Staling in two canned lager beers stored at different temperatures from sensory analyses and consumer ranking

Two canned lagers, lager A (5% abv with late hop character) and lager B (4% abv) stored for 0, 7, 14, 21 and 28 days at 4, 12, 30 and 37°C were scored by trained sensory assessors (10) for liking and stale and related attributes of: cabbagy, cardboard, catty, grainy, honey, leathery, metallic, musty, skunky, and sour. Principal component analysis explained 80% data variance in 3 significant (p < 0.05) and 75% in 4 significant factors for A and B, respectively. In both lagers, aging correlated significantly with stale, cabbagy and musty and in A with metallic and sour and in B with catty and skunky. Partial least squares regression (PLS1) models showed good explanations: stale had regression coefficients of 0.88 (calibration) and 0.84 (validation) for A, and 0.96 and 0.91 respectively, for B; for liking 0.92 and 0.90 for A and 0.96 and 0.93 for B. For both lagers, liking was positively correlated with honey and grainy, and inversely with staling attributes. Lagers from 30°C were ranked for liking by 40 consumers against fresh as a hidden reference. Significant (p = 0.05) ranking of A, but not B, correlated with that of trained assessors

Relationships of overall estery aroma character in lagers with volatile headspace congener concentrations

In lager beers the intensity of “estery” aroma character is re-garded as an important component of sensory quality, but its origins are somewhat uncertain. Overall “estery” aroma intensity was predicted from capillary gas chromatographic (GC) data following solid phase micro extraction (SPME) of headspaces. Estery character was scored in 23 commercial lagers using rank-rating, allowing assessors (13) constant access to a range of appropriate standards. From univariate data analysis, all asses-sors behaved similarly and lagers fell into three significantly different groups: low (1), high (1) and intermediate (21). The quantification of 36 flavour volatiles by SPME of headspaces was reproducible and principal component analysis explained 91% total variance. Multiple linear regression could utilise only a restricted (26) set of flavour volatiles, whereas partial least square regression, that considered all flavour components, showed significant differences and improved prediction. How-ever, an artificial neural network that could compensate for non-linearities and interactions in ester perception gave the most robust prediction at R2 = 0.88

Control of the molecular weight of bacterial poly(3-hydroxybutyrate)

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Device and method for producing photosynthetic microorganisms in a photobioreactor

Device and method for the production of photosynthetic microorganisms in a photobioreactor The present invention relates to a photobioreactor device (1) comprising a culture chamber (2), containing a reaction medium (3) for growth of microorganisms, provided with at least one means for stirring said medium (3). Said device (1) comprises a closed loop (6), starting from said enclosure of said device (1), integrating an extraction pump (7) from the reaction medium (3) to an extraction unit (9) of the biomass (10) that comprises said loop, which unit (9) incorporates a means of separating part of the biomass (10) from the reaction medium (3) to obtain a clarified reaction medium (10a) which is returned in said enclosure (2). Said device (1) further comprises at least one measuring means (14, 14a) of the concentration of biomass or of photosynthetic activity in said reaction medium (3, 10), and a unit (15) for processing measurements and control capable of actuating said pump (7). (figure 1