Identification and fermentation optimization of protopectinase-overproducing strain Aspergillus niger CD-01 for pectin production

In order to solve the citrus peel resource waste problem and minimize the drawbacks of chemical extraction of pectin, a protopectinase-overproducing strain CD-01 for pectin production was isolated from a pit soil dumped with perished orange in Changde City, Hunan Province of China. The strain CD-01 had the same morphology and 28S rRNA gene sequence (FJ184995) as that of Aspergillus niger (ATCC 64028). It was thus identified and named as Aspergillus niger CD-01. The fermentation condition was optimized based on L₉(3⁴) orthogonal experimental design and the variances analyses. The results show that the optimal condition for producing pectin is as follows: time 36 h, temperature 35 °C, pH 5, and urea as the nitrogen source. Under this condition, the pectin yield can reach up to 24.5%. This shows a great potential of Aspergillus niger CD-01 in pectin extraction from citrus. Foundation item: Projects(50621063, 50674101) supported by the National Natural Science Foundation of China     

基于超像素快速模糊C均值聚类与支持向量机的柑橘病虫害区域分割

针对目前柑橘病虫害图像数据集较少,病虫害目标复杂、散漫,难以自动定位分割的问题,提出了一种基于超像素快速模糊C均值聚类（SFFCM）与支持向量机（SVM）的农业柑橘病虫害区域分割方法。该方法充分利用了SFFCM快速、鲁棒的优点,且融合了空间信息的特点,同时避免了传统SVM在图像分割上需要人工选择样本的缺点。首先,利用改进的SFFCM分割算法对待分割图像进行预分割,得到前景和背景区域;接着利用形态学中的腐蚀和膨胀操作对前景和背景区域进行缩小,然后自动选取训练样本进行SVM模型训练;最后用训练好的SVM分类器完成整幅图像的分割。将所提方法与快速鲁棒模糊C均值聚类（FRFCM）、原始SFFCM及边缘引导网络（EGNet）这三种方法进行实验对比,结果表明所提方法的平均召回率为0.937 1,平均精确率为0.941 8,平均准确率为0.930 3,均明显优于对比算法。     

Modelling and Thermal Analysis of Tray‐layered Fruits inside Ventilated Packages during Forced‐air Precooling

Ventilated packaging is widely used in the forced‐air precooling practice for horticultural produce. Fresh fruits are living organisms which are sensitive to temperature in turn related to airflow and heat transfer inside package. In this study, a transient mathematical model considering heat of respiration and evaporation is developed to predict the thermal response of tray‐layered fruits in ventilated packages during forced‐air precooling. Specifically, the heat source is combined with the energy conservation equation and loaded into numerical solution by User Defined Function (UDF). Temperature profiles of three variously distributed circular and oblong vents in three different patterns (spaced, paralleled and crossed stacking) are simulated, separately. The results show that the heat source affects fruit cooling process, and the layered fruit in paralleled stacking pattern tends to be cooled better than others. Furthermore, the results indicate that vertical oblong vent could improve the longitudinal and lateral airflow, while non‐central vent design could greatly improve the overall cooling performance. Definitely a triangular distribution of three circular vents was superior to laterally distributed centre vents with 66.5% higher uniformity and 2.5°C lower of the highest temperature. Compared with the three identical vertical oblong vent conditions, vent design with one hand hole and two side vertical oblong vents can be cooled more uniformly with an increase of 6.5%. It is revealed that vents with large major‐to‐minor axis ratio could be applied to balance airflow and ease cooling differences for a rapid but uniform cooling. Experimental validations were performed for Sim2, Sim4 and Sim6, Sim8, Sim9, and good agreement was obtained considering the five vent conditions with the error less than 3.5°C but coordinated later (within the limits of the experimental uncertainty).Thus the numerical model can be used to predict and optimize temperature distribution within precooling packages. Copyright © 2016 John Wiley & Sons, Ltd.     

水果贮藏保鲜技术的进展

概述了中国水果生产及其贮运保鲜现状,根据中国的特点有选择地介绍国外水果贮藏保鲜新技术,探讨了中国水果贮藏保鲜的发展方向。     

利用柑桔加工废弃物制取糖蜜及乙醇

柑桔加工废弃物约占果实质量的50%,含大量糖分,适宜制备糖蜜和发酵生产乙醇.研究了用废弃物制取糖蜜及生产乙醇的工艺和条件.结果表明,柑桔皮渣制取糖蜜时,生石灰的适宜添加量为0.3%,制得的可溶性固形物为40%的糖蜜,总糖含量为34%.对pH值、糖度、接菌量和温度等影响发酵的主要因素做单因素研究基础上开展了正交试验,得到柑桔糖蜜发酵的较佳工艺条件为：发酵液的初始pH 5.0,初始含糖量25%,接种量3×107个/mL,温度保持在30℃,静置发酵.由此获得含量为10.6%的乙醇产品,为探索用柑桔糖蜜生产燃料乙醇提供了参考.     

中国果品加工产业现状及发展趋势

中国是世界上最大的水果生产和加工国,果品加工业已成为我国农产品加工业中具有明显比较优势和国际竞争力的行业.介绍了我国果品加工产业现状及发展趋势,分析了制约果品加工产业发展的主要问题,并提出相应的对策与建议.     

基于机器人采摘的柑橘机械特性研究

柑橘果实的机械特性,是设计针对柑橘采摘机器人末端执行器的重要依据.该研究利用弹性力学的赫芝(Hertz)理论对柑橘果实的受力与变形量的关系进行了理论分析,并通过对成熟柑橘进行匀速加压试验验证了该理论的分析结果,同时得到了该类柑橘果实的抗压机械特性.另外,还通过实验进一步分析研究了柑橘果实与硅胶材料之间的摩擦特性和柑橘果柄的切割特性,从而为设计实现柑橘抓持与果柄切割的柑橘采摘的机器人末端执行器提供准确的依据.     

提取方法对橙皮和桔皮中挥发油成分的影响

实验采用共水蒸馏的方法进行提取，随着蒸馏时间的延长，出现从未焦糊到完全焦糊的过程，挥发油中的主要成分的含量也随之改变．文中论述了实验室共水蒸馏的提取方法、过程，并对结果进行了分析，如果针对其中最主要的成分1-甲基-5-亚乙基环庚烯来说，焦糊状态有利于富集．