摘要:

ABSTRACTLipolysis occurs extensively in fish muscle post‐mortem and is associated with quality deterioration in the frozen tissue. Fish muscle lipolysis is presented in the context of basic fish muscle physiology and lipid composition. Phospholipase A and lipases from fish muscle have been described and characterized. The reaction is usually followed by measurement of free fatty acid production, and several colorimetric assays are available. Processing and storage treatments have been shown to influence the extent and rate of lipolysis in fish muscle; most of the research in this area has been directed at the effects of frozen storage. The interaction of lipolysis and lipid oxidation is a particularly intriguing area of study as triglyceride hydrolysis leads to increased oxidation while phospholipid hydrolysis produces the opposite effec

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1981.tb00663.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTNatural actomyosin (NAM) and “crude” actomyosin formed gels yielding maximum strengths (from back extrusion force) at pH 5.0 and 5.5, respectively. At pH 6.0, NAM gels had a least protein concentration endpoint (LCE) value of 6 mg/ml. Gel strength increased exponentially with an increase of NAM concentration from 3.75–10 mg/ml. With constant time (30 min)‐temperature heating, NAM gel forces increased by 20.5% (NS, P>0.05) in the 30–80°C range. Arrhenius plots of NAM interaction in solution and in gelation at pH 6.0 indicated two different reaction mechanisms within the temperature zones above and below approximately 35°C for solutions and 40°C for gels. Similarity of interaction slopes above the 35–40°C region suggested one reaction mechanism for NAM molecular aggregation in soluti

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1981.tb00664.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTStarch from tubers ofDioscorea alata, Dioscorea cayenensis, Dioscorea dumetorum,andDioscorea rotundatawas isolated and some of the important characteristics determined. Amylose and amylopectin fractions were obtained by aqueous leaching technique. All the starches appeared to have definite but minor differences in iodine binding capacity, swelling power, solubility, intrinsic viscosity, and amylose/amylopectin ratio. Brabender amylogram of each starch showed no distinct peak viscosity, and the general amylograph pattern was distinctly different from typical amylographs of cereal starches. Amylose fractions from each starch variety exhibited variable degree of β‐amylolysis limits ranging from 92–97.5%, and an average molecular weight for amylose triacetate of 210,000 to 265,000. Amylopectin fractions subjected to debranching by pullulanase gave essentially two chain populations of polysaccharides with degree of polymerization of approximately 13–27 and 47–65, respectively. Average unit chain length of the amylopectins ranged from 19 inDioscorea rotundatato 24 inDioscorea d

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1981.tb00665.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTMethyl esters were applied to the surface of apples and when the lipids were extracted from the fruit after four weeks of cool storage it was found that, while each methyl ester was metabolised to some extent to non‐lipid compounds, there was minimal incorporation of applied methyl ester into other lipid fractions such as glycerides or phosopholipids. Methyl esters also enhanced the metabolism of [14C]—fatty acids to nonlipid compounds. Methyl stearate and lecithin reduced the rate of ethylene production while methyl linoleate and methyl oleate had no significant effect but no compound significantly changed the rate of respiration. The principal action of methyl esters and other lipids in reducing soft scald is considered not to be due to their effect on lipid composition but rather on the amount of hexanol in the fr

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1981.tb00666.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe pectic substances in two samples of New Zealand grapefruit juice were determined by a spectrophotometric method after fractional extraction of the alcohol‐insoluble solids. No significant difference in anhydrogalacturonic acid (AGA) content was found when the chromogen was formed using m‐hydroxydiphenyl and carbazole.In the analysis of the pectic substances in red and white grape berries, chromogen formation with carbazole gave AGA contents of the water‐soluble fraction of the alcohol‐insoluble solids five to seven times greater than when the chromogen was formed using m‐hydroxydiphenyl. It is suggested that phenolic material in the grape extracts reacted with the carbazole to give the higher apparent AGA

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1981.tb00667.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe influence of gamma irradiation at a radurizing dose of 1.5 kGy on the proteins of Indian mackerel (Rastrelliger kanagurta) was examined. The fish proteins were comparatively stable towards changes by the treatment, as ascertained by several parameters. However, irradiation at 1.5 kGy resulted in enhancement in tryptic digestibility of sarcoplasmic proteins and ATPase activity of myosin.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1981.tb00668.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Book reviewed in this article:Chemical Deterioration of Proteins. John R. Whitaker and Masao Fujimaki Editors.The Analysis of Dietary Fiber in Food. Edited by W. P. T. James and Olof Theander.Vitamin E‐A Comprehensive Treatise. Edited by Lawrence J. Machlin. Marcel Dekker, Inc.Methods in Enzymology, Vol. 52, Biomembranes. Part C: Biological Oxidation

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1981.tb00669.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY