茶树精油-海藻酸钠复合涂膜对鲜切苹果品质的影响

以山东富士苹果为试材,通过测定鲜切苹果经不同浓度茶树精油(0.1％、0.3％、0.5％(V/V))和1.5％(m/V)海藻酸钠复合涂膜处理后,在4℃贮藏过程中失重率、硬度、可溶性固形物含量、色差、VC含量、总酚含量及抗氧化活性的变化,研究茶树精油-海藻酸钠复合涂膜对鲜切苹果品质的影响.结果表明:适宜浓度的茶树精油复合海藻酸钠涂膜处理可以有效保持鲜切苹果的鲜度和硬度,减少失重率的增加和可溶性固形物含量的降低,抑制褐变,同时减缓VC含量、总酚含量和DPPH自由基清除能力的下降速度.其中,1.5％海藻酸钠和0.1％茶树精油复配涂膜处理鲜切苹果的效果最佳.该研究结果可为茶树精油复合海藻酸钠涂膜在鲜切水果保鲜上的深入研究和应用提供参考.     

不同硬脂酸添加量下大豆分离蛋白/海藻酸钠膜特性研究

为改善大豆分离蛋白/海藻酸钠复合膜的耐水性,通过添加不同添加量（0、2%、4%、6%、8%、10%）硬脂酸制备大豆分离蛋白/海藻酸钠/硬脂酸三元复合膜,探究硬脂酸对大豆分离蛋白/海藻酸钠复合膜的机械性能、阻水性能和微观结构的影响,最终明确不同硬脂酸添加量对耐水性变化的影响规律。结果表明：与大豆分离蛋白/海藻酸钠二元复合膜相比,添加6%和8%硬脂酸后,复合膜的断裂伸长率、水蒸气透过率显著下降,并且对其含水率及水溶性也有显著影响。当硬脂酸添加量为8%时,三元复合膜的水蒸气渗透性最低,水蒸气透过系数为（2.95±0.49） g·mm/（m²·h·kPa）,接触角最大,为91.68°±9.02°。通过傅里叶变换红外光谱和扫描电子显微镜分析可知,大豆分离蛋白和海藻酸钠通过共价交联形成网络结构,加入的硬脂酸则分布在网络结构的缝隙中,当硬脂酸添加量为8%时,膜的表面较为光滑平整,内部结构致密,能够形成良好的网络结构,键与键之间结合较强,能有效提高复合膜的阻水性能。     

NaCl溶液处理亚热带土壤水分特征曲线差异与模型优选

携带大量盐分的低质水长期灌溉导致土壤存在极大的物理化学特性退化风险,为了探究盐分对土壤水分特征曲线影响的差异性,采用压力膜法对亚热带地区粘性潮土、沙性潮土、红壤、紫色土、水稻土等5种土壤进行室内测定,对比分析了各土壤在0、5、10、15 g/L等4个钠盐浓度水平下土壤水分特征曲线的差异,并利用RETC软件结合数理统计方法确定了各土壤不同钠盐浓度水平下相应的最优拟合模型。结果表明:钠盐处理均可提高各土壤的持水能力,且粘粒含量较高的土壤影响显著;钠盐处理减少了粘性潮土、沙性潮土和红壤的有效含水率,分别最大减少了40.8%、30.5%、31.5%,却提高了紫色土、水稻土有效含水率,分别最大提高了45.7%、28.9%。粘粒含量少或低浓度盐溶液处理的土壤水分特征曲线以BC模型拟合最优,而粘粒含量多且高浓度盐溶液处理的以DP-M模型拟合最优。     

Effect of ABA,arginine and sucrose on protein content of date palm somatic embryos

Abscisic acid (ABA), arginine and sucrose were evaluated for their effects on the morphology, germination rates and protein content of date palm somatic embryos (SE). Different concentrations of these supplements in the culture medium were used. The comparative study of SE length and thickness between treated and untreated SE revealed no differences, except for ABA (20 μM), which increased thickness. A decrease of water content (WC) in favor of an increase in dry weight (DW) was observed in all treated SE, especially with sucrose (90 g l⁻¹) and ABA (20 μM). Only ABA (20 and 4 μM) caused a proliferation rate of the cultures higher than those in the control. Although all the tested compounds increased protein content, ABA (20 μM) was more effective in protein enrichment than arginine and sucrose treatments. The SDS-PAGE protein profiles showed a significant difference between treated and untreated SE. A protein band of 22 kDa, identified as glutelin in a previous work, was accumulated after treatment with 20 μM ABA or 3 mM arginine. These findings may contribute to further understanding of the mechanisms involved in the accumulation of specific storage proteins in several plants.     

Hyperaccumulation of selenium in hybrid striped bass: a functional food for aquaculture?

One method of increasing the value of aquacultured product is to produce fillets that are fortified with minerals that are beneficial to human health – that is enhance the functionality of an already healthy product. A good candidate mineral in this regard is selenium (Se) which is of vital importance to normal metabolism in humans. In order to evaluate the dose response and tissue accumulation of supplemental dietary Se, a study was undertaken with hybrid striped bass (HSB). Animals were fed diets supplemented with either organic (0–3.2 mg kg^?1 as SelPlex^®) or inorganic (0.2 and 0.4 mg kg^?1 as sodium selenite) Se for 6 weeks. Because basal fishmeal‐based diets contained 1.22 mg Se kg^?1, doses of Se delivered equated to 1.22–4.42 mg kg^?1. At trial end, greatest weight gain was observed in fish receiving 0.2 mg Se kg^?1, irrespective of form (organic/inorganic). Se accumulation in HSB liver and fillet revealed a classical dose‐response once a threshold level of 0.2 mg Se kg^?1 was surpassed. Greatest tissue accumulation of Se was observed in fish fed the 3.2 mg Se kg^?1 level (P > 0.0001). A 100 g portion of Se‐enhanced HSB fillet would contain between 33 and 109 μg Se, amounting to a dietary intake of between 25 and 80 μg Se; a level that would satisfy present daily intake recommendations. Comparison of tissue Se levels indicated that the muscle provides a more conspicuous gauge of dietary Se dose‐response than does liver. Dietary treatments of between 0.4 and 1.6 mg organic Se kg^?1 reduced (P < 0.024) plasma glutathione peroxidase (GSH‐Px) activity. No differences were observed in ceruloplasmin, lysozyme or GSH‐Px activities between organic and inorganic Se when delivered at the 0.2 mg Se kg^?1 level. Ceruloplasmin, lysozyme and GSH‐Px levels were elevated (P ≥ 0.025) in fish fed the diet containing 0.4 mg inorganic Se kg^?1.     

石灰、硅酸钠和羟基磷灰石对烟草吸收镉的影响

为了探讨施用不同钝化剂对烟草吸收富集镉的效果,采用盆栽试验研究了石灰、硅酸钠和羟基磷灰石对Pb-Cd复合污染土壤上的烟草镉吸收富集的影响。结果表明,土壤pH值均随3种钝化剂用量的增大而升高,而土壤有效镉(DTPA-提取)含量则随之降低。土壤有效镉的最大降幅分别为:32 g/kg羟基磷灰石处理(52.4%)16 g/kg石灰处理(37.0%)12.5 g/kg硅酸钠处理(14.1%)。3种钝化剂都降低了烟株各部位镉的含量,其对烟叶镉含量的平均最大降幅分别为87%(16 g/kg石灰处理),74.7%(12.5 g/kg硅酸钠处理)和82.2%(32 g/kg羟基磷灰石处理)。石灰和羟基磷灰石对镉在根-茎之间的转移无显著影响,而硅酸钠则显著降低了镉在根-茎之间的转移。综上,镉污染的植烟土壤可以施用这些钝化剂以降低烟叶中镉的含量。     

Polymerisation of gluten proteins in developing wheat grain as affected by desiccation

The breadmaking quality of wheat is affected by the composition of gluten proteins and the polymerisation of subunits that are synthesised and accumulated in developing wheat grain. The biological mechanisms and time course of these events during grain development are documented, but not widely confirmed. Therefore, the aim of this study was to monitor the accumulation of gluten protein subunits and the size distribution of protein aggregates during grain development. The effect of desiccation on the polymerisation of gluten proteins and the functional properties of gluten were also studied. The results showed that the size of glutenin polymers remained consistently low until yellow ripeness (YR), while it increased during grain desiccation after YR. Hence, this polymerisation process was presumed to be initiated by desiccation. A similar polymerisation event was also observed when premature grains were dried artificially. The composition of gluten proteins, the ratios of glutenin to gliadin and high molecular weight-glutenin subunits to low molecular weight-glutenin subunits, in premature grain after artificial desiccation showed close association with the size of glutenin polymers in artificially dried grain. Functional properties of gluten in these samples were also associated with polymer size after artificial desiccation.     

可食性液态膜复合保鲜剂对番茄保鲜效果的研究

以番茄为试材,通过壳聚糖、可溶性淀粉、羧甲基纤维素钠配制成不同浓度的复合保鲜液浸泡涂膜处理,研究其对番茄保鲜效果的影响。结果表明,复合保鲜液涂膜可有效地降低番茄果实的失重率、腐烂率、可溶性固形物含量,抑制多酚氧化酶活性,维持番茄VC含量,保持番茄果实较好的感官品质,且以0.5%壳聚糖+0.8%可溶性淀粉+0.3%羧甲基纤维素钠复配的复合保鲜液涂膜对番茄有较好的保鲜效果,15℃环境下其货架期延长到15 d以上。     

Na2CO3胁迫对非洲凤仙种子萌发及幼苗生长的影响

采用室内水培试验,以不同浓度(10,20,30,40,50,60,70 mmol/L)的Na2CO3对非洲凤仙种子和幼苗进行胁迫处理,测定其种子发芽率、发芽指数、发芽势和叶绿素含量等指标.结果表明:各项指标与Na2CO3胁迫浓度呈明显负相关.当Na2CO3浓度达到50 mmol/L时,发芽率、发芽指数和发芽势显著下降,说明高浓度Na2CO3溶液对种子的萌发具有强烈的抑制作用.Na2CO3胁迫使叶绿素含量显著降低,严重影响幼苗的光合能力,抑制幼苗的正常生长.     

亚硒酸钠浸种对春小麦种子萌发特性的研究

为研究硒浸种对春小麦种子活力和幼苗生长特性的影响,分别设置0,0.5,1.0,2.5,3.5,5.0,10.0,50.0 mg/L共8个亚硒酸钠溶液浓度,通过发芽试验,比较研究了不同浓度的亚硒酸钠浸种对春小麦种子萌发和幼苗生长的影响.结果表明:随着亚硒酸钠溶液浓度升高,春小麦种子的发芽率、发芽势、发芽指数、活力指数、幼苗和根长以及干鲜重等指标均呈先升高后下降的趋势;1.0 mg/L的亚硒酸钠溶液对小麦种子萌发和幼苗生长有促进作用;随着亚硒酸钠浓度的升高(≥2.5 mg/L),其各项指标显著下降,并对根和苗的生长表现出抑制作用;因此在实际生产中,掌握合适的硒浸种浓度非常关键.