Use of Sorbent-Based Vacuum Extraction for Determination of Volatile Phenols in Beer

A novel method based on vacuum-assisted sorbent extraction (VASE) used with gas chromatography-mass spectrometry (GC-MS) for isolation of volatile phenols was described. The method is based on extraction of analytes into sorbent traps (sorbent pen) filled with Tenax in a vacuum system—vials with traps from which air was evaluated. The method was applied for extraction of volatile phenols from aqueous matrix and smoked beer was used as a food example. Methyl-, dimethyl-, and trimethylphenols, along with 4-ethylphenol, 4-methylguaiacol, 4-ethylguaiacol, 4-propylguaiacol, and eugenol, were used in method development. Optimal extraction parameters were elaborated. For the analysis of volatile phenols in beer matrix, the method was characterized with satisfactory linearity (r²?≥?0.99) in a range of 0.005–0.5 mg/L. Limits of detection (LODs) for analyzed compounds ranged from 0.0006 to 0.018 mg/L and repeatability for majority of compounds was <?5% for a single trap extraction. The detected volatile phenols in beer samples ranged from 0.003 to 0.672 mg/L.     

Characteristics of lactose-free frozen yogurt with κ-carrageenan and corn starch as stabilizers

Frozen yogurt is a type of dairy product that is considered to be a more healthful alternative to conventional ice cream due to its lower fat content and the presence of viable lactic acid bacteria. Lactose-free products are a growing trend in the dairy industry, and lactose-free yogurts and ice creams can both be found on the market. However, lactose-free frozen yogurt has not yet reached the market. In this study, we aimed to investigate the effect of adding κ-carrageenan (0.05, 0.1, and 0.15%) and corn starch (1, 2, and 3%) on acidity, texture, viscosity, overrun, melting properties, color attributes, and sensory characteristics of lactose-free frozen yogurts. Lactose was reduced by enzymatic hydrolysis during the fermentation process. The effectiveness of the hydrolysis was measured by HPLC, and lactose was reduced to 0.05% after 80 min of incubation with the enzyme. The addition of stabilizers did not change overrun and melting properties of frozen yogurt, but it did affect pH, titratable acidity, and color parameters. The product with 0.15% κ-carrageenan had the highest hardness and stickiness values. Moreover, κ-carrageenan had a positive effect on sensory attractiveness of lactose-free frozen yogurt, and it reduced the coarse texture in comparison with the control without stabilizers. A lactose-free frozen yogurt with good quality and nutritional characteristics was produced, particularly with the use of κ-carrageenan as stabilizer.     

Removal of Salmonella Enteritidis from commercial unpasteurized liquid egg white using pilot scale cross flow tangential microfiltration

Effectiveness of a cross flow microfiltration (MF) process for removal of a cocktail of Salmonella enterica serovar Enteritidis species from commercial unpasteurized liquid egg white (LEW) from a local egg breaking plant, while maintaining its functional properties was evaluated. To facilitate MF, LEW was wedge screened, homogenized and then diluted (1:2 w/w) with distilled water containing 0.5% sodium chloride. Diluted unpasteurized LEW was inoculated with five strains of S. Enteritidis (ATCC 4931, ATCC BAA-708, ATCC 49215, ATCC 49218, and ATCC BAA-1045) to a level of approximately 10⁷ CFU/mL of LEW and microfiltered using a ceramic membrane. Process parameters influencing egg white functional properties and pathogen removal efficiency were evaluated. Average permeates flux increased by almost 126% when pH of LEW was adjusted from pH 8 to pH 7 at 25 °C. Microbial removal efficiency was at least, on average, 6.8 Log₁₀ CFU/mL (limit of detection ≤ 0.5 Log₁₀ CFU/mL). Functional property analysis indicated that the MF process did not alter the foaming power of LEW.     

Alternative woods for aging distillates-an insight into their phenolic profiles and antioxidant activities

Work has commenced on the study and characterization of wood native species (oak, chestnut, cherry, alder, ash, and beech), employed to a minor extent in enology, for their application in the elaboration of distillates. To this end, furanic and low molecular weight phenol compounds, total phenolic content, and antioxidant activity in alcoholic extracts by maceration of wood chips at 2 toasting levels were studied. Significant differences between samples, technologically relevant, were due both to species and toasting time. Furthermore, extracts showed interesting antioxidant activities equivalent in some cases to than those reported for alcoholic beverages aged in wood.     

Influence of arsenate adsorption to ferrihydrite, goethite, and boehmite on the kinetics of arsenate reduction by Shewanella putrefaciens strain CN-32

The kinetics of As(V) reduction by Shewanella putrefaciens strain CN-32 was investigated in suspensions of 0.2, 2, or 20 g L(-1) ferrihydrite, goethite, or boehmite at low As (10 μM) and lactate (25 μM) concentrations. Experimental data were compared with model predictions based on independently determined sorption isotherms and rates of As(V) desorption, As(III) adsorption, and microbial reduction of dissolved As(V), respectively. The low lactate concentration was chosen to prevent significant Fe(III) reduction, but still allowing complete As(V) reduction. Reduction of dissolved As(V) followed first-order kinetics with a 3 h half-life of As(V). Addition of mineral sorbents resulted in pronounced decreases in reduction rates (32-1540 h As(V) half-life). The magnitude of this effect increased with increasing sorbent concentration and sorption capacity (goethite < boehmite < ferrihydrite). The model consistently underestimated the concentrations of dissolved As(V) and the rates of microbial As(V) reduction after addition of S. putrefaciens (～5 × 10(9) cells mL(-1)), suggesting that attachment of S. putrefaciens cells to oxide mineral surfaces promoted As(V) desorption and thereby facilitated As(V) reduction. The interplay between As(V) sorption to mineral surfaces and bacterially induced desorption may thus be critical in controlling the kinetics of As reduction and release in reducing soils and sediments.     

Procyanidin effects on adipocyte-related pathologies

Procyanidins, a class of flavonoids, have clear and well-defined beneficial effects against several pathologies including cardiovascular heart disease. Now, studies in vivo are revealing the effects of procyanidins against obesity, where they prevent weight gain and adipose tissue mass increase, and against diabetes and insulin resistance, where they act as antihiperglycemic agents. Several mechanisms may be responsible for these effects. One of these, due to the key role of adipose tissue in the development of obesity and insulin resistance, is their effect on adipocytes. In this review we compile the studies that indicate a protective role for procyanidins in obesity and insulin resistance, focusing on their effects on the adipocyte, where procyanidins modify lipid synthesis, lipid degradation, glucose uptake, and adipose differentiation.     

On the relative significance of bacteria for the distribution of polychlorinated biphenyls in Arctic Ocean surface waters

This study presents the first field observations of polychlorinated biphenyls (PCB) in bacteria in oceanic waters. To contribute to the limited knowledge of what role bacteria play in the dynamics of hydrophobic organic contaminants (HOCs) in surface seawater, PCB concentrations were measured in bacteria (0.2-2 microm) collected at seven stations in the northern Barents Sea marginal ice zone (MIZ) and the central Arctic Ocean. Concentrations of individual PCB congeners in bacteria were 0.5-5 ng/g oc (organic carbon), which was as high as or higher than PCB concentrations in bulk particulate organic carbon (POC, "phytoplankton"; > 0.7 microm). Considering the relative biomasses of phytoplankton and bacteria, the amount of PCB in bacteria was generally 5-20% of that in phytoplankton, but at two stations the bacterial biomass contained more PCBs than the phytoplankton pool. This study further showed that efficient PCB uptake in bacteria may be described by an apparent equilibrium partitioning model with linear regressions between the organic-carbon-normalized partition coefficient and the octanol-water partition coefficient (log K(bact-oc)-log K(ow)).