喷雾干燥在环保领域中的应用

环境保护是我国的基本国策之一,近年来呈蓬勃发展之势.本文主要介绍了喷雾干燥在半干法烟气脱硫、味精废水综合利用、造纸黑液处理等环保领域内的广泛应用.     

南宁味精厂废水处理工程剩余污泥脱水实验及工程试运行

采用加热和絮凝等方法对南宁味精厂废水处理工程剩余污泥进行调理，研究各种方法对其脱水性能的影响。结果表明，絮凝和加温的方法均能提高污泥的脱水性能，其中絮凝方法效果更为明显。水浴加热试验中，温度升到60℃时滤速达到35mL／h；微波加热试验中，只需加热50s滤速就可达到35mL/h。絮凝试验中，聚丙烯酸钠最佳投药量为50mg／L，此时滤速为5．2mL／min。从技术经济角度考虑，在实际工程运行中，采用加温(60℃左右)与投加絮凝剂(聚丙烯酸钠投量为O．2‰)相结合的方法，可使污泥脱水效果得到提高，经压滤后污泥含水率可降至60％～65％。     

Effect of monosodium glutamate on physicochemical properties and quality of Alkali‐treated Pacific white shrimp

Physicochemical properties and quality of Pacific white shrimp (Litopenaeus vannamei) treated with alkaline soaking solution (ASS; 0.75% NaOH with 2.5% NaCl) containing 3% monosodium glutamate (MSG), pH 11.5 (ASS+3% MSG) were investigated, in comparison with those treated with mixed phosphates or ASS alone. Muscle proteins underwent conformational changes as evidenced by the shift of T_max to the lower temperature and the increased negative charge when treated with ASS+3% MSG. This coincided with the higher moisture and NaCl contents (P < 0.05). Such a treatment led to the pronounced swelling of muscle fibrils as visualised by scanning electron microscope. Highest likeness score for all attributes except for flavour was observed in sample treated with ASS+3% MSG. Slightly fishy odour in the treated sample was associated with higher abundance of volatile compounds, especially alcohol and aldehyde. Thus, ASS+3% MSG could be used as the replacer of phosphate and bicarbonate for shrimp processing.     

中性红催化光度法测定微量铁

研究了在稀硫酸介质中,Fe~(3+)催化H_2O_2氧化中性红的褪色反应,建立了一种高灵敏的测定微量铁的新方法。该方法线性范围为2～32 ngFe~(3+)/mL,表观摩尔吸光系数为3.97×10~5L/(mol·cm)。用于味精中铁的分析,回收率为95%～105%,结果满意。     

Umami peptides: assessment of their alleged taste properties

 In the literature there are reports that 31 di-and tripeptides elicit umami (i.e. monosodium L-glutamate-like or MSG-like) or savoury tastes. However, the occurrence of “umami peptides” is questioned with regard to the high specificity of those that give an umami taste. A total of 12 dipeptides and 4 tripeptides were selected for a re-examination of their taste properties. Criteria were that: (1) their taste has been described as umami, savoury or brothy; (2) they have a threshold value; and (3) they should fit into the theoretical framework of L-glutamyl peptides discussed. The peptides – in aqueous solutions, at room temperature, at pH 6.0 and 4.0, and at concentrations well above the reported threshold values – were tasted. Panel members were selected on the basis of their ability to perceive the umami taste of 2.67 mM MSG at pH 6.0. None of the peptides tested was found to elicit an umami taste. The taste of L-glutamic acid in the peptides was lost and furthermore the taste of bitter amino acids in the peptides was no longer perceivable. Within the range of Glu-X peptides, even Glu-Glu and Glu-Asp, which have previously been reported to elicit umami tastes, did not taste MSG-like either in pure solution or in the presence of sodium chloride. The tripeptide Ala-Glu-Ala, reported to have an “umami threshold” value as low as 0.8 mM, was found not to have an umami taste or any other specific taste up to 10 mM. The general occurrence of umami peptides appears to be highly unlikely. Received: 6 December 1996     

膜技术在传统调味品生产中的应用

膜分离技术是一种高效分离技术，它具有无相变、能耗低和操作方便等优点，已在传统调味品生产中开始应用，并体现出巨大的优越性。对膜技术的分离原理、膜组件以及影响膜通量的因素等进行了介绍，并探讨了各种膜分离技术在酱油、食醋等发酵调味品生产及废水处理中的应用。     

酶法分离制备γ-氨基丁酸和L-天冬氨酸

以L-谷氨酸(L-G lu)和L-天冬氨酸(L-Asp)两种混合酸性氨基酸〔m(L-G lu)∶m(L-Asp)=1∶1〕为原料,利用大肠杆菌菌体内脱羧酶对L-谷氨酸的专一脱羧作用,酶法分离制备了γ-氨基丁酸和L-天冬氨酸。考察了转化体系温度、pH等影响L-谷氨酸脱羧酶活力的主要因素,实验表明,最佳工艺条件为:温度35℃,转化体系pH=5.0,ρ(菌体)=6 g/L,ρ(Tween80)=0.15 g/L,菌龄16 h,ρ(底物)=60 g/L。L-谷氨酸脱羧酶在最适转化条件下比酶活高达15 036 U。1 g湿菌体可重复使用3次共转化L-谷氨酸和L-天冬氨酸混合物30 g,其中L-谷氨酸完全转化为γ-氨基丁酸。γ-氨基丁酸及L-天冬氨酸的总收率可分别达到理论收率的88%和90%。     

鸡精发展概略

通过对鸡精、味精的对比使人们对鸡精有了更全面的了解。     

谷氨酸发酵母液提取菌体蛋白技术

采用聚丙烯酸钠絮凝－气浮分离技术处理谷氨酸发酵母液，SS和COD析去除率分别达到85％和35％，大大的减轻了后续处理的有机负荷，同时能够从1吨发酵母液中提取出20.4kg菌体蛋白饲料。     

三段式生物法处理味精和饮料生产废水

根据味精废水和饮料废水水质互补性较强的特点,将味精废水和饮料废水混合,可降低味精废水中有机污染物浓度,并提高饮料废水可生物降解性。选用水解酸化-接触氧化-生物炭三段式生物法工艺对混合废水进行处理,节省了工程投资。2年多的运行结果表明,在混合进水中有机污染物、氨氮等浓度较高的条件下,经上述工艺处理后,出水水质可达到GB 8978—1996的一级排放标准,COD和BOD的去除率均超过99%,氨氮的去除率超过96%。