摘要:

AbstractThermodynamic properties of aqueous solutions of both native and modified legumin of broad beans (Vicia fabaL.) have been examined. A restricted trypsin‐induced proteolysis was used to modify protein structure. Evaluation of protein affinity to ficoll in aqueous solutions showed that modified protein possessed higher hydrophilicity. Thermodynamic properties of diluted solutions were used to predict the phase behaviour in concentrated systems containing protein and ficoll. At specific concentrations of native legumin, the system can separate in two phases, whereas in the case of modified protein the single‐phase behaviour of the system was predicted for any concentrations of both components. The experimental data obtained in concentrated systems confirmed predictions of thermodynamic analysis of diluted soluti

ISSN:0027-769X    

DOI:10.1002/food.19920360202

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractExtraction and precipitation conditions were investigated to determine the optimum conditions for preparation of a near‐white protein isolate from grapeseed flour, treated with ammonium hydroxide and defatted. Extraction and precipitation of protein was studied under the following conditions: Particle size (80 mesh). flour to solvent ratio (1:5–1:40), pH (1–12), NaCl medium (1–10%), extraction time (15–60 min) and precipitation pH (3–5). Protein solubility was less than 65% above pH 10. Using 60–80 mesh flour and extracting at pH 11 for 30 min with a flour to solvent ratio of 1:15, a protein isolate was obtained by acidification to pH 4.5 containing 84.7% protein and representing 48.2% of the crude protein in the grapeseed. The isolate was relatively low in sulphur‐containing amino acids and lysine but rich in other essential and non‐essential amino acids and had a digestibility of 91.3%. The isolate showed reasonably good whipping and emulsifying characteristics as well as water an

ISSN:0027-769X    

DOI:10.1002/food.19920360203

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractDie effektiven Algorithmen der Objektisolierung in Binärbildern können leicht auf Grauwertbilder übertragen werden, wenn ein Entscheidungskriterium bekannt ist, mit dem die Bildpunkte in Objekt‐ und Untergrundpunkte eingeteilt werden können. Hierzu werden drei verschiedene Methoden diskutiert. Außerdem werden Objektmerkmale definiert, die aus dem Grauwert der Objektpunkte resul

ISSN:0027-769X    

DOI:10.1002/food.19920360204

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractThe stability of apple puree at different constant temperatures (‐18°C, 4°C, 20°C, 50°C and 60°C) was studied within the period of 30 days. During this time changes in the samples of apple puree, which was stored at variable temperature, were determined as well. The content of ascorbic acid, the sucrose inversion, the formation of furfural and levulinic acid as well as sensory properties were followed as criteria of the puree quality. From obtained data the temperature dependence of these reactions was derived. On this base the shelf life of apple puree (the time, after which the sensory differences became significant) was estimated. This period was relatively short, i.e. less than 100 days at 20°C. The changes in puree at variable temperature were similar to those at higher storage temperatures (40

ISSN:0027-769X    

DOI:10.1002/food.19920360205

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractInclusion of 50 μl/ml cell‐free culture liquid ofEnterococcus faecalisvar.liquefaciensin skim milk intended for culturing separately 20 multi‐ and single‐strain starters did not increase the acid production by the starters and neither the cell growth nor the proteolysis was stimulated. On the contrary, both growth and acid production were variably inhibited, with the reduction in acid production not always resulting from growth inhibition. The inhibition ranged from 0 to 99% for growth and 0.5 to 62% for acid production and was maximum by heating the cell‐free culture liquid at 100°C for 5 min. Growth of the single‐strain starter cultures was affected by the heated but not the unheated culture liquid in general.The crude inhibitor proved to be non‐neutralizable, non‐dialyzable, sensitive to proteolysis and resistant to heat (100°C for 30 min) at 0.59% acidity, implicating bacteriocin‐like agent as a participant in the antimicrobial activity. Enterococcin positive strains ofEnterococcus faecalisare, therefore, unsuitable for inclusion in the multi‐strain starter cultures in cheese making even though these variants might have a good ability to grow at low temperatures and exhibit excellent fermentative and proteolytic characteristics in addition to high salt‐tolerance. Multiplication of these strains in raw milk might also result in failure of the growth and acid production b

ISSN:0027-769X    

DOI:10.1002/food.19920360206

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractThe effect of gamma‐irradiation and the antimicrobial food additives on growth and aflatoxin B1production byA. flavusNRRL 5520 in poultry diet was investigated. By increasing the irradiation doses the viable population as well as aflatoxin B1production decreased greatly. No growth and no detection of aflatoxin production occurred in poultry diet after treatment with 6 kGy. The addition of the antimicrobial food additives resulted in a significant decrease in aflatoxin B1. Growth and toxin production was completely inhibited by 0.64% sodium propionate, 0.134% potassium sorbate and 0.1% sodium bisulfite. The combination treatments between gamma‐irradiation (3 kGy) and sodium propionate (0.48%), potassium sorbate (0.022% and 0.044%) and sodium bisulfite (0.0334% and 0.0667%) inhibited completely the fungal growth and aflatoxin B1production. At 5 kGy, no growth was recorded and aflatoxin B1production was completely inhibited at all tested levels of priopionate, sorbate and bisulfite. The combined effects between gamma‐irradiation and the antimicrobial agents had a synergistic effect on the mould growth and aflatoxin production in poultry

ISSN:0027-769X    

DOI:10.1002/food.19920360207

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractThe formation of water‐insoluble complexes of ribulose‐1,5‐bisphosphate carboxylase with pectins was studied using gel‐permeation chromatography and phase analysis. The decrease in the pectin charge density accompanying an increase of its esterification degree caused both the lowering of its content in the complex precipitate and the shift of pH value, corresponding to the maximum of ribulose‐1,5‐bisphosphate carboxylase subunit precipitation, towards the isoelectric point of the protein. The increase in ionic strength decreases the amount of pectin in the complex precipitate. Pectins with an exterification degree of 98% presumably form the soluble protein‐pectin complexes. The evidence of fractionation of protein subunits accompanying the formation of soluble and insoluble complexes with pectin has been given. The results obtained suggest a principal role of the electrostatic factor in the formation of water‐insoluble complexes of ribulose‐1,5‐bisphosphate carboxylase with pectins. The formation of water‐soluble complexes of ribulose‐1,5‐bisphosphate carboxylase with pectin of a high esterification degree presumably occurs due to the forces of

ISSN:0027-769X    

DOI:10.1002/food.19920360208

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractMikroorganismen sind in der Lage, eine große Anzahl von Aromastoffen bzw. von Aromen als Sekundärmetabolite zu synthetisieren. Daraus resultiert ein zunehmendes Interesse an der biotechnologischen Produktion solcher Verbindungen. In dieser Arbeit wird der Kenntnisstand zur mikrobiellen Aromastoffsynthese unter besonderer Berücksichtigung von Fruchtnoten mitgetei

ISSN:0027-769X    

DOI:10.1002/food.19920360209

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractDeterpenation of black pepper oil was carried out by column chromatography, and three different oil‐silica gel ratios have been studied to achieve the conditions of maximum economy with reasonable efficiency. The quantitative composition of the oils was established by physical constants and gas‐liquid chromatography. The ratio 1:2 adsorbent‐oil produced sesquiterpeneless oil with the lowest terpene content, but with lower recovery than 1:1 ratio. The last one is proposed as the best adsorbent‐oil ratio in terms of maximum economy and good

ISSN:0027-769X    

DOI:10.1002/food.19920360210

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY

摘要:

AbstractThe suitability of dynamic headspace (DHS) method for isolating the volatile components of cocoa butter for subsequent GC analysis was evaluated. Volatile trapping followed by solvent or thermal desorption was performed with different adsorbent traps. DHS analysis by thermal desorption performed with Porapak Q showed the best results in terms of reproducibility and recovery of volatiles.

ISSN:0027-769X    

DOI:10.1002/food.19920360211

出版商:WILEY‐VCH Verlag GmbH    

年代:1992

数据来源: WILEY