摘要:

AbstractEffect of extrusion (120 °C; 8–12 s; extruder S 45‐12‐10 U) on amino acids and nutritive value of casein preparations in the form of calcium and low‐calcium paracaseinates and in acidic form was studied. The following indices were found to decrease slightly: chemical score (CS) from the range 57.4–58.8 to 57.2–58.1; essential amino acids (EAA) from 86.1–88.3 to 84.9–88.1; NPU from 61.4–67.6 to 60.2–66.6; PER from 2.40–2.47 to 2.38–2.45; apparent digestibility (AD) from 84.9–87.2 to 84.8–87.2; true digestibility (TD) from 90.7–95.3 to 90.4–92.8 and biological value (BV) from 66.6–71.0 to 65.8–69.6. These results prove that the extrusion at 120 °C does not result in a significant lowering of the prote

ISSN:0027-769X    

DOI:10.1002/food.19930370102

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effects of 5‐vinyloxazolidine‐2‐thione (VOT), 1‐cyano‐3‐butene (CYB) and various isothiocyanates on parameters of hepatic phase I and phase II biotransformation were investigated in male rats after oral treatment for 3 consecutive days. The compounds with the exception of CYB caused increases in liver weight and glutathion S‐transferase activity. Cytochrome P‐450 level and monooxygenase activities were decreased by the isothiocyanates and CYB. Administration of VOT resulted in contrasting response of monooxygenases: reduced aminopyrine N‐demethylation and enhanced aniline hydroxylation. Possible mechanis

ISSN:0027-769X    

DOI:10.1002/food.19930370103

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractEffect of various preservatives, sugar, ascorbic acid and light on the stability of sunset yellow and tartrazine was studied. While sulphur dioxide enhanced the rate of degradation of sunset yellow, it stabilized tartrazine in aqueous model systems. At 30 and 45% sugar levels, the rate of degradation of both sunset yellow and tartrazine was practically same in the presence of benzoic acid and sorbic acid. At 15% sugar level, the rate of degradation of tartrazine was slightly higher in the presence of sorbic acid. Incorporation of ascorbic acid enhanced the degradation of both sunset yellow and tartrazine and its effect was considerably higher in the presence of light. Increase in sugar concentration enhanced the stability of both the dyes, but light enhanced their degradation.

ISSN:0027-769X    

DOI:10.1002/food.19930370104

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractDer Nährwert des Gemüses ist an seinem spezifischen Beitrag zur menschlichen Ernährung zu messen, wobei dem Gehalt an Vitamin C, Caroten, Rohfaser, Calcium und Eisen besondere Bedeutung zukommt und in einem “Wesentlichen Nährwertfaktor” zusammengefaßt wird. Die während der Lagerung ablaufenden Stoffwechselvorgänge und anderen biochemischen Umsetzungen erfordern allerdings eine dynamische Betrachtung des Nährwertfaktors im Hinblick auf die variablen Nährstoff‐komponenten. Auf der Basis der in Abhängigkeit von der Lagertemperatur (Θ) und der Lagerdauer in Tagen (xi) eintretenden Qualitätsveränderungen wird das Modell eines “dynamischen wesentlichen Nährwertfaktors WNFΘ;xi” für verschiedene Gemüsearten vorgelegt und durch die zugehörigen Regressionsfunktionen und Nomogramme für eine Berechnung ergänzt. Dabei wird von der ernte‐frischen Qualität ausgegangen. Bei leicht verderblichen Gemüsearten werden Abnahmen des WNFΘxibis zu 27% nachgewiesen. Bei gut lagerfähigen Arten und unter günstigen optimalen Lagerbedingungen sind die Abnahmen dagegen sehr viel geringer. Die Einführung der dynamischen Bewertung des Nährwertes ist ein Beitrag zur Präzisierung des ernä

ISSN:0027-769X    

DOI:10.1002/food.19930370105

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractSex dependence of copper, zinc, iron nutritional status and hepatic lipid peroxidation was studied in gonadectomized, hormone substituted and sham‐operated male and female rats. The experiment was performed on H‐Wistar rats (106 ± 10 g) fed conventional laboratory food ad libitum for 12 weeks. The estrogen dependence of copper status is fully confirmed by the results of this study. In hormonally active females the malondialdehyde production was depressed which is supposed to be connected with high copper and low triglyceride levels in the liver. The anaemia observed in estrogen substituted rats may be a result of lower lipid peroxidation rate. The levels of retinol and alkaline phosphatase activity in sera are probably influenced by estrogen action. It is suggested that testosterone leads to acceleration of lipid peroxida

ISSN:0027-769X    

DOI:10.1002/food.19930370106

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractThe investigations showed a significant decrease in the alkaline phosphatase activity of retinol deficient liver (48.6%), kidney (65.8%) and spleen (61.9%), as compared to the controls (100%). An increase inVmaxandKmby 12 to 51.5% and 90.4 to 189%, respectively, was observed in all the tissues in the retinol deficient group, as compared to the controls. Subsequent freezing and thawing reduced the activity of alkaline phosphatase by 22.5 to 35.8% in the experimental group; whereas the reduction in the control group ranged from 8.8 to 21.5%. In the presence of lectins and detergents the activity of alkaline phosphatase decreased in both the groups to different levels.

ISSN:0027-769X    

DOI:10.1002/food.19930370107

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractThe nitrate and nitrite levels were determined in two carrot varieties, cultivated in three Experimental Stations of Varieties Assessment in different regions of Poland in 1987–1989. The results obtained were analysed against soil conditions (kind and composition, richness), agrotechnical background (length of vegetation period, harvest time) and climatic conditions (air temperature and precipitation). The nitrate level in carrot was estimated at av. 349 mg KNO3/kg. Significant differences were found in nitrate levels depending on place and year of cultivation. The most significant effects of the studied factors on the nitrate level had soil richness in potassium and magnesium as well as length of vegetation period. The studied carrot displayed a high level of nitrites (av. 3.1 mg NaNO2/kg), which might have resulted from a microbiological reduction of nitrates occurring between harvest and the time of performing analyse

ISSN:0027-769X    

DOI:10.1002/food.19930370108

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractKinetics and mechanism of proteolysis of broad bean (Vicia fabaL.) legumin by trypsin in concentrated solutions at different enzyme‐substrate ratios (E/S= 1/40, 1/100, 1/200, 1/1000) were studied. By the method of HPLC it was established that during proteolysis process (E/S= 1/40) take place both protein content decrease in hydrolysate and change of its molecular mass (from 360 to 280 kD), which evidences for the mixed type of proteolysis, including cooperative and non‐cooperative mechanisms. Decrease ofE/Sfrom 1/40 up to 1/100–1/1000 leads not only to unproportional drop in proteolysis rate, but also to decrease of the relative contribution of cooperative proteolysis which is, possibly, connected with presence in protein molecule of at least two groups of attack sites, differentiating by their affinity with enzyme. Change of enzyme‐substrate ratio is accompanied also by change of subunit composition of product of non‐cooperative proteolysis (‘modified protein’) and also of temperature and enthalpy of its

ISSN:0027-769X    

DOI:10.1002/food.19930370109

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractYoghurt was manufactured with mixed starter ofS. thermophilusandL. bulgaricusor a single starter of either in the presence or absence of 600 ppm free amino acids mixture (glutamic acid, histidine, cysteine, valine, methionine and tyrosine) and/or 600 ppm of sodium formate. Results showed that the acidity, total volatile fatty acids (TVFA), NPN, total free amino acids and soluble tyrosine contents of different yoghurt samples increased gradually during storage at 5–8 °C for 7 days especially in the mixed starter yoghurt fortified with free amino acids mixture and Na formate. Organoleptic evaluation showed that the flavour of single strain starter yoghurt with free amino acids mixture of Na formate gave nearly the flavour of control yoghurt samples. However, the mixed starter yoghurt fortified with free amino acids mixture and Na formate gave more acceptable flavour. It could be concluded that addition of free amino acids mixture and/or Na formate to yoghurt stimulated the activity of starter bacteria. Also manufacture of yoghurt using a single starter ofS. thermophilusorL. bulgaricusshould be associated with addition of free amino acids mixture or Na formate to yoghurt milk respective

ISSN:0027-769X    

DOI:10.1002/food.19930370110

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractDie Wechselwirkungen zwischen Cyclodextrinen und α‐Amylasen verschiedener Herkunft sind widersprüchlich in der Literatur beschrieben. Einige α‐Amylasen wie isoliert ausAspergillus niger, Pankreas und Speichel hydrolisieren Cyclodextrine zu Glucose. Die Literaturangaben zur Wirkung von α‐Amylasen ausBacillus‐Species auf Cyclodextrine sind widersprüchlich dargestellt.In der vorliegenden Arbeit wird die hydrolytische Wirkung verschiedener α‐Amylasepräparate auf β‐Cyclodextrin untersucht. Es wird nachgewiesen, daß Rohalase M3 (α‐Amylase ausAspergillus oryzae) Cyclodextrine spaltet. 2 α‐Amylasen ausBacillus subtilissind nicht in der Lage, β‐Cyclodextrine zu hydrolysieren. Die Ursache für die unterschiedliche Hydrolysenwirkung wird mit der Größe und Struktur der aktiven Zentren des Enzyms diskutiert.Im 2. Teil werden verschiedene Hydrolasepräparate auf α‐Amylase‐Fremdaktivitäten untersucht. 2 Glucoamylasepräparate ausAspergillus oryzaezeigen α‐Amylasefremdaktivitäten. Mit den Hydrolase‐präparaten α‐Glucosidase aus Pilzen, β‐Amylase aus Gerstenmalz, Saccharase aus Hefen, Invertase ausSaccharomyces cerevisiaeund Pullulanase ausAerobacter aerogene

ISSN:0027-769X    

DOI:10.1002/food.19930370111

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY