ISSN:0027-769X    

DOI:10.1002/food.19950390502

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractTransfatty acids (TFA) are supposed to be related to a variety of physiological effects. Numerous studies in this field are gathered and compared, which mainly deal with the influences on lipoprotein levels in plasma and their effects with regard to coronary heart diseases. Furthermore, the analytical accessibility oftransfatty acids by different methods is presented. Thus, the most reliable method for an exact quantitation oftransfatty acids in edible fats is the combination of Ag‐TLC with GC. The contents of TFA, in particulartrans‐octadecenoic acids, in bovine and human milk fat, in partially hydrogenated vegetable fats and oils as well as in processed food from different countries, determined in numerous studies, are summarized. Especially results on the isomeric distribution of positional isomers oftrans‐octadecenoic acid may be of future interest, since negative metabolic activities might only originate from certain isomers. Finally, intake rates of TFA in several countries are presented. It can be concluded that there still is need for further nutritional studies and that the discussion about TFA should not neglect the comparison with the saturated fatty acids C12, C14 an

ISSN:0027-769X    

DOI:10.1002/food.19950390503

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the past, the ultracentrifuge has provided much information on the sizes, shapes and interaction of food proteins. The availability of new on‐line instrumentation has now extended the possibilities for analysis even further. In this short review we examine the state of the art of the technique and its past, present and potential future contributions to the field of food protein research. After a consideration of the developments in instrumentation and their implications, we focus on the contribution to the following areas: 1. gross conformation analysis (ellipsoid, bead and general conformation representations). 2. Molar mass and subunit composition analysis. 3. Self‐association 4. Protein‐polysaccharide and protein‐ligand interactions 5. Gels and matrix diffusion ph

ISSN:0027-769X    

DOI:10.1002/food.19950390504

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractChanges of the surface tension at a planar interface and of the emulsifying properties of tryptically digested legumin from faba beans (enzyme/substrate ratio = 1/40) were studied in terms of time of hydrolysis (0 – 48 h). Simultaneously, molecular changes of legumin were studied by determination of liberated amino groups, RP‐HPLC, and SDS‐PAGE analysis.While the surface tension continuously decreases with increasing amount of liberated amino groups, improved emulsion properties, i.e. decreasing droplet size and increasing coalescence as well as creaming stability, were only observed during the first 240 min of hydrolysis, where increase in the content of free amino groups amounted to 18 – 24 free amino groups per protein subunit. The surface tension during the diffusion‐controlled phase reached the lowest value after a hydrolysis time of 24 h which corresponds to an increase of 44 – 50 free amino groups per protein subunit. Additionally, the results support the view that the interfacial adsorption at quiet interfaces and during emulsion formation are governed by different transport

ISSN:0027-769X    

DOI:10.1002/food.19950390505

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractLipase from defatted rice bran has been isolated by a new procedure which yields higher enzyme activity and quantity of enzyme. The procedure involves selective ammonium sulphate precipitation followed by ion exchange chromatography using DEAE‐Sepharose CL‐6B gel and column chromatography. The purified and homogeneous enzyme is also characterized for its various optical, enzymatic, physico‐chemical and hydrodynamic properties. The enzyme has an ultraviolet absorption maximum at 276 nm with an extinction coefficient value of 15.25. The fluorescence excitation and emission maximum values for the enzyme are 285 and 344 nm, respectively. The enzyme has a specific activity of 18 units [μeq · mg−1· h−1] with a pH optimum of 7.5 and a temperature optimum of 30 °C. The enzyme has an average hydrophobicity value of 3980 J/residue and the NPS (frequency of occurrance of non‐polar side chains) and P (ratio of polar to non‐polar amino acids) values are 0.29 and 1.13, respectively. The enzyme has a sedimentation coefficient value of 2.30 S and the isopotential partial specific volume is 0.697 ml/g. The molecular weight of the enzyme is 30000 and the enzyme is made up of at least two subunits. The enzyme contains 16% alpha‐helix, 39% beta‐structure and the

ISSN:0027-769X    

DOI:10.1002/food.19950390506

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe dynamics of changes in extractable protein content, total α‐ and β‐amylolytic activity, α‐amylolytic activity, anti‐α‐amylolytic and antitryptic activities as well as of pH values during malting process of selected wheat grain variety were studied. The effect of the microflora on the native amylases and their inhibitors were accounted for by microbiological evaluation of wheat grain and malted wheat. After steeping at 72 h the pH of water extracts of wheat grain decreased from 6.4 to 6.0 in samples germinated with gibberellic acid (GA3), and to 6.1 in samples germinated without GA3added. Further decrease of pH up to 5.8 was noted during germination in the case of GA3added. On the other hand the increase of native α‐amylolytic activity and activities of endogenous inhibitors within the first 72 h (steeping) of malting process of wheat grain with and without GA3added were hightly correlated. Rapid increase of wheat grain extractable proteins were started 24 h later. Physiological importance of these findin

ISSN:0027-769X    

DOI:10.1002/food.19950390507

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of the study was to determine the effects of unintended freezing during cold storage (deep chilling conditions) and low freezing temperatures (−10 °C) of raw pork loins, cured and smoked, on their histological structure and some physicochemical characteristics. The experimental products after freezing at −10 °C, were stored at the same temperature for 0, 2, 4 and 6 days, thawed thereafter and immediately deep chilled at near cryoscopic temperature (−3 °C) for 0, 2, 4 or 6 days.These conditions were changing the histological structures of pork loin, the water holding capacity (WHC) was reduced by frozen storage but improved by deep chilling; the maximum shear force and energy were increased. The more the freezing at −10 °C was prolonged, the more unfavourable were the changes in structure, WHC and tenderness. Deep chilling at −3 °C after thawing of the experimental material on the other hand favourably affected the parameters measured. Freezing at −10 °C and deep chilling at −3 °C did not affect the electrophoretic picture of pork loin proteins nor the water activity. Freezing itself had no influence on WHC. Changes

ISSN:0027-769X    

DOI:10.1002/food.19950390508

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractFatty acid profile in plasma was examined in 12 adult vegetarians (lacto and lacto‐ovo) aged 41‐63 years with an average period of vegetarian nutrition of 9.8 years. Difference in the content of saturated and monounsaturated fatty acids in vegetarians was insignificant (compared to non‐vegetarians). Positive factor of vegetarian nutritional habit with respect to atherosclerosis included significantly elevated content of linoleic acid (C 18:2) and linolenic acid (C 18:3), as well as unchanged or only slightly reduced content of polyunsaturated fatty acids ‐ arachidonic acid (C 20:4) and docosahexaenoic acid (C 22:6,n= 3). Favourable values of prooxidative‐antioxidative parameters (significantly reduced content of conjugated dienes of fatty acids in plasma, significantly higher plasma levels of vitamin C, β‐carotene, vitamin E/cholesterol ‐ indicator of LDL protection and vitamin E/triacylglycerols ‐ indicator of fatty acid protection) demonstrated a reduced risk of lipoperoxidatio

ISSN:0027-769X    

DOI:10.1002/food.19950390509

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe kinetics of peroxide accumulation during oxidation of triacylglycerols of sunflower oil at 100 °C in presence of different concentrations of hexane, ethylacetate and ethanol extracts ofMelissa officinalisL.,Mentha piperitaL.,Mentha spicataL.,Ocimum basilicumL.,Origanum vulgareL. andSaturejae hortensisL., was followed. Ethanol extracts are the most active in retarding the autoxidation process. The most effective are the extracts ofSaturejae hortensisL. (stabilization factorFfor 0.5% direct hexane and 0.5% direct ethanol extracts being 14.8 and 24.0, respectively), followed by the extracts ofMentha piperitaL. (F= 7.4 and 19.6, respectively) andMelissa officinalisL. (F= 7.4 and 18.6, respectively). Some of the spices are recommended as sources of natural antioxidants for stabilization of polyunsaturated lipid systems

ISSN:0027-769X    

DOI:10.1002/food.19950390510

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractBenzyl‐ITC (benzyl isothiocyanate) reacts preferentially with amino groups and sulfhydryl side chains of bovine sarcoplasmic proteins to form thiourea and dithiocarbamate derivatives, generally resulting in a decrease in solubility of the derivatives along a wide pH range. Under these conditions, it was also possible to show that secondary amine side chains, as found in tryptophan. also react with benzyl‐ITC. A quenching of tryptophan fluorescence intensity after interaction with benzyl‐ITC was also observed. Polyacrylamide gel electrophoresis (PAGE) experiments in the presence of urea indicated changes in electrophoretical mobility and in composition of subfractions. Changes in surface hydrophobicity and composition as determined by the ANS (8‐anilinonaphthalene‐1‐sulfonate) methode and RP‐HPLC were also observed. Polymerisation of protein molecules after reaction with benzyl‐ITC was documented using the SDS‐PAGE technique. These investigations showed that a group of subfractions belonging mainly to glycolytic enzymes and associated proteins with molecular weight between 38 – 70 kDa

ISSN:0027-769X    

DOI:10.1002/food.19950390511

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY