Evaluating the performance of PC-ANN for the estimation of rice nitrogen concentration from canopy hyperspectral reflectance

In this study, a wide range of leaf nitrogen concentration levels was established in field-grown rice with the application of three fertilizer levels. Hyperspectral reflectance data of the rice canopy through rice whole growth stages were acquired over the 350 nm to 2500 nm range. Comparisons of prediction power of two statistical methods (linear regression technique (LR) and artificial neural network (ANN)), for rice N estimation (nitrogen concentration, mg nitrogen g^?1 leaf dry weight) were performed using two different input variables (nitrogen sensitive hyperspectral reflectance and principal component scores). The results indicted very good agreement between the observed and the predicted N with all model methods, which was especially true for the PC-ANN model (artificial neural network based on principal component scores), with an RMSE?=?0.347 and REP?=?13.14%. Compared to the LR algorithm, the ANN increased accuracy by lowering the RMSE by 17.6% and 25.8% for models based on spectral reflectance and PCs, respectively.     

采前喷施LAE提高蓝莓冷藏品质及其通径分析

目的 探究Nα-月桂酰-L-精氨酸乙酯盐酸盐(Nα-lauroyl-L-arginine ethyl ester hydrochloride,LAE)处理蓝莓影响冷藏好果率及其作用机制.方法 采用逐步多元回归和通径分析方法,研究采前喷施LAE(0,30,60,90 mg/L)对蓝莓冷藏期间果实品质理化指标的影响.结果 LAE处理的蓝莓在冷藏过程中还原糖的含量高峰比对照组推迟10 d以上,有效地使贮藏前期果实保持了较高的硬度和POD活性.在整个冷藏期中,30～60 mg/L LAE处理蓝莓果实的·OH清除率与好果率之间呈极显著正相关关系(P<0.01).30 mg/L LAE处理的蓝莓冷藏15 d后,果实的硬度、可溶性固形物和还原糖含量分别比对照组高45.27％,23.81％和28.57％,总酸含量下降37.50％,好果率(86.8％)比对照组高16.04％.结论 采前喷施30 mg/LLAE能提高冷藏蓝莓的好果率,果实的·OH清除率是影响好果率的决策因子,果实硬度通过·OH清除率对蓝莓好果率产生了较大的间接正向作用.     

荔枝加工品质评价研究进展

本文阐述了荔枝加工制品的品质评价指标、加工特性与品质的相关性.针对不同的荔枝加工产品,对其加工适宜性的评价指标、影响因素进行了总结和分析;同时对加工品质评价技术和方法进行了探讨,以期为荔枝加工品质评价提供一套可行的参考方法,亦为荔枝加工产品原料的选择和品质评价提供理论指导依据.     

浙江与日本粳稻品种品质的比较

对2个浙江晚粳优质米品种（秀水11和秀水63）和日本品种（越光和日本晴）进行品质比较.结果表明,2个浙江品种的平均垩白粒率（28.85%）、平均垩白度（6.0%）分别是日本品种均值的约3倍和约6倍;平均直链淀粉含量（17.65%）较日本品种高约2%,差异达显著水平.蒸煮试验表明,2个浙江品种蒸煮品质除饭香味相仿外,其余蒸煮指标显著不及相应蒸煮处理的日本品种,其先浸后蒸处理的蒸煮品质优于现淘现蒸处理的日本晴,与越光相仿.越光籽粒外观品质明显不及日本晴,而蒸煮品质明显优于日本晴,说明理化分析指标与食味品质具有不一致性.因此晚粳稻品质育种及稻米品质鉴定应当在评价稻米理化分析指标的基础上,注重对食味品质的评价.     

Structure and composition changes in the cell wall in relation to texture of shiitake mushrooms (Lentinula edodes) stored in modified atmosphere packaging

BACKGROUND: Firmness in shiitake mushroom (Lentinula edodes) is an important textural attribute affecting consumer attitudes toward freshness and quality. In this study, the effects of modified atmosphere packaging (MAP) treatments on structure and composition changes in cell walls in relation to the texture of mushrooms were investigated. RESULTS: Shiitake mushrooms were packaged in low density polyethylene bags with no holes (M₀₎, two microholes (M₁), four macroholes (M₂), stored at 4 °C for 16 days with non‐wrapped mushrooms as control. Control mushrooms showed the highest firmness value due to significant increase of cellulose and chitin. All three MAP treatments reduced losses of protein and polysaccharides; the M₂ treatment can best preserve the original texture while mushrooms in M₀ became soft and deteriorated, possibly due to higher CO₂ accumulation, lower cellulose and chitin content. Transmission electron microscopy performed on caps at harvest and after 16 days indicated that disintegration of plasmalemma had been alleviated by M₂ treatment, leading to better preservation of the cell wall. CONCLUSION: Our results suggest that differences in firmness of shiitake mushrooms during storage may be due to differences in cellulose and chitin concentrations. M₂ treatment may be a useful way of maintaining shiitake mushrooms texture during storage at 4 °C. Copyright © 2010 Society of Chemical Industry     

芋的贮藏与保鲜

由于芋水分含量高、酚类物质存在,整芋特别是鲜切芋的贮藏与保鲜很重要。我国常见芋艿品种的贮藏与保鲜技术,整芋的贮藏与保鲜涉及室内外贮藏差异、不同的贮存介质差异、不同的品种差异、不同的芋艿部位差异以及贮藏温度的要求;鲜切芋的贮藏与保鲜涉及不同的包装材料、不同的涂膜处理、不同的加工方法、不同的保鲜剂对鲜切芋艿的影响。为芋艿贮藏与保鲜开辟新蹊径提供新思路。     

草果抑菌物质提取分离及GC-MS分析

采用超声波提取草果中的抑菌成分,以提取率和抑菌圈大小的乘积为考察指标,通过单因素实验和正交实验设计得出草果抑菌物质超声波提取的最佳工艺条件为:以60%乙醇为提取溶剂、料液比1∶16、浸泡时间20h,超声波温度55℃、超声波时间45min,得到的草果提取物提取率为10.5%,对金黄色葡萄球菌的抑菌圈大小为19.3mm。经液-液分离实验,得出乙酸乙酯部位抑菌活性最强,经GC-MS分析定性,共定性出了88种成分。     

大米饮料的稳定性研究

研究了11种不同稳定剂和乳化剂对大米饮料稳定性的影响,从中筛选出4种效果较好的稳定剂和乳化剂进行正交试验,以期提高大米饮料的稳定性。结果表明,添加0.60%果胶、0.165%黄原胶和0.60%单甘酯时,大米饮料的稳定性最好,沉淀率仅为0.87%,常温下放置3周没有出现分层现象。此外,黄原胶对大米饮料的稳定性已达到极显著水平(P0.01),果胶为显著水平(P0.05);乳化剂单甘酯和司盘40均为不显著(P0.05),但单甘酯对大米饮料的稳定性影响远大于司盘40。     

基于气相色谱-质谱技术与多元统计分析对不同栗香特征绿茶判别分析

采用气相色谱-质谱联用技术结合多元统计分析主成分分析（principal component analysis,PCA）、偏最小二乘法-判别分析（partial least squares-discriminant analysis,PLS-DA）和系统聚类分析（hierarchical cluster analysis,HCA）对18?个不同栗香特征的绿茶开展研究。结果表明,PCA、PLS-DA和HCA均可直观地对3?种不同栗香特征的绿茶进行有效区分;PLS-DA中,18?个栗香茶样基于其香气特征实现良好分离,其中R2Y＝0.843、Q2＝0.694,说明该模型对3?种栗香特征绿茶具有良好的稳定性和较好的预测能力;HCA中,3种栗香绿茶在聚类距离12处被清晰地分成3?类,其中板栗香型和嫩栗香型距离更接近,聚类效果和感官辨识基本一致。此外,基于变量投影重要性大于1,筛选出了38?种区分不同栗香特征的重要挥发性组分。     

Corrosion kinetics and patina evolution of galvanized steel in a simulated coastal-industrial atmosphere

The corrosion kinetics and patina (corrosion products) layer evolution of galvanized steel submitted to wet/dry cyclic corrosion test in a simulated coastal-industrial atmosphere was investigated. The results show that zinc coating has a greater corrosion rate during the initial period and a lower corrosion rate during the subsequent period, and the patina composition and structure can greatly affect the corrosion kinetics evolution of zinc coating. Moreover, Zn₅(OH)₆(CO₃)₂ and Zn₄(OH)₆SO₄ are identified as the main stable composition and exhibit an increasing relative amount; while Zn₁₂(OH)₁₅Cl₃(SO₄)₃ cannot stably exist and diminish in the patina layer as the corrosion develops.