摘要:

ABSTRACTIsoelectric focusing (IEF) polyacrylamide gel containing an 80% pH 4–6.5 and 20% pH 3–10 ampholyte mixture greatly improved protein banding pattern for species identification of water extracts of raw pink, white and rock shrimp compared with the system using only the pH 3–10 range ampholyte. Identification of a specific species in mixture samples was achieved by the detection of water‐extractable shrimp specific protein bands present in the gel. Sodium dodecyl sulfate (SDS) was a better protein extractant than water for cooked shrimp. Both water and SDS extracts of cooked shrimp showed specific protein banding patterns and improved resolution for species identif

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00823.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTTreatment of mushroom tyrosinase with reducing agents such as hydrogen peroxide, ascorbic acid, phenylhydrazine, gallic acid, ferrocyanide and NH2OH resulted in inactivation of the enzyme. Under the conditions tested, 50% inactivation of the enzyme was obtained with 4 μM H2O2, 20 μM ascorbic acid, 40μM phenylhydrazine, 6 mM gallic acid, 12 mM ferrocyanide and 22 mM NH2OH.The ability of the reducing agents to reduce Cu2+in a chemical model system was determined and it was found that gallic acid, phenylhydrazine, ascorbic acid and NH2OH are relatively good reductants of Cu2+while H2O2and ferrocyanide are relatively poor ones.The copper content of mushroom tyrosinase before and after inactivation by each of the reducing agents was determined. The copper content of the enzyme inactivated by H2O2, NH2OH, phenylhydrazine, ferrocyanide, gallic acid and ascorbic acid was 100%, 90%, 90%, 85%, 85% and 76% compared to that of the control (enzyme not treated).It was concluded that the degree of inactivation of mushroom tyrosinase by the reducing agents was not correlated with the decrease in the copper content of the enzyme nor with their ability to reduce Cu2+in a chemical model syst

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00824.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTHigh levels of lectin activity were found in sixty cultivated and ten wild tepary(Phaseolus acutifolius)accessions. No lectin deficient varieties were observed and all examples studied contained both the phytohemagglutinin‐E and L‐like lectins previously described (Pusztaiet al.1987). There appeared to be no obvious differences between the wild and cultivated forms of the tepary lectins and all teparies studied contained lectin‐like proteins in addition to the tepary lectins. One of the lectin related proteins (40 Kdalton subunit) was present in all teparies and may be comparable to arcelin, a lectin found in certain wild accessions ofPhaselus vulgaris.All wild teparies contained a lectin related polypeptide of about 34 Kdaltons which appears to distinguish the wild teparies from the cultivated forms. Three tepary‐common bean hybrids were examined and one hybrid was found to be expressing both tepary and common bean lecti

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00825.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTPort‐Salut, Gouda and Edam cheeses were analyzed for fat, protein moisture and ammonia evolution during commercial curing (50 days for the first two cheeses and 57 days for the last one). Fat (approximately 33%), protein (approximately 31%) on a wet basis and moisture (between 25 and 37%) content of the cheeses remained practically constant throughout the experiment, while considerable changes were observed for ammonia evolution when analyzed by direct microdistillation and by ammonia sensitive electrode, as well as between whole and defatted samples. Ammonia recovery for the microdistillation method was below the expected value for the 3 cheeses analyzed; the contrary happened with the ammonia sensitive electrode, where higher ammonia values were detected in the whole cheese samples: Gouda, 2089 mg/kg; Edam, 756 mg/kg and Port‐Salut, 2857 mg/kg. These data suggest that the use of the electrode can be a useful tool in ammonia determination, avoiding losses during sample preparation, as normally happens during microdistillation that requires defatt

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00826.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTGreen pea peroxidase isoenzymes were partially purified, identified, and grouped by preparative isoelectric focusing in granulated gel (PEGG), using a modified cascade method. Isoenzyme patterns were detected utilizing a substrate‐impregnated paper print technique.Direct application of crude extract on PEGG proved to be a valuable tool for partial purification of peroxidase isoenzymes. A substrate‐impregnated paper print technique enabled the detection of isoenzyme patterns and may replace the time‐consuming conventional peroxidase activity assay.Twelve isoenzymes (pIs ranging from 5.5–8.6), isolated on analytical thin‐layer isoelectric focusing on polyacrylamide gel, were isoelectrically ho

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00827.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTPhorone added to apples after harvest stimulated the rate of accumulation of surface lipid and decreased the rate of water loss when fruit were stored at 0°C but had the opposite effect in fruit stored at 5, 10 or 20°C where lipid accumulation was inhibited and water loss enhanced. The fatty acid composition of surface lipid from phorone‐treated fruit showed a higher proportion of linoleic acid at all temperatures. For oleic and linolenic acids, a differential effect of storage temperature occurred with phorone‐treated fruit at 0°C developing a lower proportion of oleic acid and a higher proportion of linolenic acid compared to control fruit whereas at 5° and 20°C the reverse

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00828.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe preparation and properties of polyvinylpolypyrrolidone (PVPP) and silica gel and the mechanisms by which they stabilize beer are discussed. In stabilized beer, chill stability was associated with lower protein sensitivity to precipitation with tannins. Approximately 60% of the proteoses were of low molecular weight (<10,000 daltons). The most acidic of these proteoses were the least stable in solution, being precipitated from beer by cold treatment and adsorbents.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00829.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Book reviewed in this article:What is Unique: Structure, Composition, Processing, End‐Use Properties, and Products. Y. Pomeranz, ed. 198

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00830.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY