Quantification of the 3D microstructure of SC surfaces

This study presents the development of an ImageJ plugin for surface characterization. Based on gradient analysis, parameters, such as the gradient magnitude, orientation, mean resultant vector and surface area are derived. A comparative study of supercalendered (SC) papers was performed to verify the surface representations yielded by a laser profilometer. The surface representations of samples covered with carbon and gold were compared to untreated samples. The results confirm the suitability of gold coating for reducing the artefacts encountered on laser profilometry surface representations of paper. In addition, a complete scanning electron microscopy analysis is performed on the assessed samples to quantify the surface fraction covered by mineral fillers and to reveal the true 3D microstructure of SC surfaces. The influence of filler coverage and filler type on the gloss level of commercial SC papers is evaluated. The relationship between the surface topography, gloss and PPS roughness for a series of commercial SC papers is established.     

Volatile Compounds Characterizing the Aroma of Fresh Atlantic and Pacific Oysters

Volatile compounds which contribute to the distinct melon-like aroma of fresh Pacific oysters (Crassostrea gigas) were identified as (E,Z)-2,6-nonadienal and 3,6-nonadien-1-ol, but these compounds were not found in the less intensely flavored Atlantic oysters (Crassostrea virginica). 1-Octen-3-one, 1-octen-3-ol, 1,5-octadien-3-one, 1,5-octadien-3-ol, and 2,5-octadien-1-ol were found in both species of oysters, and contributed a characteristic heavy, planty aroma to each. Sensory panel scores for intensity of fresh melon-like flavors were significantly higher for both raw and steamed Pacific oysters than for comparable Atlantic oysters. Enzymic generation of alcohols and carbonyls that comprise the characterizing aroma compounds from polyunsaturated fatty acids was demonstrated by preventing their formation with specific inhibitors for cyclooxygenase (acetylsalicylic acid) and lipoxygenase [tin (II) chloride].     

EFFECT OF ULTIMATE pH ON THE QUALITY CHARACTERISTICS OF PORK

A study was conducted to characterize the relationship between Longissimus thoracis ultimate pH(LTpH) and pork quality. Animals (n = 47) were selected based on LTpH measured at 24 h postmortem. Data were analyzed using regression procedures with ultimate pH as the independent variable, and relationships were determined to be linear (L), quadratic (Ql or cubic (C). Ultimate pH explained 79% (C) of the variation in subjective color, which increased as pH increased. Drip loss, purge loss and L* value decreased as LTpH increased (R²= 0.57C, 0.77 Q and 0.68 Q, respectively). Shear force decreased and sensory juiciness increased as LTpH increased (R²= 0.26Q and 0.46C, respectively). However, of flavor intensity increased as LTpH fell below pH 5.2 or exceeded 6.1(R²=0.52C). Increasing LTpH, up to a point, will improve fresh pork quality and processed meat properties, whereas, above approximately 6.1, of-flavor may increase.     

Use of near infrared spectroscopy to evaluate the intensity of extrusion-cooking processing of pea flour

Twenty-five different pea extrudates were produced using a Clextral BC45 twinscrew extruder. Near infrared reflectance (NIR) spectra of the extrudates were recorded between 1100 and 2500 nm. the application of principal component analysis (PCA) on these spectral data permitted discrimination between the extrudates produced under moderate, intermediate or severe conditions of extrusion-cooking. the study of protein quality through solubility experiments, polyacrylamide gel electrophoresis, determination of available basic amino acids and brown colour measurement showed that, under moderate conditions of extrusion-cooking, protein was only slightly affected. All protein subunits could be restored after solubilization in phosphate buffer containing a detergent and a reducer of disulphide bonds. However, under severe conditions of extrusion-cooking, the extrudates exhibited a relatively intense brown colour and all protein fractions were implicated in non-disulphide covalent bonds and underwent some macromolecular degradation. Therefore, the spectral discrimination between pea extrudates which was related to the processing parameters, could also be related to the degree of transformation of these extrudates. Thus, the method may be used to classify an extrudate produced under unknown conditions by projecting its spectrum on the similarity maps obtained by PCA on a known collection of extrudates.     

Finite sized coherent and incoherent detectors in confocal microscopy

We consider the effects of finite sized coherent and incoherent detectors on the axial resolution of confocal microscopes. We adopt a high-angle vector approach which takes the polarization property of the object into account. We further consider polarization imaging and show that coherent detection has an advantage over incoherent detection in terms of the value of the extinction coefficient. The desirability of aberration correction is briefly discussed.     

Transpiration-assisted perfusion fixation provides in situ preservation of developing ray parenchyma cells in Eucalyptus nitens

The technique of animal vascular perfusion fixation was adapted for in situ fixation of the fragile and difficult to access cells of the ray parenchyma system in stems of 10-year-old Eucalyptus nitens trees. In situ fixation enabled tissue to be safely dissected for histological processing without risk of damage to microstructure or initiation of wound response. Fixative was perfused through the active vascular system under hydrostatic and transpiration pressure directly to vessel-associated ray cells. Diffusion from vessels allowed fixative to access nonvessel-associated ray cells. Acrolein was included to aid diffusion fixation and safranin dye was included to define fixed regions within the xylem. Sections prepared for light and electron microscopy from samples cut from regions showing intense safranin staining showed good microstructural preservation and were free of artefacts caused by mechanical injury or wound response.     

CONTENT AND STABILITY OF HEXANE EXTRACTABLE LIPID AT VARIOUS STEPS OF PRODUCING MACARONI CONTAINING GROUND FLAXSEED

Research was conducted to determine changes in content and stability of hexane extractable lipid during processing of macaroni containing 15% (w/w) ground whole flaxseed and ground flaxseed hull. Dry mixture, hydrated mixture, extruded macaroni, dried macaroni and cooked macaroni were evaluated. Results were similar for macaroni containing ground whole flaxseed or ground flaxseed hull. Hydration decreased extractable lipid. Hydration decreased the amount of α-linolenic acid (ALA) and free fatty acid (FFA) and increased the amount of conjugated diene in the extracted lipid. Little or no conjugated triene was detected in lipid extracted from samples containing flaxseed, regardless of the processing step. Extruding, drying and cooking had little or no effect on the stability of lipids in macaroni containing flaxseed. The low levels of FFA, conjugated diene and conjugated triene indicate that lipid remained relatively stable during processing and cooking of macaroni containing ground flaxseed.     

LIPID AND LIPID SOLUBLE COMPONENTS OF GONADS OF GREEN SEA URCHIN (STRONGYLOCENTROTUS DROEBACHIENSIS)

Seasonal changes in the lipid and lipid soluble components of gonads of green sea urchin (Strongylocentrotus droebachiensis) were investigated. The lipid content was highest in the spring while it was lowest in the winter. The composition of nonpolar and polar lipid classes of sea urchin gonads were not affected qualitatively, but there were significant (P<0.05) quantitative variations. Major nonpolar lipid classes were triacylglycerols (TAG), free fatty acids (FFA) and sterols (ST) while dominant polar lipid components were phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The fatty acids 16:0 and 14:0 were the major saturated fatty acids (SFA) consistently present in total, nonpolar and polar lipids of sea urchin gonads. The 5-olefinic acid 20:1 n-15 was the dominant monounsaturated fatty acid (MUFA) while 20:4 n-6 and 20:5 n-3 were the major polyunsaturated fatty acids (PUFA) present. The content of PUFA increased during cold climatic conditions with a simultaneous decrease in the content of SFA. These changes were reversed during warm seasons. Total carotenoid content was highest in the spring. Echininone was the major carotenoid present and its relative content varied significantly (P<0.05) with the season; being highest in the spring and lowest in the summer. In addition, β-carotene was present in each season. Thus, the importance of seasonal variations on the lipid and lipid soluble components of sea urchin gonads is evident.