Rheology of commercial chestnut flour doughs incorporated with gelling agents

The rheological properties of chestnut flour (CF) doughs incorporated with agar, hydroxypropylmethyl cellulose (HPMC) and xanthan at different concentrations (0.5, 1.0, 1.5, 2.0%, flour basis) were determined at 30 °C using a controlled stress rheometer. The mixing behavior at the same temperature was achieved by the Mixolab^® apparatus. The tests conducted in the rheometer were shear (0.01–10 s⁻¹), oscillatory (1–100 rad s⁻¹ at 0.1% strain), creep-recovery (loading of 50 Pa for 60 s) and temperature sweep (30–100 °C) measurements. These rheological properties were significantly modified by the type and content of gelling agent added. The values of apparent viscosity in all tested shear rate range as well as the values of storage (G′) and loss (G″) moduli of CF doughs in the tested angular frequency decreased with increasing agar and HPMC concentration and increased with xanthan addition. Flow curves and storage and loss moduli of assayed doughs were satisfactorily fitted using Cross model and a potential model, respectively. The initial gelatinization temperature decreased with agar and increased with xanthan as well as the gelatinization temperatures range with HPMC addition was shorter. This pasting trend was also noticed using Mixolab^®. Creep-recovery data, successfully fitted using Burgers model, showed that elasticity of doughs improved significantly with HPMC and xanthan addition.     

Development and use of polyethylene passive samplers to detect triclosans and alkylphenols in an urban estuary

To be able to use polyethylene passive samplers (PE) in the field, the partitioning constants between PE and water (K(PEw)) of the compounds examined must be known. The K(PEw)s of triclosan (TCS), methyl-triclosan (MTCS), n-nonylphenol (n-NP), nonylphenol-technical mix (NP-tech), n-octylphenol (n-OP), and t-octylphenol (t-OP) were measured as a function of pH, temperature, and salinity, and a salt effect was calculated for TCS, n-OP, and t-OP. Log K(PEw)s used for calculating dissolved concentrations were taken from 20 °C studies taking salt into account: 3.42 (TCS), 4.53 (MTCS), 4.20 (n-NP), 3.69 (n-OP), and 2.87 (t-OP). The K(PEw) of hydroxyl-group containing compounds were strongly affected by pH, whereas MTCS with its methoxy-group was not. Measured K(PEw)s could not be estimated from octanol-water partitioning constants due to the semipolar makeup of the compounds investigated. Instead, a good correlation (K(PEw) = 0.679 × K(hdw) + 1.033, r(2) = 0.984, p = 0.001) was obtained with hexadecane-water partitioning constants (K(hdw)) predicted from COSMOtherm. During deployments in Narragansett Bay (RI) in the fall of 2009, concentrations of MTCS and t-OP in surface and bottom waters ranged from 40-225 pg L(-1) and 3.5-11 ng L(-1), respectively. These concentrations are far below EC(50) values for rainbow trout. Surface/bottom and bottom/porewater activity ratios were calculated. These indicated surface waters as the main source of MTCS, while surface water as well as sediments were sources of t-OP.     

Advances in possibilities for protein evaluation

With protein evaluation the changing abilities of food proteins are characterized with regard to their covering the requirements of the organism for protein or amino acids, respectively. The biological value of proteins is influenced by several factors. Measuring the reaction of the whole organism (of man or animal) to the food protein the sum of all influencing factors is covered. Hence, these direct evaluation methods have priority. The general dose-reaction curve demonstrates the direct evaluation methods: The evaluation criteria protein efficiency or minimum protein requirement are presented and the different possibilities of interpretion are compared. Most direct evaluation methods are performed with suboptimal protein supply, therefore values for an optimum protein supply can be derived only with reservation. Improved values for protein evaluation can be obtained from investigations of the protein metabolism. With that the substrat-related evaluation can be more orientated to a organism-related one. Indirect biochemical evaluation methods are less important. That does not concern in-vitro evaluation by amino-acid analysis and/or in-vitro digestibility tests. Possibilities and limits of these methods are discussed.     

Ultra-high pressure homogenisation of milk: technological aspects of cheese-making and microbial shelf life of a starter-free fresh cheese

Fresh cheeses from pasteurised (80 °C for 15 s), homogenised-pasteurised (15 + 3 MPa at 60 °C; 80 °C for 15 s) or ultra-high pressure homogenised milks (300 MPa and inlet temperature of 30 °C) were produced in order to evaluate different technological aspects during cheese-making and to study their microbial shelf life. Although the coagulation properties of milk were enhanced by ultra-high pressure homogenisation (UHPH), the cheese-making properties were somewhat altered; both conventional homogenisation and UHPH of milk provoked some difficulties at cutting the curd due to crumbling and improper curd matting due to poor cohesion of the grains. Cheese-milk obtained by UHPH showed a higher microbiological quality than milk obtained by conventional treatments. Starter-free fresh cheeses made from UHPH-treated milk showed less syneresis during storage and longer microbiological shelf-life than those from conventionally treated milk samples.     

Pasteurization of grapefruit juice using a centrifugal ultraviolet light irradiator

Studies are lacking on the nonthermal pasteurization of liquid foods using UV irradiators that centrifugally form very thin films to overcome the problem of limited penetration depth of UV. Grapefruit juice inoculated with Escherichia coli or Saccharomyces cerevisiae was processed at the following conditions: UV dose 4.8–24 mJ/cm²; treatment time 3.2 s, cylinder rotational speed 450–750 rpm, cylinder inclination angle 15–45°, outlet temperature 11 °C, and flow rate 300 ml/min, and was stored for 35 days. Appropriate dilutions of the samples were pour plated with TSA and TSA + 3% NaCl for E. coli and Sabouraud dextrose agar (SDA) and SDA + 5% NaCl for S. cerevisiae. Nonthermal UV processing at 19 mJ/cm², 450 rpm and 15° reduced E. coli in grapefruit juice by 5.1 log₁₀. A dose of 14 mJ/cm² reduced S. cerevisiae by 6.0 log₁₀. Inactivation increased linearly with increasing UV dose. The inactivations at 600 and 750 rpm were similar, and were better than at 450 rpm. The results at 30° and 45° were similar, and were better than at 15°. The occurrence of sublethal injury in either microorganism was not detected. Storing UV processed grapefruit juice at 4 and 10 °C reduced the surviving E. coli to below 1 log₁₀ cfu/ml in 14 days. Processing UV juice reduced the population of S. cerevisiae to less than 1 log₁₀ cfu/ml where it remained for 35 days during refrigerated storage. These results suggest that grapefruit juice may be pasteurized using a nonthermal UV irradiator that centrifugally forms a thin film.     

Comparison of ultra high pressure homogenization and conventional thermal treatments on the microbiological,physical and chemical quality of soymilk

The effect of ultra high pressure homogenization (UHPH) at 200 and 300 MPa in combination with different inlet temperatures (55, 65 and 75 °C) on soymilk was studied. UHPH-treated soymilk was compared with the base product (untreated), with pasteurized (95 °C for 30 s) and with ultra high temperature (UHT; 142 °C for 6 s) treated soymilks. Microbiological (total aerobic meshophilic bacteria, aerobic spores, and Bacillus cereus), physical (dispersion stability and particle size distribution) and chemical (lipoxygenase activity, hydroperoxide index and trypsin inhibitor activity) parameters of special relevance in soymilk were studied. Microbiological results showed that pressure and inlet temperature combination had a significant impact on the lethal effect of UHPH treatment. While most of UHPH treatments applied produced high quality of soymilks better than that pasteurized, the combination of 300 MPa and 75 °C produced a commercially sterile soymilk. UHPH treatments caused a significant decrease in particle size resulting in a high physical stability of samples compared with conventional heat treatments. UHPH treatment produced lower values of hydroperoxide index than heat treated soymilks although trypsin inhibitor activity was lower in UHT-treated products.     

Synthesis and structure of a dimeric scandium bis(μ-methoxy) complex

Reaction of hydrated scandium nitrate with 1,10-phenanthroline (phen) in methanol leads to formation of the unusual dimeric complex [(phen)(NO₃)₂Sc(μ-OMe)₂Sc(NO₃)₂(phen)], in which the scandium centres are eight co-ordinate. The complex features two bridging methoxy ligands, as well as bidentate nitrates and chelating 1,10-phenanthroline ligands.     

Characterization of electrosynthesized polydihaloanilines

The nucleation and growth mechanism of some homopolymers of aniline (six monomers were studied: 3,5‐dichloroaniline, 2,5‐dichloroaniline, 2,6‐dichloroaniline, 2,3‐dichloroaniline, 2,5‐dibromoaniline, and 2,6‐dibromoaniline), synthesized by potentiostatic methods, was determined with a mathematical model that considers different contributions from current–time transients with a gold‐disc electrode. Deconvolution of the transients for the dichlorinated monomers showed IN3D_ct and PN3D_dif contributions (where IN3D_ct refers to an instantaneous nucleation and three‐dimensional growth mechanism under charge‐transfer control and PN3D_dif refers to a progressive nucleation and three‐dimensional growth mechanism under diffusion control), whereas IN2D and PN3D_dif components and IN2D, IN3D_ct, and PN3D_dif components (where IN2D refers to an instantaneous nucleation and two‐dimensional growth mechanism) were needed for 2,5‐dibromoaniline and 2,6‐dibromoaniline, respectively. The percentage of the contribution of the current–time transient to the total charge was worked out for each monomer. The effect of the scan rate on the voltammetric profile during the potentiodynamic electrosynthesis of the polymers was studied too. Curves of the current versus the square root of the potential scan rate were recorded for a selected group of monomers, and the slope was considered an estimation of the diffusion coefficient of the respective monomer. Furthermore, the electrosynthesized polymers were characterized with Fourier transform infrared, ultraviolet–visible, X‐ray photoelectron spectroscopy, and scanning electron microscopy. Microanalysis, used to establish the ratio of the atomic percentages of P and N for each polymer synthesized at a constant potential, was performed for doped and undoped polymers. This parameter was a measure of the degree of electrochemical doping. The conductivity of the doped and undoped polymers was also measured. Hence, the systematic characterization of this analogue series of monomers allows, before generalization, an adequate experimental design to prepare polymers with the properties required for their use. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010