Physicochemical Measurements Research Articles

Commercial spread optimization using experimental design and sensory data

AbstractThe cost and quality of food products are issues that concern both the consumer and producer. In this research, the process used for the production of a commercial spread was subjected to a statistical experimental design for the purpose of reducing the cost of production while maintaining or improving the sensory quality. Three factors—the amount of oil added (x1), the speed of puddling (x2), and the temperature treatment (A or B; x3)—were varied according to a full‐factorial design at two levels. The experiments were performed over 2 d, and the factorial design was complemented with three replicates for temperature treatments A and B, which were performed on different days. The products were evaluated with both sensory and physicochemical measurements. Special attention was paid to the hardness of the product since it was permissible to reduce it slightly. In contrast, sensory quality aspects of the product including butter‐aroma and off‐flavor, as well as other quality properties such as spreadability, shine, and meltability, had to be maintained at the present level or improved. Statistical evaluation of the data showed that it was possible to add high amounts of oil (x1) without impairing the sensory quality of the product and, hence, reduce the cost of production. The hardness of the product was also slightly reduced when using the high level of oil. In maintaining other sensory qualities such as shine and spreadability at the present levels, the choice of temperature treatment (x3) was important.

Evaluation of the relative sensitivity of chromosome painting (FISH) as an indicator of radiation-induced damage in human lymphocytes.

Fluorescence in situ hybridization with whole chromosome libraries, also known as chromosome "painting", is an easy and rapid method for detection of chromosome aberrations. To evaluate the sensitivity of this in radiation dosimetry we have made comparisons with G-banding analysis and also with physicochemical measurements of radiation induced DNA damage (DNA strand breaks and 8-hydroxydeoxyguanosine formation). Heparinised human blood was irradiated at room temperature with a range (0-10 Gy) of gamma irradiation from a cobalt 60 source. Chromosome spreads prepared from phytohaemagglutinin stimulated "whole blood" lymphocyte cultures were hybridized in situ with the whole chromosome 1 library, coded, and scored for aberrant cells. Dose response curves plotted as percent abnormal cells obtained by the two cytogenetic methods were similar and it would appear that chromosome "painting" compared favourably with G-banding for the detection of aberrations. The measurement of DNA strand breaks by a fluorimetric alkaline unwinding assay showed similar sensitivity to chromosome "painting" whereas the formation of 8-hydroxydeoxyguanosine did not correlate with aberration frequencies.

Analysis of the tastes of brown rice and milled rice with different milling yields using a taste sensing system

The tastes of brown rice and milled rice with different milling yields were analyzed by a taste sensing system, chemical methods and sensory evaluation. In addition, a study of some physicochemical properties of samples was carried out. Using the taste sensing system with ten sensors made from lipid membranes, both raw and cooked samples of brown rice and milled rice, with different milling yields, were distinguished. A multiple regression analysis, based on taste sensor response electric potential patterns, was conducted to evaluate sensory taste scores and chemical taste components of rice. For both raw and cooked rice, the highest accuracy, shown by coefficient of determination ( R 2) and the lowest standard error of the prediction (SEP), were obtained when using a combination of two or three sensors. Hence, differences of tastes between brown rice and milled rice with various milling yields can be evaluated not only by physicochemical measurements but also by the taste sensing system.

PIXE, PIGE and NMR study of the masonry of the pyramid of Cheops at Giza

The mystery of the construction of the great pyramids of Egypt could be elucidated by physico-chemical measurements on small pieces of the material. In this paper, we give several arguments against the present point of view of most Egyptologists who do not admit another method than hewn blocks. We give several pieces of evidence that the masonry was entirely built by a moulding procedure involving the use of ingredients that were all available in the region of Cairo.

Analysis of ion-association reaction in aqueous solution and its utilization by capillary zone electrophoresis.

Electrophoretic migration of analytes in capillary zone electrophoresis (CZE) reflects the dissolved status of analytes in solution, and the electrophoretic mobility is controlled to develop the resolution among analytes by adding a "modifier" to the migrating solution. Such addition of modifier is essentially the utilization of molecular interactions. Precise measurement of electrophoretic mobility by CZE allows analyzing molecular interactions, and CZE apparatus is very useful for physicochemical measurements. This review focuses on the advantages on using CZE to analyze equilibrium reaction; the capillary electrophoretic method and mathematical analyses that apply acid dissociation and complex formation reactions are also validated. Ion association reactions are deeply related to analytical chemistry and separation science, and CZE has been used for the investigation of ion-ion interactions. Various types of interactions have been clarified through the CZE measurements: contributions of hydrophobicity, probability, and aromatic-aromatic interaction were quantitatively evaluated. Ion association reaction in aqueous solution also elucidates the stepwise reactions of liquid-liquid distribution of ion associates. Development and applications of ion association reaction in CZE analysis are also introduced.

Catalytic activity of chromium(III), iron(III) and bismuth(III) complexes of 1,2-bis(2-hydroxybenzamido)ethane (H2hybe) encapsulated in zeolite-Y for liquid phase hydroxylation of phenol

Iron(III), chromium(III) and bismuth(III) complexes of amidate ligand 1,2-bis(2-hydroxybenzamido)ethane (H2hybe) encapsulated in the super cages of zeolite-Y have been isolated and characterized by various physico-chemical measurements. 3D model structure generated for [Fe(hybe)·2H2O]+ suggests that zeolite-Y can accommodate these complexes in its super cages without any strain. These encapsulated complexes catalyze hydroxylation of phenol using H2O2 as oxidant to give catechol as a major and hydroquinone as a minor product. A suitable reaction condition has been optimized for [Fe(hybe)·2H2O]Cl–Y by considering the effect of various parameters such as concentration of substrate, amount of oxidant and catalysts, reaction time, temperature, and volume of solvent for the maximum hydroxylation of phenol. The results obtained over these new encapsulated catalysts showed that selectivity of the catechol formation is ca. 85%, though transformation of phenol varied in the order [Fe(hybe)·2H2O]Cl–Y (43.5%)>[Cr(hybe)·2H2O]Cl–Y (32.8%)>[Bi(hybe)·2H2O]Cl–Y (30.6%). Catalytic performance of these catalysts has been compared with different metal complexes encapsulated in zeolite-Y.

High frequency monitoring of the coastal marine environment using the MAREL buoy.

The MAREL Iroise data buoy provides physico-chemical measurements acquired in surface marine water in continuous and autonomous mode. The water is pumped 1.5 m from below the surface through a sampling pipe and flows through the measuring cell located in the floating structure. Technological innovations implemented inside the measuring cell atop the buoy allow a continuous cleaning of the sensor, while injection of chloride ions into the circuit prevents biological fouling. Specific sensors for temperature, salinity, oxygen and fluorescence investigated in this paper have been evaluated to guarantee measurement precision over a 3 month period. A bi-directional link under Internet TCP-IP protocols is used for data, alarms and remote-control transmissions with the land-based data centre. Herein, we present a 29 month record for 4 parameters measured using a MAREL buoy moored in a coastal environment (Iroise Sea, Brest, France). The accuracy of the data provided by the buoy is assessed by comparison with measurements of sea water weekly sampled at the same site as part of SOMLIT (Service d'Observation du Milieu LIToral), the French network for monitoring of the coastal environment. Some particular events (impact of intensive fresh water discharges, dynamics of a fast phytoplankton bloom) are also presented, demonstrating the worth of monitoring a highly variable environment with a high frequency continuous reliable system.

Thylakoid-associated Polyamines Adjust the UV-B Sensitivity of the Photosynthetic Apparatus by Means of Light-harvesting Complex II Changes¶

The sensitivity of the photosynthetic apparatus to ultraviolet-B (UV-B) irradiation was studied in cultures of unicellular green alga Scenedesmus obliquus incubated in low light (low photosynthetically active radiation intensity [LL]) and high light (high photosynthetically active radiation intensity [HL]) conditions, treated or not with exogenous polyamines. Biochemical and physicochemical measurements showed that UV-B radiation induces a decrease in the thylakoid-associated putrescine (Put) and an increase in spermine (Spm), so that the reduction of Put/Spm ratio leads to the increase of light-harvesting complex II (LHCII) size per active reaction center and, consequently, the amplification of UV-B effects on the photosynthetic apparatus. The separation of oligomeric and monomeric forms of LHCII from isolated thylakoids showed that UV-B induces an increase in the oligomeric forms of LHCII, which was more intense in LL than in HL. By manipulating the LHCII size with exogenous polyamines, the sensitivity degree of the photosynthetic apparatus to UV-B changed significantly. Specifically, the addition of Put decreased highly the sensitivity of LL culture to UV-B because of the inhibitory effect of Put on the LHCII size increasing, whereas the addition of Spm enhanced the UV-B injury induced in HL culture because of the increasing of LHCII size. The ability of the photosynthetic apparatus to recover the UV-B induced changes was also investigated.

Cu/Co-salen immobilized MCM-41: characterization and catalytic reactions

Copper and cobalt (salen) complexes immobilized on the walls of MCM-41 modified with aminopropyl groups have been synthesized and characterized by various physico-chemical measurements such as XRD, FTIR, UV–Vis, EPR, TGA. UV–Vis and FTIR spectra reveal adduct formation of metal–salen complexes with the amino groups tethered to the SiO 2 surface. EPR studies indicate molecular dispersion of the salen complex inside the pores of MCM-41. The activity of the immobilized complexes as catalyst for the liquid phase oxidation of olefins was investigated.

Physico-chemical measurements of CL-20 for environmental applications: Comparison with RDX and HMX

CL-20 is a polycyclic energetic nitramine, which may soon replace the monocyclic nitramines RDX and HMX, because of its superior explosive performance. Therefore, to predict its environmental fate, analytical and physico-chemical data must be made available. An HPLC technique was thus developed to measure CL-20 in soil samples based on the US Environmental Protection Agency method 8330. We found that the soil water content and aging (21 days) had no effect on the recoveries (>92%) of CL-20, provided that the extracts were kept acidic (pH 3). The aqueous solubility of CL-20 was poor (3.6 mg l −1 at 25 °C) and increased with temperature to reach 18.5 mg l −1 at 60 °C. The octanol–water partition coefficient of CL-20 ( log K OW =1.92 ) was higher than that of RDX ( log K OW =0.90 ) and HMX ( log K OW =0.16 ), indicating its higher affinity to organic matter. Finally, CL-20 was found to decompose in non-acidified water upon contact with glass containers to give NO 2 − (2 equiv.), N 2O (2 equiv.), and HCOO − (2 equiv.). The experimental findings suggest that CL-20 should be less persistent in the environment than RDX and HMX.

Synthesis and physicochemical characterization of oxo and phenylimido Re(V), Re(III) and Ni(II) complexes with the 2-[bis(ethoxyethyl)phosphino]phenolato ligand and derivatives

2-[Bis(ethoxyethyl)phosphino]phenol P 1–OH reacts in basic refluxing solvents with ReOCl 3(PPh 3) 2, in a 2/1 molar ratio, to give the green ReOCl(P 1–O) 2 complex. Structure elucidation by 31P NMR is consistent with a cis-PP “twisted” octahedral complex, which is the preferred conformation on electronic grounds. The complex is unique in toluene while several species were present in ethanol. When the reaction is performed with Re(NPh)Cl 3(PPh 3) 2, a mixture of trans-PP (major) and cis-PP(minor) species in a 3/1 ratio is obtained. These geometric isomers were distinguished by their 2 J PP coupling constants. Only cis-PP-Re(NPh)Cl(P 1–O) 2, less soluble, could be isolated and its molecular structure determined by physicochemical measurements. This is the first example of cis-PP phosphinophenolato complex with the [ReNPh] 3+ core, thus illustrating the importance of the steric demand of the phosphine substituent. Reaction of P 1–OH with NiCl 2 gives Ni(P 1–O) 2 as an orange oily solid with a cis-PP square planar structure. This structure is the most probable based on the 31P, 13C NMR data.

Characterization of environmental gradients using physico-chemical measurements and diatom densities in Nairobi River, Kenya

Degradation of water resources due to anthropogenic activities is a major problem all over the world. Monitoring changes in water quality is expensive but essential for management of water resources. Diatom assemblages can serve as useful indicators of changes in water quality. In order to determine changes in stream water quality in an urban environment, densities of epilithic diatom communities on both natural and artificial substrates were sampled in Nairobi River, Kenya in September 2000. Sampling of water and diatoms was carried out in almost equidistant sites along a 60 km stretch of the Nairobi River. Environmental (water physico-chemical and nutrients) data was explored by Principal Correspondence Analysis (PCA) and sites split into three groups of upper-, mid- and lower stream. Most abundant diatom taxa on both substrates were selected and their relationship with environmental variables determined. On artificial substrates, Gomphonema parvulum, Nitzschia palea and Nitzschia umbonata were the most abundant and were significantly related with total dissolved solids, nitrate, conductivity and turbidity. Temperature, altitude and pH interacted significantly with dominant diatom species on natural substrates, which included Gomphonema parvulum, Nitzschia palea and Navicula subminuscula. Non-parametric analyses showed that diatom densities in natural and artificial substrates were significantly different and were affected by different environmental variables. Our results indicate that abundant diatom species can be used to describe major types of aquatic environmental gradients and can serve as good indicators of ecological conditions in tropical streams and rivers. This study also showed that diatoms from artificial and natural substrates can be used to provide complementary information.

Analysis of the Differential Conformational Behavior of Two Antigens of the Hepatitis A Virus through Molecular Dynamics and Physicochemical Measurements

The surface activity of peptides with proven antigenic activity toward the hepatitis A virus (HAV), [Glu 1 1 4 ]VP3(110-121) and [Lys 1 1 3 ]VP3(110-121), analogues of the VP3(110-121) antigen of HAV with sequence FWRGDLVFDFQV, was deduced from compression isotherm experiments. The results showed that the lysine analogue exhibits a surface area about three times smaller than that of the glutamic acid analogue. To understand whether this observed differential conformational behavior of the two peptide analogues is a characteristic feature of the peptide sequences, we carried out 10 ns molecular dynamics simulations of the two analogues in water. The results of this study confirm a differential conformational behavior of the two peptides and provide support to the hypothesis of this observed behavior as the reason for the different surface areas obtained from compression isotherm experiments.

The Use of Visible and Near-Infrared Reflectance Measurements to assess Sensory Changes in Carrot Texture and Sweetness during Heat Treatment

The use of non-destructive near-infrared reflectance (NIR) measurements to predict the change in sensory quality of carrot discs during heat treatment was investigated. Near-infrared reflectance measurements were performed on five different batches of carrots, cooked for 0, 1, 2, 5, 10, or 15 min, with a spectrophotometer with a wavelength range of 400–2500 nm. Per combination of batch and heat treatment, 20 carrot discs with a height of 8 mm and a diameter of 25 mm were tested. As instrumental reference measurements the dry matter content (DM), soluble solids content (SSC), compressive strength F C and tensile strength F t were recorded on carrots from the same batches and heat treatments. Sensory profiling was carried out on three of the five batches. The sensory attributes considered were hardness, crispness, juiciness, sweet smell, and sweet taste. The shape of the NIR spectra was determined by the water absorption bands and the absorption by carotenoids in the visual light region. Partial least-squares regression (PLSR) was used to predict the average sensory scores for each batch and cooking time from the NIR spectra obtained from individual carrot discs. Second-order derivative pre-processing combined with meancentring, provided a better prediction capability than first-order derivation or multiplicative scatter correction. The root mean square errors of prediction (RMSEP) amounted to 1·13, 1·20, 0·89, 0·78, and 1·06 for hardness, crispness, juiciness, sweet smell and sweet taste, respectively, in sensory units (scale 0 to 15). To obtain the best possible prediction, it appeared to be important to include batch-specific information in the model. Compared with a PLSR model based on the four physico-chemical reference measurements, the NIR model provided a better estimation of hardness, crispness, and sweet smell. Measurements for one batch on xylem and phloem parts of the carrot discs separately, showed that a further improvement of the model calibration could be obtained by taking the NIR spectrum on the phloem part. The average physico-chemical results for a specific batch and heat treatment, could be estimated from a PLSR model based on the NIR spectra, with an average RMSEP of 7–13% of the measurement range under consideration. The results suggest that NIR measurements could be successfully used to control sensory quality during heat treatment.

Physicochemical Measurements by the Reversed‐Flow Version of Inverse Gas Chromatography

AbstractFor Abstract see ChemInform Abstract in Full Text.

Prediction of technological quality (cooking loss and Napole Yield) of pork based on fresh meat characteristics

In order to investigate if cooking loss and Napole Yield can be predicted from various fresh meat characteristics, pH (1, 15, 30, 60, 120 min and 24 h post mortem), temperature (1, 15, 30, 60, 120 min and 24 h post mortem), water-holding capacity (Honikel's drip loss method and centrifugation loss), and NMR T2 relaxation 24 h post mortem were measured in fresh porcine M. longissimus dorsi from 102 Hampshire crossbreeds of known RN − genotype. Subsequently, cooking loss and Napole Yield were determined on cooked and cured, cooked samples, respectively, and partial least squares regression (PLS) was carried out to investigate possible intercorrelations between the physico-chemical measurements performed on the fresh meat and cooking loss/Napole Yield. Significant correlations were found between NMR T2 relaxation measured in fresh pork 24 h post mortem and the cooking loss ( R=0.64) and Napole Yield ( R=0.58), whereas no correlations were found between traditionally applied methods such as pH measurements, Honikel's method and centrifugation, and the cooking loss/Napole Yield. Consequently, it is concluded that NMR T2 relaxation characteristics of fresh pork in contrast to traditional fresh meat characteristics contain information about factors of importance for cooking loss/Napole Yield from cooked uncured/cured pork. The result implies that low-field (LF) NMR data from fresh meat reflects information about water compartmentalisation and mobility that is partly decisive for subsequent heat-induced changes of importance for the distribution of water within the cooked meat. In addition, the obtained results show that LF NMR data measured on fresh meat also seems to contain information about the inherent water of importance for the technological characteristics of the meat even when the meat is cured before cooking.

Statistical analysis of the physico-chemical data on the coastal waters of Cochin.

Measurements of temperature, salinity, dissolved oxygen, nitrogen as ammonia, nitrate and nitrite, and phosphate along with chlorophyll were carried out at three stations on the coastal waters of Cochin, south west India, at two-levels of the water column over a period of five years. The data set has been factorised using principal component analysis (PCA) for extracting linear relationships existing among a set of variables. A graphical display of the scores generated from the PCA was done by means of boxplots and biplots, which helped in the interpretation of the data. The major factors conditioning the system are related to the input of fresh water from the estuary of the Periyar river and the high organic load of the bottom sediment in the coastal area which results in a reducing environment, as reflected in the parameters of dissolved oxygen, ammoniacal-nitrogen and nitrite-nitrogen. Another factor which contributes to the variation in the system is related to the unloading activity in the port area. The present approach presents a logical way to interpret the complex data of the physico-chemical measurements.

Differences in composition of macroinvertebrate communities with invasive and native Gammarus spp. (Crustacea: Amphipoda)

SUMMARY 1. Assessing the effects on communities of invasive species is often confounded by environmental factors. In Irish rivers, the introduced amphipod Gammarus pulex replaces the native G. duebeni celticus in lowland stretches. The two amphipods are associated with different macroinvertebrate communities, which may in part be the result of natural longitudinal physicochemical change. However, this hinders assessment of any direct community impacts of the invasive as compared with the native species. Here, we report on a fortuitous circumstance that allowed us to uncouple the community effects of Gammarus species from environmental differences.2. The lowland stretch of the River Lissan is dissected by a weir, which has slowed the upstream invasion by G. pulex. We took physicochemical measurements and macroinvertebrate samples from three contiguous 150 m reaches of this stretch with G. pulex only, mixed Gammarus and G. d. celticus only communities.3. We found no biologically significant differences in physicochemistry among the three reaches. Overall invertebrate densities did not differ among reaches. However, G. pulex numerically dominated its reach, whilst G. d. celticus abundance was relatively low in its reach. The G. pulex reach had significantly higher overall biomass because of high invader abundance. In addition, both diversity and species richness of macroinvertebrate communities were lower in the G. pulex than the G. d. celticus reach, with the mixed Gammarus reach intermediate.4. Ordination indicated distinctly different associations of invertebrate community samples and taxa that were best explained by the distributions of the Gammarus species. Again, the mixed Gammarus species samples were intermediate.5. This study indicates that the invasive G. pulex has a greater impact on macroinvertebrate community composition than the native G. d. celticus, probably through biotic interactions such as predation.

Streams in the Harz National Parks (Germany) — a hydrochemical and hydrobiological evaluation

Between 1995 and 2001, 16 measuring points at small and medium sized brooks in the Harz National Parks were sampled. The samples have been evaluated by means of hydrochemistry and macroinvertebrate biology. Although nearly all streams are largely uncontaminated by oxygen-consuming substances, they are settled only by a small number of macroinvertebrate species. There is a clear correlation between this number and pH. The reduction in species number with decrease of pH is mainly caused by the absence of most Ephemeroptera, some Coleoptera and Trichoptera. Comparing biological evaluation of acidity with physico-chemical measurements, a unacceptable underestimation was found. The reason could be that different sensitivities to acidification between regional populations seem to exist. Despite of the low species number, there is a very specific macroinvertebrate fauna that emphasizes the conservation value of the Harz National Parks.

Preservation of raspberry fruits by freezing: physical, physico-chemical and sensory aspects

Physical, physico-chemical, and sensory analysis were performed during freezing and long-term frozen storage (12 months) at –24 °C of four Spanish raspberry cultivars (Rubus idaeus), Heritage, Autumn Bliss (early cultivars), Zeva and Rubi (late cultivars). The purpose was to study the effect of the genetic origin and seasonal period of harvesting on the quality of the processed fruit with the aim of selecting the most suitable cultivar for frozen storage. Samples were evaluated by panellists through a 1-year period of storage at –24 °C in terms of three sensory attributes: firmness, colour, and taste/flavour. These sensory aspects were compared to the experimental physical and physico-chemical measurements of colour (L*, a*, b*, h, C and ΔE) and taste components (soluble solids content, titratable acidity, and quality index: °Brix/acidity). The freezing process itself did not produce significant changes in the more commonly assessed sensory quality parameters of firmness, colour, and taste/flavour. However, during storage at –24 °C, changes in sensory characteristics occurred and became more evident as storage continued (>6 months), especially in the late cultivars Zeva and Rubi. This evidence supports the notion that the early cultivars, Heritage and Autumn Bliss, could be more suitable for long-term frozen storage in terms of sensory aspects.