摘要:

ABSTRACTPepsin A was isolated from the gastric mucosa of two year old harp seal (Pagophilus groenlandicus). Seal pepsin A has a relatively high CU/PU ratio of 0.074, although it is lower than that of calf chymosin (0.170). Equivalent milk clotting units of chymosin and seal pepsin A catalyzed formation of the same amount of nonprotein nitrogen (NPN) when incubated with 2% casein and for both there was no appreciable increase in NPN formation in the second hour of incubation. Seal pepsin A was similar to chymosin in clotting milk substrate with respect to the influence of pH, dilution, calcium chloride and temperature.Cheddar cheeses prepared with either calf rennet or pepsin A as coagulating agent were similar in yield, chemical composition and taste as judged by sensory preference tests. Estimation of protein degradation in the aged cheeses by ultraviolet absorption of citrate‐HC1 extracts, gel filtration chromatography of protein soluble in 6 N urea, and determination of amino acids indicated there was slightly more protein degradation in cheese prepared with calf rennet after 30 weeks aging.Sal pepsin A appears to make a major contribution to the excellent cheese‐making characteristic of crude seal pepsin(s). However, other components of the seal mucosa extract are probably responsible for the accelerated aging of Cheddar cheese noted in previous repo

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00348.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTIn screening 72 Candida strains for extracellular enzymes, one acidic and seven alkaline proteases, one amylase and six pectinases were found.Candida kefyr, Candida macedoniensisand four strains fromCandida pseudotropicaliswere pectinolytically active;Candida kefyrshowed considerable activity also under aerobic conditions but the highest activities were attained under strictly anaerobic conditions with N2gassing.YNB and peptone were the best nitrogen sources as regards enzyme production. The highest enzyme activities were achieved with succinic acid (aerobic) and inulin (anaerobic) as carbon sources. Enzyme production under aerobic conditions was considerably increased at pH 3.0. The addition of inducers (pectins or pectin ballast substances) led only to very slightly increased enzyme production.From kinetic studies of the enzyme, optimum activity was found to lie at pH 5.0 and 50°C. Subsequent characterization of the enzyme showed it to be an endo‐polygalacturonase.Eight to ten bands could be resolved by analytical isoelectric focussing. The Kmvalue was found to be 1.14 × 10−5mol. The maceration test, using potato, carrot and apple tissue as substrate, showed considerable maceration activity, especially in the case of

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00349.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTThe effects of brine treatments (CaCl2and NaCl) and storage on pectic substances and texture of cucumber pickles were examined. Firmness of cucumber pickles was closely associated with the solubility characteristics and degree of esterification (DE) of pectic substances. Brining, storage, time of CaCl2addition and concentration of NaCl and CaCl2were all observed to influence the characteristics of pectic substances. Important to preventing softening was maintenance of pectic substances not extractable (NXP) by conventional methods, i.e., by water (WSP), the chelator sodium hex‐ametaphosphate (CSP), and dilute alkali (OHSP). Erosion of NXP consistently resulted in increased levels of CSP and reduced firmness. Reducing the amount of demethylation of pectins was also associated with maintaining firmness. Although the DE declined rapidly during brining, tissues from treatments that enhanced firmness had pectic substances with the highest DE. CaCl2added to brine at the beginning of fermentation was most effective in preventing the demethylation of pectins and solubilization of NXP. In contrast, delayed addition of CaCl2and storage in low NaCl concentration (5% or less) caused greater pectin demethylation, erosion of NXP with concomitant increases in CSP and tissue softenin

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00350.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTThe hydrolysis of [14C]‐labelled tobacco starch byRhizopus niveusglucoamylase was investigated using thin‐layer and gel filtration chromatography. Hydrolysis was characterized by a period of rapid [14C]‐glucose release, representing 15–30% of the total radioactivity, followed by a prolonged period of slow [14C]‐glucose release. Pullulanase enhanced [14C]‐glucose release, suggesting the presence of α‐(1→6) branch points. Thin‐layer chromatography was used as a rapid screening method for detecting glucoamylase activity in fractions eluted from a DEAE column of aThermomyces lanuginosusculture filtrate, and gave results comparable to a coupled enzymatic method. [14C]‐Labelled starch fromCannaleaf was less susceptible to amylolytic digestion than [14C]‐l

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00351.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTThe effect of fermentation on the fatty acids (FA) content and composition of cassava tuber meal has been investigated. The major FA of the cassava tuber meal (CTM) lipid were oleic and palmitic acids. Other FA found in decreasing order were linoleic, linolenic, palmitoleic, stearic, myristic, pentadecanoic, heptadecanoic and nonadecanoic acids. Fermentation of the CTM resulted in substantial increases in the absolute quantities of the individual FA detected except linolenic acid. However fermentation did not alter the pattern of composition of the FA, but it caused increases in the composition of saturated FA and decreases in certain unsaturated ones. Stearic acid increased in composition by about 92.6% and pentadecanoic by about 50%. A reduction of about 72% of the linolenic acid and 24.2% of the palmitoleic acid composition were obtained in the fermented CTM lipid.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00352.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTDuring the incubation of cassava flours with or without yeast, there was an increase in the lipid with the mobility of diglyceride. Glycolipids were metabolized during the fermentation as evidenced by 17% less of hexose in the lipids. Linolenic acid fell from 11% in unincubated flour to 7% in the fermented flour. Palmitoleic acid which was a major yeast fatty acid was absent in the fermented product.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00353.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:Developments in Food Proteins—3 (ED) B. J. F. HudsonThe Chemistry of Cereal Proteins.R. LasztityStarch, 2nd Edition, Edited By R. L. Whistler, James N. BeMiller and Eugene F. PaschallFood Hydrocolloids, Vol. 2, Martin Glicksman, ed.Food Analysis, Principles and Techniques, Vol. 2. Physicochemical Techniques. D. W. Gruenwedel and J. R. Whitaker, eds.Developments in Food Analysis Techniques—3. R. D. King, ed.Modern Methods of Food Analysis.Edited by K. K. Stewart and J. R. WhitakerMethods in Enzymology.Volume 104. Enzyme Purification and Related Techniques, part C. Edited by William B. JakobyPost‐Harvest Pathology of Fruits and Vegetables.Edited by Colin DennisFood Microbiology, Volume 8, The Economic Microbiology Series, (ISBN 0–12–596558–3) A. H

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00354.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1985.tb00347.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY