FLAVOUR STABILITY STUDIES: THE USE OF FRACTIONAL FACTORIAL DESIGNS

The number of taste tests that can be undertaken by the average flavour profile panel places a severe constraint on the study of flavour stability. The use of fractional factorial designs has been shown to be an effective approach to this problem. In this work, the effect of eight process variables on both beer flavour and flavour stability have been assessed using only eight experimental beers plus one control. The efficacy of the method is demonstrated by the ease with which the flavour profile panel results can be explained by accepted theories of flavour stability. Thus the variables examined could be divided into three groups. The first group includes headspace air, pasteurization and copper content: an increase in any of these variables leads to a marked increase in oxidized flavours during storage. The second group, which includes sulphur dioxide, PVPP treatment and lupulin (dry hop) addition, reduces oxidation. The remaining variables, proteolytic enzymes and iron content had no obvious effect on oxidation.     

Origins of Flavour in Whiskies and a Revised Flavour Wheel: a Review

The nature and origins of flavour in whiskies are reviewed with the aim of developing a revised and simplified flavour wheel for training of sensory assessors. Scotch whiskies are perceived as having distinctive characters, generally recognised in pattern recognition (perception, macroscopic brain processing), rather than being subjected to a deconstruction process of evaluating attributes (sensation, microscopic brain processing). Although consumers use simple recognition judgements on whisky flavour in categorical assimilation, industry has a requirement for monitoring spirit quality that necessitates a more reductionist approach. Whisky flavour wheels identify attributes, specific components of flavour character, which can be demonstrated to sensory assessors using reference standards. The advent of cyclodextrin bound reference standards has enabled communication of information on flavour character in training of assessors, as exploited in the brewing industry. A revised flavour wheel, with characters illustrated by reference standards, is proposed to assist sensory training on attributes of whisky flavour character.     

五大香型白酒的相互关系与微量成分浅析

白酒在五大香型指浓香,清香,亲王香,米香和其他香型,其中浓,清,酱,米四大香型为基本香型,相互独立,其他香型均由这四大香型生而出,有兼香,药香,芝麻香,凤香,特6香和豉香6个类别,其典型代表分别为浓香泸州老窑,五粮液,清香汾酒,酱香茅台,米香桂林三花,其他香型的兼香白云边,药香董酒,芝麻香景芝白干,凤香西凤,特香四特和豉香玉冰烧,其微量成分特征为：浓香型 己酸乙酯为主,含量在160－250mg/100ml,占总酯40％以上,清香型 乙酸乙酯为主体香,占总酯的50％以上,乙酸乙酯与乳酸乙酯的含量占总酯90％以上,酱香型白酒的主体香暂无定论,其糠醛含量较高,达260mg/100ml,米香型白酒以β－苯乙醇的特征成分,乳酸乙酸含量占总酯高达73％,其他香型白酒因门类不同,以数种成分为其特征。     

125th Anniversary Review: The Non‐Biological Instability of Beer

Unlike many alcoholic beverages beer is inherently unstable. In chemical (as opposed to microbiological) terms this instability can be considered — and is here reviewed — in the categories of colloidal instability, foam, gushing, flavour instability and light sensitivity     

Improving Malaysian cocoa quality through the use of dehumidified air under mild drying conditions

BACKGROUND: Various studies have been conducted in the past to improve the quality of Malaysian cocoa beans. However, the processing methods still remain crude and lack technological advancement. In terms of drying, no previous study has attempted to apply advanced drying technology to improve bean quality. This paper presents the first attempt to improve the quality of cocoa beans through heat pump drying using constant air (28.6 and 40.4 °C) and stepwise (step‐up 30.7–43.6–56.9 °C and step‐down 54.9–43.9 °C) drying profiles. Comparison was made against hot air drying at 55.9 °C. RESULTS: Product quality assessment showed significant improvement in the quality of Malaysian cocoa beans. Quality was found to be better in terms of lower acidity (higher pH) and higher degree of browning (cut test) for cocoa beans dried using the step‐up profile. All heat pump‐dried samples showed flavour quality comparable to that of Ghanaian and better than that of Malaysian and Indonesian commercial samples. Step‐up‐dried samples showed the best flavour profile with high level of cocoa flavour, low in sourness and not excessive in bitterness and astringency. CONCLUSION: Dried cocoa samples from the step‐up drying profile showed the best overall quality as compared with commercial samples from Malaysia, Indonesia and Ghana. The improvement of Malaysian cocoa bean quality is thus achievable through heat pump drying. Copyright © 2010 Society of Chemical Industry     

Quality characteristics of high salt fermented fish sauce (budu) produced using autochthonous Virgibacillus halodenitrificans PS21 and Staphylococcus simulans PMRS35

This study evaluated the effects of autochthonous starters on the quality characteristics of budu. The effects of individual or combined inoculation of Virgibacillus halodenitrificans PS21 and Staphylococcus simulans PMRS35 were compared to those of non-inoculation during 150 days of budu production. The starters directly affected characteristics of budu with browner colour and enhanced proteolysis and lipolysis as indicated by degree of hydrolysis and free fatty acid contents. The combined starter inoculation resulted in a high aspartic acid, glutamic acid and lysine levels. Additionally, key desirable volatiles, including 2-methylbutanal, 3-methylbutanal, benzaldehyde and 2-ethyl furan, were dominant in the starter-inoculated budu. In a sensorial analysis, the highest scores for appearance, colour, taste and flavour were assigned for inoculated budu with combined starters. Therefore, the addition of starters (V. halodenitrificans PS21 and S. simulans PMRS35) in budu production improved the quality characteristics and reduced the fermentation period.     

An overview of selected specialty beers: developments,challenges and prospects

The brewing industry has devoted much research effort into the development of new technologies and innovations for the expansion of the assortment of specialty beers in response to increased consumer demand. Specialty beers are more or less the catch‐all for beer styles, which do not fit into conventional beer categories and five types of specialty beers are of particular interest – low‐calorie beer, low‐alcohol or nonalcohol beer, novel‐flavoured beer, gluten‐free beer and functional beer. The selected beer types are technologically challenging to produce relative to the traditional approach of ingredient addition, yet offer special appeal to consumers from the perspective of health and flavour. Biological processes that make use of the equipment of a traditional brewery plant should be better exploited in comparison with nonbiological technologies such as thermal and membrane processes. Probiotic beer could be the specialty beer of the future in light of the increasing popularity of probiotics. These beers are reviewed in terms of developments, challenges and prospects.     

Development of a flavour fingerprint by GC‐MS and GC‐O combined with chemometric methods for the quality control of Korla pear (Pyrus serotina Reld)

Based on solid‐phase micro‐extraction/gas chromatography‐mass spectrometry (SPME/GC‐MS) and gas chromatography‐olfactometry (GC‐O), a new method was described for the first time to establish flavour fingerprint for the quality control of Korla pear. Twenty‐three batches of Korla pear collected from different regions in Xinjiang, China were analysed via GC‐MS, among which 21 were selected to establish the fingerprint. The results of the analysis were combined with GC‐O assessment to obtain 26 common odour‐active compounds as the characteristics of the Korla pear flavour fingerprint. The method for flavour fingerprint analysis was then validated on the basis of the relative retention time and relative peak area of the common peaks, sample stability and similarity analysis. The similarities in the 21 Korla pear samples were more than 0.80, thereby indicating that the samples from different batches were consistent to a particular extent. The chemometrics method (principal component analysis, PCA) was performed to develop a flavour fingerprint that is suitable for identifying and differentiating Korla pears and can be used for quality control.