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Food Materials (food + material)
Selected AbstractsApplication of a Depth Sensing Indentation Hardness Test to Evaluate the Mechanical Properties of Food MaterialsJOURNAL OF FOOD SCIENCE, Issue 5 2002N. ÖZkan ABSTRACT: A depth sensing indentation hardness test with an associated analysis is described as a convenient and simple technique for characterizing mechanical properties of food materials, such as hardness (H), elastic modulus (E), and an elasticity index (IE), which represents the ratio of elastic to total deformation. Storage modulus (G,) and loss tangent (tan§) of the selected model food material, a whey protein concentrate (WPC) gel, have also been determined using an oscillatory dynamic testing. Fractal dimension (D) and strain rate (or frequency) exponent (n) of the WPC gels were determined using both the indentation and dynamic test results. A good correlation between the results from the indentation and the dynamic tests was established. The effects of protein concentration, deformation rate, and chemical treatment on the mechanical properties of the WPC gels were clearly illustrated using the indentation test. [source] Soil and plant diet exposure routes and toxicokinetics of lindane in a terrestrial isopodENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2000José Paulo Sousa Abstract In most studies dealing with effects of toxic substances in saprotrophic isopods, animals are exposed to the test substance through contaminated food. Because these animals can be in a close contact with the soil surface, the substrate, as an exposure pathway, should not be neglected. Here the authors analyze the toxicokinetic behavior of lindane (,-hexachlorocyclohexane [,-HCH]) in the isopod species Porcellionides pruinosus, comparing two exposure routes: food and two soil types (artificial Organisation for Economic Cooperation and Development [OECD] soil and a natural agricultural soil). In the feeding experiment, a strong decrease of ,-HCH concentration over time was observed on the food material, with the animals showing a broader range in chemical assimilation efficiency values (averaging 17.7% and ranging from 10 to 40%). The ,-HCH bioaccumulation results indicate that when animals incubated under both soil types reached a steady state, they displayed much higher body burdens (1,359.60 pg/animal on OECD soil and 1,085.30 pg/animal on natural soil) than those exposed to contaminated food (43.75 pg/animal). Kinetic models also revealed much lower assimilation and elimination rates in the food experiment (20.66 pg/d and 0.10 pg/d) than in both soil experiments (238.60 pg/d and 350.54 pg/d for the assimilation rate and 0.19 pg/d and 0.32 pg/d for the elimination rate). Differences in results between exposure routes are discussed according to equilibrium-partitioning theory and the enhanced relevance of the substrate exposure route is analyzed under future prospects on chemical toxicity testing using isopods. [source] Standing oral extraction of cheek teeth in 100 horses (1998-2003)EQUINE VETERINARY JOURNAL, Issue 2 2005P. M. DIXON Summary Reasons for performing study: Extraction of cheek teeth (CT) by the conventional repulsion technique requires general anaesthesia and carries a high rate of post operative complications. Consequently, an alternative method of extraction, i.e. orally in standing horses, was evaluated. Hypothesis: The need for and risks of general anaesthesia could be avoided and post extraction sequelae reduced by performing extractions orally in standing horses. Methods: One hundred mainly younger horses (median age 8, range 2-18 years) with firmly attached CT that required extraction because of apical infections, displacements, diastemata, idiopathic fractures and the presence of supernumerary CT had the affected teeth (n = 111) extracted orally under standing sedation. Follow-up information was obtained for all cases, a median of 16 months later. Results: Oral extraction was successful in 89 horses and unsuccessful in 11 due to damage to the CT clinical crown (n = 9) during extraction, for behavioural reasons (n = 1) and because the apex of a partly extracted CT fell back into the alveolus following sectioning (n = 1). Predispositions to extraction-related CT fractures were present in 5 of the 9 cases, i.e. advanced dental caries (n = 2) and pre-existing ,idiopathic' fractures (n = 3). The iatrogenically fractured CT were later repulsed under standing sedation (n = 3) and under general anaesthesia (n = 6). Eighty-one of the remaining 89 horses had successful oral CT extraction with no or minimal intra- or post operative complications occurring. Post operative complications in the other 8 cases included post extraction alveolar sequestration (n = 3), alveolar sequestration and localised osteomyelitis (n = 1), localised osteomyelitis (n = 1), incorporation of alveolar packing material into alveolar granulation tissue (n = 1), and nasal discharge due to continued intranasal presence of purulent food material (n = 1) and to ongoing sinusitis (n = 1). The above sequelae were treated successfully in all cases, with general anaesthesia required in just one case. Following oral extraction, significantly (P<0.001) fewer post operative problems developed in 54 horses with apically infected CT in comparison with 71 previous cases that had repulsion of apically infected CT at our clinic. Conclusions and potential relevance: Oral extraction of cheek teeth is a successful technique in the majority of younger horses with firmly attached CT and greatly reduces the post operative sequelae, compared with CT repulsion. Additionally, the costs and risks of general anaesthesia are avoided. Further experience and refinement in the described protocol could potentially increase the success of this procedure and also reduce the incidence of post operative sequelae. [source] Extraction Using Moderate Electric FieldsJOURNAL OF FOOD SCIENCE, Issue 1 2004I. SENSOY ABSTRACT: During moderate electric field (MEF) processing, a voltage applied across a food material may affect the permeability of cell membranes. It is known that high electric fields can cause either reversible or irreversible rupture of cell membranes. In this research, the effect of MEF processing on permeability was studied. Effects of frequency and electric field strength were investigated. Cellular structure was investigated by transmission electron microscopy (TEM). Fermented black tea leaves and fresh or dry mint leaves were placed in tea bags or cut in 1 cm2 squares, depending on the experiment, and immersed in an aqueous fluid medium. Control samples were heated on a hot plate. MEF treatments were conducted by applying a voltage across electrodes immersed in opposite sides of the beaker. Control and MEF-treated fresh mint leaf samples heated to 50°C were analyzed by TEM. MEF processing significantly increased the extraction yield for fresh mint leaves because of additional electric field effects during heating. Dried mint leaves and fermented black tea leaves were not affected by the treatment type. Low frequency resulted in higher extraction rates for fresh mint leaves. The electric field strength study showed that electrical breakdown is achieved even at low electric field strengths. MEF treatment shows potential to be used as an alternative to conventional heating for extraction from cellular materials. [source] Application of a Depth Sensing Indentation Hardness Test to Evaluate the Mechanical Properties of Food MaterialsJOURNAL OF FOOD SCIENCE, Issue 5 2002N. ÖZkan ABSTRACT: A depth sensing indentation hardness test with an associated analysis is described as a convenient and simple technique for characterizing mechanical properties of food materials, such as hardness (H), elastic modulus (E), and an elasticity index (IE), which represents the ratio of elastic to total deformation. Storage modulus (G,) and loss tangent (tan§) of the selected model food material, a whey protein concentrate (WPC) gel, have also been determined using an oscillatory dynamic testing. Fractal dimension (D) and strain rate (or frequency) exponent (n) of the WPC gels were determined using both the indentation and dynamic test results. A good correlation between the results from the indentation and the dynamic tests was established. The effects of protein concentration, deformation rate, and chemical treatment on the mechanical properties of the WPC gels were clearly illustrated using the indentation test. [source] Factors influencing food collection behaviour of Brants' whistling rat (Parotomys brantsii): a central place foragerJOURNAL OF ZOOLOGY, Issue 1 2001T. P. Jackson Abstract The hypothesis that Brants' whistling rat Parotomys brantsii is a central place forager, whose foraging decisions are modified by (a) predation risk, (b) time of day, and (c) food choice, was tested. Field observations showed that whistling rats followed central place foraging rules for a single-prey loader and much of their food material was brought back to burrow entrances to feed on, with larger food items being carried back greater distances than small ones. Small food items were consumed in situ more often than large ones, suggesting that predation risk may also play a role in their foraging behaviour. Larger food items were preferentially stored at burrow entrances or carried underground, whilst smaller items tended to be consumed immediately. Individuals foraged more actively in the afternoon than in the morning and, although there was no tendency for individuals to eat more food at this time, far more food was stored or taken underground during the afternoon. Different foraging strategies were used for different plant species with some species preferentially eaten, and others stored or taken below ground more frequently. This study shows that the foraging behaviour of Brants' whistling rats is complex, and whilst they may follow simple central place foraging strategies, other factors such as the time of day and food plant species also influence their foraging behaviour. [source] Infrared Heating in Food Processing: An OverviewCOMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2008Kathiravan Krishnamurthy ABSTRACT:, Infrared (IR) heating provides significant advantages over conventional heating, including reduced heating time, uniform heating, reduced quality losses, absence of solute migration in food material, versatile, simple, and compact equipment, and significant energy saving. Infrared heating can be applied to various food processing operations, namely, drying, baking, roasting, blanching, pasteurization, and sterilization. Combinations of IR heating with microwave heating and other common conductive and convective modes of heating have been gaining momentum because of increased energy throughput. This article reviews aspects of IR heating and presents a theoretical basis for IR heat processing of food materials and the interaction of IR radiation with food components. The effect of IR on food quality attributes is discussed in the context of samples and process parameters. Applications of IR heating in food processing operations and future research potential are also reviewed. [source] Immunoassays: their history, development and current place in food science and technologyINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2004Graham A. Bonwick Abstract The purpose of this paper is to introduce the reader to immunoassays. This paper is the first in a themed issue of the Journal in which a number of papers have been brought together in order to demonstrate the types and variety of immunoassays, which are currently available. Indeed it might be said that all an analyst needs to do is to name a molecule and somewhere there will now be an immunoassay for the detection of that molecule. This obviously is not entirely accurate, however immunoassays do provide a powerful tool, which can be used in the analysis and quality control of food materials. For both the novice and the experienced worker the specialist terminology of a subject presents an initial barrier, which must be overcome before full understanding is achieved. In this paper an attempt is made to introduce the important terms with which the reader should be familiar and to try to set the various technologies in context. The various basic methods are described and the theoretical and practical basis of more sophisticated assays now being devised are introduced. [source] Aspects of the feeding habits and reproductive biology of the Ghana mole-rat Cryptomys zechi (Rodentia, Bathyergidae)AFRICAN JOURNAL OF ECOLOGY, Issue 2 2002S. Yeboah Abstract The feeding habits and reproductive biology of the Ghana mole-rat, Cryptomys zechi (Matchie), were studied in a Guinea savanna woodland in Ghana. Both tunnel contents and stomach content analysis indicated that bulbs and tubers constituted the commonest and most preferred food items, although some animal food materials were also consumed. Five plant species, Urgenia altissima, Manihot utilisima, Curuligo sp., Oxalis corniculata and Archis hypogea, were the most popular plant food source. Breeding occurred during the rainy season (March,August) and was at its peak in July. There is evidence that the species is capable of producing two litters in a year. In a colony, reproduction is restricted to one female and one male. Males reached sexual maturity at a lower body weights (105 g) than females (155 g). Estimated mean litter size was 1.5 (range 1,2), the smallest among the bathergids. Available data on birth weights of three other species of social Cryptomys indicate that C. zechi has the highest birth weight, which is comparable to that of solitary bathyergids. Résumé On a étudié les habitudes alimentaires et la biologie de la reproduction du rat-taupe du Ghana, Cryptomys zechi (Matschie), dans une savane guinéenne arborée au Ghana. L'analyse du contenu des terriers et des estomacs indique que les bulbes et les tubercules constituent les aliments les plus fréquents et les plus appréciés, bien qu'ils mangent aussi un peu de matière animale. Cinq espèces végétales, Urgenia altissima, Manihot utilissima, Curuligo sp., Oxalis corniculata et Archis hypogeaétaient les sources de nourriture végétale les plus appréciées. L'accouplement a lieu pendant la saison des pluies (mars , août) et est à son maximum en juillet. Des preuves montrent que l'espèce peut produire deux nichées par an. Dans une colonie, la reproduction est limitée à un mâle et une femelle. Les mâles atteignent la maturité sexuelle à un poids inférieur (105 gr) à celui des femelles (155 gr). On a estimé que la taille moyenne d'une nichée était de 1,5 jeune (allant de 1 à 2), la plus petite chez les rats-taupes. Les données disponibles sur le poids à la naissance de trois autres espèces de Cryptomys sociaux indiquent que C. zechi a le poids le plus important à la naissance, comparable à celui des rats-taupes solitaires. [source] A Noncontact Ultrasound Approach for Mechanical Property Determination of CheesesJOURNAL OF FOOD SCIENCE, Issue 7 2003B.-K. Cho ABSTRACT: Noncontact ultrasound parameters, such as velocity and attenuation coefficient, were directly measured using air instability compensation transducers and correlated with Young's modulus, hardness, and toughness of different types of cheeses. Ultrasound velocity was highly correlated with the mechanical properties of cheeses whereas no significant relationship between the ultrasound energy attenuation coefficient and the mechanical properties were shown. The noncontact ultrasound technique demonstrated excellent performance for thickness measurement of cheeses with an accuracy of 99.98% (standard error = 0.089 mm). Results indicated that noncontact air instability compensation ultrasound technique has a good potential for nondestructive and accurate measurement of ultrasound parameters, thickness, and mechanical properties of food materials. [source] Application of a Depth Sensing Indentation Hardness Test to Evaluate the Mechanical Properties of Food MaterialsJOURNAL OF FOOD SCIENCE, Issue 5 2002N. ÖZkan ABSTRACT: A depth sensing indentation hardness test with an associated analysis is described as a convenient and simple technique for characterizing mechanical properties of food materials, such as hardness (H), elastic modulus (E), and an elasticity index (IE), which represents the ratio of elastic to total deformation. Storage modulus (G,) and loss tangent (tan§) of the selected model food material, a whey protein concentrate (WPC) gel, have also been determined using an oscillatory dynamic testing. Fractal dimension (D) and strain rate (or frequency) exponent (n) of the WPC gels were determined using both the indentation and dynamic test results. A good correlation between the results from the indentation and the dynamic tests was established. The effects of protein concentration, deformation rate, and chemical treatment on the mechanical properties of the WPC gels were clearly illustrated using the indentation test. [source] A Simple Laboratory Exercise in Food Structure/Texture Relationships Using a Flatbed ScannerJOURNAL OF FOOD SCIENCE EDUCATION, Issue 1 2002D.W. Stanley ABSTRACT: A laboratory experiment is described that has been designed to allow students to gather meaningful structural and mechanical data with limited equipment. Images are acquired using a computer-interfaced flatbed scanner. Although intended for bread, this approach can be applied to other food products as well. This experiment may be as broad or narrow and as complex or simple as desired. Students have the decided advantage of gathering data themselves, not merely viewing a demonstration of expensive research-grade instrumentation. Experience with image analysis software facilitates a better understanding of quantifying structural data than can be obtained from lecture or text material. Students should become aware of the dependence a specific property, texture, on the underlying structure of food materials and gain an appreciation of the role food structure has in determining many quality parameters. [source] STIFFNESS OF COMPRESSION TESTING MACHINESJOURNAL OF TEXTURE STUDIES, Issue 2 2000HARALD ROHM ABSTRACT A ring test with six participating laboratories and rubber stoppers as reference material was performed to monitor the performance of commercial compression testing instruments. Testing conditions were chosen to be in the range of regular compression testing. Small, single screw instruments with a cantilever exhibited a significant deviation in the force/deformation-response compared with double-screw instruments with a crosshead. Additional tests made with an external device for displacement recording revealed that these differences have to be attributed to insufficient stiffness and some compliance in the cantilever of the tested single-screw instruments. Some consequences of the test results for experiments on soft, semi-soft and rigid food materials are discussed and an equation is developed to correct for the flexing of the cantilever beam in the single screw machine. [source] Seligman lecture 2005 food product engineering: building the right structuresJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2006José Miguel Aguilera Abstract Driven by consumers' expectations and new knowledge, a paradigmatic shift is occurring in food engineering from the prior emphasis in processes and unit operations to the design of products that provide convenience, health and well-being. The structure of foods affects their sensorial, physical and transport properties as well as the bioavailability of some nutrients. Food structure is provided by nature or imparted during processing and preparation. Presently, food product engineering is stabilizing, transforming and creating edible microstructures that are desired by consumers using conventional unit operations. This paper revises the progress in the science of food materials and its contribution to the understanding of how food structures are formed from the molecular to the macromolecular level. Food product design of the future will be based on a wider scientific knowledge adopted from many disciplines and advanced tools that reduce the scale of fabrication. This poses a challenge to food engineering education. Copyright © 2006 Society of Chemical Industry [source] Infrared Heating in Food Processing: An OverviewCOMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2008Kathiravan Krishnamurthy ABSTRACT:, Infrared (IR) heating provides significant advantages over conventional heating, including reduced heating time, uniform heating, reduced quality losses, absence of solute migration in food material, versatile, simple, and compact equipment, and significant energy saving. Infrared heating can be applied to various food processing operations, namely, drying, baking, roasting, blanching, pasteurization, and sterilization. Combinations of IR heating with microwave heating and other common conductive and convective modes of heating have been gaining momentum because of increased energy throughput. This article reviews aspects of IR heating and presents a theoretical basis for IR heat processing of food materials and the interaction of IR radiation with food components. The effect of IR on food quality attributes is discussed in the context of samples and process parameters. Applications of IR heating in food processing operations and future research potential are also reviewed. [source] | ||||||||||||||||