ISSN:0027-769X    

DOI:10.1002/food.19970410602

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractAlmost 2000 bovine milk fats were analysed by gas chromatography to investigate the influence of typical barn and pasture feeding of cows ontrans‐C18:2 isomers (with at least onetransdouble bond) including the conjugated linoleic acidcisΔ9,transΔ11 (c9,t11) as well as thecisΔ9,cisΔ12 linoleic acid. Moreover, small cow herds were used to determine the influence of pasture feeding with young and older grass as well as the impact of an energy deficit or the variation of quantity and technical treatment of fed rape‐seed on the content of C18:2 isomers in milk fat. The contents oftrans‐C18:2 (w/o c9,t11) and c9,t11 in 1756 milk fats on average amounted to 0.63% resp. 0.75%. These contents increased from barn feeding in winter with 0.46% resp. 0.45% over the transiton period in spring and late autumn with 0.66% resp. 0.76% to pasture feeding in summer with 0.87% resp. 1.20%. Milk fat samples from bulk milk obtained weekly during one year from 4 large West German milk collection areas confirmed and completed the data found for the 1756 milk fats. The percentage of linoleic acid with a mean value of 1.24 (n = 1756) varied irregularly during the different feeding periods. The content of the conjugated linoleic acid c9,t11 could be raised considerably up to triple the normal amount by different changes in feeding. However, the content oftrans‐C18:1 fatty acids was strongly increased as well, r

ISSN:0027-769X    

DOI:10.1002/food.19970410603

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractFlow properties at pH 5.5‐7.5 of whey protein isolate (WPI)‐xanthan solutions containing 0‐0.5 w/w% xanthan were studied by viscosimetry, although rigidity and fracture properties of the corresponding heat‐set gels (90°C, 30 min) were determined by uniaxial compression. All the studied solutions displayed generalized shearthinning flow behaviour. Synergistic WPI‐xanthan interactions has been revealed by observing that rheological parameters [σmsf, K, n, η (γ)] characterizing blends were larger than those calculated from the two separated solutions. Such a behaviour was attributed to segregative phase separation of whey proteins and xanthan.Effects of xanthan on WPI‐xanthan gel properties both depended on pH and xanthan concentration. Simultaneous increased xanthan concentration and decreased pH inhibited gelation of WPI‐xanthan blends. Regarding gel strength, synergistic WPI‐xanthan interactions were observed at pH>7.0 and low xanthan concentration (0.05 or 0.1 w/w%). Antagonism between the two macromolecules occurred at low xanthan concentration and pH ≤6.5, and high xanthan concentration (0.2 or 0.5 w/w%) at all pH tested. Low xanthan concentration rendered mixed gels more brittle than protein gels, and high xanthan concentration decreased pH effects on gel stress‐strain relationships. The balance between strong thermal aggregation of concentrated whey proteins ‐ in presence of incompatible xanthan ‐, high viscosity of blends and repulsive surface forces of protein molecules was thought to be at the origin of WPI‐xant

ISSN:0027-769X    

DOI:10.1002/food.19970410604

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractGuava seeds were chemically evaluated for their moisture, fat, protein, ash, fibre and minerals content. The fatty and amino acids composition was also studied. Guava seed meal was used in the preparation of cookies. Chemical composition, dough characteristics as well as cookies baking quality were studied to evaluate its possible utilization. The water absorption, dough development time and stability were decreased and dough weakening was increased as the level of guava seed meal in the dough increased. Adding guava seed meal to wheat flour improved volume, specific volume, diameter and thickness of the cookies after baking. Using 9% guava seed meal gave an acceptable, but comparatively inferior product.

ISSN:0027-769X    

DOI:10.1002/food.19970410605

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractEs wurde die Möglichkeit untersucht, die Gleichgewichtsfeuchte verschiedener Stoffe durch eine geringere Anzahl von Versuchen zu bestimmen. Bei einer großen Gruppe von Lebensmitteln ist festgestellt worden, daß die Gleichgewichtsfeuchte linear von der Temperatur bei konstanter relativer Luftfeuchte abhängt. Zur Bestimmung der Gleichgewichtsfeuchte dieser Lebensmittel bei verschiedenen Temperaturen und relativen Luftfeuchten sind experimentell nur zwei Gleichgewichtsisothermen zu ermitt

ISSN:0027-769X    

DOI:10.1002/food.19970410606

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractFrom faba bean (Vicia faba L.), two new saponins were isolated by Sephadex LH‐20 gel filtration, ODS column chromatography and semi‐preparative HPLC. Their molecular weights determined by FAB‐MS were 978 and 962, respectively. Results of TLC and FTIR analyses showed that these compounds are similar to soya saponin group B. The presence of separated saponins was confirmed by TLC for seeds of four cultivars of faba

ISSN:0027-769X    

DOI:10.1002/food.19970410607

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractSince biologically active carotenoids play a significant role in metabolism and because of the fact that its stability can be affected by various factors decomposition degree of β‐carotene of various kinds of fruits after drying, freezing, blanching as well as after drying and freezing of blanched fruits has been researched in order to prolong their consumption time‐limit. The β‐carotene content was determined by means of the spectrophotometric method measuring adsorbance intensity at 450 nm. The results of investigation reveal that the decomposition degree of β‐carotene increases significantly with storage time. Depending on the kind of fruits, treatment and storage time it ranged from 6.10% to 68.74%. No significant differences have been found after a longer storage between blanched and non‐blanched fruits, either dri

ISSN:0027-769X    

DOI:10.1002/food.19970410608

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractSafrole was determined using gas‐liquid chromatography in some common spices as star anise, cumin, black pepper and ginger. Safrole concentration in these spices was 9325, 3432, 955 and 500 mg · kg−1, respectively. Black pepper was chosen to use in the following experiments.UsingAmes‐test withSalmonellaTA 98 and TA 100 proved high cytotoxic effects due to pure safrole and black pepper volatile oil in both of them.The degradation of safrole was obvious after drying of the washed seeds of black pepper especially at 70 °C for 30 min or with sun‐drying. Also, high irradiation doses (20 and 30 kGy) caused high degradation of more than 90% of the initial toxic concentration in black pepper. Whereas, microwave caused same effects at 75 s, but unfortunately, the powder was burned due to moisture absence. Boiling whole seeds or powder of black pepper during cooking for few minutes (1‐5 min) were more efficient in decreasing safrole content.Finally, these results proved that the mutagenicity of some spices due to presence of safrole can be destructed during drying of the washed seeds or during cooking either with or without any additional treatment as irradiation. But irradiation of these spices became more necessary for using in some food industries as milk products to get more safe for human

ISSN:0027-769X    

DOI:10.1002/food.19970410609

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractAn investigation was made for the occurrence of Zearalenone (ZEN) and Zearalenone producing fungi in cereals (corn, 50 samples; rice, 45 samples; wheat, 40 samples) collected from Egypt. ZEN was detected in 15 of 50 corn samples with an average concentration of 22.3 ppb. The incidence of ZEN in rice samples was 8.9% (4 samples of 45), and the average was 15.5 ppb. Out of 40 wheat samples 5 samples were contaminated with ZEN (12.5%) with an average of 8.8 ppb. Seventy‐nineFusariumstrains belonging to 9 different species were isolated from Egyptian cereals, and when tested for ZEN production only 26 isolates were Zearalenone producer. Efficiency of H2O2for destruction of ZEN in contaminated corn was studied at different concentration (3, 5 and 10%). The results revealed that per cent of disappearance of ZEN was found to be dependent upon the concentration of H2O2, temperature and period of exposure. The highest per cent of degradation was 83.9%, with 10% H2O2at 80 °C for 16 h, followed by 75% at the same conditions for 8 h, while the lowest one obtained by 3% H2O2at 50 °C for

ISSN:0027-769X    

DOI:10.1002/food.19970410610

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe instrumental and sensory texture attributes of beef muscles (M. longissimus dorsiandM. semimembranosus) were compared after curing and thermal treatments. Shear, compression and puncture tests were carried out with an UTM Instron 4301 and the sensory evaluation was made with the score method. The force values obtained for puncture test gave a greater degree of correlation with the sensory tenderness, hardness and elasticity than the shear test forces. The shear test forces were found to significantly correlate with sensory tenderness only for muscles with perpendicular orientation of fibres to the direction of shear blade movement. The evaluation of beef texture with compression test was dependent on the level of sample deformation degree. The force values of compression were found to correlate significantly with elasticity and juiciness of meat up to 60% deformation levels, but at deformation levels higher than 60% appeared significant correlation with tenderness and hardness. The obtained results showed the usefulness of puncture test with proposed parameters for the instrumental measurements of beef texture.

ISSN:0027-769X    

DOI:10.1002/food.19970410611

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY