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101.
Lactose solutions of up to 50% (w/v) were incubated with lactases and glucose isomerases for subsequent implementation in dairy product samples to enhance sweetness. A degree of hydrolysis of >90% and of isomerisation of 50% were attainable. The sensory sweetening power of lactose in solutions of up to 50% (w/v) can be enhanced 2–3 times. Based on sensory experiments, application of this bi‐enzymatic system in yoghurt and pudding samples allowed for a 10–20% (w/w) reduction in the total sugar content, whilst retaining equal sweetness. The growth of yoghurt starter cultures was not affected, yet furosine formation more than doubled in high heated, enzyme‐modified milk.  相似文献   
102.
Application of a comparative aroma extract dilution analysis on the volatiles isolated from five different hops (Hallertau Perle, Hallertau Hersbrucker Spät, Slowenian Golding, Hallertau Smaragd, US Cascade) revealed linalool and myrcene with the highest Flavour Dilution (FD)-factors in all varieties, followed by 2-isopropyl-3-methoxypyrazine, 3-methylbutanoic acid and geraniol. Some odourants, however, showed high FD-factors only in certain varieties, for example, (5Z)-octa-1,5-dien-3-one and germacrene B in Hersbrucker Spät, (3E,5Z)-undeca-1,3,5-triene in Hersbrucker Spät and Cascade and nonanal in Cascade. The overall odour profile of the Cascade sample clearly differed from the other varietes, and was dominated by a black currant like odour note. The identification experiments revealed 4-methyl-4-sulfanylpentan-2-one, so far unknown as hop constituent, as key contributor to this odour. In addition, an odour-active undecatetraene was present, in particular, in Perle and Cascade. Synthesis and structural assignment of the four stereoisomers of (3E)-undeca-1,3,5,9-tetraene allowed the identification of the fresh, pineapple-like smelling compound as (3E,5Z,9E)-undeca-1,3,5,9-tetraene. Among the four isomers synthesised, this compound showed by far the lowest odour threshold of 0.01 ng/L in air.  相似文献   
103.
介绍了Voith造纸技术控股股份有限公司近期研发的新技术和新装备,包括CompactPulper 损纸碎浆机,经过优化设计的回收浆车间废渣处理系统,适合于所有纸种脱水的靴式压榨技术--NipcoFlex和TissueFlex,PrintFlex P压榨毛布,VTT真空引纸系统,Duoshake摇振器,Strato系列橡胶包覆层新品种等.  相似文献   
104.
105.
Contribution to the Biosynthesis of High-amylose Pea Starches Biosynthesis of starch is a complex process but few details are still unknown. This paper describes an investigation upon pea starch biosynthesis. Peas as a source of starch offer two qualities, a pea starch with 40% amylose content (smooth pea starch) and a pea starch with more than 60% amylose content (wrinkled pea starch). Samples for analysis were taken during growth. According to the quantitative determination of starch and amylose the accuracy of amylose detection was tested. Furthermore a qualitative analysis was carried out by molecular weight estimation of the starch. Both kinds of peas showed a high amylose synthesis during the last few days of growth, whereas amylopectin synthesis was highly in earlier stages. Wrinkled peas have shown only little synthesis activity of amylopectin during maturity. Therefore the amylose content of these peas was higher, instead of equal amylose synthesis quotas of both smooth and wrinkled peas.  相似文献   
106.
SEM and UV-microscopic investigation of glue lines in Parallam® PSL   总被引:1,自引:0,他引:1  
? PSL were investigated using scanning electron- and UV-microscopy. In the SEM it was found that resin penetrates predominantly through cut open tracheids and rays. Bordered pits block the flow of resin from cell to cell whereas simple pits are only a minor obstacle. UV-absorbance spectra of cells from the glue line area indicated the presence of phenol-formaldehyde resin in the wood cell wall. Compared to the pattern of absorbance of pure cell wall substance, spectra of cells embedded in the glue showed significant differences which were attributed to the penetration of phenol-formaldehyde resin during the process of gluing.
? PSL wurden mit dem Rasterelektronenmikroskop und dem UV-Mikroskop untersucht. Im REM zeigte sich, da? Leim vor allem in angeschnittene Tracheiden und in Holzstrahlen eindringt. Ein Flie?en durch Hoftüpfel konnte nicht nachgewiesen werden, wohingegen einfache Tüpfel ein geringeres Hindernis darstellen. UV-Absorptionsspektren von Holzzellen aus dem Leimfugenbereich deuteten auf das Vorhandensein von Phenol-Formaldehydharz in der Zellwand hin. Die Spektren dieser Zellen wiesen im Vergleich zum Absorptionsverhalten der reinen Zellwandsubstanz deutliche Unterschiede auf, die auf das Eindringen von Phenol-Formaldehydharz w?hrend des Verleimvorganges schlie?en lie?en.
  相似文献   
107.
On alternation     
Summary Every alternating t(n)-time bounded multitape Turing machine can be simulated by an alternating t(n)-time bounded 1-tape Turing machine. Every nondeterministic t(n)-time bounded 1-tape Turing machine can be simulated by an alternating (n + (t(n)) 1/2)-timebounded 1-tape Turing machine. For wellbehaved functions t(n) every nondeterministic t(n)-time bounded 1-tape Turing machine can be simulated by a deterministic ((nlogn)1/2 + (t(n))1/2)-tape bounded off-line Turing machine. These results improve or extend results by Chandra-Stockmeyer, Lipton-Tarjan and Paterson. A preliminary version of this paper was presented at the 19th IEEE-FOCS  相似文献   
108.
109.
    
Zusammenfassung Die Aromastoffe wurden aus Kirschsaft isoliert durch simultane Destillation/Extraktion (Extrakt I) und durch Destillation in Vakuum mit anschließender Extraktion des Destillates (Extrakt II). Die beiden Extrakte wurden entsäuert, fraktioniert und durch HRGC analysiert. Die chemischen Strukturen wurden nur von den Aromastoffen analysiert, die im Sniffing-port nach der HRGC-Trennung zu erkennen waren. Identifiziert wurden 28 Aromastoffe im Extrakt I und 18 im Extrakt II; 16 davon enthielt auch Extrakt I. Beim Abriechen der schrittweise verdünnten Extrakte im Sniffing-port wurden in beiden Extrakten dieselben sieben Verbindungen mit den höchsten Aromawerten gefunden: Benzaldehyd, Linalool, Hexanal, 2(E)-Hexanal, Phenylacetaldehyd, 2(E),6(Z)-Nonadienal und Eugenol. Extrakt I enthielt zusätzlich einen fruchtigen Aromastoff unbekannter Struktur mit hohem Aromawert.
Identification of highly aromatic volatile flavour compounds from cherries (Prunus cerasus L.)
Summary The flavour compounds were isolated from cherry juice by simultaneous distillation/extraction (extract I) and also by vacuum distillation followed by extraction of the condensate (extract II). Both extracts were freed from the acids, fractionated and then analyzed by HRGC. The chemical structures of only the flavour compounds detectable at the sniffing-port of the HRGC-effluent were determined. 28 Flavour compounds were identified in extract I; 18 in extract II of which 16 occurred also in extract I. Sniffing the stepwise diluted extracts I and II revealed the same seven compounds with the highest aroma values: benzaldehyde, linalool, hexanal, 2(E)-hexanal, phenylacetaldehyde, 2(E),6(Z)-nonadienal and eugenol. Extract I contained in addition a flavour compound of high aroma value, whose structure is unknown.
  相似文献   
110.
    
Zusammenfassung Sieben Aromastoffe, isoliert durch Destillation im Vakuum aus Sauer- und Süßkirschprodukten, wurden vergleichend analysiert. In den frisch gepreßten Säften aus je fünf Sorten Sauer- und Süßkirschen wurden große Konzentrationsunterschiede (gm/l) gefunden: Benzaldehyd (18–393), Linalool (0,5–1,7), Hexanal (0,3–54,7), 2(E)-Hexenal (2,4220), 2(E),6(Z)-Nonadienal (0,1–2,4), Phenylacetaldehyd (2,1–5,6) und Eugenol (1,0–22,2). Die Benzaldehydkonzentration zeigte die höchste Korrelation zur Erkennungsschwelle für den Kirschgeruch der Säfte. Bei der Herstellung von Konfitüren veränderte sich die Zusammensetzung der Aromastoffe: Benzaldehyd und Linalool nahmen um den Faktor 7 bzw. 13 zu; Hexanal, 2(E)-Hexenal sowie Phenylacetaldehyd nahmen stark ab. Der Anstieg von Benzaldehyd und Linalool, der auch bei der simultanen Destillation/Extraktion der Säfte auftrat, beruht auf einer Hydrolyse entsprechender Glykoside, die durch eine Hitzebehandlung stark beschleunigt wird.
Quantitative analysis of the volatile flavour compounds having high aroma values from sour (Prunus cerasus L.) and sweet (Prunus apium L.) cherry juices and jams
Summary The analysis results for seven of the aroma compounds obtained by vacuum distillation from sweet and sour cherry products were compared. The freshly pressed juices from 5 varieties of sour and 5 varieties of sweet cherries showed great differences in concentrations (g/1): benzaldehyde (18–393), linalool (0.5–1.7), hexanal (0.3–54.7), 2(E)-hexenal (2.4–220), 2(E),6(Z)-nonadienal (0.1–2.4), phenylacetaldehyde (2.1–5.6) and eugenol (1.0–22.2). The benzaldehyde content of the juices showed the highest correlation to the recognition threshold of the cherry aroma note. The cherry jam showed a drastic change in the aroma composition: benzaldehyde and linalool increased greatly (7 and 13-times, respectively), while hexanal, 2(E)-hexenal and phenylacetaldehyde strongly decreased. The increase in benzaldehyde and linalool, which was also observed during simultaneous distillation/extraction of the juices, is caused by the hydrolysis of the corresponding glycosides during the heat treatments.
  相似文献   
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