Behaviour of Antioxidants Derived from Hops During Wort Boiling

The oxidative stability of wort at different stages during wort production and the radical scavenging characteristics of α‐, β‐, iso‐α‐acids and a hop polyphenol extract were evaluated using ESR spectroscopy and DPPH• radical quenching measurements. Radical generation in unhopped wort was significantly, positively correlated with heating rate prior to boiling but not with dissolved oxygen content. Hop α‐ and β‐acids showed similarly significant radical quenching abilities, while iso‐α‐acids and a hop polyphenol extract displayed a negligible effect. Isomerization of α‐acids to iso‐α‐acids reduced wort's antioxidative capacity. Commercially available hop products with varying polyphenol content showed similar radical inhibiting properties, which were a function of hop acid content. Relative to an unhopped treatment, hop additions to wort resulted in significantly lower amounts of Strecker aldehydes in stored beer.     

风味油脂的研制报告

以菜子色拉油为原料，添加天然香味物料（葱、姜、茴香），经过加热、脱水、保温、冷却、过滤等工序制成具有独特风味的油脂。采用正文试验方法研究不同的工艺条件对三种风味油脂品质的影响。     

盐水化雪

探讨盐水化雪的机理,列举盐水化雪的实例及其负面效果。     

肉类的风味化学

肉类香精是国际上重点开发的三类香精之一,而发展肉类香精的基础是对肉类风味的研究。本文对肉类风味化合物的分类以及风味前驱物作了报道,重点讨论了肉类风味化合物的几种形成途径,即硫胺素的热分解、半胱氨酸或胱氨酸的热分解,糖与氨基酸的美拄德反应。     

Release of distillate flavour compounds in Scotch malt whisky

Equilibration of a flavour volatile between a distilled spirit and the headspace is a two‐stage process. The first equilibrium occurs between the bulk solution and the headspace spirit interface, and the second between the surface layer and the headspace. The first stage is represented by the activity coefficient of the flavour volatile, which, for hydrophobic compounds, is greatly reduced by the aggregation of ethanol molecules in aqueous solution. The second equilibrium is governed by the vapour pressure of the solute and the ambient temperature and pressure. In mixed saturated solutions the composition of the surface layer and consequently the headspace is determined by the concentration and activity coefficients of the mixture components. Components of wood extract were found to act principally on the first equilibrium. Ethanol lignin acted in the same manner as high molecular weight esters and alcohols of the distillate, displacing volatile components from the surface layer. The suppressant effect of ethanol lignin was lost at 37 °C and consequently would only be important in nosing of spirit samples. Wood extract was found to decrease the critical point for the aggregation of ethanol, resulting in reduced activity coefficients for ethyl decanoate from 5 to 30% ethanol at both 25 and 37 °C. This effect would reduce the spirit–mouthspace partition coefficient with the resulting decreased release of flavour volatile in the mouth. This mechanism would explain the decreased impact of undesirable, immature aromas when wood matured spirits are consumed. © 1999 Society of Chemical Industry     

Analysis of volatile components of fruits by HS‐PTV‐GC

A method for the analysis of fruit headspace using a programmed temperature vaporiser (PTV) gas chromatographic injector as an intermediate trap is proposed. The method consists of a purge of the volatile compounds into the PTV glass‐liner filled with a packing material of high surface area. The trapped compounds are thermally desorbed in the PTV injector and transferred to the gas chromatographic column. The variables that influence the extraction and transfer processes have been optimised for fruit flavour analysis. Examples of the application of the method to the analysis of bananas, blackberries and raspberries are given. © 1999 Society of Chemical Industry     

Development of a model for intensity of flavour character in blackcurrant concentrates

The feasibility of routine quantification of flavour character intensity in fruit concentrates by chromatography was studied. A set of 37 volatile components, previously identified as flavour-active by gas chromatography-olfactometry, were quantified in 133 different blackcurrant concentrates from three seasons, by gas chromatography with flame ionisation detection. Sensory data on intensities of flavour character in these concentrates were obtained using ratio scaling. Partial least squares regression (PLS) was employed to develop models describing relationships between intensity of flavour character and concentrations of specific flavour components. Separate models were obtained for concentrates produced within three single seasons. Individual concentrates varied in: geographical origin; post-harvest fruit storage (chilled or frozen); and concentration strategy, either conventional thermal or freeze technology. Cross-validation (by PLS) determined the number of correlation factors required to reach minimum prediction error for each model. The final model had a regression coefficient of 0.80, dependent upon 10 flavour components, and was suited for predicting flavour character intensity in blackcurrant drinks from concentrates. © 1999 Society of Chemical Industry     

Identification of impact odorants of young red wines made with Merlot,Cabernet Sauvignon and Grenache grape varieties: a comparative study

An Aroma Extract Dilution Analysis (AEDA) has been carried out on three monovarietal young red wines plus a mixture of wines aged one year. The aromograms contain 85 odour-active regions classified in four categories of intensity. The 11 most powerful odorants, 14 out of the 17 second-most powerful, and 34 of the rest could be identified using a HPLC prefractionation method and standard HRGC-MS-olfactometric techniques. The most active odorants of the monovarietal wines were isoamyl and β-phenylethyl alcohols, the ethyl esters of butyric, isobutyric, 2-methyl butyric and hexanoic acids, γ-nonalactone and eugenol. Some others worth mentioning are ethyl isovalerate, isoamyl acetate, hexanol, c-3-hexenol, linalool, geraniol, guaiacol, ethyl cinnamate, ethyl dihydrocinnamate, β-damascenone, δ-decalactone and wine lactone. Compounds with less aromatic intensity but also present in some of the wines were sotolon, isopropyl- and isobutylmethoxypyrazines and 4-mercapto-4-methylpentan-2-one. Data show that there are no impact compounds characteristic of only one variety, and that differences between varieties are quantitative rather than qualitative. © 1999 Society of Chemical Industry     

Multigram-scale production of aliphatic carboxylic acids by oxidation of alcohols with Acetobacter pasteurianus NCIMB 11664

Acetobacter pasteurianus NCIMB 11664 was selected for multigram-scale production of different aliphatic carboxylic acids through oxidation of the corresponding alcohols after screening different acetic acid bacteria. Continuous production was carried out using an air-lift reactor, with overall yields of 1-propionic, 1-butyric, 2-methyl-1-butyric and 3-methyl-1-butyric acids ranging from 45 to 61 g dm⁻³. ©1997 SCI     

Myosin affects the structure and volatile flavour compounds binding of G-actin in grass carp

The effects of myosin (0, 0.2, 0.4, and 0.6 mg mL⁻¹) on the protein structure and volatiles adsorption capacity of G-actin from grass carp were investigated. The results showed that the myosin addition increased the surface hydrophobicity and sulfhydryl contents of G-actin. The Raman spectroscopy analysis showed that the α-helix and β-sheet of G-actin were converted into β-turn and random coil with 0.2 and 0.4 mg mL⁻¹ of myosin, while only the β-turn content increased with 0.6 mg mL⁻¹ of myosin. The GC-MS analysis indicated that with myosin addition, the adsorption capacities of G-actin on alcohols (1-pantanol, 1-hexanol, 1-octen-3-ol, and 1-octanol) and ketones (2-pentanone, 2-heptanone, 2-octanone, and 2-nonanone) were enhanced; meanwhile, the binding of G-actin to aldehydes (pentanal, hexanal, octanal, and nonanal) was weakened. It was probably due to the formation of actomyosin, and also the excess myosin when treated with high concentrations (0.4 and 0.6 mg mL⁻¹) of myosin.