Effect of contamination of foods by Aspergillus flavus on the nutritive value of protein

The effect of aflatoxin was measured on the protein quality of peanut meal (PNM) and fish meal (FM) Total protein efficiency, protein efficiency ratio, net protein utilisation, examination of the histopathology of the liver, ileal digesion of amino acids and plasma amino acid concentration were used as bioassays together with chemical score (CS), dye binding capacity (DBC), essential amino acid index (EAAI), and discriminant computered PER (DC-PER) as chemical methods. In trial 1, aflatoxin-free PNM was compared with infected PNM at graded levels of toxin when fed to chickens and ducklings. In trial 2, various mixtures of PNM and FM at a constant aflatoxin level (280 μg kg^?1) were fed to compare the effects of aflatoxin on proteins of differing quality. Ducks were more sensitive to the toxin than chickens, as indicated by deterioration of protein quality, and the effects on growth and the histological appearance of the liver were magnified on diets of low quality (PNM), but not of high quality (FM). Contamination of PNM resulted in progressive increase in DBC and, to a lesser extent, in DC-PER, while EAAI and CS were not affected. The importance of these findings lies in the problems of mould contamination of animal feedstuffs in humid, tropical conditions, which may affect the more sensitive animals, and may not be detected by chemical methods of measuring protein quality, nor by bioassay on chickens, if the levels of contamination are low.     

酶法处理对花生水剂法制油的影响

在花生水剂法制油工艺中,利用以纤维素酶为主体包含果胶酶的复合酶系处理碾磨后的油料能显著提高花生油收率及花生蛋白得率。经研究得出酶处理的最适参数范围如下：加酶量０ ．２ ％ ～０ ．３ ％ ,酶反应时间４ｈ ,ｐＨ６ ～７ ,温度４０ ～５０ ℃。     

花生壳/PP复合材料的制备及其性能研究

为了实现对花生壳这一农产品的回收利用,采用花生壳粉末与PP制备应用于家居填充物的复合材料,对其最优工艺条件进行了研究,测试了所制备材料的拉伸、弯曲以及冲击特性.结果表明,随着花生壳粉末质量分数的增加,所制复合材料的拉伸、弯曲强度在花生壳粉末质量分数为40%时取得最大值,而冲击强度随着花生壳粉末质量分数的增加反而变小.所制备复合材料满足家居填充物要求的最优工艺为:当花生壳粉末质量分数为40%,热压温度175℃,热压压力12MPa,热压时间5min时.其弯曲性能、拉伸性能和冲击性能均较好.     

Peanut FAD2 Genotype and Growing Location Interactions Significantly Affect the Level of Oleic Acid in Seeds

The level of oleic acid is an important parameter in determining seed nutritional quality and oil stability. The level of oleic acid in peanut is genetically controlled by a pair of fatty acid desaturase genes (FAD2A and FAD2B), but the environmental conditions of the production sites can also have a significant effect. To investigate the effect of gene and environment interaction, 45 accessions were grown at three locations for 2 years. Environmental data were collected; individual plants were genotyped with functional SNP markers from FAD2A and FAD2B; and seed level of oleic acid was determined by gas chromatography. Three FAD2A/FAD2B genotypes (448G/no insertion 442A, 448A/no insertion 442A, and 448A/insertion 442A) were identified and designated as G/W, A/W, and A/A, respectively. A/A genotype averaged the highest level of oleic acid (80.0%), followed by A/W (56.0%), and then G/W (40.7%). Analysis of gene and environment interaction revealed that oleic acid phenotype plasticity could be explained by the interaction of FAD2 genotype and photothermal time, which quantified environmental conditions. The A/W genotype was the most sensitive to photothermal time changes. The oleic acid plasticity revealed in this study would be useful for breeders, farmers, and product processors.     

Effect of Industrial Chemical Refining on the Physicochemical Properties and the Bioactive Minor Components of Peanut Oil

The effect of the industrial chemical refining process on the physicochemical properties, fatty acid composition, and bioactive minor components of peanut oil was studied. The results showed that the moisture and volatile matter content, acid value, peroxide value, and p‐anisidine value were significantly changed (P < 0.05) after the complete refining process. No significant variation (P > 0.05) in the iodine value was observed among all the peanut oil samples. Similar changes were observed in the DPPH radical scavenging activity and the total tocol content during chemical refining. In addition, chemical refining did not have much effect on the fatty acid composition, except for certain changes of several individual fatty acids. Moreover, the chemical refining resulted in 23.6, 23.1, and 9.5 % losses of squalene, total phytosterols, and total tocols (α, β, γ, δ‐tocopherols and α, β, γ, δ‐tocotrienols), respectively. The degumming–neutralization step caused the greatest overall reduction of these bioactive minor components. However, the concentrations of α‐tocotrienol and γ‐tocotrienol increased after full refining. Furthermore, chemical refining slightly changed the relative proportions of individual phytosterols and individual tocols.     

微波消解原子荧光光度法测定花生样品中的汞

采用微波消解技术—原子荧光光度法测定花生样品中痕量 Hg.方法检出限为0.0004μg/g,线性范围:0.001~6μg/g,相关系数 r=0.99995,相对标准偏差(RSD,n=7)4.84%~5.30%,加标回收率在91%~114%之间.实验证明:花生中有害元素 Hg 的含量远低于我国粮食(成品粮)总 Hg 允许限标准.方法简便、快速,结果准确、可靠,能够满足花生样品中痕量 Hg 的测定.     

Experimental study on separation of valuable refractory aggregate from investment casting ceramic shell waste

In the present study, a processing technique for recycling investment casting ceramic shel waste was proposed to separate valuable refractory aggregate zircon sand. The microstructure and phase constituents of the shel waste and separation process were investigated. The results show that the characteristics of microstructure and phase constituents of the shel waste can meet the conditions for preferentialy separating zircon sand, and zircon sand can be separated by gravity separation on a shaking table. The separated zircon sand has good shape and high purity, and can be used for the production of castings and other applications.     

Microwave moisture meter for in-shell peanut kernels

A microwave moisture meter built with off-the-shelf components was developed, calibrated and tested in the laboratory and in the field for nondestructive and instantaneous in-shell peanut kernel moisture content determination from dielectric properties measurements on unshelled peanut pod samples. The meter operates at a single frequency of 5.8 GHz and uses free-space transmission measurement principles for determining the dielectric properties of the peanut pods. From these properties, a dielectric-based algorithm provides peanut kernel moisture content from measurements on pods. Field tests at a peanut buying station showed that moisture content of peanut kernels can be determined with a standard error of performance of 0.82% when compared to the official moisture meter which required the pods to be shelled before kernel moisture content can be determined. When performance of both the microwave moisture meter and the official meter were compared to the oven-drying standard method, values of the standard errors of performance were 0.53% for the microwave moisture meter and 0.87% for the official moisture meter.     

Rocket immunoelectrophoresis (RIE) for determination of potentially allergenic peanut proteins in processed foods as a simple means for quality assurance and food safety

 Peanuts are one of the most allergenic foods known. The presence of hidden allergens in processed food for reasons of mislabelling or cross-contamination expose allergic individuals to unpredictable risks, especially since highly sensitized subjects may experience severe anaphylactic reactions. The protection of consumers requires specific and sensitive methods for the detection of trace amounts of potentially allergenic peanut components. A rocket immunoelectrophoresis (RIE) procedure was developed allowing the detection of even spurious contaminations with peanut protein. For precipitation of peanut protein a commercially available antiserum was used. By amplifying precipitates with a secondary immunodetection step, 20 ng/ml peanut protein in chocolate extract, equivalent to 0.0002% peanut in chocolate, could still be detected. Model chocolate spiked with various amounts of peanut was investigated down to 0.001% peanut (10 ppm), the limit of quantitative determination. The method was optimized for detection of peanut in chocolate samples. Non-chocolate samples had to be standardized with a chocolate matrix prior to analysis in order to obtain a uniform response. Cross-reactivities with other food proteins did not occur. The method showed high recoveries of 85–101% for chocolate samples down to 10 ppm peanut and good reproducibility with coefficients of variation of ≤ 5 % for samples of ≥ 15 ppm peanut protein. The applicability of this method in the detection of peanut protein in various food commodities was demonstrated: two unlabelled products and two products which did not have peanut listed as an ingredient were identified as containing peanut protein. In all cases where peanut was listed, peanut protein could be determined. The results of RIE were always confirmed by those of a new cell-mediator-release assay that is based on a rat basophil leukaemia (RBL) cell-line (RBL-2H3), cells that are a functional equivalent to mucosal mast cells. Measuring the release of β-hexosaminidase resulting from cross-linking of basophil-bound peanut-specific immunoglobulin E, the assay mimics a main event of the allergic type-I reaction. The cell assay was adapted for food matrices and peanut could be detected down to 0.01% which additionally demonstrated in vitro that even trace amounts of peanut protein could elicit allergic reactions. Received: 28 May 1997 / Revised version: 11 July 1997     

东部陆相断陷盆地及近海陆架盆地CO2成因类型

中国东部陆相断陷盆地及近海陆架盆地CO₂资源丰富,CO₂成因类型较复杂,根据CO₂通常的成因判识与划分参数及标准(δ¹³C_CO2和³He/⁴He),可明确划分为壳源型(有机和无机)、壳幔混合型及火山幔源型等3型4类,但依据20世纪90年代初以来诸多学者提出的CO₂/³He比值来判识划分CO₂成因类型,则存在较大的偏差和复杂性。通过对CO₂成因判识划分方法的对比,遵循科学性、实用性、通用性及简洁性的原则,采用通常的成因判识划分方法,对中国东部及近海陆架盆地CO₂成因进行了综合判识划分。研究结果表明,对于CO₂成因的判识划分,仍应以通常的判识与划分方法,应用δ¹³C_CO2和³He/⁴He参数指标及划分标准,对其进行综合判识划分为宜。