摘要:

ABSTRACTA gel prepared by heating pepsin‐hydrolyzed soy protein isolate (HSPI) had a higher turbidity and viscosity and less solubility than did its starting hydrolyzate. The gelling characteristics of the heated hydrolyzate were possibly due to hydrophobic interactions, as opposed to peptide bond reformation. The presence of pepsin was found to be necessary for gel formation at 37°C but could be successfully replaced by heat. Incubation of the concentrated HSPI at 95°C for 30 min was optimal for heat‐induced gel formation. When soy protein isolate (SPI) was hydrolyzed with papain or bacterial protease, little gelation occurred (either by heat or enzyme induced gelation treatm

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00817.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTHeat induced gels can be obtained from partially hydrolyzed soy protein isolate (HSPI). The gel forming ability of each of the HSPI fractions (peptides of varying molecular weight and solubility) were studied, after being separated by preparative Sephadex gel filtration chromatography. The insoluble peptide fraction had no gel forming ability. Peptides larger than 5,000 Daltons, those lower than 5,000 Daltons and a fraction of the very hydrophobic peptides formed weak gels when heated alone. Interactions between several peptide fractions were necessary in order to yield a gel with the strength of the one formed by whole HSPI. A mechanism explaining (1) the action of the proteolytic enzyme in breaking down the protein and (2) the peptide interaction needed for the gel formation, is proposed.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00818.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTChanges in cell wall pectic substances, degree of pectin methylation, bound Ca++, neutral sugar composition, and firmness were determined in mesocarp tissue of pasteurized and nonpasteurized fresh pack cucumber pickles. Large changes in solubility characteristics of pectic substances occurred in cell walls of nonpasteurized pickles that were attenuated by pasteurization. In particular, water and alkali soluble pectins declined, and nonextractable pectins increased during the first month of storage. The major changes in pectic substance solubility appeared to be related to reductions in the degree of pectin methylation with a minor influence of CaCl2. Galactose in cell walls of nonpasteurized pickles was substantially reduced, and the reduction in galactose was hindered by CaCl2or pasteurization. The amount of bound Ca++appeared to be associated with tissue firmness after one month in storage, since firmer tissue had more cell wall bound Ca++. While firmness was associated with the amount of bound Ca++, the amount of bound Ca++was dependent on the supply of Ca++and the degree of pectin methylation.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00819.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTGerminating seeds ofCassia sericeaSw. contain two molecular forms of α‐galactosidase which were partially purified and characterized. Both enzyme forms had an optimum pH of 5.0 and an optimum temperature of 50 °C. Kmvalues for the substrate p‐nitrophenyl‐α‐D‐galactoside (PNPG) were 0.91 mM and 1.05 mM for the two forms, and substrate inhibition was observed at high concentrations of PNPG. The two forms of the enzyme had molecular weights of 46,000 and 33,000 by gel filtration. The enzyme forms were inhibited completely by Ag+, Cu2+and Hg2+ions and by p‐chloromercuribenzoate showing that thiol groups are probably involved in catalysis.Both α‐galactosidases hydrolyzed melibiose and raffinose, although hydrolysis of stachyose could not be detected. The enzyme may find potential use in the food industry to hydrolyze flatulence‐causing sugars in processed foods and in production of sucrose from high‐raffinose sugar beets. That the source(C. sericeaseeds) of the enzyme is inexpensive provides an added advantage over use of cultivated legumes as a sour

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00820.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe fibrous protein paramyosin is characteristic of invertebrate muscles. It is distributed in the phyla Platyhelminthes, Nematoda, Nematomorpha, Annelida, Mollusca, Arthropoda and Echinodermata. Of these, the last three contain important edible seafood species. The molecular weights, amino acid profile and immunological features of the paramyosins isolated from many invertebrate phyla are surveyed comparatively. In addition, the paramyosin literature reported predominantly from the investigations on bivalve molluscs(Mercenaria and Mytilusspecies) is reviewed under categories (1) microstructure, (2) solubility and stability characteristics, (3) phosphorylation, and (4) involvement in catch contraction. The importance of paramyosin to the quality of seafood systems has not been studied in detail so far.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00821.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Book reviewed in this article:Muscle and Meat Biochemistry. By A. M. Pearson and R. B. Young.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1990.tb00822.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY