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

Higher-Order Assembly of BRCC36-KIAA0157 Is Required for DUB Activity and Biological Function

BRCC36 is a Zn²⁺-dependent deubiquitinating enzyme (DUB) that hydrolyzes lysine-63-linked ubiquitin chains as part of distinct macromolecular complexes that participate in either interferon signaling or DNA-damage recognition. The MPN⁺ domain protein BRCC36 associates with pseudo DUB MPN⁻ proteins KIAA0157 or Abraxas, which are essential for BRCC36 enzymatic activity. To understand the basis for BRCC36 regulation, we have solved the structure of an active BRCC36-KIAA0157 heterodimer and an inactive BRCC36 homodimer. Structural and functional characterizations show how BRCC36 is switched to an active conformation by contacts with KIAA0157. Higher-order association of BRCC36 and KIAA0157 into a dimer of heterodimers (super dimers) was required for DUB activity and interaction with targeting proteins SHMT2 and RAP80. These data provide an explanation of how an inactive pseudo DUB allosterically activates a cognate DUB partner and implicates super dimerization as a new regulatory mechanism underlying BRCC36 DUB activity, subcellular localization, and biological function