Influence of high molecular weight polypeptides on the mouthfeel of commercial beer

Low malt beers have high sales volumes in Japan, but improving their mouthfeel, including softness, smoothness and decreasing astringency, is challenging because the compounds responsible remain unclear. In this study, beer was fractionated by preparative size‐exclusion chromatography, with the polypeptide and maltodextrin fractions purified using solid‐phase extraction and ion‐exchange resin. Sensory data from a spike test showed that the mouthfeel (softness, smoothness, and reduced astringency) of low malt beer was improved both by the degree of polymerisation (DP) of maltodextrins (DP of 2‐10; at increased concentration of 40 to 60%; P < 0.01) and by 10 ‐ 20 kilodalton (kDa) high molecular weight (HMW) polypeptide and 2‐3 kDa low molecular weight polypeptide fractions (at a 50% increase in concentration; P < 0.01). Furthermore, highly purified 10 to 20 kDa HMW polypeptides improved the softness and smoothness and decreased the astringency (at a 25% increase in concentration). This report is the first to provide experimental sensory data indicating that HMW polypeptides improve the mouthfeel of beer. Based on these findings, a new low malt beer was developed that showed significantly higher levels of the 10‐20 kDa HMW polypeptides with an overall improved mouthfeel. Mass spectrometric analysis of the 10 to 20 kDa proteins identified several unique foam positive proteins, including barley dimeric alpha‐amylase inhibitor‐1 and non‐specific lipid‐transfer protein 1. These 10‐20 kDa HMW proteins are likely to be responsible for the improved mouthfeel of beer. © 2020 Kirin Holdings Kabushik Kaisha Co. Ltd. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling     

Binding affinity of tea catechins for HSA: Characterization by high‐performance affinity chromatography with immobilized albumin column

Catechins are the major polyphenols in green tea leaves. Recent studies have suggested that the catechins form complexes with HSA for transport in human blood, and their binding affinity for albumin is believed to modulate their bioavailability. In this study, the binding affinities of catechins and their analogs were evaluated and the relationship between the chemical structure of each catechin and its binding property were investigated. Comparing these catechins by HPLC analysis with the HSA column, we showed that galloylated catechins have higher binding affinities with HSA than non‐galloylated catechins. In addition, pyrogallol‐type catechins have a high affinity compared to catechol‐type catechins. Furthermore, the binding affinity of the catechin with 2,3‐trans structure was higher than those of the catechin with 2,3‐cis structure. The importance of the hydroxyl group on the galloyl group and B‐ring was confirmed using methylated catechins. These results indicate that the most important structural element contributing to HSA binding of tea catechins is the galloyl group, followed by the number of hydroxyl groups on the B‐ring and the galloyl group or the configuration at C‐2. Our findings provide fundamental information on the relationship between the chemical structure of tea catechins and its biological activity.     

Beef texture characterization using internationally established texture vocabularies in ISO5492:1992: Differences among four different end-point temperatures in three muscles of Holstein steers

‘Tenderness’ has been an important sensory characteristic for beef, although ‘tenderness’ has not been commonly defined. On the other hand, ISO5492:1992 provides internationally established vocabularies for sensory analysis with simple definition. The aim of this study was texture characterization for three beef muscles cooked to four end-point temperatures using ISO5492:1992 texture terms in Japanese to develop objective sensory evaluation terms for beef texture other than ‘tenderness.’ Longissimus, semitendinosus, and psoas major muscles harvested from three Holstein steers were cooked to 45, 60, 72, and 92 °C end-point temperatures and evaluated by a trained sensory panel. Correspondence analysis indicated that the ‘chewiness’ and ‘hardness’ defined in ISO5492 were distinguished in each muscle. Changes in the ‘chewiness’ and ‘hardness’ qualities during cooking were different from each other. These findings suggest that both ‘chewiness’ and ‘hardness’ as defined in ISO5492:1992 should be evaluated simultaneously to determine the sensory texture of beef.     

A learning method of immune multi-agent neural networks

Many different learning algorithms for neural networks have been developed, with advantages offered in terms of network structure, initial values of some parameters, learning speed, and learning accuracy. If we train the networks only on good examples, without noise and shortage, the neural network can be trained to classify, with reasonable accuracy, target patterns or random patterns, but not both. To solve this problem, we propose a learning method of immune multi-agent neural networks (IMANNs), which have agents of macrophages, B-cells and T-cells. Each agent employs a different type of neural network. Because the agents work cooperatively and competitively, IMANNs can automatically classify the training dataset into some subclasses. In this paper, two types of IMANNs are described and their classification capabilities are compared. In order to verify the effectiveness of our proposed method, we used two datasets: the dataset of the MONKs problem (as a traditional classification problem) and a dataset from a medical diagnosis problem (hepatobiliary disorders).     

Precipitation of nonionic surfactants by polymeric acid

Nonionic surfactants of the polyethylene oxide type are precipitated by carboxy vinyl polymer (CVP) in its acid form. While the reduced viscosity of the CVP solution is affected more markedly by a surfactant with a longer polyethylene oxide chain, the binding to CVP of the nonionic surfactants with the same hydrophobic parts occurs more effectively with shortening of the polyethylene oxide chain or with lowering of the critical micelle concentration. The structure of the complexes formed is discussed.     

The Dyeing Properties of Monoazo Dyes Derived from Substituted 2-Aminobenzothiazole-3N-oxides

The preparation of new monoazo dyes from substituted 2-aminobenzothiazole-3N-oxides and the dyeing properties of these dyes are reported.     

Molecular basis of IsK protein regulation by oxidation or chelation

Slowly activating IsK channels were expressed in Xenopus oocytes and exposed to oxidative agents. Oxidative treatment reduced the resulting current IsK, while no inhibition was observed for IsK protein mutants carrying a Ser mutation instead of a highly conserved Cys residue in the intracellular domain. In contrast, Hg2+, which may not only oxidize thiol groups but also form chelates with dibasic amino acids, caused a use-dependent, positive regulation of IsK. This effect was reversed in an IsK protein mutant with a deletion in the extracellular domain. These data suggest opposite effects of peroxides and Hg2+ on IsK, a peroxide-mediated IsK inhibition by intracellular oxidation and a Hg(2+)-mediated IsK increase, caused by extracellular Hg2+ chelation of the IsK protein.     

EXAFS characterization and selective olefin hydroformylation on Rh4, Rh2Co2 and RhCo3 carbonyl clusters attached to tris-hydroxymethylphosphine-grafted silica

Rh_4-xCo_x(CO)₁₂ (x = 0, 2, 3) are attached by carbonyl substitution to THP (tris-hydroxymethylphospine)-grafted silica keeping their cluster frameworks. They have been characterized by Rh K-edge EXAFS (extended X-ray absorption fine structure) and Fourier transform IR spectroscopy. They exhibited high catalytic activity with > 98% selectivity in gas phase hydroformylation of ethene and propene to give aldehydes under mild conditions (40 kPa and 300–373 K).On leave from Research Center, Arakawa Chemical Industries, LTD, Tsurumi, Osaka 538, Japan.On leave from Department of Chemistry, National University of Literal, Santiago del Estero, 2829-3000, Santa Fe, Argentina.     

SMA micro-hand implemented in small robot for generating gestures

Intelligent Service Robotics - Research on robots that can be used for communication with humans has become popular in recent years. Communication robots should ideally be as small as an infant in...     

Expression of Pit-1 mRNA and activin/inhibin subunits in clinically nonfunctioning pituitary adenomas. In situ hybridization and immunohistochemical analysis

Autonomic nervous activity is involved in the onset of paroxysmal atrial fibrillation, but it is not clear how the sympathetic and parasympathetic nervous systems interact before the onset of atrial fibrillation. Twelve lone atrial fibrillation patients and 10 healthy volunteers were studied using 24-hour Holter electrocardiography monitoring. A total of 17 episodes were analyzed. Autonomic nervous activity was assessed based on the high frequency power (HF) spectrum (HF represents parasympathetic nervous activity) and the ratio to the low frequency power (LF) spectrum (L/H represents sympathetic nervous activity) of heart rate variability during sinus rhythm, and the 24-hour averaged autonomic indices were compared between atrial fibrillation patients and healthy volunteers. Comparative data were obtained 30, 20, 10, and 2 min before the onset of atrial fibrillation for each episode. There were no significant differences in the HF and L/H ratio between the patients and healthy volunteers. There were no significant differences in the HF values before the onset of paroxysmal atrial fibrillation, but the L/H ratio before the onset of atrial fibrillation at 30, 20 and 10 min was 1.03 +/- 0.42, 0.95 +/- 0.50, and 1.32 +/- 0.46, respectively, and just before the episode was 1.73 +/- 0.73, so the Spearman's rank correlation coefficient was 0.43. Basal autonomic nervous activity in patients with paroxysmal atrial fibrillation showed no changes compared with healthy volunteers. Sympathetic nervous activity increased progressively from about 30 min before the onset of atrial fibrillation, but parasympathetic nervous activity showed no significant changes. Therefore, a transient augmentation of sympathetic tone may be important in the onset of atrial fibrillation.