VOLATILE CONSTITUENTS OF VINEGAR. IV. FORMATION OF VOLATILES IN THE FRINGS PROCESS AND A CONTINUOUS PROCESS OF MALT VINEGAR MANUFACTURE

Gas liquid chromatography was used to fractionate and measure volatiles formed during the Frings process and during a continuous process of malt vinegar manufacture. Acetaldehyde, ethyl alcohol, iso-amyl alcohol, acetic acid, n-propyl alcohol, sec-butyl alcohol, isobutyl alcohol, n-amyl alcohol, and also sec-butyl acetate, isobutyl acetate and n-amyl acetate were detected during the alcoholic fermentation but propionic acid, isobutyric acid and acetoin were produced during acetification. The increase in the number and concentration of the volatiles of these processes has been compared with those found for the Quick method.     

VOLATILE CONSTITUENTS OF VINEGAR. III. FORMATION AND ORIGIN OF VOLATILES IN LABORATORY ACETIFICATIONS

The volatiles produced during commercial malt vinegar manufacture have been examined using laboratory scale acetifications. The formation and changes of these volatiles in surface culture, aerated and submerged fermentations were found to be substantially similar to those found in the commercial process. Losses resulted with higher temperatures and submerged aeration. With maximum aeration the levels of propionic acid and acetoin decreased. The oxidations of n-propyl, isobutyl, sec-butyl, n-amyl and iso-amyl alcohols relative to ethanol have been compared to those found by Tanaka. The metabolic pathways which are probably responsible for the origin of these volatiles are discussed.     

TRACE VOLATILE CONSTITUENTS OF BEER DIMETHYL SULPHIDE FORMATION IN MALT

Dimethyl sulphide formation in malt occurs primarily during the kilning process, and is significantly dependent upon the maximum kilning temperature. During mashing a considerable fraction of the dimethyl sulphide of malt is transferred to the wort. Since this is not always completely removed by the wort boiling process, the remaining dimethyl sulphide, although decreased during fermentation, may be sufficient to impart a noticeable dimethyl sulphide aroma to the finished beer.     

VOLATILE CONSTITUENTS OF VINEGAR. I. A SURVEY OF SOME COMMERCIALLY AVAILABLE MALT VINEGARS

Gas liquid chromatography was used to fractionate the alcohols, esters, carbonyls and acids in commercial malt vinegars. A qualitative and quantitative study was made using two different stationary phases; methyl formate, acetaldehyde, ethyl acetate, ethyl alcohol, isobutyl acetate, n-propyl alcohol, n-butyl acetate, isobutyl alcohol, amyl alcohol, acetoin, propionic acid and acetic acid were identified and estimated in eleven different malt vinegars. The results of this survey were compared with the information previously found for malt and other types of vinegars. A preliminary assessment has been made of the origins of these volatiles.     

宣威火腿加工过程中挥发性风味化合物分析

根据传统宣威火腿的生产工艺条件,实施标准化生产关键工艺控制。用同时蒸馏萃取法(SDE)结合气相色谱/质谱(GC/MS)对宣威火腿生产过程中形成的挥发性风味化合物进行分析。结果表明:挥发性化合物的种类随着加工时间的延续逐渐增多,挥发性化合物的相对总含量则在6月龄时最高,两者均存在肌肉部位的差异;从0、4、6、12月龄火腿样品的半膜肌和股二头肌中鉴定出的挥发性化合物分别为48、29和19、79和50、98和67种;相对总含量分别为1685.50、3433.40和6677.56、9240.16和13227.85、5550.80和9675.81μg壬烷·100g-1(DM)。醛类是重要的挥发性风味化合物,由于它们的风味阈值较低,对宣威火腿的风味有重要贡献;杂环化合物和含硫化合物,因其含量低、变异大,对宣威火腿风味的贡献还不能定论。     

VOLATILE HOP CONSTITUENTS IN WORT

Using a distillation-extraction technique, a commercial wort, both before and after hopping, was analysed by GLC for the presence of volatile compounds contributed by hops. The hopped wort contained at least 0·32 p.p.m. of volatile hop constituents which is probably sufficient to influence flavour. Most of these belonged to a group of water-soluble compounds which have not previously been detected in worts or beers.     

气相色谱-质谱联用法测定川贝母中的挥发性化学成分

研究川贝母的挥发性化学成分.川贝母样品经水蒸气蒸馏得挥发油,并用气相色谱一质谱法进行分析,按峰面积归一化法求出挥发性化学成分的相对含量.分离出39个峰,已鉴定了14个化合物,占其挥发油总相对含量的81.92%.已鉴定的化合物主要包括1-十八烯(16.38%),1-十二烯(15.09%),十六烷基一环氧乙烷(11.38%),棕榈醇(10.65%),花生醇(7.95%),9-十八炔酸甲酯(6.94%),n-十六酸(5.41%).     

THE VOLATILE WATER-SOLUBLE FRACTION OF HOP OIL. II. FORMATION FROM RESINS IN BOILING WORT

The volatile water-soluble compounds produced when hop soft resins were boiled in wort were shown, by GLC, to correspond to those previously isolated from hops. Distillation-extraction of resins from a buffer solution and from water gave similar results. Recovery of volatile water-soluble compounds was shown to be poor. The disadvantages of distillation-extraction for the determination of volatile water-soluble compounds are discussed.     

EFFECTS OF PROCESS VARIABLES ON RETENTION OF VOLATILES IN FREEZE-DRYING

SUMMARY— Retention of organic volatiles in freeze-dried solutions of mono-, di- end polysaccharides was studied as a function of different process conditions. Under the experimental conditions used, slow freezing and decreasing sample thickness promoted retention. The effects of platen temperature and of concentration of solution components were more complex. Effects of process variables were explained on the basis of a mechanism which postulates formation of microregions due to association of carbohydrate molecules. These microregions become impermeable to organic compounds when their water content decrease below a critical level.     

VOLATILE AMINES OF MALT AND BEER

Twelve volatile amines have been derived from malt and commercial beers and ten of these compounds have been identified. Analysis of beers showed large variations in volatile amine content although dimethylamine and ethylamine appeared to be the dominant compounds in all cases. The effect of these two compounds on beer flavour has been assessed.     

TRACE VOLATILE CONSTITUENTS OF BEER. HOP SEED OIL

The fatty acid profile of hop seed oil has been examined and shown to be very similar to the fatty acid profile of the lipid fraction of both hops from which the seeds have been removed and seedless hops. The fates of the hop lipids and in particular the fatty acid fraction, both in conventional hopping procedures and in the preparation of an isomerised extract are discussed with reference to their possible effect on beer flavour.     

PHENOLIC CONSTITUENTS OF BEER AND BREWING MATERIALS. II. THE ROLE OF POLYPHENOLS IN THE FORMATION OF NON-BIOLOGICAL HAZE

Simple and polymeric polyphenols differ in the way in which they influence the development of chill and permanent hazes in bottled beer. The addition of simple anthocyanogens to beer causes a marked increase in the rate of haze formation whereas added polymeric materials induce immediate and intense turbidities. Beer anthocyanogens constitute a class of materials ranging in complexity from simple compounds to heterogeneous polymers which sometimes include polyphenolic units that are incapable of yielding anthocyanidins with acid. The extent to which the various anthocyanogens present in beer are involved in haze formation is not reflected by their contributions to the overall anthocyanogen value of the beer. Haze-inducing polymers which contain no anthocyanogen residues may also be present in beer. The nature and origin of polyphenolic substances in beer and the methods by which they may polymerize to give immediate haze precursors are discussed.     

STUDIES ON THE PROTEOLYTIC ENZYMES OF A COMMERCIAL MALT

Two proteolytic enzymes, Hb-ase and BAPA-ase, were partially purified from commercial malt. Hb-ase was inhibited by bromate, N-ethylmaleimide and p-chloromercuriphenylsulphonic acid and activated by ethylenediaminetetra-acetic acid. BAPA-ase was inhibited by N-ethylmaleimide and p-hydroxychloromercuribenzoate but not by bromate or phenylmethylsulphonylfluoride, a specific trypsin inhibitor. The results obtained suggested that BAPA-ase, like the Hb-ase, is a thiol enzyme.     

APPLICATION OF A COMMERCIAL ENZYME PREPARATION IN THE BARLEY MALTING PROCESS

This paper presents data on barley micromalting with addition of the CELLUCLAST enzyme complex. This is a commercial, multicarbohydrase with distinct β-glucanase and proteinase activities. The enzyme was added to steeping and germination phases, in different quantities (0.05%; 0.75% and 0.1% of initial barley). The enzyme was added to different malting phases: to the 2nd and 3rd steep water, at the beginning of germination on the 1st day by spraying, on the 2nd day of germination and in combination of addition to 3rd steeping water and in germination start (50% of total quantity of each). CELLUCLAST enzyme had a significant effect on reduction of wort viscosity, extract difference, wort filterability and protein breakdown, depending on the quantity of added enzyme and the malting phase to which it was added. There was no negative effect on other malt quality parameters. The best values of cytolytic breakdown parameters (viscosity, extract difference, filtration rate) were obtained with addition of 0.075% of CELLUCLAST, on the first day of germination.     

METHODS FOR THE DETERMINATION OF VOLATILE NITROSAMINES IN MALT,WORT AND BEER

Methods for the analysis of beer, wort and malt for NDMA at the one in 10⁹ level using the thermal energy analyzer have been evaluated. The beer and wort procedure using Preptube extraction has been shown to give excellent results. For malt, the preparation of an aqueous extract, followed by analysis by the beer procedure, also gives excellent results. Vacuum distillation from mineral oil has also been examined for the analysis of malt. Providing sufficient aqueous phase is initially present, this procedure yields results similar to those from aqueous extraction. The methods will also detect NDEA, although no NDEA has been observed in any of the beer, wort or malt samples examined. NDMA has been observed to be present in bound forms in malt and Preptubes and is released by the addition of water     

VOLATILE AMINES IN THE BREWING PROCESS. THE IDENTIFICATION AND OCCURRENCE OF PYRROLIDINE

Pyrrolidine has been identified as a component of the volatile amine fraction in barley, malt, hops, worts and beer.