Effect of small, acid-soluble proteins on spore resistance and germination under a combination of pressure and heat treatment

To find the range of pressure required for effective high-pressure inactivation of bacterial spores and to investigate the role of alpha/beta-type small, acid-soluble proteins (SASP) in spores under pressure treatment, mild heat was combined with pressure (room temperature to 65 degrees C and 100 to 500 MPa) and applied to wild-type and SASP-alpha(-/)beta(-) Bacillus subtilis spores. On the one hand, more than 4 log units of wild-type spores were reduced after pressurization at 100 to 500 MPa and 65 degrees C, On the other hand, the number of surviving mutant spores decreased by 2 log units at 100 MPa and by more than 5 log units at 500 MPa. At 500 MPa and 65 degrees C, both wild-type and mutant spore survivor counts were reduced by 5 log units. Interestingly, pressures of 100, 200, and 300 MPa at 65 degrees C inactivated wild-type SASP-alpha(+)/beta(+) spores more than mutant SASP-alpha(-)/beta(-) spores, and this was attributed to less pressure-induced germination in SASP-alpha(-)/beta(-) spores than in wild-type SASP-alpha(+)/beta(+) spores. However, there was no difference in the pressure resistance between SASP-alpha(+)/beta(+) and SASP-alpha(-)/beta(-) spores at 100 MPa and ambient temperature (approximately 22 degrees C) for 30 min. A combination of high pressure and high temperature is very effective for inducing spore germination, and then inactivation of the germinated spore occurs because of the heat treatment. This study showed that alpha/beta-type SASP play a role in spore inactivation by increasing spore germination under 100 to 300 MPa at high temperature.

Modelling and validation of Lactobacillus plantarum fermentations in cereal-based media with different sugar concentrations and buffering capacities

An unstructured mathematical model is proposed to describe the fermentation kinetics of growth, lactic acid production, pH and sugar consumption by Lactobacillus plantarum as a function of the buffering capacity and initial glucose concentration of the culture media. Initially the experimental data of L plantarum fermentations in synthetic media with different buffering capacity and glucose were fitted to a set of primary models. Later the parameters obtained from these models were used to establish mathematical relationships with the independent variables tested. The models were validated with 6 fermentations of L. plantarum in different cereal-based media. In most cases the proposed models adequately describe the biochemical changes taking place during fermentation and are a promising approach for the formulation of cereal-based probiotic foods. (C) 2008 Elsevier B.V. All rights reserved.

Flavor characterization of sugar-added pennywort (Centella asiatica L.) juices treated with ultra-high pressure and thermal processes

The flavor characteristics of pennywort juices with added sugar treated by ultra-high pressure, pasteurization, and sterilization were investigated using solid phase microextraction combined with gas chromatography-mass spectrometry. It was found that sesquiterpene hydrocarbons comprised the major class of volatile components present and the juices had a characteristic aroma due to the presence of volatiles including beta-caryophyllene and humulene and alpha-copaene. In comparison with heated juices, HPP-treated samples could retain more volatile compounds such as linalool and geraniol similar to those present in fresh juice, whereas some volatiles such as alpha-terpinene and ketone class were apparently formed by thermal treatment. All processing operations produced juice that was not significantly different in the concentration of total volatiles. Practical Application: Pennywort juice is considered a nutraceutical drink for health benefits. Therefore, to preserve all aroma and active components in this juice, a nonthermal process such as ultra-high pressure should be a more appropriate technique for retention of its nutritive values than pasteurization and sterilization.

In vitro fermentation of sugar beet arabinan and arabino-oligosaccharides by the human gut microflora

Aims: To determine the fermentation profiles by human gut bacteria of arabino-oligosaccharides of varying degree of polymerization. Materials and Methods: Sugar beet arabinan was hydrolyzed with a commercial pectinase and eight fractions, of varying molecular weight, were isolated by gel-filtration chromatography. Hydrolysis fractions, arabinose, arabinan and fructo-oligosaccharides were fermented anaerobically by gut bacteria. Total bacteria, bifidobacteria, bacteroides, lactobacilli and the Clostridium perfringens/histolyticum sub. grp. were enumerated using fluorescent in situ hybridization. Results: Bifidobacteria were stimulated to different extents depending on molecular weight, i.e. maximum increase in bifidobacteria after 48 h was seen on the lower molecular weight fractions. Lactobacilli fluctuated depending on the initial inoculum levels. Bacteroides numbers varied according to fraction; arabinan, arabinose and higher oligosaccharides (degree of polymerization, dp > 8) resulted in significant increases at 24 h. Only carbohydrate mixtures with dp of 1-2 resulted in significant increases at 48 h (log 8.77 +/- 0.23). Clostridia decreased on all substrates. Conclusions: Arabino-oligosaccharides can be considered as potential prebiotics. Significance and Impact of the Study: Arabinan is widely available as it is a component of sugar beet pulp, a co-product from the sugar beet industry. Generation of prebiotic functionality from arabinan would represent significant added value to a renewable resource.

Synthesis of cationic water-soluble copolymers and hydrogels based on [2-(methacryloyloxy)ethyl]trimethylammonium cloride and 2-hydroxyethylacrylate and their complex formation with poly(acrylic acid)

Water-soluble cationic copolymers and hydrogels were synthesized by radical copolymerization of [2-(methacryloyloxy)ethyl]trimetilylammonium chloride (MADQUAT) and 2-hydroxyethylacrylate (HEA). The kinetics of copolymerization has been studied and the reactivity ratios were determined. It was found that MADQUAT exhibits higher reactivity in copolymerization. The complexation between linear MADQUAT-HEA and linear poly(acrylic acid) (PAA) has been studied in aqueous solutions at different pH. It results in the formation of insoluble polyelectrolyte complexes, whose composition and stability to aggregate depends on MADQUAT content in copolymers and pH. The hydrogels were synthesized by three-dimensional radical copolymerization of MADQUAT and HEA in the presence of a crosslinker. The effects of the feed mixture composition on yield and swelling properties of the hydrogels were studied. The interactions of these hydrogels with linear PAA result in formation of gel-polyelectrolyte complexes and contraction of the samples. It was found that the contraction depends on copolymer composition, PAA molecular weight, and solution pH. (c) 2006 Wiley Periodicals, Inc.

Temperature-responsive water-soluble copolymers based on 2-hydroxyethyl acrylate and butyl acrylate

Amphiphilic copolymers have been synthesised by free radical copolymerisation of 2-hydroxyethyl acrylate with butyl acrylate, the reactivity ratios of which indicate practically equal reactivity. The copolymers containing less than 30 mol-% of BA were soluble in water and exhibited a LCST in aqueous solutions. It was found that the interaction between these copolymers and poly(acrylic acid) in aqueous solutions resulted in the formation of interpolymer complexes stabilised by hydrogen bonds and hydrophobic interactions. This interaction was significantly affected by solution I pH and led to modification of the temperature-responsive behaviour of the copolymers.

Novel temperature-responsive water-soluble copolymers based on 2-hydroxyethylacrylate and vinyl butyl ether and their interactions with poly(carboxylic acids)

Novel water-soluble amphiphilic copolymers have been synthesized by free radical copolymerization of 2-hydroxyethylacrylate with vinyl butyl ether. In water these copolymers exhibit lower critical solution temperature, which depends on the content of hydrophobic vinyl butyl ether units. The interaction between these copolymers and poly(acrylic acid) or poly(methacrylic acid) in aqueous solutions results in formation of interpolymer complexes stabilized by hydrogen bonds and hydrophobic interactions. An increase in hydrophobicity of the copolymers leads to the enhancement of their complex formation ability with respect to poly(acrylic acid) and poly(methacrylic acid). Poly(methacrylic acid) forms stronger complexes with the copolymers when compared with poly(acrylic acid). The complexes exhibit dual sensitivity to pH- and temperature and this property may be easily adjusted regulating the strength of interaction. (c) 2005 Wiley Periodicals, Inc.

Determination of some water-soluble aroma precursors in goat meat and their enrolment on flavour profile of goat meat

Selected water-soluble precursors, including sugars, free amino acids and nucleotides, were quantified in raw and cooked goat meat, as a part of a study which the main aim was to better understand the aroma formation in goat meat. When compared with the same precursors in beef, lamb and chicken, levels in goat meat were generally similar, except for fructose and glycine, which were present at higher concentrations in goat meat. Fructose, glucose, IMP, and cysteine suffered the greatest losses during the cooking process and seem to be most involved in aroma formation in goat meat. The effects of these precursor changes on the volatile compound composition and formation process of them on cooked goat meat are discussed.

Phenol-soluble modulins of Staphylococcus aureus lure neutrophils into battle

Epidemics of community-acquired Staphylococcus aureus are caused by strains producing high concentrations of phenol-soluble modulins (PSMs). How neutrophils sense PSMs is revealed in this issue of Cell Host & Microbe. Such interactions are key to infection outcome and may be the basis for development of new treatment strategies.

Use of water-miscible retinyl palmitate as markers of chylomicrons gives earlier peak response of plasma retinyl esters compared with oil-soluble retinyl palmitate

Delayed peak response of plasma retinyl esters (RE) relative to plasma triacylglycerols (TAG) and apolipoprotein (Apo) B-48 responses following a fat load supplemented with vitamin A raised doubts about the use of vitamin A to label dietary-derived lipids and lipoproteins. The present study compared the use of water-miscible and oil-soluble retinyl palmitate (RP) as markers of dietary-derived lipoproteins in healthy subjects along with the measurements of postprandial plasma TAG and ApoB-48 responses to investigate whether the delayed peak response observed was due to delayed intestinal output of RE from oil-based solutions. Nine healthy female subjects were given a standard test meal containing a dose (112 mg) of RP in either water-miscible or oil-soluble form in random order, on two separate occasions after a 12 h overnight fast. The results showed that the mean plasma RE concentrations reached a peak significantly later than mean plasma TAG and ApoB-48 concentrations when oil-soluble RP was consumed, whereas plasma RE peaked earlier relative to plasma TAG and ApoB-48 responses when water-miscible RP was used. The results suggested a more rapid absorption with a significantly higher and earlier peak response of plasma RE when water-miscible RP was consumed. This was in contrast to the delayed initial appearance and later sustained higher concentrations of plasma RE during the late postprandial period when oil-soluble RP was consumed. The RE response to the water-miscible RP showed better concordance with plasma TAG response than that of oil-soluble RP.

Synthesis of water-soluble and ether-soluble tetra-μ-acetatodiruthenium(II,III) complexes and X-ray crystal structure of [Ru2(μ-O2CC6H5)4(C2H5OH)2][Ru2(μ-O2CC6H5)4(HSO4)2]

[Ru2(μ-O2CCH3)4Cl] reacts readily with aqueous Ag2SO4 (2: 1 molar ratio) to give the sulphate salt [Ru2(μ-O2CCH3)4(H2O)2]2(SO4) (1). Addition of NaBPh4 to an aqueous solution of 1 produces the ether-soluble tetraphenylborate salt [Ru2(μ-O2CCH3)4(H2O)2][BPh4] (2). A methanolic solution of 1 reacts with Ba(C6H5CCCO2)2 · H2O to give the tetraacetatemonophenylpropynoate complex [Ru2(μ-O2CCH3)4(O2CCCC6H5)] · H2O (3). The reaction of an ethanolic suspension of [Ru2(μ-O2CC6H5)4Cl] with Ag2SO4 and H2SO4 (2 : 1 : 1 molar ratio) leads to the tetra-μ-benzoatodiruthenium(II,III) double complex salt [Ru2(μ-O2CC6H5)4(C2H5OH)2][Ru2(μ-O2CC6H5)4(HSO4)2] (4). Complex 4 is also obtained by reacting an ethanolic solution of 1 with an excess of benzoic acid in the presence of H2SO4. The X-ray crystal structure of 4 shows it to consist of [Ru2(μ-O2CC6H5)4(C2H5OH)2]+ and [Ru2(μ-O2CC6H5)4(HSO4)2]− ions, which are linked together by hydrogen bonds into an infinite polymeric chain. The RuRu distances in the cation and anion are very similar [2.265(2) and 2.272(2) Å, respectively]. Spectroscopic, magnetic, conductivity and cyclic voltammetry data are given for the complexes.

Effect of water-soluble polymers, polyethylene glycol and poly(vinylpyrrolidone),on the gelation of aqueous micellar solutions of Pluronic copolymer F127

The micellization of F127 (E98P67E98) in dilute aqueous solutions of polyethylene glycol (PEG6000 and PEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamic radius (rh,app) obtained from the dynamic light scattering technique increased with increase in PEG concentration but decreased on addition of PVP, results which are consistent with interaction of the micelles with PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversion was used to determine the onset of gelation. The critical concentration of F127 for gelation increased on addition of PEG and of PVP K30 but decreased on addition of PVP K90. Small-angle X-ray scattering (SAXS) was used to show that the 30 wt% F127 gel structure (fcc) was independent of polymer type and concentration, as was the d-spacing and so the micelle hard-sphere radius. The maximum elastic modulus (G0 max) of 30 wt% F127 decreased from its value for water alone as PEG was added, but was little changed by adding PVP. These results are consistent with the packed-micelles in the 30 wt% F127 gel being effectively isolated from the polymer solution on the microscale while, especially for the PEG, being mixed on the macroscale.

Novel polyvinylpyrrolidones to improve delivery of poorly-water soluble drugs; from design to synthesis and evaluation

Polyvinylpyrrolidone is a widely used in tablet formulations with the linear form acting as a wetting agent and disintegrant whereas the cross-linked form is a super-disintegrant. We have previously reported that simply mixing the commercial cross-linked polymer with ibuprofen disrupted drug crystallinity with consequent improvements in drug dissolution behavior. In this study, we have designed and synthesized novel cross-linking agents containing a range of oligoether moieties which have then be polymerized with vinylpyrrolidone to generate a suite of novel excipients with enhanced hydrogen-bonding capabilities. The polymers have a porous surface and swell in most common solvents and in water; properties which suggest their value as disintegrants. The polymers were evaluated in simple physical mixtures with ibuprofen as a model poorly-water soluble drug. The results show that the novel PVPs induce the drug to become “X-ray amorphous”, which increased dissolution to a greater extent than that seen with commercial cross-linked PVP. The polymers stabilize the amorphous drug with no evidence for recrystallization seen after 20 weeks storage.

Influence of sugar type on the bioavailability of cocoa flavanols.

The beneficial effects of cocoa on vascular function are mediated by the absorption of monomeric flavanols into the circulation from the small intestine. As such, an understanding of the impact of the food matrix on the delivery of flavanols to the circulation is critical in assessing the potential vascular impact of a food. In the present study, we investigated the impact of carbohydrate type on flavanol absorption and metabolism from chocolate. A randomised, double-blind, three-arm cross-over study was conducted, where fifteen volunteers were randomly assigned to either a high-flavanol (266 mg) chocolate containing maltitol, a high-flavanol (251 mg) chocolate with sucrose or a low-flavanol (48 mg) chocolate with sucrose. Test chocolates were matched for micro- and macronutrients, including the alkaloids theobromine and caffeine, and were similar in taste and appearance. Total flavanol absorption was lower after consumption of the maltitol-containing test chocolate compared with following consumption of its sucrose-containing equivalent (P = 0·002). Although the O-methylation pattern observed for absorbed flavanols was unaffected by sugar type, individual levels of unmethylated ( - )-epicatechin metabolites, 3'-O-methyl-epicatechin and 4'-O-methyl-epicatechin metabolites were lower for the maltitol-containing test chocolate compared with the sucrose-containing equivalent. Despite a reduction in the total plasma pool of flavanols, the maximum time (T max) was unaffected. The present data indicate that full assessment of intervention treatments is vital in future intervention trials with flavanols and that carbohydrate content is an important determinant for the optimal delivery of flavanols to the circulation.