘种类和矿渣/粉尘体积比的影响。矿渣粒径越大、矿渣/滑石粉的体积比越大,矿渣/滑石粉分离越容易,矿渣/滑石粉比矿渣/粉煤灰体系更易形成巴西果。在45 Hz的最优频率下,矿渣/滑石粉和矿渣/粉煤灰分别在1.01和1.36 mm的较低振幅下,可实现垂直振动分离。采用基于巴西果效应的垂直振动方式分离颗粒床中含尘滤料是可行的,该分离方式有利于滤料的重复利用和提高颗粒床捕集细小粉尘粒子的能力,是一种具有应用前景的颗粒床滤料再生方式。     

基于正交试验的车用螺母成形分析及模具磨损优化

以某车用锁紧螺母冷镦成形为研究对象,基于Archard磨损理论,采用有限元分析软件DEFORM-3D对模具磨损及成形载荷进行模拟分析。结果表明:制件成形符合工艺要求。为得到更优的成形效果,选取上冲头切入角、冲压速度、模具表面硬度、摩擦系数作为因素,设计正交试验,以降低模具磨损和成形载荷为目标对因素进行优选。分析得出各因素对结果的影响趋势,并通过综合考虑生产效率、能量消耗、设备磨损等因素,得到了最优工艺参数组合为上冲头切入角20°、冲压速度5 mm·s-1、模具表面硬度61 HRC、摩擦系数0. 12。采用最优参数重新进行模拟,上冲头使用寿命得到了大幅提升,并予以试模验证。     

响应面法优化GA3、6-BA及果蜡最佳浓度配比保鲜槟榔

以海南本地种新鲜槟榔为研究对象,采用不同浓度的GA3、6-BA以及果蜡处理,通过响应面法优化组合浓度,通过对处理后槟榔的失水率、变色指数、叶绿素及其他的品质测定,确定3种保鲜剂对槟榔果实的最佳配比,结果如下:100mg/LGA3+100mg/L6-BA+50%的果蜡对槟榔果实保鲜效果最佳,贮藏15d后,其失水率为9.56%,叶绿素含量为1.28mg/g,弹性为1.37mm,第一硬度为1395g,咀嚼性为9.3mJ。