紫花苜蓿对九种杂草的化感作用

试验运用生物测定法研究了紫花苜蓿叶化感物质对九种受体植物的作用.结果表明,紫花苜蓿叶提取物对多变小冠花的发芽势和发芽率具有抑制作用,与对照差异显著(P＜0.05);提取物对高羊茅种子的发芽势有促进作用,与对照差异显著(P＜0.05),其最终发芽率也增加(P＜0.05);除狗尾草外,其余八种受体植物的胚根长度都受到紫花苜蓿叶提取物的抑制,与对照的差异均显著(P＜0.05);提取物对稗草、狗尾草、高羊茅、毛马唐和多变小冠花的苗长具有促进作用,与对照差异均显著(P＜0.05);反枝苋的苗长则受到抑制(P＜0.05);提取物对受体植物的幼苗鲜重均有不同程度的影响,虎尾草、匍匐翦股颖、巴哈雀稗、反枝苋和多变小冠花幼苗鲜重明显降低,与对照差异达显著水平(P＜0.05).     

奶酪风味的研究进展

综述了奶酪风味的研究进展,对奶酪的风味物质以及风味物质的提取与分析方法作了重点概述.     

Allelopathic potential of watermelon tissues and root exudates

Allelopathic potential of watermelon in hydroponic culture was investigated using the continuous root exudates trapping system (CRETS). Laboratory bioassays and high-performance liquid chromatography (HPLC) were used for quantification of phytotoxins in different plant tissues and root exudates collected using XAD-4 resin. Seedling growth of both watermelon and lettuce was significantly inhibited by watermelon root exudates and the degree of inhibition increased with increasing concentration of exudates. Root exudates had inhibitory effects throughout the experiment and these were most pronounced during the period 41–50 days after transplanting. Inhibitory effects of various plant tissues were demonstrated using the bioassay tests. Frulic acid was the dominant component found using HPLC and the amounts of allelochemicals found in the plant extracts were correlated with the bioassay results using the Petri dish test. The results indicate that the allelopathic potential of watermelon may play an important role in the phenomenon referred to as ‘soil sickness’.     

Concentrations of constitutive alk(en)ylresorcinols in peel of commercial mango varieties and resistance to postharvest anthracnose

Mature green mango fruits of commercially important varieties were screened to investigate the levels of constitutive antifungal compounds in peel and to assess anthracnose disease after inoculation with Colletotrichum gloeosporioides. High-pressure liquid chromatography was used to quantify the levels of 5-n-heptadecenylresorcinol and 5-n-pentadecylresorcinol in the peel extracts. The fruit peel of the varieties ‘Kensington Pride’ and ‘Keitt’ were observed to have the highest levels of both 5-n-heptadecenylresorcinol (107.3–123.7 and 49.9–61.4 μg/g FW, respectively) and 5-n-pentadecylresorcinol (6.32–7.99 and 3.30–6.05 μg/g FW, respectively), and the fruits of the two varieties were found to have some resistance to postharvest anthracnose. The varieties ‘Kent’, ‘R2E2’, ‘Nam Doc Mai’, ‘Calypso’ and ‘Honey Gold’ contained much lower concentrations of resorcinols in their peel and three of these varieties were found to be more susceptible to anthracnose. Concentrations of 5-n-heptadecenylresorcinol were significantly lower at the ‘sprung’ and ‘eating ripe’ stages of ripening compared to levels at harvest. Concentrations of 5-n-pentadecylresorcinol did not differ significantly across the three stages of ripening. The levels of these two resorcinols were found to be strongly inter-correlated (P<0.01, r²=0.71), with concentrations of 5-n-heptadecenylresorcinol being an average 18 times higher than those of 5-n-pentadecylresorcinol. At the ‘eating ripe’ stage, significant relationships were observed between the concentrations of each type of alk(en)ylresorcinol and anthracnose lesion areas following postharvest inoculation, P<0.001, r²= 0.69 for 5-n-pentadecylresorcinol, and P<0.001, r²= 0.44 for 5-n-heptadecenylresorcinol.     

常用国产阳离子季胺盐在蚕业消毒中的性能与应用

本文作了若干国产季胺盐对蚕业病原物的杀灭效果试验,并探讨了环境中的pH、温度,有机物,作用时间,无机离子,纤维物等对季胺盐药效的影响,及添加1％新鲜石灰后季胺盐的杀菌情况变化,认为季胺盐石灰浆在蚕业消毒中应该与漂白粉类互相补充,作为蚕业环境的常用消毒剂。文中还对季胺盐消毒效果测定中的若干问题进行了分析与讨论。     

麒麟菜即食风味食品杀菌技术研究

通过对麒麟菜多种杀菌工艺进行探讨，比较不同杀菌条件对麒麟菜风味食品外观、口感、质量的影响。结果表明：过氧化氢溶液对麒麟菜杀菌有显著效果，0.3%浓度过氧化氢杀菌10 min为其最佳杀菌工艺，经处理的产品杀菌效果符合要求，感官品质令人满意；醋酸对麒麟菜即食食品杀菌结果表明，2.5%浓度醋酸杀菌40 min，可以达到理想的效果；紫外线杀菌20 min，杀菌效果较明显，相对于产品的感官影响较小。     

Spontaneous postharvest fermentation of açai (Euterpe oleracea) fruit

Açai (Euterpe oleracea) fruit (EOF) are widely commercialized in the Brazilian Amazon. These fruit contain a high bacterial load and are transported on boards stowed inside or outside the holds of small boats. In this context, postharvest parameters were assessed under conditions that simulated these two methods of EOF transport: stowage in closed polystyrene boxes, simulating the inside of cargo holds, i.e., transport in a closed system; and open baskets, simulating transport in an open environment, i.e., transport in the prow or bow of the boat. EOF suffered spontaneous fermentation of alcoholic, acetic, and lactic types in the closed system, which is the most common type of transportation of this fruit. In the closed system, there was a predominance of lactic acid bacteria over acetic acid bacteria, with 82% and 95% of the initial content of d-glucose and d-fructose being consumed, respectively, after 27 h of experiment. The weight loss reached 1.7% and there was a logarithmic decrease of the major phenolic compounds of the fruit in the closed system, with losses of 78% of cyanidin-3-rutinoside, 88% of cyanidin-3-glucoside, 78% of homorientin, and 72% of orientin after 27 h, which was higher than in the open system (58%, 66%, 73% and 62%, respectively). Analyses on EOF stowed in a closed system indicated that the respiratory rate was characteristic of a non-climacteric fruit, i.e., it showed a logarithmic decay in the production of CO₂ (R² = 0.995; P < 0.05). Thus, transport in a closed system results in more drastic nutritional and functional changes on EOF than when transport is carried out in an open system, suggesting that transportation in continuous aerobic conditions and a short period of time between picking and processing are preferable.     

俄罗斯风味红枣枸杞酸奶的研制

目的 以鲜牛乳、红枣、枸杞为主要原料,利用俄罗斯生产的特色菌种进行发酵,探究俄罗斯风味红枣枸杞酸奶的加工工艺。方法 以感官评分和乳清析出率为指标,在单因素试验的基础上,采用正交试验确定混合汁添加量、白砂糖添加量、接种量、发酵温度和发酵时间。结果 俄罗斯风味红枣枸杞酸奶的最佳加工工艺为混合汁20%,白砂糖3%,接种量3%,发酵温度42 ℃,发酵时间4 h。结论 制得的产品呈红褐色,口感软滑,酸甜可口,质地均匀。     

圆柏枝叶对小鼠自发行为及生理生化指标的影响

选择城市绿化重要树种圆柏为研究对象,探讨北美圆柏枝叶对小鼠自发活动及其生理生化指标的影响及挥发性物质与环境间的关系。采用旷场分析法,将入组的30只昆明小鼠分成3组:对照组、低剂量组和高剂量组,低剂量组和高剂量组分别对应地暴露于210 g和420 g圆柏枝叶中,每天4 h,连续处理6 d,观察小鼠各行为指标,结合医学手段分析小鼠相应的生理生化指标。结果表明,小鼠的中央格运动路程、总路程及中央格运动时间都呈现一定的剂量反应;体质量呈稳定增长趋势;生理指标正常,生化指标有部分超出正常范围。经低浓度枝叶挥发物处理的小鼠兴奋性增强,探究和认知能力增强,且其食欲没有受到影响,但是引起部分生化指标的异常,其作用机制还需进一步的探索。研究结果为圆柏作为生态保健树用于城市森林人居环境建设绿化配置提供科学依据。     

光肩星天牛对干旱胁迫下复叶槭挥发物的嗅觉反应

对干旱胁迫下3a生复叶槭的挥发物进行了鉴定。当复叶槭受到干旱胁迫时，9种化合物释放量升高(包括：丁醇、戊醇、反—2—己烯—1—醛、顺—3—己烯—1—醇、戊醛、戊酸、己醛、己酸、苯乙酮)，而长叶烯释放量降低：复叶槭复水后苯乙酮升高，但其他挥发物释放量降低。通过GC—EAD检测了光肩星天牛对其中某些化合物的触角电位反应，并使用诱捕器和人工合成单体进行了田间生测实验。丁醇、戊醇和顺—3—己烯—1—醇能引起光肩星天牛的触角反应，这一结果在田间实验中得到了证实。这表明干旱胁迫在光肩星天牛选择寄主植物方面起着重要作用。