SPME method optimized by box-behnken design for impact odorants in reduced alcohol wines

The important sampling parameters of a headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) procedure such as the extraction temperature, extraction time, and sample volume were optimized to quantify 23 important impact odorants in reduced alcohol red and white wines. A three-factor design of Box-Behnken experiments was used to determine the optimized sampling conditions for each analyte, and a global optimized condition at every ethanol concentration of interest determined using a desirability function that accounts for a low signal response for compounds. Shiraz and Chardonnay wines were dealcoholized from 13.7 and 12.2% v/v ethanol respectively, to 8 and 5% v/v, using a commercially available membrane-based technology. A sample set of the reduced alcohol wines were also reconstituted to their natural ethanol level to evaluate the effect of the ethanol content reduction on volatile composition. The three-factor Box-Behnken experiment ensured an accurate determination of the headspace concentration of each compound at each ethanol concentration, allowing comparisons between wines at varying ethanol levels to be made. Overall, the results showed that the main effect of extraction temperature was considered the most critical factor when studying the equilibrium of reduced alcohol wine impact odorants. The impact of ethanol reduction upon the concentration of volatile compounds clearly resulted in losses of impact odorants from the wines. The concentration of most analytes decreased with dealcoholization compared to that of the natural samples. Significant differences were also found between the reconstituted volatile composition and 5% v/v reduced alcohol wines, revealing that the dealcoholization effect is the result of a combination between the type of dealcoholization treatment and reduction in wine ethanol content

Q fever endocarditis masquerading as Mixed cryoglobulinemia type II. A case report and review of the literature

BACKGROUND: The clinical manifestations of Q fever endocarditis are protean in nature. Mixed cryoglobulinemia type II is rarely a facet of the presenting clinical manifestations of Q fever endocarditis. CASE PRESENTATION: We report a case of a 65-year-old pensioner with such an association and review the literature. As transesophageal echocardiograms are usually normal and blood cultures are usually negative in Q fever endocarditis, many of the manifestations (fever, rash, glomerulonephritis/evidence of renal disease, low serum C4 complement component, presence of mixed type II cryoglobulin, constitutional symptoms as arthralgias and fatigue) can be attributed to Mixed cryoglobulinemia type II per se. The use of Classic Duke Endocarditis Service criteria does not always suffice for the diagnosis of Q fever. CONCLUSION: The application of the modified criteria proposed by Fournier et al for the improvement of the diagnosis of Q fever endocarditis will help to reach the diagnosis earlier and thus reduce the high mortality of the disease. We would like to stress the importance of ruling out the diagnosis of Q fever endocarditis in cases of mixed type II cryoglobulinemia

Combined rheological and optical investigation of maize, barley and wheat starch gelatinisation

Microstructural and rheological changes during gelatinisation are important indicators of starch functionality. A combined rheometer and optical microscope system (Rheoscope 1, Thermo Haake) was used to monitor the gelatinisation of different starches (maize starch containing 0%, 24%, 55% and 85% amylose; wheat starch and barley starch) suspended in a 0.1% guar solution (to minimise settling during the initial stages of gelatinisation). The 0.1% guar solution was selected after Rapid Visco Analyser, Modulated DSC and settling studies indicated that it minimised any effect on starch gelatinisation compared to carboxy methyl cellulose and xanthan. The Rheoscope study demonstrated that the viscosity of the starch during gelatinisation is related to changes in starch granules as a result of swelling. There was a two to threefold increase in starch granule size during the gelatinisation for all starches except for high amylose maize starches. Viscosity development during the gelatinisation was affected by the presence of B-type granules, whose presence tended to reduce the overall viscosity increase, indicating the importance of starch granules size and their distribution in determining the rheological responses of starch during gelatinisation

Parboiled rice: Understanding from a materials science approach

The material properties like glass transition temperature, diffusion, microstructures of rice kernels and gelatinisation and retrogradation of the rice starch are reviewed to understand the nature and quality of the parboiled rice. Details of the diffusion related material properties of rice kernels such as the rate of diffusion, different models of diffusion, diffusion in glassy and rubbery state and diffusion in the gelatinised starch are discussed. The influences of hydrothermal treatment on the properties of the rice kernel are also highlighted to understand the overall quality of parboiled rice

Colour change in rice during hydration: Effect of hull and bran layers

The colour change (yellowing or reddening) that occurs during parboiling affects the consumer acceptance of parboiled rice. In order to understand the factors controlling colour change in rice during hydration, trials were performed that examined the effect of variety (four commercial varieties: Kyeema, Langi, ReiziqP and SherpaP), milling properties (SherpaP High Head Rice Yield and SherpaP Low Head Rice Yield), degree of processing before hydration (paddy, brown rice, milled rice) and hydration temperature (below and above gelatinisation temperature: 60 C and 90 C respectively). The total colour difference (DE00) was calculated and four different models (zero order, first order, fractional and Page) were evaluated in order to predict the DE00. The Page model was found to be the best model for predicting DE00. There was no difference in DE00 between the breakage resistant and breakage prone grains however the varietal effect was observed. The degree of processing of rice before hydration affected the total colour change where the brown rice had the highest DE00 followed by paddy and milled rice

The diffusion of moisture in paddy during hydration and dehydration processes

Hydration and dehydration behavior and the effective diffusivity of paddy during the process of parboiling were studied. Hydration of three different paddy samples (Sherpa low and high head rice yield and Reiziq) were performed below (60°C) and above (90°C) the gelatinization temperature. The hydration period ranged from 5 to 300 minutes at 60°C and 5 to 90 minutes at 90°C. All of the paddy samples showed different hydration behavior below and above the gelatinization temperature, discerned with two different stages at 60°C and three stages at 90°C. Dehydration was carried out at 40°C just after hydration (without tempering the kernel), which mostly took place at the falling rate period. The hydration and dehydration pattern was not different between the high HRY and low HRY paddy, indicating a limited contribution of microfissures to the diffusion rate in the paddy. Five commonly used semi-empirical models were used to predict the hydration and dehydration behavior of paddy and, among them, the Page model was found to be the most suitable. The effective diffusivity during hydration was dependent on the temperature of hydration, which was 1.83 × 10-11 to 2.11 × 10-11 m2/s at 60°C and 6.68 × 10-11 to 7.94 × 10-11 m2/s at 90°C. The effective diffusivity during dehydration depended on the soaking temperature and period of soaking; it was lower for high-temperature-hydrated samples than low-temperature-hydrated samples. The study concluded that the mass water diffusivity was not affected by the microfissures within the paddy kernel, and the hydration pattern was strongly dependent on whether the temperature was above or below the gelatinization temperature

Gelatinization of starch in mixed sugar systems

Sugars affect the gelatinization of starch, with the effect varying significantly between sugars. Since many food products contain a mixture of sugar sources, it is important to understand how their mixtures affect starch gelatinization. In a Rapid Visco Analyser study of maize starch gelatinization, changing proportions in binary mixtures of refined sugars saw a largely proportionate change in starch gelatinization properties. However, binary mixture of pure sugars and honey, or a model honey system (the main sugars in honey) and honey responded differently. Generally, replacing 25% or 50% of the refined sugar or model honey system with honey gave a large change in starch gelatinization properties, while further increases in honey level had little further effect. Differences between honey and buffered model honey system (either gluconic acid, or a mixture of citric acid and di-sodium phosphate) showed the sensitivity of starch gelatinization to the composition of the nonsaccharide component. (c) 2004 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved