摘要:

ABSTRACTKojic acid (5‐hydroxy‐2‐(hydroxymethyl)‐4H‐pyran‐4‐one; also named 5‐hydroxy‐2‐(hydroxymethyl)‐γ‐pyrone) in the presence of hydrogen peroxide, but not in its absence, can be oxidized by hemoglobin (Hb) to a yellow product(s). The yellow product(s) formed is characterized by a peak at 370–380 nm and is fluorescent. The relationship between the rate of oxidation of kojic acid and various concentrations of hemoglobin and of H2O2is described. The changes with time in the spectrum of product(s) obtained when kojic acid is acted upon by the Hb/H2O2system and the relationship between the various concentrations of hemoglobin, of kojic acid and of H2O2on the spectrum of the “final

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1995.tb00523.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTCasein was phosphorylated under mild conditions with low molar ratios of POCl3(25, 50 and 100 mole POCl3/mole protein) in the presence of equivalent amounts of triethylamine. Consequently, the resulting modified proteins (4–21 mole P/mole protein) had increased negative charges, lower isoelectric points and existed mainly in a monomeric form. The extent of change in functional properties depended mainly on the degree of phosphorylation and the initial casein

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1995.tb00524.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe major globulin fraction from lentil seeds was investigated with respect to in vitro hydrolysis by trypsin and chymotrypsin. Globulin was isolated by a NaCl‐ascorbate extraction procedure and purified by DEAE‐cellulose chromatography and gel filtration chromatography on Sepharose CL‐6B. The purity and identification of the protein were performed by PAGE. The native globulin, with a molecular weight of 375 kD, was resolved by SDS‐PAGE into twelve polypeptides with molecular weights ranging from 61 to 14.5 kD. Native and heated globulin G1 was hydrolyzed with trypsin and chymotrypsin. SDS‐PAGE indicated that native globulin was more resistant to digestion than heated protein. Amino acid analysis of the major globulin revealed that glutamic acid was present in the largest concentration, followed by aspartic acid, arginine and leucine. As is also the case for other legumin‐like globulins, lentil G1 was deficient in sulfur‐containin

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1995.tb00525.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe effect of radapertization using60Co gamma radiation on the chemical and organoleptic properties of ground and whole dry pungent red pepper has been investigated. The fungal population was eliminated with a dose of 7.5 kGy and a dose of 10 kGy was required to radapertize the samples. Irradiation up to 10 kGy did not produce any significant (P>0.05) changes in the contents of capsaicin and carbohydrate. Oleoresin content was significantly (P<0.05) increased from 24.45 to 31.61% and lipid from 16.80 to 19.30%. The observed effect on apparent oleoresin and lipid contents was due to enhanced extractability. Storage time had no effect on the sensory properties of the spice but rather enhanced microbial load reduction in the medium dose (5.0 and 7.5 kGy) treated samples.A dose of 10 kGy has been certified to pose no health hazard to humans; hence decontamination of red pepper with up to 10 kGy gamma radiation does not require any further toxicological study and is therefore recommended.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1995.tb00526.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe extractability of polygalacturonase (PG) activity from alcohol‐insoluble solids (AIS) prepared from red‐ripe tomato pericarp tissue was investigated using acetate (pH 4.5), citrate (pH 4.5) and MES (pH 6.0) buffers. The acetate buffer was also investigated with increasing concentrations of NaCl, CaCl2, MgCl2, ethylenediaminetetraacetic acid (EDTA) or ethyleneglycol‐bis(β‐aminoethylether)‐N,N'‐tetraacetic acid (EGTA). Heat treatment of AIS to prepare control material suppressed PG extractability but not in situPG activity, as evidenced by the release of significant quantities of soluble uronides into extraction media. With only a single extraction, acetate buffer containing>1MNaCl yielded the greatest amount of PG activity (>50% of maximum extractability), with MES buffer being only marginally less efficient. However, 3 successive extractions over a 2 h period yielded significantly greater amounts of PG activity. The greatest yields of PG activity were obtained by successive extraction with parent MES and acetate buffers. There appeared to be little benefit in adding NaCl or a chelating agent to the extraction medium. Use of these extractants is suggested to have led to losses of PG activity during dialysis, via coprecipitation of PG protein with otherwise soluble uronide material that was released in greater quantities when these extractants were used. Increasing CaCl2and MgCl2concentrations reduced the amount of extracted PG activity similarly, to about 50% of maximum levels with successive

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1995.tb00527.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY