Set-membership estimation from poor quality data sets: Modelling ammonia volatilisation in flooded rice systems

A set-membership (bounded-error) estimation approach can handle small and poor quality data sets as it does not require testing of statistical assumptions which is possible only with large informative data sets. Thus, set-membership estimation can be a good tool in the modelling of agri-environmental systems, which typically suffers from limited and poor quality observational data sets. The objectives of the paper are (i) to demonstrate how six parameters in an agri-environmental model, developed to estimate NH₃ volatilisation in flooded rice systems, were estimated based on two data sets using a set-membership approach, and (ii) to compare the set-membership approach with conventional non-linear least-squares methods. Results showed that the set-membership approach is efficient in retrieving feasible parameter-vectors compared with non-linear least-squares methods. The set of feasible parameter-vectors allows the formation of a dispersion matrix of which the eigenvalue decomposition reflects the parameter sensitivity in a region.     

电感耦合等离子体质谱法和液相色谱-原子荧光联用法分析广西籼稻谷中砷含量的分布

选取广西区内100份籼稻谷作为实验材料,将籼稻谷脱壳分别制成糙米和精度一级的大米,用电感耦合等离子体质谱仪(Inductively coupled plasma mass spectrometer,ICP-MS)和液相色谱-原子荧光联用仪(Liquid chromatography-atomic fluorescence spectrometer,LC-AFS)检测技术分别检测总砷和无机砷含量。结果表明该方法的标准曲线线性良好,总砷的检出限为0.0030ng/mL,无机砷的检出限为0.0139ng/mL;总砷和无机砷在糙米和精米中的分布不同,糙米总砷含量约是精米总砷含量的1.5倍,糙米无机砷含量约是精米无机砷含量的1.8倍,可见砷元素在稻谷中的分布主要富集在皮层中;而糙米中总砷含量约是糙米无机砷含量的1.6倍,可知糙米总砷含量高,其无机砷含量不一定高。     

真空包装对酵子储存品质影响的研究

研究了在不同储存条件下,真空包装和自封袋包装的酵子发酵力及其制做的馒头质构的差别,并对不同储存条件下的酵子制做的酵子馒头作感官评分。结果表明,真空包装对酵子的储存品质有较好影响,因此,酵子产品要实现工业化生产,可采用真空包装方式进行包装。     

水分对酵子储存品质影响的研究

酵子是中国人自己的传统发酵剂,在中国北方许多城市依旧使用。而酵子的研究却刚刚开始,水分是影响酵子储存品质的重要因素。制作10%、18%、30%、40%、46%不同水分含量酵子,分别测定其发酵力、pH及制作出的酵子馒头质构与白度,并作馒头感官评价。结果显示,高水分(30%、40%、46%)酵子储存品质不稳定,各项指标总体呈下降趋势;10%水分酵子因水分过低,品质虽稳定但各项指标偏低;18%水分酵子品质稳定,且各项指标优良。因此酵子储存的适宜水分为18%。     

主成分分析法用于调和油配方设计的研究

利用主成分分析,对市售38种调和油的27个因素进行分析,得到影响调和油产品得分排名的主要因素。根据分析结果,在调和油配方设计中,将油茶籽油等油酸含量较高的植物油作为优选原料油进行添加,并依据膳食脂肪酸均衡的需求,强化添加二十碳五烯酸(DHA)、二十六碳六烯酸(EPA)长链多不饱和脂肪酸成分,生产调和油。研究结果为调和油配方设计中基油的选取提供了依据。     

Control of citrus blue mold by the antagonist yeast Pichia guilliermondii Z1: Compatibility with commercial fruit waxes and putative mechanisms of action

Pichia guilliermondii strain Z1, which was previously proven to be effective against blue mold of citrus fruit, has been further tested in controlled conditions to determine whether the yeast, as an alternative for synthetic fungicides, would be compatible with other postharvest practices used commercially. In particular, commercial fruit waxes can reduce their survival and effectiveness. The commercial fruit waxes tested, in combination at 20% with strain Z1, included microcrystalline, ester gum, candelilla, beeswax, montan, paraffin, rice bran, rosin maleic, carnauba, shellac, and one mixture shellac plus carnauba. Beeswax, paraffin, rosin maleic, carnauba, and shellac increased significantly strain Z1 survival in Petri dish assays. Candelilla, beeswax, rice bran, rosin maleic, carnauba, shellac, and shellac–carnauba mixture did not significantly reduce the strain Z1 yield on orange fruit surfaces compared to other waxes. With the exception of rosin maleic wax, none of the commercial fruit waxes or mixture increased significantly the ability of the formulated product of strain Z1 to control the postharvest pathogen Penicillium italicum on wounded orange fruit. When the formulated product of strain Z1 was used in combination with beeswax, strain Z1 retained the same efficacy. In contrast, microcrystalline, ester gum, candelilla, montan, paraffin, rice bran, carnauba, shellac, and shellac-carnauba mixture significantly reduced the effectiveness of the formulated product of strain Z1. No antibiosis was detected for strain Z1 against P. italicum. Strain Z1 inhibited the spore germination for the low juice concentration (up to 5%) when compared to the control. However, the addition of fresh juice after antagonist removal allowed the restoration of the germination of P. italicum spores; suggesting the possibility of competition for nutrients in the biocontrol activity of strain Z1. The study demonstrates the potential commercial application of strain Z1 with beeswax and rosin maleic wax for postharvest control of citrus blue mold. As biocontrol relies on competition for nutrients, an enriched formulation with nutrients is needed for reliable antifungal activity of this yeast strain.     

不同干燥方式对酵子储存品质影响的研究

酵子作为多菌体混合发酵剂,其品质明显受到干燥方式的影响。采用自然风干、鼓风干燥、真空干燥和真空冷冻干燥4种常用的干燥方式分别对同一批酵子进行干燥处理,测定不同干燥方式下酵子的发酵力、pH及其制做的馒头质构、白度和并作感官评分。结果显示:酵子在鼓风干燥过程中品质降低程度较小,且相比自然风干、真空干燥和真空冷冻干燥,鼓风干燥具有干燥时间短,费用低等优点。     

太阳能低温储粮新技术

对国内低温储粮技术的现状以及发展趋势进行了探讨,重点介绍了太阳能吸附式和浅层地能低温储粮技术,分析了两种技术的工作原理、技术特点及储粮应用实例,指出了两项技术是今后低温储粮技术的发展趋势。     

液相色谱法同时快速测定植物油中TBHQ、BHA、BHT探讨

采用NY/T 1602-2008液相色谱条件分析TBHQ、BHA和BHT时,结果发现色谱图基线不稳,有杂峰干扰结果准确定量,导致BHT不能建立良好线性标准工作曲线。为建立同时快速测定该三种抗氧化剂方法,该研究采用甲醇―水(体积比85∶15)进行等梯度洗脱,对比三种标准物质色谱图;结果表明,荧光检测器(FLD)更适于定量检测TBHQ和BHA;紫外检测器(VWD)更适于定量检测BHT;色谱图均基线平稳、峰形良好,无杂峰干扰,TBHQ、BHA和BHT均能建立良好线性标准工作曲线,相关系数分别为0.99999、0.99963和0.99999;TBHQ、BHA和BHT平均加标回收率分别为102.68%、110.97%和102.39%;相对标准偏差分别为3.87%、2.46%和1.98%(n=10)。该法前处理简单、定量快速准确、方法回收率高、精密度好,适于同时快速测定植物油中TBHO、BHA、BHT三种抗氧化剂。     

利用超临界CO_2对山茶籽毛油提炼初步研究

为解决油茶籽收获季节性强和原料相对匮乏及避免常规化学精炼方法造成山茶籽油品质安全等问题,该研究以压榨山茶籽毛油为原料,采用超临界CO2技术对压榨山茶籽毛油进行提炼处理,探索提高山茶籽油品质绿色提炼方法;分析超临界CO2工艺条件对山茶籽油净油率、水分、酸价、色泽等影响;经处理后,山茶籽油品质已有明显改善。