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Isoamyl Acetate (isoamyl + acetate)
Selected AbstractsINFLUENCE OF AROMA COMPOUNDS ON LARGE DEFORMATION PROPERTIES OF STARCH-BASED SYSTEMS DURING AGINGJOURNAL OF TEXTURE STUDIES, Issue 3 2001G. ARVISENET The effect of aroma compounds on the texture of gelled aqueous corn starch systems was studied by uniaxial compression during aging for 18 days. Three different types of behavior were observed, depending on the nature of the added aroma compound. Isoamyl acetate did not modify the measured parameters, compared with nonflavored products. Linalool, known for its ability to form inclusion complexes with amylose, modified the parameters which are usually considered to be governed by the rearrangement of amylose chains. Ethyl hexanoate modified the parameters depending mostly on amylopectin. These results suggest that the nature of the aroma compound may play a major role in interactions with starch. These interactions can be different from inclusion complexes involving amylose chains only, the latter being widely described by different authors. [source] Odorant specificity of three oscillations and the DC signal in the turtle olfactory bulbEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Ying-Wan Lam Abstract The odour-induced population response in the in vivo turtle (Terepene sp.) olfactory bulb consists of three oscillatory components (rostral, middle and caudal) that ride on top of a DC signal. In an initial step to determine the functional role of these four signals, we compared the signals elicited by different odorants. Most experiments compared isoamyl acetate and cineole, odorants which have very different maps of input to olfactory bulb glomeruli in the turtle and a different perceptual quality for humans. We found substantial differences in the response to the two odours in the rise-time of the DC signal and in the latency of the middle oscillation. The rate of rise for cineole was twice as fast as that for isoamyl acetate. Similarly, the latency for the middle oscillation was about twice as long for isoamyl acetate as it was for cineole. On the other hand, a number of characteristics of the signals were not substantially different for the two odorants. These included the latency of the rostral and caudal oscillation, the frequency and envelope of all three oscillations and their locations and spatial extents. A smaller number of experiments were carried out with hexanone and hexanal; the oscillations elicited by these odorants did not appear to be different from those elicited by isoamyl acetate and cineole. Qualitative differences between the oscillations in the turtle and those in two invertebrate phyla suggest that different odour processing strategies may be used. [source] Effect of fermentation on free and bound volatile compounds of orange juiceFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2009Gang Fan Abstract Aroma is one of the most important attributes of orange wine quality. The volatile compounds in orange wine mainly derive from oranges, yeast fermentation and compounds released from odourless glycosidic precursors present in the orange. In this study, free volatile compounds in orange juice and wine made from Citrus sinensis (L). Osbeck cv. Washington Sanguine were analysed by SPME-GC,MS. Bound fractions were isolated and extracted with methanol and Amberlite XAD-2 resin and then hydrolysed by almond , -glucosidase. Totals of 31 and 19 free volatiles were identified in orange juice and wines, respectively. Terpenes were the most abundant compounds in orange juice, while esters were quantitatively the dominant group in orange wine and most of them were compounds newly formed during fermentation, such as isoamyl acetate, ethyl hexanoate, ethyl benzoate, diethyl succinate, ethyl decanoate and ethyl laurate. In total, 11 and three released bound volatiles were found in orange juice and wine, respectively, and most of them were not found in free form. Only ethyl 3-hydroxyhexanoate and cis -carveol were found present in both the free and bound forms of orange juice. Copyright © 2009 John Wiley & Sons, Ltd. [source] Perceptual interactions between fruity and woody notes of wineFLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2004Boriana Atanasova Abstract The quantitative olfactory interactions in three binary mixtures of wine aroma compounds were studied. For the ,rst two mixtures, whisky lactone (woody note) was mixed separately with two esters (fruity note), ethyl butyrate and isoamyl acetate. For the third mixture, guaiacol (woody note) was mixed with ethyl butyrate (fruity note). Perceived odour intensity of 24 stimuli (four supra-threshold concentration levels of two compounds and the respective 16 mixtures) were evaluated in ,ve replications, by a trained panel of 13 subjects. The results showed that for the three binary mixtures studied, quantitative perceptual interactions were non-level independent, non-symmetrical, and reached the compromise level of hypo-addition. The experimental data highlighted that generally mixtures with high whisky lactone levels led to the compromise level of mixture intensity perception, whereas mixtures with high fruity note intensity proportions did not. A tendency to hyper-addition was observed in iso-intense mixtures only at the lowest intensity level. Copyright © 2004 John Wiley & Sons, Ltd. [source] Inhibition of the decrease of volatile esters and terpenes during storage of a white wine and a model wine medium by glutathione and N -acetylcysteineINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2008Despima Papadopoulou Summary Glutathione and N -acetylcysteine, each at 20 mg L,1, were tested as inhibitors of the decrease of volatile esters and terpenes during storage of Debina white wine. Moreover, the inhibition of the decrease of isoamyl acetate, ethyl hexanoate and linalool in a model wine medium by glutathione and N -acetylcysteine, each at 0,20 mg L,1, was also tested. Several volatiles, such as isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate and linalool, decreased during wine storage. Glutathione or N -acetylcysteine significantly restricted the decrease of these volatiles. In the model medium, each thiol inhibited the decrease of the three volatiles in a dose-dependent manner. N -acetylcysteine inhibited the decrease of all three volatiles at 2.5 mg L,1 while glutathione at 2.5 or 5.0 mg L,1. The present results indicate that glutathione and N -acetylcysteine may be taken into account as potent inhibitors of the disappearance of aromatic esters and terpenes in wines. [source] Metabolic engineering of the anaerobic central metabolic pathway in Escherichia coli for the simultaneous anaerobic production of isoamyl acetate and succinic acidBIOTECHNOLOGY PROGRESS, Issue 5 2009Cheryl R. Dittrich Abstract An in vivo method of producing isoamyl acetate and succinate simultaneously has been developed in Escherichia coli to maximize yields of both high value compounds as well as maintain the proper redox balance between NADH and NAD+. Previous attempts at producing the ester isoamyl acetate anaerobically did not produce the compound in high concentrations because of competing pathways and the need for NAD+ regeneration. The objective of this study is to produce succinate as an example of a reduced coproduct to balance the ratio of NADH/NAD+ as a way of maximizing isoamyl acetate production. Because the volatility of the two compounds differs greatly, the two could be easily separated in an industrial setting. An ldhA, adhE double mutant strain (SBS110MG) served as the control strain to test the effect of an additional ackA - pta mutation as found in SBS990MG. Both strains overexpressed the two heterologous genes pyruvate carboxylase and alcohol acetyltransferase (for ester production). The triple mutant SBS990MG was found to produce higher levels of both isoamyl acetate and succinate. At the optimal condition of 25°C, the culture produced 9.4 mM isoamyl acetate and 45.5 mM succinate. SBS990MG produced 36% more ester and over 700% more succinate than SBS110MG. In addition, this study demonstrated that a significantly higher isoamyl acetate concentration can be attained by simultaneously balancing the carbon and cofactor flow; the isoamyl acetate concentration of 9.4 mM is more than seven times higher than an earlier report of about 1.2 mM. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | |||||||||||||