A FLAVOUR MODEL FOR BEER FERMENTATION

A new beer fermentation model is developed based upon fundamental knowledge of biochemical pathways. The model can be subdivided into a growth model, an amino acid model, and a flavour/aroma model. Experimentation allowed for accurate model parameter identification. The results demonstrate the capability to accurately describe batch beer fermentation dynamics.     

Olfaction and taste: Human perception, physiology and genetics

Drinking wine is a manifestly sensuous experience. Wine stimulates most of our senses; particularly smell (olfaction) and taste, and, to a lesser extent, sight and touch. These sensory inputs interact with the limbic system in our brain which is associated with emotions and memory. Agreeable smells can thus evoke feelings of enjoyment and nostalgia. But how are tastants and aromas detected? Over the past few years a great deal has been learnt about how small tastant and odorant molecules are detected by specific protein receptors located in our mouth and in nasal cavities, respectively. Indeed, we have a vast array of olfactory receptors encoded by a group of genes that represent a significant part of the human genome. Interestingly, many more aroma compounds can be detected and discriminated than can be accounted for by the number of olfactory receptors that are encoded by our genes. Such disparity implies a level of complexity in this system which is not yet fully understood. Sophistication in olfaction is something that winemakers (and drinkers!) have long appreciated, and now scientists are beginning to unravel some of the underlying mysteries. Discovering why some individuals are more receptive to different tastes and smells than others will help wine producers understand variation in consumer preferences between different parts of the world, and possibly capture new opportunities in a changing global marketplace. Given such prospects, this present review offers a timely summary of some key developments in our understanding of odorant and tastant detection. We also consider how genetic components in human olfaction might be utilised to develop a ‘biosensor’ for aroma detection and discrimination.     

A RAPID METHOD FOR THE EXTRACTION AND ANAYLSIS OF BEER FLAVOUR COMPONENTS

Dispersal of beer on a commercially available tube of kieselguhr and elution with dichloromethane was found to be a much faster and more efficient method of obtaining a beer flavour extract than liquid-liquid extraction. The constitution of each type of extract was qualitatively similar. The use of an internal standard allowed major flavour components to be quantitatively analysed.     

Physicochemical characterization of sahti,an ‘ancient’ beer style indigenous to Finland

Sahti, a strong, unhopped farmhouse beer flavoured with juniper, is still actively brewed in rural areas in Finland. Presented here is the first comprehensive analysis of the physical and chemical properties of this unique beer style. Twelve sahti samples from the southwest of Finland were analysed and, while properties varied, the beers generally had high levels of alcohol (mean = 7.9% ABV) and high residual extract (mean = 9.5°P). Foam stability was negligible, as is typical for the style, and glycerol concentrations at 3.1 – 4.7 g L^?1 were higher than in reference beers (commercial lager, wheat beer and porter). These features may be attributed to the very high gravity conditions employed in brewing sahti beers. Bitterness levels were relatively low (3–13 IBU) owing to the absence or moderate use of hops. All samples contained detectable levels of the clove‐like compound 4‐vinylguaiacol owing to the use of baker's rather than brewer's yeast for brewing. Concentrations of higher alcohols and esters were high, with many individual aroma compounds being above the normal flavour thresholds. Results have highlighted the uniqueness of this style of beer in comparison to commercially available beers and have contributed to our understanding of the reasons for the particular sensorial properties of this traditional beer style. Copyright © 2015 The Institute of Brewing & Distilling     

啤酒发酵的风味模型

介绍了以已知的生化途径为基础的新的啤酒发酵模型。模型又进一步分为生长模型、氨基酸模型及风味（香味）模型，适用于啤酒发酵的联机测定、联机控制及工艺过程最佳化的研究。     

Improving 2‐phenylethanol and 6‐pentyl‐α‐pyrone production with fungi by microparticle‐enhanced cultivation (MPEC)

Trichoderma atroviride IMI 206040 synthesizes the coconut lactone 6‐pentyl‐α‐pyrone (6‐PAP) de novo and Aspergillus niger DSM 821 produces the rose‐like flavour compound 2‐phenylethanol (2‐PE) from the precursor l ‐phenylalanine. Here, microparticles of different chemical composition and nominal particle diameter in the range 5–250 µm were added to shake‐flask cultures of both fungi to investigate the particles' effect on product formation. Maximum 2‐PE concentration increased by a factor of 1.3 to 1430 mg/l with the addition of 2% w/v talc (40 µm diameter). Maximum 6‐PAP concentration increased by a factor of 2 to 40 mg/l with the addition of 2% w/v iron (II, III) oxide. The influence of ions leaching out of the particles was investigated by cultivating the fungi in leached particle medium. For the first time, the positive effect of the microparticle‐enhanced cultivation (MPEC) technique on the microbial production of volatile metabolites, here flavour compounds from submerged fungal cultures, is demonstrated. The effect is strain‐ and particle‐specific. Copyright © 2014 John Wiley & Sons, Ltd.     

Properties of encapsulated wasabi flavour and its application in canned food

The encapsulated wasabi flavour prepared from 100% modified starch (HICAP^? 100), HICAP^? 100: maltodextrin (1:1), HICAP^? 100:CAPSUL (1:1) at various flavouring agent concentrations (10, 15 or 20% w/w) was determined for physicochemical properties. All encapsulated treatments were stored at various relative humidity (RH) levels (11%, 33% and 52% RH) and intervally evaluated for encapsulation efficiency (EE) during 60 days of storage. Microcapsules of 20% wasabi flavour derived from the mixture of HICAP^? 100 with maltodextrin and HICAP^? 100 with CAPSUL demonstrated excellent properties including low moisture content, acceptable flowing properties, surface appearance and EE. The release rate of encapsulated flavour increased as the RH increased for most encapsulated treatments. A difference‐from‐control test was conducted to evaluate the magnitude of wasabi‐flavour retention added in the canned tuna spread. The intensity of wasabi‐flavour retention in the canned tuna spread with encapsulated flavour agents added was higher than that of the samples without flavour encapsulation.