M. Tech. Electrical Engineering. / Food security has become a global epidemic over the years. The objective of this research is to perform laboratory tests in order to measure and evaluate the electrical properties of different food materials using Radio Frequency (RF) channels. Presented in this document is a literature review which focuses on the dielectric and electrical properties of specific food materials, food media characteristics, transmission properties, the methods of testing that have been used as well as the achieved results, which provide a broader perspective of and about the food specimen that have undergone the experiment. The research is directed towards sensing food items through practical and experimental measurements as a contribution towards the development and erection of a future design and the operation of a device that will beam RF waves through food to detect any bacterial infections that may be present in the food.

Als Reaktion auf die Verbreitung von globalen privaten Lebensmittelstandards gehen einige Entwicklungsländer mit der Gründung eigener nationaler Food Standards einen Weg, um sich in wichtigen Exportländern zu positionieren. Allerdings wirken negative Herkunftsimages dem Aufbau von Glaubwürdigkeit und Anerkennung bei wichtigen internationalen Akteuren entgegen. Diese Studie untersucht die Wirkung von Herkunftsland-Effekten auf die wahrgenommene Glaubwürdigkeit der nationalen Lebensmittelstandards und beurteilt die Benchmarking-Strategien, wie sie von GLOBALG.A.P. und der Global Food Safety Initiative (GFSI) angeboten werden. Die Daten von 301 Lebensmittel-Managern aus Industrie- und Entwicklungsländern wurden durch eine Online-Befragung im Frühjahr 2010 erhoben. Die Befragten wurden gebeten, verschiedene Aspekte der Glaubwürdigkeit von Standards generell zu beurteilen sowie die Glaubwürdigkeit der Food Standards von acht Ländern spezifisch zu bewerten: Australien, China, Ghana, Indien, Italien, Mexiko, dem Vereinigten Königreich und den Vereinigten Staaten. Durch eine Faktorenanalyse und eine lineare Regression wird ein empirisches Modell zur Glaubwürdigkeit von Lebensmittelstandards analysiert. Im Ergebnis zeigt sich, dass "Benchmarking-Signale" erheblich dazu beitragen können, die Glaubwürdigkeit von Lebensmittelstandards in entwickelten Ländern und in Entwicklungsländern zu verbessern.

One of the major costs of group living is increased competition due to social information. Social information allows foragers to gain information about the location and the quality of food patches from observing other group members. Ultimately, this allows social foragers to use resources more efficiently. However, the distribution and quality of food varies both spatially and temporally and social information may result in aggregations of foragers around favourable food patches when they are available. This results in individuals of various dominance ranks aggregating around food resources and competing for food. In order to understand how dominance and patch quality interact to determine foraging behaviour, various foraging models have been created. In particular, producer-scrounger social foraging models are used to understand foraging behaviour and patch choice under competitive conditions. In producer scrounger games, individuals can either find their own food patches (produce) or join other individuals at food patches (scrounge). This study focused on how the combination of patch holder dominance status and patch quality interacts to influence patch joining decisions by scroungers. According to producer-scrounger models scroungers only join patches held by subordinate individuals. However, I found that a scrounger will join any patch as long as the patch holder is not within the top five most ranked individuals in the herd. However, as patch quality increased, fewer of the top ranked patch holders were avoided at each patch quality. This suggests that foraging is a trade-off between the costs of an aggressive interaction and the benefits gained from each patch. Behavioural titrations found that the initial density of food at a patch needs to be 2.3 times greater for a scrounger to feed from the next dominant patch holder. At high patch qualities there was a threshold point where patch quality became the driving force behind patch joining decisions and no patch holders were avoided, no matter their dominance status. Scroungers that fed from the top ranked patch holders had the same intake rate when compared with feeding with subordinate patch holders. This could be due to an increased level of vigilance by the scrounger in order to avoid an aggressive interaction with the dominant patch holder. However, scrounger’s intake rate increased when they fed from dominant patch holders that were not the top ranked herd members. This suggests that only the top ranked herd members are aggressive enough to prevent scrounging attempts. A novel discovery of this study was that although the goats formed a linear dominance hierarchy, they did not forage in accordance with it, with lower ranking individuals avoiding dominant patch holders. This suggest that in social herbivores dominance hierarchies are not maintained to determine who has priority access to food. This study shows that even large differences in dominance are not sufficient enough to prevent scrounging decisions and only the top ranked patch holders have the ability to prevent joining attempts. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Life history theory assumes that correlations among fitness-related life history traits should be negative among individuals, reflecting resource allocation constraints among traits such as growth and reproduction. These traits trade off because they cannot be simultaneously maximized in individuals facing finite resource acquisition. Positive correlations among traits that are expected to be negative (e.g. between energetically costly traits) have been regularly observed, however, and have usually been ascribed to genetic or resource acquisition differences. In the freshwater zooplankton Cladoceran Daphnia, positive correlations have been particularly well documented even when genetic and environmental variation have been controlled. The sign of these correlations represent a problem for life history theory, which is underpinned by the notion of universal and unavoidable costs associated with investing in a given trait. It has been suggested, however, that costs vary with environment and thus can change the sign of a correlation. A change in correlation sign over an environmental gradient may indicate that the assumed universality of costs and constraints are not as universal as expected by life history theory. Few life history experiments have examined traits in multiple environments, and fewer have done so while controlling resource acquisition and genetic variation. Here I ask whether the positive genetic correlations among somatic growth rate, egg production rate, and longevity are present in the face of equal ingestion, clonal individuals, and a finely resolved gradient of food quality, an environmental factor that frequently affects Daphnia. I partition trait covariation into genetic and residual, or environmental, sources. All resulting genetic correlations were non-significant. Residual correlations trended from significantly positive to negative between longevity and growth rate and remained near zero between longevity and egg rate. The residual correlation between growth and reproduction, two expensive traits, displayed significantly positive residual correlations across the food quality gradient remained significantly positive. Given the experimental controls in place, I suggest that differences in individual ontogeny may give rise to differential resource utilization or assimilation efficiency. This may be a mechanism for differential resource acquisition in the absence of ingestion variation. Additionally, the different ways genetic and residual correlations change over an environmental gradient may provide insight on one manner by which genotypes might coexist and provide a candidate explanation for the second paradox of the plankton. / Thesis (Master, Biology) -- Queen's University, 2014-03-31 07:01:21.774

In the agri-food industry, carbon dioxide sensors can be used for process control, monitoring quality, and assessing safety. A carbon dioxide sensor was developed using poly aniline boronic acid (PABA) conducting polymer as the electrically conductive region of the sensor for use in the agri-food industry and was demonstrated for use in detecting incipient or ongoing spoilage in stored grain. The developed sensor dynamically detected up to 2455 ppm CO2 concentration levels. The performance of the sensor in measurements of low concentrations of dissolved CO2 was characterized using standard solutions of NAHCO3. The dynamic range for the detection of H2CO3 was 4.91X10-4 to 9.81X10-3 mol L-1. The dc resistance values decreased with increasing CO2 concentration indicating an increase of conductivity due to increase in the amount of protonation. The developed CO2 sensor was evaluated for the influence of temperature (by storing it at – 20°C and 0°C as well as at operating temperatures of +10°C to 55°C) and relative humidity (from 20 to 70%). Temperature dependence of sensor's resistance values were observed possibly due to the change in conduction mechanism at different temperatures. The variation in the resistance with humidity was curvi-linear and repeatable, indicating that humidity has a less pronounced effect on the sensor’s performance. The sensor’s response to changes in CO2 concentrations at various humidity and temperature levels was stable indicating that the sensor can detect CO2 levels under fluctuating environmental conditions. The response of the PABA film to CO2 concentration was not affected by the presence of alcohols and ketones, proving that the developed CO2 sensor is not cross-sensitive to these compounds which may be present in spoiling grain. The sensor packaging components were selected and built in such a way to avoid contamination of the sensing material and the substrate by undesirable components including grain dust and chaff. The developed conducting polymer CO2 sensor exhibited dynamic performance in its response, recovery times, sensitivity, selectivity, stability and response slope when exposed to various CO2 levels inside simulated grain bulk conditions.

Given the credence nature of food quality and food safety attributes, consumers cannot easily verify whether food is high quality or is safe to eat, thus they rely on abstract systems of regulation and quality signals such as brands to make informed consumption choices. In fact, trust is recognized as a rational strategy that reduces consumers’ uncertainty when purchasing goods with credence attributes. While trust in food is a topical issue in an era of increasingly complex food systems, how trust and more precisely brand trust affects consumers’ perceptions of food is a relatively new research area in food economics. This thesis aims to answer questions such as what drives trust in the actors within the Canadian food system (i.e. government, farmers, food manufacturers, and food retailers) and in food brands, and the relationship between that trust and consumer confidence in food quality and food safety. Previous studies on institutional and system trust have been carried out primarily in the sociology, marketing and political sciences disciplines, while a few studies in food economics have investigated the influence of institutional trust and reported the degree of public trust in market actors. This study extends previous research on consumer trust in the context of food by developing a conceptual model in which trust in the food system and brand trust are expected to evolve to public confidence in credence attributes and lead to consumer commitment to food brands. Inspired from a comprehensive synthesis of the literature on consumer trust, the theoretical background suggests that consumer confidence in food attributes is jointly determined by trust in the food system (system-based trust) and brand trust (product-based trust), and it is moderated by consumer characteristics (personal-based trust) – namely: risk, past consumption experience and ethically-motivated behaviour. As well, consumers are assumed to perceive an actor or a brand as trustworthy through the influence of four postulated dimensions of trust: perceived competence, credibility, benevolence and reputation. A Structural Equation Modelling (SEM) approach is used for the empirical analysis. Data were gathered through an online survey of consumers conducted across Canada in July 2012 focusing on fresh chicken and packaged green salad products. The results show that individually none of the postulated antecedents of trust (i.e. competence, credibility, benevolence and reputation) was a significant driver for trust, especially for packaged salad. Unlike previous research on institutional trust and brand trust that uses a number of separate dimensions to measure trust predominantly in non-food contexts, this thesis finds that trust in the food system and food products could be measured differently by taking into account the interactive effects of perceived competence, credibility, reputation and benevolence on public trust. As such, the findings suggest that Canadian consumers tend to trust brands of chicken and packaged salad when these products are perceived as high quality, are backed by credible information, have a good reputation and, at the same time, enhance consumers’ welfare. In fact, a brand cannot be perceived as high quality and safe to eat (brand competence) without containing transparent information signalling its quality and safety (brand credibility). Additionally, results reveal some apparent product-specific effects: brand trust matters in fostering consumer confidence in chicken but not for salad. Furthermore, trust in the food system as a whole appears to be more influential in leading to public confidence in credence attributes than trust in food brands in the case of chicken. As such, it appears that trust in actors within the food supply chain is more important than relying on individual products. As well, the analysis shows that while psychographic variables (risk aversion, past consumption experience) and some demographics (e.g. gender, education) moderate the relationship between trust in the food system and brands for chicken, this is not the case for salad. In terms of marketing implications, the results suggest that while brands are useful signalling mechanisms, trust in these brands is not the main driver for consumer confidence in credence attributes. Furthermore, the much stronger effect of system trust implies that decision-makers would benefit by investing in building trust relationships with the public. Transparent communication and credible assurances about the practices and the intentions within the food system could be a way to gain and maintain public trust and, ultimately, consumer confidence in food quality and food safety.

In the agri-food industry, carbon dioxide sensors can be used for process control, monitoring quality, and assessing safety. A carbon dioxide sensor was developed using poly aniline boronic acid (PABA) conducting polymer as the electrically conductive region of the sensor for use in the agri-food industry and was demonstrated for use in detecting incipient or ongoing spoilage in stored grain. The developed sensor dynamically detected up to 2455 ppm CO2 concentration levels. The performance of the sensor in measurements of low concentrations of dissolved CO2 was characterized using standard solutions of NAHCO3. The dynamic range for the detection of H2CO3 was 4.91X10-4 to 9.81X10-3 mol L-1. The dc resistance values decreased with increasing CO2 concentration indicating an increase of conductivity due to increase in the amount of protonation. The developed CO2 sensor was evaluated for the influence of temperature (by storing it at – 20°C and 0°C as well as at operating temperatures of +10°C to 55°C) and relative humidity (from 20 to 70%). Temperature dependence of sensor's resistance values were observed possibly due to the change in conduction mechanism at different temperatures. The variation in the resistance with humidity was curvi-linear and repeatable, indicating that humidity has a less pronounced effect on the sensor’s performance. The sensor’s response to changes in CO2 concentrations at various humidity and temperature levels was stable indicating that the sensor can detect CO2 levels under fluctuating environmental conditions. The response of the PABA film to CO2 concentration was not affected by the presence of alcohols and ketones, proving that the developed CO2 sensor is not cross-sensitive to these compounds which may be present in spoiling grain. The sensor packaging components were selected and built in such a way to avoid contamination of the sensing material and the substrate by undesirable components including grain dust and chaff. The developed conducting polymer CO2 sensor exhibited dynamic performance in its response, recovery times, sensitivity, selectivity, stability and response slope when exposed to various CO2 levels inside simulated grain bulk conditions.

Maisto sauga vienodai svarbi visoms institucijoms, susijusioms su žaliavų ir maisto produktų gamyba, pardavimu, apdorojimu bei kitokiu tvarkymu. Su maistu susijęs verslas turi būtų vykdomas pagal tinkamą maisto saugos valdymo programą, kuri sudaroma atsižvelgiant, pirmiausia, į verslo vaidmenį maisto grandinėje. Laikotarpiu nuo 2001 iki 2011 m. vidutiniškai kasmet bendras skundų skaičius padidėdavo 142 skundais arba 7,54 proc. per metus, t.y. 2001 metais buvo pateikti 1328 skundai, o 2011 metais - 2748 skundai. / Food safety is equally important for all bodies concerned with raw materials and food production, marketing, processing and other processing. For food-related business should be conducted in accordance with proper food safety management program which shall be based, in particular, the role of business in the food chain. In the period from 2001 to 2011 the average annual increases in the total number of complaints received was 142 complaints, or 7.54 percent per year, 2001 year have been made 1328 complaints and in 2011 - 2748 complaints.

Thesis (MSc Food Sc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The microbial growth, colour stability and pH changes for black wildebeest (Connochaetes gnou) meat under chilled (4.2±0.8°C) vacuum storage were investigated. The investigation centred on the role of ultimate muscle pH on shelf life of the meat. Although bacterial growth was observed over time for both DFD (pH >6) and Normal (pH <6) meat, DFD meat exhibited higher growth rates for lactic acid bacteria (LAB), total viable counts (TVC) and total coliforms. This was attributed to the combination of high pH and possibly the depletion of glucose in the DFD muscles. On the other hand, the growth rate of total coliforms was less than what was observed for the other microorganisms tested. It was assumed that chilled vacuum storage in combination with the high levels of LAB inhibited the growth of total coliforms. Salmonella was not detected in any of the samples analysed. There were no changes in pH during the 12 days storage period for DFD meat whereas pH for Normal meat decreased towards the end of storage possibly due to lactic acid production by LAB. The colour changes were more noticeable in Normal meat (more browning) than in DFD meat after blooming for 30 min. The conclusion for this study was that DFD meat spoiled faster than Normal meat. The meat was further subjected to preservation by oregano essential oil (1% v·v-1). In this case, there was an initial inhibition of TVC, LAB and total coliforms. Furthermore, the growth rates for TVC and LAB were lower (p<0.05) in the oregano oil treatment group than in the control. For total coliforms however, there was only an initial inhibition observed and no effect on the growth rate. Addition of oregano essential oil also resulted in a significant lowering of meat pH. This may have added to the microbial inhibition observed. Based on TVC values, addition of oregano essential oil extended the shelf-life of black wildebeest meat by 3 days. At the beginning of the study, the lipid oxidation (TBARS) values were above the threshold for detection. Also, the percentage of metmyoglobin had exceeded the levels at which browning becomes visible. Therefore, conclusions on the effects of oregano essential oil on the colour and lipid oxidations were not made in this study. However, oregano essential oil inhibited microbial growth and stabilised TBARS throughout the 9 day storage period. Therefore there is potential to use oregano essential oil as a preservative for black wildebeest meat, although more research is needed. / AFRIKAANSE OPSOMMING: In hierdie studie word die mikrobiese groei, stabiliteit en pH kleur verandering ondersoek vir swartwildebeestevleis onder verkoelde (4.2 ± 0.8 ° C) vakuum berging. Die ondersoek is spesifiek gefokus op die rol van die eind-spier pH op die raklewe van die vleis. Alhoewel mikrobiese groei vir beide DFD (pH >6) en Normal (pH <6) vleis waarneembaar was met verloop van tyd, het die DFD vleis hoër groeitempo vir melksuurbakterieë (MSB) en totale lewensvatbare tellings (LVT) getoon. Dit was as gevolg van die kombinasie van hoë pH en die moontlikheid van die vermindering van die glukose in die DFD spiere. Aan die ander kant was dit waargeneem dat die groeikoers van die totale kolivormig bakterieë minder was, teenoor die ander mikro-organismes wat getoets was. Dit was aangeneem dat die verkoelde vakuum stoor die groei van die totale kolivormig bakterieë geïnhibeer het. Salmonella was nie opgespoor in enige van die geanaliseerde monsters nie. Daar was geen verandering in pH tydens die stoor tydperk vir DFD vleis nie, maar die pH vir normale vleis het tydens die einde van die stoor tydperk afgeneem. Die kleur verandering onder vakuum stoor was meer waarneembaar in die normale vleis as wat dit was in die DFD vleis. Die gevolgtrekking van hierdie studie was dat DFD vleis baie vinniger bederf teenoor normale vleis. Maar daar was variasie op die gewig van die oorspronklike mikrobiese lading en dit kon die bakteriese groeitempo van die normale vleis beïnvloed. Die vleis is verder behandel met oregano essensiële olie ( 1 % v·v-1) vir preservering . In hierdie geval, was daar 'n aanvanklike inhibisie van LVT, MSB en totale kolivormig bakterieë. Verder was die groeitempo vir LVT en MSB aansienlik laer (p<0.05 ) in die behandelings groep teenoor die in die kontrole . Vir die totale kolivormig bakterieë was daar egter net 'n aanvanklike inhibisie waargeneem en geen effek op die groeikoers nie. Die byvoeging van oregano essensiële olie het ook gelei tot 'n beduidende verlaging van die pH. Dit kon gelei het tot die mikrobiese inhibisie wat waar geneem was. Gebaseerd op die LVT, het die byvoeging van oregano essensiële olie gelei tot die verlenging van die swartwildebeeste vleis se raklewe met 3 dae. Aan die begin van hierdie studie was die lipied oksidasie (TBARS) waardes bo die drumpel van opsporing. Ook, die persentasie van metmyoglobin het die vlakke waarop verbruining sigbaar word, oorskry. Daar is potensiaal vir die gebruik van oregano essensiële olie as n middel vir die verlenging van swartwildebees vleis, maar nog navorsing is nodig.

L’emballage intelligent (EI) est une technologie émergente basée sur la fonction communicative des emballages. La radio-identification (RFID) est considérée comme le concept le plus prometteur de l’EI. La RFID fait référence aux technologies et systèmes qui utilisent les ondes radio (sans fil) pour transmettre et identifier de manière exclusive et/ou suivre des objets avec une information précise en temps réel.Cette thèse est basée sur une recherche innovante des propriétés électriques (capacité, permittivité réelle et perte) de la protéine de soja isolée, de la gélatine et du caséinate de sodium, et vise leur utilisation comme capteurs de température, associés à l’étiquette RFID. Les variables étaient la température (20°C jusqu’à 80°C) et l’humidité (90% HR) qui sont normalement utilisées pour la cuisson de la viande. La gélatine s’est révélée être le capteur le plus sensible. Après cette partie, plusieurs étapes ont été menées :• L’analyse de l’impact de l’épaisseur du film de gélatine sur la capacité et la détermination de plusieurs paramètres tels que la sensibilité, l’hystérésis et la répétabilité;• La couverture de gélatine sur l’étiquette RFID, testée à 90% HR et à température variable (de 20°C à 80°C) en condition pilote. L’impact sur la bande de lecture a été analysé.Le potentiel de la gélatine en tant que capteur a été démontré à une épaisseur de 38 µm à laquelle la capacité était stable de 20°C à 80°C et à Ultra-Haute Fréquence (300-900 MHz). L’échantillon de 125 µm a subi une dégradation électrothermique entre 60°C et 80°C. Pour surmonter ce phénomène, 600 MHz ont été appliqués. Un équilibre entre l’épaisseur et la fréquence devrait être considéré pour augmenter la sensibilité qui était de 0,14 pF/°C (125 µm à 600 MHz) et 0,045 pf/°C (38 µm à 868 MHz), influençant les résultats lors de la simulation de cuisson de la viande. La réutilisation du même capteur a conduit à une perte de masse réduisant la sensibilité. L'étiquette RFID couverte d’un film de gélatine sur l'antenne a pu donner de différence significative (p <0,05) dans la bande de lecture théorique (BLT) à 868, 915 et 960 MHz. Également dans cette layout, la BLT a été la même pour la même température croissante et décroissante (pas de hystérésis) dans la zone critique (60°C-80°C et 60°C-20°C) à 915 MHz. Ces résultats prometteurs ouvrent une porte à une nouvelle conception de capteurs de température basés sur les biomatériaux, renouvelable at à faible coût, couplé avec des étiquettes RFID passives pour l’emballage intelligent. / Intelligent packaging (IP) is an emerging technology based on the communication function of packages. Radio frequency Identification (RFID) is considered the most promising concept of IP. RFID refers to technologies and systems that use radio waves (wireless) to transmit and uniquely identify and/or track objects with accurate information in a real time.The present thesis is based on an innovative study of the electrical (capacitance) and dielectric properties (real permittivity and loss factor) of soybean isolated protein, gelatin and sodium caseinate aiming at their use as a sensor of temperature coupled with RFID tags. The environmental variables were temperature (range from 20°C up to 80°C) and humidity (90% RH) that are normally used for meat cooking. Gelatin was the most sensitive sensor. After this first part, several steps have been set up:• Analysing the impact of gelatin film thickness on electrical capacitance and the determination of several parameters such as sensitivity, hysteresis and repeatability;• The coating of gelatin on a RFID tag tested at 90% RH and variation of temperature (20°C up to 80°C) in a pilot condition. The impact on the reading range was analysed.The potential of gelatin as a sensor was demonstrated at thickness of 38 µm and 125 µm. For the first case, the capacitance was stable at 20°C up to 80°C and at Ultra High Frequency band (300-900 MHz). Sample with 125 µm has suffered the electro-thermal breakdown between 60-80°C. To overcome this phenomenon, 600 MHz was applied. A balance between thickness and frequency should be consider to increase the sensitivity that was 0.14 pF/°C (125 m at 600 MHz); this value was higher than 0.045 pF/°C (38 m at 868 MHz) influencing the results in the simulation of meat cooking. Reuse of the same sensor has led to mass loss reducing the sensitivity. The feasibility of gelatin sensor-enable RFID tag was demonstrated. The tag covered by gelatin film in the whole antenna was suitable because it was able to deliver different Theoretical Reading Range (TRR) (p<0.05) for 868 MHz, 915 MHz and 960 MHz. At this layout also, the TRR was the same (without hysteresis) for the rising and descending temperature at the critical zone (60°C- 80°C and 60°C-20°C) at 915 MHz. These promisor results open a window for new conception of temperature sensor based on biomaterial that confers advantages, such as low cost and eco-friendly property sought to be interfaced to passive RFID tags for intelligent packaging.