基于多元图像分析的包装罐内壁缺陷检

为提高包装罐生产线内壁缺陷检测准确性与可靠性,研究了一种采用单摄像机的内壁缺陷检测系统.利用基于形态学的区域提取算法,从罐内图像中分割出内壁检测区域图像.提出基于多元图像分析(MIA)的内壁缺陷检测算法.利用图像融合构成环形合格样本图像,消除罐内焊缝区域的影响,把多个环形合格样本图像与测试样本内壁检测区域图像堆叠起来,用重合区域的图像构造多元测试图像.用基于主成分分析(PCA)的多元图像处理方法获得多元测试图像的主分量表示,将去掉第一主分量和噪声后的Q统计图像作为内壁缺陷特征的检测空间,利用阈值处理检测缺陷,解决了罐体内壁照明困难、亮度不均造成缺陷误检率高的问题,提高了检测系统的准确性和鲁棒性.实验表明对内壁缺陷检测的误检率降低到2%,验证了检测系统的有效性和可靠性.     

包装机粘稠物料断流管径数学模型的推导与验证

活塞式计量泵出口管道直径的大小直接影响着包装质量和包装效率,通常采用试验的方法找出合适直径的管道,不但浪费大量不锈钢管材,而且费时费力。经过理论推导和在试验基础上合理简化,得出了包装机粘稠物料断流管径理论数学模型。通过试验验证,该模型具有比较高的精度。     

Effects of new packaging solutions on physico-chemical,nutritional and aromatic characteristics of red raspberries (Rubus idaeus L.) in postharvest storage

Postharvest life of raspberries (Rubus idaeus L.) is limited due to their high respiration rate, loss of firmness and freshness and susceptibility to fruit rot. The aim of this research was to evaluate the effects of various packaging solutions on physico-chemical, nutritional and aromatic properties of raspberries during storage at +4 °C up to 7 days. Plastic materials with low (LDPE) and high (LDPE/EVOH/LDPE) gas barrier, a biopolymeric film (PLA) with medium gas barrier and micro perforated stretch film (PVC) were used. The packaging material modified the composition of the atmosphere in the package, which depended on the combined action of the respiration activity of the fruit and the permeability of the material. Results showed that the most sensitive parameters for the assessment of raspberry decay were percentage of damaged berries, weight loss, fruit softening and the aromatic profile development, evaluated by an electronic nose; these parameters showed significant changes during storage and were influenced by the packing material. All samples showed a clear loss of firmness after 4 days of storage, which was maximally reduced in the case of LDPE/EVOH/LDPE and PLA packages. Raspberries stored in PVC packaging material had an aromatic development similar to the control, whereas berries stored in the medium and high barrier materials showed important changes in the aromatic profile, reflecting anaerobic metabolism of fruit. Soluble solids, pH, total phenolics and ascorbic acid did not change significantly; changes in colour and total anthocyanins were observed, with differences depending on the kind of packaging.     

Losses in litchi at various stages of supply chain and changes in fruit quality parameters

During May and June of 2012 and 2013, a study was conducted to assess losses at the farm, wholesale and retail levels in the supply chain of litchi in India. Changes in fruit quality parameters after harvest and the effectiveness of an improved corrugated fibre board (CFB) box versus conventional wooden box packaging to minimize postharvest losses were also studied. Farm-level samples were collected immediately after harvest from farmers' orchards in the Muzaffarpur district of Bihar state. Wholesale market samples were procured from the Delhi market, and retail samples from the Muzaffarpur and Delhi market. Real-time data on losses and quality parameters of fruits were recorded by transporting litchi from Muzaffarpur to Delhi (distance 1000 km) by truck. Studies indicated that the average loss (fruits discarded at sorting) apparent at the farm level during 2012 and 2013 was 30.4% and 25.8%, respectively. The average loss at the wholesale market level in Delhi was 15.8% and 12.4% during 2012 and 2013, respectively. The highest mean loss (up to 20.5%) was observed at the retail level. The mean fruit weight loss during transport to Delhi was 9.42% and 7.07% during 2012 and 2013, respectively. The mean total loss in the supply chain of litchi ranged from 35.3% to 43.8%. The total soluble solids, respiration and ethylene evolution in litchi fruits were found to increase after transport, whereas acidity and colour parameters (L*, a* and b* values) significantly decreased over time. The predominant pathogen associated with fruit decay was Alternaria alternata (Fr.) Keissler. CFB packaging significantly reduced various losses, thus indicating its effectiveness in its current use in non-refrigerated trucks for transport.     

荔枝常温保鲜技术研究

为延长荔枝常温保藏期,将柠檬酸、脱氢乙酸、氯化钠配合使用,分别对兰竹和乌叶两个品种的荔枝进行处理。结果表明:常温下,乌叶比兰竹耐贮藏,使用复配保鲜剂处理结合保鲜膜包装荔枝,兰竹可贮藏5d,好果率达100%;乌叶可贮藏6d,好果率达100%。为实现远距离输送,先用双乙酸钠进行抑菌处理,再进行冰块结合泡沫箱包装可贮藏6d,果实仍保持原来色泽和香味,适合于少于4d的汽车运输,从而打破荔枝的区域间的限制。     

Modified atmosphere packaging alleviates chilling injury in cucumbers

Cucumbers (Cucumis sativus L.) packaged in perforated or sealed 31.75 μm (1.25 mil) low density polyethylene (LDPE) bags were found to have less severe chilling injury than nonwrapped fruit in storage at 5 °C and 90–95% relative humidity. The onset of chilling injury was also delayed by the LDPE packaging compared to the nonpackaged control. The concentrations of CO₂ increased to 3% while O₂ levels decreased to 16% in the sealed bags. Fruit in the sealed bags had the least decay. The O₂ and CO₂ concentrations inside the perforated bags changed very little from the ambient atmosphere. However, there was a marked difference in the weight loss between nonwrapped cucumbers and fruit from perforated or sealed bags. The weight loss of nonwrapped fruit reached 9% in 18 days while perforated and sealed samples lost less than 1% during the same period. Chilling stress induced increases in putrescine levels in all treatments but the sealed fruit had the highest levels of putrescine. Sealed fruit and perforated fruit also had higher content of spermidine than non-wrapped fruit. These high levels of polyamines may have contributed to the increase of chilling tolerance in fruit from perforated and sealed packages.     

秸秆包装容器挤压机关键部件的设计研究

为了生产环保型秸秆包装容器,针对包装容器制作工艺进行分析,阐述了挤压机工作原理.通过对植物秸秆和添加剂混合后的物料进行力学参数测量及挤压工艺的分析,确定秸秆包装容器挤压机关键部件定量送料机构,采用螺杆式输送给料机构;挤压机构采用凸轮式挤压进给机构.根据设计要求,进行了螺杆式输送给料机构的参数化设计和凸轮曲线外廓的设计.设计分析表明,秸秆包装容器挤压机关键部件的设计能够满足挤压工艺要求,结构简单、可靠,能完成工作要求.     

气调包装对冷却肉护色保鲜效果的研究

不同气体成分比例和不同包装材料影响冷却肉的贮藏保鲜品质。本研究通过填充不同比例的CO、CO₂和N₂,结合不同阻隔性能的包装材料,分析气调包装对冷却肉护色保鲜的效果。结果表明当充气比例为1%CO、25%CO₂和74%N₂时冷藏21d,冷却肉的出水率为1.54%,红度值(a*)值最大,细菌总数增加量最少,挥发性盐基氮含量最低,色泽、风味和外观感官性能最佳,综合护色保鲜效果最优。同时,高阻隔性的包装材料能显著性地维持冷却肉的色泽,降低失水率,抑制微生物的生长。本研究显示适宜的气体成分组成配合高阻隔性的包装材料,更加有利于冷却肉的护色保鲜。     

韭菜薄膜包装的冷藏效果

模拟舰船冷藏库温度(2℃,9℃),应用海军医学研究所和国家农产品保鲜工程技术中心提供的保鲜袋对韭菜进行保鲜贮藏。结果表明,2℃贮藏条件下用适当的塑料袋(如HDPE+CaCO3、HDPE+分子筛)不密封包装,可使韭菜贮藏期迭15 d,失水率1％左右,腐烂率几乎为0,感官新鲜。     

不同包装材料对生菜采后生理及保鲜效果的影响

为探索低温条件下适宜的包装材料,以5种不同包装材料PA/PE、OPP/CPP、HDPE、PE、PD961包装的生菜为研究对象,研究不同包装材料对生菜采后生理及保鲜效果的影响。结果表明:经过包装处理的生菜贮藏效果优于无包装组,其中HDPE包装材料较好地保持了叶用生菜的叶绿素含量和感官品质,延缓了呼吸高峰的出现、抑制PPO酶活性,贮藏效果最好。不同包装材料对生菜采后生理及保鲜效果存在明显差异,其效果依次为HDPEOPP/CPPPEPA/PEPD961。