金属表面处理工艺水洗过程研究

水洗是金属表面处理工艺中不可缺少的组成部分,其过程质量好坏直接影响到产品的表面质量。本文主要对金属表面处理工艺中水洗过程的质量要求、水洗方法、水洗水的循环再利用等进行了研究,并例举了一些应用实例,希望对金属表面处理工艺用水及供排水管理有一定的参考价值。     

PHYSIOCHEMICAL PROPERTIES AND DETERMINATION OF BIOGENIC AMINES IN KOREAN MICROBREWERY BEER PRODUCTS

In this study, 20 microbrewery beer samples collected from different regions in Korea were analyzed for their contents of biogenic amines as well as for their physiochemical properties (pH, acidity and alcohol content). The separation of biogenic amines involved derivatization with dansylchroride followed by subsequent analysis by high‐performance liquid chromatography. As a result, biogenic amines such as tryptamine (nd–1.10), 2‐phenylethylamine (nd–0.69), putrescine (0.53–3.56), cadaverine (0.10–1.56), histamine (0.13–2.65), tyramine (0.10–4.96), spermidine (nd–2.29) and spermine (nd–1.02) mg/100 mL were detected in the analyzed beer samples. Agmatine was not detected in any of the beer samples processed. The pH, acidity and alcohol contents of the tested beer samples were found in the range of 3.92–4.57, 0.17–0.38 and 3.8–7.0%, respectively. It was found in this study that threshold toxic level of the beer products analyzed was at acceptable consuming limit.     

EVALUATION OF SWEET POTATO CULTIVARS AND HEATING METHODS FOR CONTROL OF MALTOSE PRODUCTION, VISCOSITY AND SENSORY QUALITY

Two varieties of sweet potato were subjected to four cooking temperature‐time combinations. A fifth treatment involved adding maltose syrup. Raw comminuted sweet potato mash and cooked sweet potato puree were evaluated for total solids, alcohol insoluble solids, commonly occurring sugars, viscosity (puree only) and for starch gelatinization temperatures. The uncooked Owairaka Red variety was higher in total solids and in alcohol insoluble solids than the Toka Toka Gold. With the exception of the cooked puree with added maltose, baking at 200C resulted in puree with the highest maltose levels. A very fast cooking procedure tended to result in puree with lower levels of maltose and high viscosity. Sensory studies revealed that the Owairaka Red variety produced puree with more viscous and adhesive mouth feel. It was concluded that cooking alone could not be used to optimize both maltose production and viscosity.     

DISINFECTION OF SHREDDED SALAD INGREDIENTS WITH SODIUM DICHLOROISOCYANURATE

Raw salads are frequently subjected to hypochlorite wash to reduce microbial numbers, retard enzymatic activity and improve shelf-life of sensory quality. Hypochlorite dips significantly reduce the initial population of natural contaminants on lettuce. However, populations on treated and untreated samples are not significantly different after four days storage at refrigeration temperature. Increasing the level of free available chlorine does not improve the microbicidal effect.
In this study sodium dichloroisocyanurate (NaDCC) was used to disinfect salad vegetables. Though the principal salad vegetable used was butterhead lettuce, results show that the efficacy of NaDCC in reducing total aerobic mesophile levels varies with vegetable type. NaDCC gives an acid pH in solution and has significantly higher activity than sodium hypochlorite.
For longer term storage, preparation of lettuce which included a 30 min soak in NaDCC improved the microbiological quality of the produce at the end of the storage period. The microbial load on disinfected produce was between 0.62 and 0.98 log cycles lower than on lettuce prepared without a disinfection step for up     

Solid-particle erosion of hot-pressed silicon carbide and SiC-TiB2 composite

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.