金枪鱼酶解液脱色工艺及其对腥味物质和金属元素的影响

为了研究活性炭对金枪鱼酶解液脱色的最佳条件,本文利用活性炭对金枪鱼暗色肉酶解液进行处理,研究活性炭添加量、pH值、温度(T)和脱色时间(t)对脱色率和蛋白质损失率的影响,采用正交试验对脱色工艺进行优化,同时探究了活性炭脱色工艺对酶解液腥味物质和金属元素含量的影响.结果表明,金枪鱼暗色肉酶解液最佳脱色条件为活性炭添加量3％、pH值3.0、温度70℃、时间1h.该条件下脱色率为89.77％±0.77％,蛋白质损失率为13.47％±0.72％;脱色后酶解液挥发性物质含量降低了85.39％,其中三甲胺、己醛、壬醛等特征腥味物质显著降低;活性炭对Pb的吸附作用较明显,其吸附率为93.2％,而对其他金属元素的吸附率不大.研究表明,经过活性炭处理过的酶解液颜色浅,腥味低,具有一定的应用前景,可为酶解液的进一步利用提供依据.     

酶处理对绿茶浸提液成分及膜过滤通量影响的研究

为解决绿茶饮料生产中出现的沉淀问题，研究了酶处理对绿茶浸提液成分及膜通量的影响。结果表明双酶水解后绿茶汁的膜过滤通量比未经过酶处理的茶汁提高21%～40%；粘度下降6%～13%，氨基态氮增加11%～41%，而茶多酚、咖啡碱等成分变化不大。并且双酶混合酶解处理后的绿茶浸提液经过超滤能有效解决绿茶饮料“冷后浑”的现象。     

Soil Chemical and Biological Activities under Vegetable Intensive Colocasia-based Cropping System in Indian Sub-Himalayas

ABSTRACT

Lack of crop diversification with suitable vegetable-based cropping system is a major constraint in limiting the productivity and sustainability of north-western Indian sub-Himalayas. To find out a sustainable vegetable-based cropping system in this region, a three year colocasia-based vegetable intensive experiment was conducted at Hawalbagh, Almora, India in a sandy clay loam soil under sub-temperate climatic conditions. Seven colocasia-based vegetable cropping systems along with rice–wheat system were compared under recommended package and practices. The system productivity in terms of colocasia equivalent yield was highest under colocasia–onion–frenchbean (52.38 Mg ha^?1) system. Sustainable yield index was highest with colocasia–gardenpea–frenchbean system (0.86). After 3 years, total soil organic carbon (0–5%), available N (2–22%), P (–7% to 14%) and K (3–15%) concentrations were increased in all cropping systems except rice–wheat system, where negative balance of available P (7%) was observed over that of initial soil. Significantly higher soil microbial activity, soil carbohydrate, dehydrogenase, protease, acid and alkaline phosphatases activity were observed under colocasia–onion system. The results suggest that colocasia–onion–frenchbean system with higher productivity improves soil fertility and enhances enzymatic activities.     

潮土和潮褐土中重金属形态与土壤酶活性的关系

采用大田取样 ,运用连续提取方法 ,研究了河北平原潮土、潮褐土两种土壤中Cd、Pb的化学形态特征与四种土壤酶 (脲酶、H2 O2 酶、转化酶、碱性磷酸酶 )活性间的关系。结果表明 :大田两种土壤中交换态Cd、Pb对脲酶活性有显著抑制作用。因此 ,在石灰性土壤中 ,把交换态Cd、Pb和脲酶活性共同作为评价土壤Cd、Pb污染程度的主要生化指标是可行的     

木瓜蛋白酶凝固大豆蛋白质机理

本文研究了木瓜蛋白酶对豆浆的凝固机理，通过酶反应过程中游离氨基和蛋白质表面疏水性的变化，初步确定酶法凝固的机理是在酶的作用下，蛋白质暴露了一些疏水基,并立即通过蛋白质分子间的疏水相互作用结合成凝胶。     

Calcium and magnesium interactions in browning of ‘Golden Delicious’ apples with bitter pit

The role of Ca and Mg in the enzymatic browning of ‘Golden Delicious’ apples was explored. Enzymatic browning due to polyphenol oxidase (PPO) was stimulated with the addition of 0.8–10 mM MgCl₂ to the reaction mixture, whereas 0.8–10 mM CaCl₂ had little effect or decreased the rate of enzymatic browning. Within a week after vacuum infiltration with MgCl₂, treated fruits exhibited browning symptoms that were similar to bitter pit. Six months after vacuum infiltration, when analyzed for enzyme activity, MgCl₂-treated fruits exhibited higher rates of PPO activity, whereas CaCl₂-treated fruits had lower activity than the MgCl₂-treated fruits and the controls. A hypothesis is advanced that the initial visible symptoms of bitter pit, i.e. the localized browning, is caused by PPO, its activity being stimulated by the localized Mg/Ca imbalance present in the tissue. The results indicate that Ca is predominant in the prevention of this disorder, whereas a deficiency of Ca is involved in its induction.     

Demonstration of inflammatory cell population changes in rat lungs in response to intratracheal instillation of spring wheat dust using lung enzymatic digestion and centrifugal elutriation

The inhalation of grain dust by grain workers is responsible for a large number of pulmonary pathophysiologies. These problems may be acute or chronic and may be mediated by the chronic activation of the immune system. Constant inflammatory states in the lung may eventually lead to tissue damage and respiratory deficit. This study was designed to measure the changes in the relative number of inflammatory cells in peripheral blood, bronchoalveolar spaces, and lung interstitium that occur in response to intratracheally instilled airborne spring wheat dust in rats. It was found that 6h after instillation with dust, neutrophils were present in greater numbers in the blood and bronchoalveolar spaces than in lung interstitium. After 24h, there appeared to be a larger number of neutrophils in the lung interstitium in dust-instilled animals than in saline-instilled controls. These results indicate that intratracheal instillation of grain dust initiates an acute inflammatory reaction, and that there is an initial influx of neutrophils into the air spaces of the lung followed by transit of these cells into the lung interstitium.     

橄榄浓缩汁加工过程中的褐变类型

通过检测橄榄浓缩汁加工过程中的多酚氧化酶(PPO)活性,多酚、VC、5-羟甲基糠醛(5-HMF)含量和褐变度等指标,研究整个加工过程中各阶段的褐变类型,分析褐变机制.结果表明:橄榄浓缩汁在加工过程中,热烫基本抑制了橄榄汁的酶促褐变,全过程以非酶促褐变为主;VC氧化褐变持续存在,加工过程中损失了90%以上;热烫、酶解和浓缩阶段发生了美拉德反应,最终5-HMF的含量升高至0.9174 mg·L-1.     

磷酸预处理对小麦秸秆酶解糖化的影响

为提高小麦秸秆木质纤维素的能源化利用效率,在常压温和条件下用磷酸对小麦秸秆进行预处理,研究了预处理秸秆颗粒度、固液比、温度、时间对小麦秸秆酶解糖化率的影响,并用扫描式电镜分析了预处理前后小麦秸秆结构的变化.结果表明,在小麦秸秆颗粒度60目、固液比1.0∶8.5、温度70℃、处理时间1.0h的预处理条件下,小麦秸秆酶解糖化率50 min时从25.4％(未预处理)提高到70.3％(预处理).SEM分析表明,经磷酸预处理后小麦秸秆崩解为碎片,为后续的酶解糖化提供了良好的条件.     

酶-超声波法提取红薯茎叶中绿原酸的工艺研究

以红薯[Ipomoea batatas(L.) Lam]茎叶为原料,采用酶-超声波提取绿原酸.对料液比、加酶量、超声功率和超声时间进行了单因素和正交试验.确定绿原酸提取的最佳工艺为料液比1∶20、加酶量1.5％、超声波功率175W、提取时间20 min,在此条件下,绿原酸的提取率为3.45％.