Multivariate modeling of aging in bottled lager beer by principal component analysis and multiple regression methods

Simultaneous determination of diethylacetal and acetaldehyde during beer fermentation and storage process

BACKGROUND

Acetaldehyde is an important flavor component in beer which is possibly carcinogenic to humans. Owing to the limitations of present detection methods, only free-state acetaldehyde in beers has been focused on, while acetal in beers has hardly been reported so far.

RESULTS

A sensitive headspace gas chromatography method was developed for the determination of diethylacetal and acetaldehyde in beer. The column DB-23 was chosen with a total run time of 22.5 min. The optimal addition amount of NaCl, equilibrium temperature and equilibrium time were 2.0 g, 70 °C and 30 min respectively. For both diethylacetal and acetaldehyde analyses, the limit of detection was 0.005 mg L^-1 with relative standard deviation < 5.5%. The recoveries of acetaldehyde and diethylacetal were 95-110 and 95-115% respectively. The diethylacetal and acetaldehyde average contents in 24 beer products were 11.83 and 4.36 mg L^-1 respectively. The Pearson correlation coefficient between diethylacetal and acetaldehyde was the highest (0.963). Both diethylacetal and acetaldehyde contents increased to a peak value after fermentation for 3 days and then decreased to a lower value. During both normal and forced aging storage, the diethylacetal content decreased and the acetaldehyde content increased gradually over time. When beers were forced aged for 4 days, the increased ratio of acetaldehyde could be above 40.00%.

CONCLUSION

The newly established method can be used to assess acetaldehyde level and flavor quality in beer more scientifically. © 2018 Society of Chemical Industry.

Influence of ultrasound assisted thermal processing on the physicochemical and sensorial properties of beer

The aim of this study was to investigate the effect of ultrasound assisted thermal processing also known as thermosonication (TS) on selected physicochemical and sensorial properties of beer. A typical Chinese lager beer was treated by TS (24kHz frequency and 2.7W/mL volumetric power) for 2min at 40, 50, and 60°C, respectively. The main quality attributes of the beer, such as ethanol content, original extract, pH, and bitterness, were scarcely affected by three TS treatments. However, a significant increase in color value was observed after TS treatment at 60°C during storage. The protein sensitivity and colloidal haze of three TS-treated beers increased slightly. The results also revealed that the development of both yeast and spoilage bacteria (including lactic acid bacteria and aerobic bacteria) was inhibited for 12months of storage for the TS-treated samples except for the TS-treated beer at 40°C. Additionally, the TS-treated beer at 60°C resulted in a higher thermal load relative to other two TS samples (at 40 and 50°C) based on the results of oxidative stability. TS treatment at 60°C also had a minor negative effect on the volatile profile by increasing staling compounds compared with other two TS treatments. These results obtained therefore may serve as a reference of the potential application of the ultrasound assisted thermal treatment for the beer processing.

Associated factors of acute primary angle closure glaucoma in a sub-group of Chinese people: comparison between attack eyes and normal controls

Acute primary angle closure glaucoma (APACG) is an ophthalmic emergency that may lead to irreversible blindness. Although efforts were made to control intraocular pressure, disease progression still existed. Anterior segment optical coherence tomography (AS OCT) may provide a new insight into mechanism of APACG. In order to seek out associated factors by AS OCT, We compared anterior segment parameters between 74 APACG and 48 normal eyes. Analysis of variance, principle component analysis and logistic regression were used. APACG group had more women (75.7% vs 47.9%, p = 0.002), smaller anterior chamber (anterior chamber depth, ACD; anterior chamber area, ACA; all p = 0.001), narrower angle (AOD500, AOD750, angle opening distance at 500um and 750um; TISA500, TISA750, trabecular-iris space area at 500um and 750um; ARA500, ARA750, angle recess area at 500um and 750um; all p < 0.001), thinner iris (iris thickness at 750um, IT750; maximum of iris thickness, ITMAX; all p < 0.001), larger iris area (IA, p < 0.001) and lens vault (LV, p = 0.005). Principle component extracted were AOD500, AOD750, TISA500, TISA750, ARA500, ARA750, IA, PD (pupillary diameter), ACD, ACA and IT750. After adjusting for confounding factors, AOD750 (b = 12.40 ± 2.56, p < 0.001), IT750 (b = 10.50 ± 3.45, p = 0.002) and IA (b = −1.56 ± 0.77, p = 0.044) were significantly associated with occurrence of APACG.

Combination of chemical fingerprint and bioactivity evaluation to explore the antibacterial components of Salvia miltiorrhizae

The aim of this study was to explore the possible antibacterial components of Salvia miltiorrhizae on Pseudomonas aeruginosa using a combination of chemical fingerprint and bioactivity evaluation. The chemical fingerprints of 32 batches of S. miltiorrhizae samples from different sources were developed using high-performance liquid chromatography with diode array detection, and then were evaluated by similarity analysis and hierarchical clustering analysis. Anti-P. aeruginosa activity was determined by microcalorimetry. Some crucial thermokinetic parameters obtained from the heat-flow power-time curves of P. aeruginosa growth in the absence or presence of these S. miltiorrhizae samples were evaluated using principal component analysis. Thereafter, multiple linear regression analysis was used to analyze the fingerprint-activity relationship between the chemical fingerprints and anti-P. aeruginosa activity. This established the related equation between the inhibition ratio (I, %) of S. miltiorrhizae samples on P. aeruginosa and the peak areas of the common peaks. The results showed that the 32S. miltiorrhizae samples could be grouped into three clusters according to their chemical fingerprints and anti-P. aeruginosa activities. Protocatechualdehyde, salvianolic acid B, together with three unidentified compounds might be the major components that contributed largely to the antibacterial properties of S. miltiorrhizae and should be the focus of S. miltiorrhizae quality control. Thus, this study provided a preferred way for exploring the bioactive components of medicinal plants.

Lactobacillus plantarum CCFM639 alleviates aluminium toxicity

Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity.

Influencing factors of hydrogen bonding intensity in beer

The hydrogen bonding was prone to be formed by many components in beer. Different sorts of flavor substances can affect the Chemical Shift due to their different concentrations in beer. Several key factors including 4 alcohols, 2 esters, 6 ions, 9 acids, 7 polyphenols, and 2 gravity indexes (OG and RG) were determined in this research. They could be used to investigate the relationship between hydrogen bonding intensity and the flavor components in bottled larger beers through the Correlation Analysis, Principal Component Analysis and Multiple Regression Analysis. Results showed that ethanol content was the primary influencing factor, and its correlation coefficient was 0.629 for Correlation Analysis. Some factors had a positive correlation with hydrogen bonding intensity, including the content of original gravity, ethanol, isobutanol, Cl(-), K(+), pyruvic acid, lactic acid, gallic acid, vanillic acid, and Catechin in beer. A mathematic model of hydrogen bonding Chemical Shift and the content of ethanol, pyruvic acid, K(+), and gallic acid was obtained through the Principal Component Analysis and Multiple Regression Analysis , with the adjusted R(2) being 0.779 (P = 0.001). Ethanol content was proved to be the most important factor which could impact on hydrogen bonding association in beer by Principal Component Analysis. And then, a multiple non-linearity model could be obtained as follows: [Formula: see text]. The average error was 1.23 % in the validated experiment.

Chemometric approach to texture profile analysis of kombucha fermented milk products

In the present work, relationships between the textural characteristics of fermented milk products obtained by kombucha inoculums with various teas were investigated by using chemometric analysis. The presented data which describe numerically the textural characteristics (firmness, consistency, cohesiveness and index of viscosity) were analysed. The quadratic correlation was determined between the textural characteristics of fermented milk products obtained at fermentation temperatures of 40 and 43 °C, using milk with 0.8, 1.6 and 2.8% milk fat and kombucha inoculums cultivated on the extracts of peppermint, stinging nettle, wild thyme and winter savory. Hierarchical cluster analysis (HCA) was performed to identify the similarities among the fermented products. The best mathematical models predicting the textural characteristics of investigated samples were developed. The results of this study indicate that textural characteristics of sample based on winter savory have a significant effect on textural characteristics of samples based on peppermint, stinging nettle and wild thyme, which can be very useful in the determination of products texture profile.

Phytochemical and biological activities of four wild medicinal plants

The fruits of four wild plants, namely, Capparis decidua, Ficus carica, Syzygium cumini, and Ziziphus jujuba, are separately used as traditional dietary and remedial agents in remote areas of Khyber Pakhtunkhwa, Pakistan. The results of our study on these four plants revealed that the examined fruits were a valuable source of nutraceuticals and exhibited good level of antimicrobial activity. The fruits of these four investigated plants are promising source of polyphenols, flavonoids, alkaloids, terpenoids, and saponins. These four plants' fruits are good sources of iron, zinc, copper, manganese, selenium, and chromium. It was also observed that these fruits are potential source of antioxidant agent and the possible reason could be that these samples had good amount of phytochemicals. Hence, the proper propagation, conservation, and chemical investigation are recommended so that these fruits should be incorporated for the eradication of food and health related problems.

Simultaneous determination of seven bioactive components in Oolong tea Camellia sinensis: quality control by chemical composition and HPLC fingerprints

A simple and reliable method of high-performance liquid chromatography (HPLC) was developed for the quality control of oolong tea (the dry leaves of Camellia sinensis ): the quality control included the HPLC fingerprint and the quantitative determination of seven bioactive compounds chemicals, namely, (-)-gallocatechin, (-)-epigallocatechin, (-)-epigallocatechin gallate, caffeine, (-)-epicatechin, gallocatechin gallate, and (-)-epicatechin gallate. The developed analyses of the chemicals excelled in quantifying the chemicals in oolong tea. The chemical fingerprint of oolong tea was established using the raw materials of three main production sites in China, that is, Fujian (southern and northern parts), Taiwan, and Guangdong. The fingerprints from different cultivated sources were analyzed by hierarchical cluster analysis, similarity analysis, principal component analysis (PCA), analysis of variance (ANOVA), and discriminant analysis. The results indicated that the combination of chromatographic fingerprint and quantification analysEs could be used for the quality assessment of oolong tea and its derived products.