Heat Gelation of Oil-in-Water Emulsions Stabilized by Whey Protein

The conditions under which a high volume fraction of oil can be trapped in whey protein gels were studied. Oil-in-water emulsions of whey protein and vegetable oil were subjected to heat treatment. Such emulsions, depending on their protein and oil content, on their pH and on the emulsification technique used, gelled or remained liquid. Homogenization was the major factor to achieve gelation and the firmness of heat-induced gels increased with increasing emulsion fineness and homogeneity. Emulsions with a high gelation capacity were characterized by a single droplet family of relatively narrow size distribution and a mean droplet diameter ranging from roughly 300–700 nanometers. The pH range suitable for gelation extended from 3.5–8.0.     

Effect of Processing on Proximate Composition and Mineral Content of Sea Cucumbers (Parastichopus spp.)

The nutrient content, texture and holothurin content of two sea cucumber species were determined for fresh, dried and canned products. Fresh sea cucumber contained 89–91% moisture, 5–6% protein, 0.3% fat, 3% ash and 0.3% carbohydrate; dried sea cucumber contained 2–6% moisture, 61–70% protein, 2–3% fat, 16–24% ash, and 2–3% carbohydrate. Fresh sea cucumber contained 90 mg of holothurin per 100g of tissue. Canned sea cucumber contained moisture and protein levels similar to those generally found in marine finfish. Processing methods for canned sea cucumber resulted in a significant (P<0.01) decrease in potassium and increase in sodium. No significant differences (P<0.01) were found in the texture of canned products made from fresh-cooked, salted-cooked and cooked-dried raw material.     

OPTIMIZATION OF THE LACTIC ACID FERMENTATION OF HYDROLYZED COD GURRY WITH MOLASSES

ABSTRACT The purpose of this study was to determine the optimum concentration of blackstrap molasses required in conjunction with the use of several species of homofermentative lactic acid bacteria in the fermentation of hydrolyzed cod gurry. Blackstrap molasses at a concentration of 7.5% was found to be optimum for achieving a successful lactic acid fermentation of hydrolyzed cod gurry. Among the three homofermentative lactic acid bacteria studied (Lactobacillus plantarum, Pediococcus acidilactici and Streptococcus faecium) L. plantarum resulted in the most rapid fementation. S. faecium was the least desirable bacterium on the basis of fermentation rates and extent of pH decrease after 72 h of incubation. All three organisms failed to utilize significantly the sucrose derived from molasses, even though sucrose was the most abundant carbohydrate in the molasses. P. acidilactici was unable to utilize sucrose when present as a sole carbohydrate, while L. plantarum and S. faecium decreased the pH in broth cultures with sucrose as a sole carbohydrate. These results suggest that glucose in molasses functions as a repressor of invertase formation in L. plantarum and S. faecium, and that the use of derepressed mutants should allow a significant decrease in the amount of molasses required for a satisfactory fermentation.     

THE EFFECTS OF TURGOR PRESSURE ON PUNCTURE AND VISCOELASTIC PROPERTIES OF TOMATO TISSUE

The effects of turgor pressure on puncture and viscoelastic properties of mature-green tomato pericarp were examined using tissue discs soaked in a range of osmotica (0.0–0.6 M mannitol) for at least 36 h at 4C. Turgor pressure was estimated from the osmotic potential of soaking solutions that induced incipient plasmolysis. Based on volume changes, the osmotic potential and turgor pressure of fresh tissue were estimated to be −0.56 ± 0.08 MPa and 0.20 MPa, respectively. However, puncture and viscoelastic properties corresponded to a turgor pressure of 0.15 MPa. The discrepancy between calculated and actual turgor pressures was attributed to the presence of apoplastic solutes. The data from this study revealed a general increase in cell wall stress, strain and elasticity with increasing turgor. With increases in turgor above that of untreated tissue both wall extensibility and elasticity became limiting and thus cell wall stiffness increased. Conversely, a decrease in turgor below that of untreated tissue led to an increase in viscoelasticity. Increases in bioyield and pseudoplastic bioyield strains with a variation in turgor from that of untreated tissue were consistent with cell debonding as a dominant mechanism of tomato tissue bioyielding. The reduced failure force, deformation and firmness with increasing turgor were consistent with cell rupture as a predominant mechanism of failure of mature-green tomato pericarp tissue.     

HOW THE PAST MATTERS: North American Cities in the Twentieth Century

ABSTRACT: The past matters because it affects the present, and we can make serious errors of judgment when we ignore this fact. In studying the past, however, we should try to view it in its own terms and not simply in the light of current concerns. This will not only make for better history, but may be useful in broadening the terms of contemporary debates. These themes are illustrated in terms of the twentieth-century North American city. The influence of the past, and the errors of judgment caused by ignoring its effects, can be seen in Toronto. There, in the postwar era, the health of the central city and the viability of public transit have been attributed to good planning and urban governance. In fact, these features are partly the unintended consequences of the way the urban area developed in the first half of this century. The limitations of viewing the past in terms of the present are illustrated by the way that scholars have allowed current concerns to shape our conception of cities in the first half of this century. For example, the sharp distinction of city from suburb and the search for the origins of the modern land development industry have narrowed our vision of urban areas before World War II. The case of housing policy indicates that this narrowing has not only distorted our view of the past, but also has compelled us to reinvent mechanisms of housing provision, such as cooperatives and self-help, that had been attempted decades ago and subsequently forgotten.     

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].     

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.