气相色谱法测定黄瓜、苹果中的虫螨腈残留量

为了对虫螨腈在黄瓜和苹果上的残留分析方法进行探讨,采用乙腈提取、Flolisil 小柱净化、GC-μECD进行检测。结果表明：黄瓜上添加标准品0.005、0.01、0.5μg/g 的回收率分别为115.6%、86.4%、82.8%,相对标准偏差分别为2.6%、7.6%、9.2%;苹果上添加标准品0.005、0.1、0.5μg/g 的回收率分别为109.2%、95.9%、94.6%,相对标准偏差为8.0%、4.2%、7.6%;田间试验得到的虫螨腈在黄瓜的消解动态方程为y ＝0.0431e － 0.1665x,半衰期为4.2d;虫螨腈在苹果上的消解动态方程为y=0.1115e － 0.0734x,半衰期为9.4d。本方法灵敏度、准确度、精密度高,能够为大规模监测蔬菜水果中虫螨腈的残留情况提供参考。     

海藻糖涂膜对鲜切苹果品质的影响

目的为了抑制鲜切苹果发生酶促褐变,改善其口感,延长其保质期。方法以富士苹果为实验材料,研究质量分数不同(0%,0.1%,0.5%,1%,5%)的海藻糖涂膜剂处理对鲜切苹果的保鲜效果,并测定褐变指数、Vc含量、SSC含量、可滴定酸含量、MDA含量等指标。结果采用海藻糖涂膜剂处理鲜切苹果的最佳质量分数为1%,可显著提高其品质。经质量分数为1%的海藻糖处理鲜切苹果后,其色泽口感俱佳,褐变抑制作用较强,明显降低了褐变指数和MDA的增长率,延缓了Vc、SSC和可滴定酸等含量的下降。结论海藻糖涂膜处理不仅可以抑制鲜切苹果在贮藏期间的褐变进程,而且还可以赋予其更好的风味,提高产品的品质,延长其保质期,对鲜切果蔬的保鲜研究具有重要意义。     

枸杞糕的研制

通过正交实验,研究了不同糖酸比、增稠剂种类和浓度以及苹果含量对枸杞糕的风味、质地、颜色的影响,从而确定其最佳配方。     

基于电子鼻表征霉心病苹果特征气味及无损检测模型建立

为探究电子鼻检测技术对霉心病苹果的判别效果,以富士健康苹果和霉心病苹果为试材,基于SIMCA软件对采集的不同病变程度霉心病苹果的电子鼻信息进行表征,基于SPSS 23.0软件建立霉心病苹果Fisher函数、多层感知器神经网络(muhilayer perceptron neural network,MLPNN)和径向基函...     

Liquid chromatography–electrospray ionization–tandem mass spectrometry method for determination of twenty multi-class pesticide residues in cashew

This paper describes an analytical methodology employing the extraction QuEChERS (Quick, Easy, Cheap, Effective, Robust and Safe) method and liquid chromatography coupled to mass spectrometry using electrospray ionization source (LC–ESI–MS/MS). The methodology was validated for the determination of twenty multiclass pesticides in cashew. It was evaluated for selectivity, linearity, limits of detection (LOD) and quantification (LOQ), matrix effect, as well as the precision and accuracy in terms of percentage of recovery. Analyses were performed by selected reaction monitoring (SRM) using two transitions (precursor ion → ion product). All pesticides studied showed good linearity with correlation coefficient greater than 0.99. LODs and LOQs ranged from 0.10 to 0.25 ng g⁻¹ and 0.30 to 0.75 ng g⁻¹, respectively. Due to the complexity of the sample, study the effect matrix was performed. Cashew apples samples spiked (5, 50 and 100 ng g⁻¹) showed recovery results ranging from 66 to 119 g/100 g, and RSD ≤ 12%, which is in accordance with standard recommended by Brazilian rules (ABNT NBR 14029/2005), except simazine. The validated method was applied to commercial samples obtained in Fortaleza-CE, Brazil, but no contamination of pesticides residues was observed.     

一种集苹果自动筛选、装套的流水线设备

文中设计了一种能帮助果农实现苹果颜色的自动化筛选及给苹果装网套的设备,可以对不同种类的苹果进行颜色筛选以及装套两种操作。该设备的高度集成一体化设计,使其具有结构简单、使用方便、操作简捷等特点,既可以用于大规模种植苹果的个体户,也可以用于大型农业合作社。     

Sensory effects of hexanal vapor on fresh-cut slices of golden delicious apples

Hexanal is a natural antimicrobial molecule that characterizes apples aroma. In this paper, the sensory effects of hexanal, as a component of packaging atmosphere, on fresh sliced Golden Delicious apples after storage at 4 °C for 8 d were evaluated. In particular, a colorimetric analysis of slices treated with different concentrations of hexanal vapor (coming from 3.040 to 0.076 mmol of liquid aldehyde per liter of air) fixed at 0.076 mmol/L the amount of hexanal in evaluating sensory effects in the subsequent analysis. Color and texture evaluation of slices by Two-out-of-Five method did not highlight any significant difference between treatment and control. The results from olfactory evaluation showed instead that treated samples had an intense odor compared with those untreated (P < 0.001). A significant difference between treatment and control was also highlighted during the flavor evaluation (P < 0.01); however, from the panelists' observations it emerged that such an effect would work negatively. The positive effect of the tested dose of hexanal on the odor of Golden Delicious slices and its flavor acceptability were verified by using regular apple consumers. A significant preference (P < 0.001) for the odor of treated apple slices came out, so the small dose of hexanal intensifies the odor of apples pleasantly. The different flavor of treated samples was not identified by the consumers, who altogether expressed positive judgments about it. This suggests the nicety of this difference that in the absence of an untreated reference sample is very difficult to detect.     

苹果脆度的近红外无损检测

为了更好的对苹果的脆度进行检测,试验应用波长范围为643.26～985.11nm的Purespect近红外透射光谱仪对60个富士苹果的校正集样品和20个预测集样品进行了光谱扫描,比较了不同的光谱预处理方法和不同建模波段对模型的影响,最终确立的模型相关系数(Rc)为0.941,校正均方根误差(RMSEC)为0.390。对模型预测性能的验证结果表明:建立的苹果脆度模型性能较稳定,能满足实际应用的要求。