Active packaging systems can offer significant advantages in preventing quality loss in horticultural products through control of microbial and/or physiological activity. By delivering and sustaining volatile active agents at effective levels in a package atmosphere, significant shelf life extension can thus be achieved. Design of these systems is complicated by the number of possible package, product, active agent and carrier combinations that can be employed and the significant interactions that may occur between these components. Mathematical modelling can be used to simplify system design and reduce the number of experimental trials required to achieve optimal active packaging systems. In this study a generalised modelling methodology was developed and validated to facilitate the design of active controlled volatile release packaging systems for horticultural products. The modelling methodology was developed using an example system which comprised tomatoes packed under a modified atmosphere (MA; 5 % (v/v) CO2 and 10 % (v/v) O2) in a LDPE bag with a polymer film sealed sachet containing silica gel pre-saturated with the antifungal agent hexanal. Experimental trials showed that for this system a target sustained hexanal concentration of 40-70 ppm was required. This was shown to be (i) the minimum inhibitory concentration (MIC) for controlling Botrytis cinerea growing on tomatoes stored at 20°C and ~99%RH, (ii) to have only a relatively minor influence on the postharvest quality of tomatoes under these active MA conditions, and (iii) to promote only a small apparent uptake of hexanal from the atmosphere by the tomatoes. The effective hexanal permeabilities of Tyvek , LDPE and OPP sachet films were characterised using the isostatic method and shown to exhibit a dependence on both temperature (10 and 20°C) and concentration (over a range of 0.01-0.22 mol m[superscript -3). Average permeabilities decreased in the order of Tyvek > LDPE > OPP, respectively, at all temperatures at comparable hexanal partial pressures. Hexanal sorption isotherms for silica gel at both 10 and 20ºC were determined using the gravimetric method and were reasonably well described by the Langmuir equation. The equilibrium amount adsorbed was significantly reduced at the higher temperature but the pre-adsorption of water vapour on hexanal uptake on silica gel showed no uniform trend on the sorption characteristics suggesting that multicomponent sorption is complex. A generalised modelling methodology was developed through conceptualising key mass transfer processes involved in these active MA packaging systems. Quantitative methods for deciding the relative importance of each process were established together with guidelines for when simplifying assumptions could be made. This information was formalised into a decision tree to allow appropriate assumptions to be made in model formulation without unacceptable loss of model accuracy. Methods to develop generalised equations from these assumptions to describe changes in the sachet, package headspace and outer bag film with respect to an active agent and MA gases were then identified. The mathematical modelling methodology was applied to the example hexanal release active MAP tomato packaging system. For these systems there was a high initial peak in package headspace concentration during the first 24 h which declined to a quasi steadystate concentration over a period of days. The quasi steady-state headspace concentrations were generally in the MIC range and were well predicted by the model. Interactions between water vapour and silica gel may have been responsible for the relatively higher hexanal concentration at the onset of release from the Tyvek sachet (a highly porous material). However the influence of water vapour (>95% RH in the MA bag containing tomatoes) during the quasi steady-state period appeared to be insignificant for all sachet films. The model was successfully applied to a range of packaging configurations and storage temperatures. A lack of fit was evident between model predictions and experimental trials during the initial (unsteady-state) stages of the release pattern for both headspace vapour concentrations and adsorbed mass on the silica gel. These differences were attributed to (i) model input uncertainties, chiefly with regard to the estimated coefficients of both the Langmuir isotherm equation and film permeability, and (ii) overestimated effective permeability values predicted by extrapolation of the concentration dependence of film permeability beyond the conditions for which the permeability was measured. These results suggest improved models for the effective permeabilities of the films, quantified under a range of vapour concentrations and concentration gradients, are required for better describing fluxes across the sachet film. Despite these limitations, the model did describe the general release pattern. The model was then used to pose a range of ‘what-if’ scenarios investigating the release patterns predicted for different active packaging designs. This analysis gave useful insights into how sorption isotherm shape and package/sachet design parameters can be manipulated to achieve different volatile release platforms. The work clearly demonstrated the importance of accurate data for permeability of volatile compounds through polymer films and for sorption of the active agent on the carrier phase. More work on characterising these systems is recommended to further improve modelbased design methods for active MAP systems. Overall the generalised methodology developed can be confidently adopted for constructing a mathematical model that provides sufficient accuracy and simplicity to be implemented for designing active packaging systems for horticultural and food products.

Derome Skog AB is a purchase company whose main task is to provide Derome Timber's sawmills in Halland with timber raw material. Because of the very hard competition in the roundwood market it is important to know what kind of purchase offers are required in order to buy a valuable product from forest owners. This study aims to elucidate the crucial factors when private forest owners choose to harvest and sell their forest. As base for this study, a questionnaire has been performed with private forest owners. The result of the study shows that it is not particularly often that the timber price is the crucial factor why the forest owners choose to harvest and sell the forest products; i.e. timber, pulpwood as well as energy assortments. Most often, it is entirely other reasons which drive the forest owner to harvest. The price of timber is however very important and can very well be the factor that determine to whom the forest owner chooses to sell his timber.

Gulf oysters are harvested and consumed year-round, with more than 90% consumed in a raw, unprocessed state. A chief concern of policymakers in recent years is the incidence of Vibrio vulnificus infection following raw seafood consumption. V.vulnificus refers to a halophilic bacterium naturally occurring in brackish coastal waters, which concentrates in filter-feeding oysters. Proposed FDA legislation requiring processing of all raw Gulf oysters sold during warmer summer months threatens the Gulf oyster industry, as little to no research regarding demand for post-harvest processing (PHP) has preceded the potential mandate. This research endeavors to examine the relationship between oyster consumers' fears of V.vulnificus infection and their willingness-to-pay (WTP) for processing of an oyster meal. The psychological model of Protection Motivation Theory (PMT) is employed alongside the economic framework of contingent valuation (CV) to result in an analysis of oyster processing demand with respect to threats and efficacy. A survey administered to 2,172 oyster consumers in six oyster producing states elicits projected consumption and PMT data. Principal Component Analysis is used to reduce the number of PMT variables to a smaller size, resulting in five individual principal components representing the PMT elements of source information, threat appraisal, coping appraisal, maladaptive coping, and protection motivation. Using survey data, the marginal willingness-to-pay (MWTP) for PHP per oyster meal is also calculated, and the five created PMT variables are regressed on this calculation using four separate OLS models. Results indicate significant correlation for four of the five created PMT variables. In addition, a mean MWTP for PHP of $0.31 per oyster meal is determined, contributing to the demand analysis for processing of Gulf oysters. The findings suggest a strong relationship between the fear elements and the demand for processing, and support arguments in favor of further research on specific PHP treatments and the necessity for a valid PMT survey instrument.

Maize (Zea mays L.) ranks third as a food crop after wheat and rice and is characterized not only as a cereal crop but also as a vegetable. Maize used as a vegetable is known as “baby corn”. Baby corn consists of unfertilized young ears harvested 2 or 3 days after silk emergence. The present study was implemented in 2009 at Western Kentucky University Agriculture Research and Education Center (36.93 N, 86.47 E) in Bowling Green, Kentucky. The purpose of the study was to compare the effect of different schemes of harvest on baby corn (BC) yield, grain maize (GM) yield, and estimated economic return. Experimental harvest treatments were 1) no BC harvest, only GM harvest, 2) first harvest as BC, final harvest as GM, 3) first and second harvests as BC, final harvest as GM, and 4) first, second, and third harvests as BC, final harvest as GM. Average estimated BC yields (Kg/ha) for Treatments 2, 3, and 4 were 1445.1, 2681.8, and 3437.5; GM yields (Kg/ha) for Treatments 1, 2, and 3 were 12522.2, 8226.5, and 1380.9; respectively. Since few grain kernels were found after three harvests for BC (Treatment 4), no usable GM yield was produced. BC and GM yields were used for evaluating the economic returns. Results indicated that the sequence of best economic returns would be obtained by harvesting BC three times (Treatment 4), first two harvests for BC and the final for GM (Treatment 3), first harvest for BC and subsequent for GM (Treatment 2), and only for GM harvest (Treatment 1). Although the pattern for only BC harvest was the most profitable system, the human labor requirement and critical timing of harvest limited its production. In states similar to Kentucky, BC could only be grown as an additional crop or to supplant a limited amount of traditional GM hectarage.

No description available.

No description available.

In South Australia, overabundant kangaroo populations are managed through commercial harvest. Kangaroo harvest rates over the past decade have averaged only 40% of the harvest quota despite strong demand for the product. With kangaroo populations increasing, the problem of low kangaroo harvest rate in South Australia requires research attention. Previous research regarding kangaroo harvest has focused on questions of biology and ecology and little attention has been directed towards advancing understanding of the human dimensions of kangaroo management. This research sought to fill this gap in knowledge. Qualitative research methods were most appropriate due to the focus on social and institutional dimensions of kangaroo management. Data were collected during interviews with people involved in commercial kangaroo harvest: landholders, harvesters and meat processors. The main topics covered were regnlations and policy, economic issues, the rights and interests of various industry stakeholders and South Australian harvest rates. The views of Aboriginal people were also sought including the significance of kangaroos to Aboriginal people, access to kangaroos for subsistence harvest, kangaroo management and the kangaroo industry. The main findings of this research are presented as a series of peer-reviewed articles: • Article I introduces the research topic and presents preliminary findings of this study. • Article 2 establishes that an increase in South Australia's low harvest rate is needed if kangaroo harvest is to make greater contributions to regional communities, and recommends institutional reform to meet this goal. • Article 3 examines the management regime for kangaroos in South Australia and shows how the informal rules in use are often incongruent with the formal rules established by management administrators. • Article 4 describes the undervalued position of landholders in the kangaroo industry and the obstacles to landholders deriving income from kangaroo harvest. • Article 5 discusses the cultural basis of Aboriginal perspectives on kangaroo harvest and includes suggestions for appropriate ways for Aboriginal people to contribute to kangaroo management. The main findings of this research were applied in a comparative study of kangaroo management with that of moose management in Finland. This study found that similar social and institutional factors impact on the management of moose and kangaroos. The broad lessons for wildlife management drawn from the comparative study are: • mobile wildlife resources require flexible management systems • stakeholder involvement is critical to management • hunters/harvesters are conservative of their resource base • declining harvester numbers need to be addressed through support, incentives and training. These lessons can be applied in part, or in whole, to other overabundant and mobile wildlife species. Thus this thesis makes contribution to kangaroo management by making specific recommendations for the industry, but also contributes to wildlife management in a broader sense through the application of findings to other species. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1298303 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

In South Australia, overabundant kangaroo populations are managed through commercial harvest. Kangaroo harvest rates over the past decade have averaged only 40% of the harvest quota despite strong demand for the product. With kangaroo populations increasing, the problem of low kangaroo harvest rate in South Australia requires research attention. Previous research regarding kangaroo harvest has focused on questions of biology and ecology and little attention has been directed towards advancing understanding of the human dimensions of kangaroo management. This research sought to fill this gap in knowledge. Qualitative research methods were most appropriate due to the focus on social and institutional dimensions of kangaroo management. Data were collected during interviews with people involved in commercial kangaroo harvest: landholders, harvesters and meat processors. The main topics covered were regnlations and policy, economic issues, the rights and interests of various industry stakeholders and South Australian harvest rates. The views of Aboriginal people were also sought including the significance of kangaroos to Aboriginal people, access to kangaroos for subsistence harvest, kangaroo management and the kangaroo industry. The main findings of this research are presented as a series of peer-reviewed articles: • Article I introduces the research topic and presents preliminary findings of this study. • Article 2 establishes that an increase in South Australia's low harvest rate is needed if kangaroo harvest is to make greater contributions to regional communities, and recommends institutional reform to meet this goal. • Article 3 examines the management regime for kangaroos in South Australia and shows how the informal rules in use are often incongruent with the formal rules established by management administrators. • Article 4 describes the undervalued position of landholders in the kangaroo industry and the obstacles to landholders deriving income from kangaroo harvest. • Article 5 discusses the cultural basis of Aboriginal perspectives on kangaroo harvest and includes suggestions for appropriate ways for Aboriginal people to contribute to kangaroo management. The main findings of this research were applied in a comparative study of kangaroo management with that of moose management in Finland. This study found that similar social and institutional factors impact on the management of moose and kangaroos. The broad lessons for wildlife management drawn from the comparative study are: • mobile wildlife resources require flexible management systems • stakeholder involvement is critical to management • hunters/harvesters are conservative of their resource base • declining harvester numbers need to be addressed through support, incentives and training. These lessons can be applied in part, or in whole, to other overabundant and mobile wildlife species. Thus this thesis makes contribution to kangaroo management by making specific recommendations for the industry, but also contributes to wildlife management in a broader sense through the application of findings to other species. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1298303 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

The seafood industry is of considerable importance to both the New Zealand and global economies and therefore tissue preservation technologies that increase product quality and/or prolong shelf life have the potential to add significant value. Technologies for maintaining the viability of isolated tissues also have a wide range of other medical and industrial applications. This thesis examines the relationship between metabolic function, oxidation and cell death and the resulting stability of the non-viable tissues during long term storage in chinook salmon (Oncorhynchus tshawytscha) red and white skeletal muscle tissue. This research also looks at the role of the aquatic anaesthetic AQUI-S™, in which the active ingredient is isoeugenol (a lipid soluble antioxidant), and other antioxidant compounds in preserving metabolic function in viable tissues and tissue stability in nonviable tissues. Perfusion of salmon tails at 15℃ over 5 or 10 hours with oxygen saturated saline resulted in significant increases in protein and lipid oxidation (protein carbonyl and TBARS concentrations respectively) in the red muscle, but not the white muscle. The introduction of ascorbic acid and uric acid into the saline did not reduce the oxidation in the red muscle despite significantly increasing their respective concentrations in the tissue. This indicates the difficulties associated with attempting to extend tissue viability by delivering free oxygen to the tissue and also highlights the difference in susceptibility of the two muscle types to oxidation. Tail fillets from salmon harvested in both rested and exhausted physiological states using AQUI-S™, and fillets from exhausted salmon harvested without AQUI-S™, were exposed to air at 15℃ for up to 96 hours. Protein carbonyls increased in a roughly linear fashion over the entire 96 hours in all three groups. Both lipid peroxides (TBARS) and uric acid concentrations began to increase in the exhausted group after 30 hours. In contrast, no significant increases in lipid peroxides or uric acid was seen in the fillets from either group harvested using AQUI-S™. Vitamin E concentrations reduced slowly but did not change significantly despite the oxidation that was evident in the tissue. These processes also occurred in salmon tail fillets during storage at 6℃. The measurement of ATP related compounds provides an effective indicator of both the metabolic state of the tissue post-harvest and the quality. The breakdown of these compounds is also associated with the production of ammonia and hydrogen peroxide. Fresh rested salmon fillets had high concentrations of ATP and creatine phosphate, which were both depleted after 12 hours storage at 15℃. This indicates that cell viability lasted a number of hours following harvesting. These metabolites were depleted in exhausted fillets and metabolic potential appeared to be immediately compromised. The concentration of the taste enhancing compound IMP was significantly reduced in fresh rested tissue, but increased during storage, and was significantly higher than in exhausted tissues following 12 hours of storage at 15℃. This indicates that some properties of rested tissues may improve with limited storage times. The accumulation of uric acid - the metabolic end point for ATP related compounds - was also significantly reduced in rested tissue and increases in K-value were slowed. AQUI-S™ showed an ability to preserve tissue function through its anaesthetic action allowing tissue to be harvested in a rested state, and to reduce late stage lipid oxidation in stored salmon tail fillets. The antioxidant action of isoeugenol in salmon fillets may be mediated through its ability to chelate transition metals released during tissue degradation. This research shows that during reperfusion and during fillet storage there is a significant level of oxidative stress, which needs to be minimized while maintaining basic tissue metabolism to prolong tissue and cellular viability. The development of future technologies to preserve tissue viability may depend on the development of a synthetic oxygen carrying compound with properties similar to red blood cells. This may allow more control over oxygen delivery, potentially reducing the oxidative stress associated with high concentrations of free oxygen in solution. However, preserving cell viability will also require the maintenance of endogenous antioxidant function and there is also the potential to use iron chelating compounds including plant derived flavonoids to preserve non-viable tissues. Future research in these areas is necessary.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this research was to develop a seed moisture measurement system (M.M.S.) prototype that could be embedded on a combine to harvest and analyze experimental plots. It must be able to reach the claims of seed research companies. This kind of system is trade available, though there is no technology designed in Brazil and it is imported in a high cost. To reach the aim, seven construction requirement were defined. The M.M.S. was designed and constructed obeying such requirements. Fixed frequency in 10 kHz, its operation distinguishes itself by gathering constructive characteristics capacitive sensors of parallel plates as well as concentric cylinders. Its calibration was performed using corn seeds (Zea mays L.) artificially moistened through methodology that was preliminarily developed. The calibration curve was obtained by the correlation between the sensor output voltage and the moisture seed sample. Modeling (estimated by Linear Least Squares Fitting technique and evaluated by analysis of variance) consists of three lines which delimit three reading bands (selected automatically by system). The total M.M.S. reading extends from 10 to 30 %. The system checking was comprised by comparing the prototype results to results obtained by standard oven method and three other indirect measurement methods. Thus, the prototype was achieved through the construction of a moisture measurement system that attends the construction requirements, using automatic reading temperature correction and taking into account all the conditions to be embedded on combines. / O objetivo deste trabalho foi o desenvolvimento do prot´otipo de um sistema de medi¸c ao de umidade de sementes, que possa ser embarcado em uma colhedora para colheita e an´alise de parcelas experimentais e que atenda `as necessidades das empresas de pesquisa que atuam no melhoramento de plantas. Este sistema est´a dispon´ıvel no com´ercio, por´em ´e importado a alto custo. A constru¸c ao do sistema de medi¸c ao de umidade foi feita obedecendo a alguns requisitos previamente definidos. Trabalhando com uma freq¨u encia fixa de 10 kHz, distingue-se por reunir caracter´ısticas construtivas dos sensores capacitivos de placas paralelas bem como os de cilindros conc entricos. Sua calibra¸c ao foi feita utilizando sementes de milho (Zea mays L.) umedecidas artificialmente mediante metodologia desenvolvida preliminarmente. A curva de calibra¸c ao foi obtida pela correla¸c ao da tens ao de sa´ıda do sensor com o teor de ´agua presente na amostra de sementes. O modelo (estimado pelo m´etodo de regress ao por m´ınimos-quadrados e avaliado por an´alise de vari ancia) consiste de tr es retas que delimitam tr es faixas de leitura (selecionadas automaticamente pelo sistema). A faixa capaz de medi¸c ao de umidade corresponde `a de 10 a 30 %. A aferi¸c ao do sistema foi delineada pela compara¸c ao dos resultados do prot´otipo com os resultados obtidos por um m´etodo padr ao de estufa e auxiliada por outros tr es m´etodos indiretos de medi¸c ao. Assim, a proposta de desenvolvimento do prot´otipo foi atingida atrav´es da constru- ¸c ao de um sistema de medi¸c ao de umidade que atende aos requisitos de constru¸c ao impostos, possuindo corre¸c ao autom´atica de leitura em fun¸c ao da temperatura ambiente e atendendo a todas as condi¸c oes para ser embarcado em colhedoras. / Doutor em Engenharia Mecânica