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ing, fermentation, drying and roasting but stopping short at chocolate manufacture. Second to be described are the flavours from cheese production in respect of process conditions and the role of both lipids and pro- teins. The formation of both volatiles and peptides with a flavour impact is recognized. Finally the book con- cludes with a short chapter on an overview of savoury flavours in general.

To bring this review full cycle, the book is one of many parts and each part is capable of standing on its

own. The editors have introduced a welcome format in which each chapter is prefaced by an abstract followed by an introduction and ending with a discussion, con- clusion and references. However, search as one might, no attempt has been made to define the naturality of either flavours or flavors.

A. M. HUMPHREY Chorleywood, Herts., UK

TRENDS IN FLAVOUR RESEARCH, Proceedings of the 7th Weurman Flavour Research Symposium, Noord- wijkerhout, The Netherlands, 15-18 June 1993, edited by H. Maarse and D. G. van der Heij. Developments in Food Science Volume 35, Elsevier, Amsterdam, 1994. No of pages: xii + 516, price Dfl. 315.00, US$180.00. ISBN 0-444-81587-2.

The 7th Weurman Flavour Research Symposium returned to The Netherlands where Dr G. Weurman organized the first such symposium in 1975. Attend- ance at the Weurman symposia has always been by invitation, limited to 100, of which 10% should be young scientists, and this has ensured a high standard of presentation, seen again in the present volume. This contains 32 papers, 31 posters and reports on two workshops-in all the work of 167 authors. The contents are divided into five sections: flavour release (5,3,1; papers, posters, workshop reports), instru- mental analysis (4,9,0), correlations between sensory and instrumental analysis (9,7,1), precursor systems (5,3,0), flavour stability and off-flavours (5,4,0), and biogenesis and biotechnology (4,5,0). In a review such as this it is not possible to do more than mention the subjects covered.

In the first section there are papers on method- ology for measuring flavour release, on mathematical models for predicting the same, and on the release of flavours from model systems, chocolate, cheese, bell pepper cuttings and tomatoes. The workshop that followed identified the following areas for further investigation - development of better instrumental methodology for measuring volatile release during eating, the relationship between individuals’ time/ intensity measurements and their mouth-related variables (saliva flow, rate of chewing, swallowing etc.), measurement of flavour release under stan- dardized mouth conditions and its relation to flavour perception, and correlation of nosespace volatile profiles with perceived flavour.

In the section on ‘Instrumental analysis’ there are papers on a dual-column gas chromatography re- trieval system, on enantioselective GC and compara- tive stable isotope ratio mass spectrometry, on

pyrolysis-direct chemical ionization mass spec- trometry, and on GC-MS analysis of tomato sauces. The posters in this section include a comparison of the isolation of volatiles by SDE and co-distillation, isolation of flavours by microwave treatment, auto- matic processing of GC-MS analysis using a two- dimensional search system, and on a standard GC retention index library of flavour compounds. Further posters discussed aroma-binding in maltodextrin solutions, the binding of acetaldehyde by quarg cheese, the prediction of late gas formation in Cheddar cheese, the aroma components of pan-fried lamb, and the isolation of oct-3-en-1-01.

The longest section of the book is concerned with correlations between sensory and instrumental analysis. It is largely devoted to gas chromatography-olfac- tometry-Aroma Extract Dilution Analysis, ‘Charm’ analysis and a new technique, ‘Osme’, and their appli- cation to the flavour characteristics of model systems, apple products, bell peppers, blue, Dutch and Emmen- tal cheese, chocolate, meat flavourings, tomatoes and wine. A decision-making support system for aroma research is outlined and the advantages of instrumental procedures for measuring flavour characteristics is stressed. The workshop on gas chromatography- olfactometry agreed inter uliu that AEDA, ‘Charm’ analysis and ‘Osme’ are essentially screening procedures, the results of which depend on the representativeness of the sample and the capabilities of the assessors.

The section on precursor systems has papers on lipid- Maillard interactions, the roles of 3-deoxyglucosone and inosine monophosphate as flavour precursors, heat-induced changes in the flavour of strawberries, and dicarbonyl compounds in wine. In a poster, ‘Trends in aroma research’, advances in knowledge since the first Weurman symposium are reviewed. Over 6300 volatile compounds have now been recorded, 1180 volatile esters, and 55 disulphides, oxazoles, thiazoles and dithiazines. The importance of optical isomers, especially metabolites of isoleucine was also high- lighted. Other posters deal with flavour changes during alkaline treatment of protein hydrolysates and pre- cursors of bovolide.

In the section on flavour stability and off-flavours

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there are papers on the stability of industrial flavours, on the chemical and sensory effects of intense sweeten- ers (aspartame and sodium cyclamate) on the flavour of diet orange soft drinks, and on freight containers as the major sources of chloro-anisoles and chlorophenols in foodstuffs. AEDA is used to investigate flavour changes in oatmeal extrusion products during storage and off-flavours in boiled trout and butter oil. Posters describe: how the Australian saltwater fish Girella tricuspidata can develop an off-flavour due to 2,6- dibromophenol present in the algae which make up its diet: how strawberries stored under COz can develop ethyl acetate as an off-flavour: whether interior lacquers can influence the flavour of carbonated mineral waters: and how interactions with food can influence the sorption of aroma compounds into food contact polymers.

In the final section on biogenesis and biotechnology there are papers on the microbial production of natural furfurylthiol, a key flavour compound in coffee and roast beef aroma; the isolation of seven new cembrane-

derived compounds from tobacco; the formation of volatile sulphur compounds in cut onions; and green note production - a challenge for biotechnology . Posters describe the production of natural 6- decalactone by reduction of Massoi lactone with baker’s yeast and by biodegradation of coriolic acid. 2H-NMR allows verification of the origin of the lac- tone. Other lactones, mainly (Z)-y-dodec-6-enolide, are formed by Fusariumpoae. A further poster describes changesin the level of olive oil odourants during ripening, and the last poster describes the bioconversion of terpe- noid hydrocarbons by basidiomycetes.

This excellent book will be welcomed by all flavour chemists, especially those not invited to Noordwijker- hout. The editors are to be congratulated on the uniform style and format of the book-no so-called camera-ready copy - and on the fact that they pro- cessed the papers within four months.

ROGER STEVENS Threlkeld