844 resultados para Microbiology of food
Resumo:
Drying has been extensively used as a food preservation procedure. The longer life attained by drying is however accompanied by huge energy consumption and deterioration of quality. Moisture diffusivity is an important factor that is considered essential to understand for design, analysis, and optimization of drying processes for food and other materials. Without an accurate value of moisture diffusivity, drying kinetics, energy consumption, quality attributes such as shrinkage, texture, and microstructure cannot be predicted properly. However, moisture diffusivities differ due to variation of composition and microstructure of foodstuff and drying variables. For a particular food, it changes with many factors including moisture content, water holding capacity, process variables and physiochemical attributes of food. Published information on moisture diffusivities of banana is inadequate and sometimes inconsistent due to lack of precise repeatable analysis techniques. In this work, the effective moisture diffusivity of banana was determined by Thermogravimetric Analysis (TGA), which ensures precise measurements and reproduction of experiments. A TGA Q500 V20.13 Build 39 was deployed to obtain the drying curve of the food material. It was found that effective moisture diffusivity ranged from 6.63 x10-10 to 1.03 x10-9 and 1.34 x10-10 to 6.60 x10-10 for isothermal at 70 0C and non-isothermal process respectively.These values are consistent with the value of moisture diffusivity found in the literature.
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Although local food consumption is growing in importance there remains a lack of research addressing local food consumption preferences in less-developed countries. This paper aims to examine the drivers of local food purchase intentions for Chilean consumers. A model of local food behavioral intention was developed from consumer behavior theory. The model was tested using structural equation modeling with data from Chilean shoppers located in Santiago (n=283). The analysis revealed that Chilean consumers are willing to purchase local food based on their positive attitude towards buying local food and their feelings of connectedness with the environment, but not because they have a desire to support local businesses. These findings have implications for retailers, marketers and food producers.
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This thesis is a trans-disciplinary study of domestic food waste in Australia. Firstly, it examines why consumers are prone to waste food. Secondly, it explores several situated design interventions to reduce domestic food waste by informing consumer food supply and location awareness, and improving the level of food literacy among consumers. The thesis outcomes have implications for academic and industry domains within the fields of Human-Computer Interaction, urban informatics, environmental sustainability, food security and public health.
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Dried plant food materials are one of the major contributors to the global food industry. Widening the fundamental understanding on different mechanisms of food material alterations during drying assists the development of novel dried food products and processing techniques. In this regard, case hardening is an important phenomenon, commonly observed during the drying processes of plant food materials, which significantly influences the product quality and process performance. In this work, a recent meshfree-based numerical model of the authors is further improved and used to simulate the influence of case hardening on shrinkage characteristics of plant tissues during drying. In order to model fluid and wall mechanisms in each cell, Smoothed Particle Hydrodynamics (SPH) and the Discrete Element Method (DEM) are used. The model is fundamentally more capable of simulating large deformation of multiphase materials, when compared with conventional grid-based modelling techniques such as Finite Element Methods (FEM) or Finite Difference Methods (FDM). Case hardening is implemented by maintaining distinct moisture levels in the different cell layers of a given tissue. In order to compare and investigate different factors influencing tissue deformations under case hardening, four different plant tissue varieties (apple, potato, carrot and grape) are studied. The simulation results indicate that the inner cells of any given tissue undergo limited shrinkage and cell wall wrinkling compared to the case hardened outer cell layers of the tissues. When comparing unique deformation characteristics of the different tissues, irrespective of the normalised moisture content, the cell size, cell fluid turgor pressure and cell wall characteristics influence the tissue response to case hardening.
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Urban agriculture refers to the production of food in urban and peri-urban spaces. It can contribute positively to health and food security of a city, while also reducing ‘food miles.’ It takes on many forms, from the large and organised community garden, to the small and discrete backyard or balcony. This study focuses on small-scale food production in the form of residential gardening for home or personal use. We explore opportunities to support people’s engagement in urban agriculture via human-computer interaction design. This research presents the findings and HCI design insights from our study of residential gardeners in Brisbane, Australia. By exploring their understanding of gardening practice with a human-centred design approach, we present six key themes, highlighting opportunities and challenges relating to available time and space; the process of learning and experimentation; and the role of existing online platforms to support gardening practice. Finally we discuss the overarching theme of shared knowledge, and how HCI could improve community engagement and gardening practice.
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This study assessed environmental health risk from dioxin in foods and sustainability of risk reduction programs at two heavily contaminated former military sites in Vietnam. The study involved 1000 household surveys, analysis of food samples and in-depth discussions with residents and officials. The findings indicate that more than 40 years after the war, local residents still experience high exposure to dioxin if they consume local high risk foods. Public health intervention programs were rated moderately to well sustained. Internal migration, and lack of clear, official guidance and sensitivity regarding dioxin issues were the main challenges for sustainability of prevention programs.
Resumo:
Drying of food materials offers a significant increase in the shelf life of food materials, along with the modification of quality attributes due to simultaneous heat and mass transfer. Shrinkage and variations in porosity are the common micro and microstructural changes that take place during the drying of mostly the food materials. Although extensive research has been carried out on the prediction of shrinkage and porosity over the time of drying, no single model exists which consider both material properties and process condition in the same model. In this study, an attempt has been made to develop and validate shrinkage and porosity models of food materials during drying considering both process parameters and sample properties. The stored energy within the sample, elastic potential energy, glass transition temperature and physical properties of the sample such as initial porosity, particle density, bulk density and moisture content have been taken into consideration. Physical properties and validation have been made by using a universal testing machine ( Instron 2kN), a profilometer (Nanovea) and a pycnometer. Apart from these, COMSOL Multiphysics 4.4 has been used to solve heat and mass transfer physics. Results obtained from models of shrinkage and porosity is quite consistent with the experimental data. Successful implementation of these models would ensure the use of optimum energy in the course of drying and better quality retention of dried foods.
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Stakeholders commonly agree that food systems need to be urgently reformed. Yet, how food systems should be reformed is extremely contested. Public international law and regulations are uniquely placed to influence and guide law, policy, programmes and action at regional, national and local levels. Although plenty of international legal instruments intersect with food-related issues, the international regulation of food systems is fragmented, understudied and contested. In order to address these issues, this paper maps and analyses the public international regulatory aspects of food production with a view to providing recommendations for reform. Accordingly, this paper brings together a variety of binding and non-binding international regulatory instruments that to varying degrees and from a range of angles deals with the first activity in the food system: food production. The following paper traces the regulatory tools from natural resources, to the farmers and farm workers that apply skill and experience, and finally to the different dimension of world trade in food. The various regulatory instruments identified, and their collective whole, will be analysed against a rights-based approach to food security.
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In the United States, there has been fierce debate over state, federal and international efforts to engage in genetically modified food labelling (GM food labelling). A grassroots coalition of consumers, environmentalists, organic farmers, and the food movement has pushed for law reform in respect of GM food labelling. The Just Label It campaign has encouraged United States consumers to send comments to the United States Food and Drug Administration to label genetically modified foods. This Chapter explores the various justifications made in respect of genetically modified food labelling. There has been a considerable effort to portray the issue of GM food labelling as one of consumer rights as part of ‘the right to know’. There has been a significant battle amongst farmers over GM food labelling – with organic farmers and biotechnology companies, fighting for precedence. There has also been a significant discussion about the use of GM food labelling as a form of environmental legislation. The prescriptions in GM food labelling regulations may serve to promote eco-labelling, and deter greenwashing. There has been a significant debate over whether GM food labelling may serve to regulate corporations – particularly from the food, agriculture, and biotechnology industries. There are significant issues about the interaction between intellectual property laws – particularly in respect of trade mark law and consumer protection – and regulatory proposals focused upon biotechnology. There has been a lack of international harmonization in respect of GM food labelling. As such, there has been a major use of comparative arguments about regulator models in respect of food labelling. There has also been a discussion about international law, particularly with the emergence of sweeping regional trade proposals, such as the Trans-Pacific Partnership, and the Trans-Atlantic Trade and Investment Partnership. This Chapter considers the United States debates over genetically modified food labelling – at state, federal, and international levels. The battles often involved the use of citizen-initiated referenda. The policy conflicts have been policy-centric disputes – pitting organic farmers, consumers, and environmentalists against the food industry and biotechnology industry. Such battles have raised questions about consumer rights, public health, freedom of speech, and corporate rights. The disputes highlighted larger issues about lobbying, fund-raising, and political influence. The role of money in United States has been a prominent concern of Lawrence Lessig in his recent academic and policy work with the group, Rootstrikers. Part 1 considers the debate in California over Proposition 37. Part 2 explores other key state initiatives in respect of GM food labelling. Part 3 examines the Federal debate in the United States over GM food labelling. Part 4 explores whether regional trade agreements – such as the Trans-Pacific Partnership (TPP) and the Trans-Atlantic Trade and Investment Partnership (TTIP) – will impact upon
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Although a number of studies have examined the role of gastric emptying (GE) in obesity, the influences of habitual physical activity level, body composition and energy expenditure (EE) on GE have received very little consideration. In this study, we have compared GE in active and inactive males, and we have characterised relationships with body composition (fat and fat free mass) and EE. Forty-four males (Active: n=22, Inactive: n=22; range BMI 21-36kg/m2; range percent fat mass 9-42%) were studied, with GE of a standardised (1676 kJ) pancake meal being assessed by 13C-octanoic acid breath test, body composition by air displacement plethysmography, resting metabolic rate (RMR) by indirect calorimetry and activity EE (AEE) by accelerometry. Results showed that GE was faster in active compared to inactive males (mean ±SD half time (t1/2): Active: 157±18 and Inactive: 179±21 min, p<0.001). When data from both groups were pooled, GE t1/2 was associated with percent fat mass (r=0.39, p<0.01) and AEE (r =-0.46, p<0.01). After controlling for habitual physical activity status, the association between AEE and GE remained, but not that for percent fat mass and GE. BMI and RMR were not associated with GE. In summary, faster GE is considered to be a marker of a habitually active lifestyle in males, and is associated with a higher AEE and lower percent fat mass. The possibility that GE contributes to a gross physiological regulation (or dysregulation) of food intake with physical activity level deserves further investigation.
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This paper addresses the gap in economic theory underlying the multidimensional concept of food security and observed data by deriving a composite food security index using the latent class model. The link between poverty and food security is then examined using the new food security index and the robustness of the link is compared with two unidimensional measures often used in the literature. Using Vietnam as a case study, it was found that a weak link exists for the rural but not for the urban composite food security index. The unidimensional measures on the other hand show a strong link in both the rural and urban regions. The results on the link are also different and mixed when two poverty types given by persistent and transient poverty are considered. These findings have important policy implications for a targeted approach to addressing food security.
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The increase in the number of individuals living alone has implications for nutrition and health outcomes. This review aimed to investigate whether there is a difference in food and nutrient intake between adults living alone and those living with others. Eight electronic databases were searched, using terms related to living alone, nutrition, food, and socioeconomic factors. Forty-one papers met the inclusion criteria, and data of interest were extracted. Results varied but suggested that, compared with persons who do not live alone, persons who live alone have a lower diversity of food intake, a lower consumption of some core foods groups (fruit, vegetables, and fish) and a higher likelihood of having an unhealthy dietary pattern. Associations between living alone and nutrient intake were unclear. Men living alone were more often observed to be at greater risk of undesirable intakes than women. The findings of this review suggest that living alone could negatively affect some aspects of food intake and contribute to the relationship between living alone and poor health outcomes, although associations could vary between socioeconomic groups. Further research is required to help to elucidate these findings.
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Background: Appetitive traits and food preferences are key determinants of children’s eating patterns but it is unclear how these behaviours relate to one another. This study explores relationships between appetitive traits and preferences for fruits and vegetables, and energy dense, nutrient poor (noncore) foods in two distinct samples of Australian and British preschool children. Methods: This study reports secondary analyses of data from families participating in the British GEMINI cohort study (n=1044) and the control arm of the Australian NOURISH RCT (n=167). Food preferences were assessed by parent-completed questionnaire when children were aged 3-4 years and grouped into three categories; vegetables, fruits and noncore foods. Appetitive traits; enjoyment of food, food responsiveness, satiety responsiveness, slowness in eating, and food fussiness were measured using the Children’s Eating Behaviour Questionnaire when children were 16 months (GEMINI) or 3-4 years (NOURISH). Relationships between appetitive traits and food preferences were explored using adjusted linear regression analyses that controlled for demographic and anthropometric covariates. Results: Vegetable liking was positively associated with enjoyment of food (GEMINI; β=0.20 ± 0.03, p<0.001, NOURISH; β=0.43 ± 0.07, p<0.001) and negatively related to satiety responsiveness (GEMINI; β=-0.19 ± 0.03, p<0.001, NOURISH; β=-0.34 ± 0.08, p<0.001), slowness in eating (GEMINI; β=-0.10 ± 0.03, p=0.002, NOURISH; β=-0.30 ± 0.08, p<0.001) and food fussiness (GEMINI; β=-0.30 ± 0.03, p<0.001, NOURISH; β=-0.60 ± 0.06, p<0.001). Fruit liking was positively associated with enjoyment of food (GEMINI; β=0.18 ± 0.03, p<0.001, NOURISH; β=0.36 ± 0.08, p<0.001), and negatively associated with satiety responsiveness (GEMINI; β=-0.13 ± 0.03, p<0.001, NOURISH; β=-0.24 ± 0.08, p=0.003), food fussiness (GEMINI; β=-0.26 ± 0.03, p<0.001, NOURISH; β=-0.51 ± 0.07, p<0.001) and slowness in eating (GEMINI only; β=-0.09 ± 0.03, p=0.005). Food responsiveness was unrelated to liking for fruits or vegetables in either sample but was positively associated with noncore food preference (GEMINI; β=0.10 ± 0.03, p=0.001, NOURISH; β=0.21 ± 0.08, p=0.010). Conclusion: Appetitive traits linked with lower obesity risk were related to lower liking for fruits and vegetables, while food responsiveness, a trait linked with greater risk of overweight, was uniquely associated with higher liking for noncore foods.
Resumo:
Contemporary food systems promote the consumption of highly processed foods of limited nutrition, contributing to overweight and obesity, diet-related disease and significant financial burden on healthcare systems. In part, this has resulted from highly successful design, development and marketing strategies for processed foods. The successful application of such strategies to healthy food options, and the services and business plans that accompany them, could assist in enhancing health and alleviating burden on health care systems. Product designers have long been aware of the importance of intertwining emotional experiences with new products. However, a lack of theoretical precision exists for applying emotional design beyond food products, to the food systems, services and business models that drive them. This article explores emotional design within the context of food and food systems and proposes a new concept – Emotional Food Design (EFD), through which emotional design is integrated across levels of a food system. EFD complements the dominating deductive view of food systems research with an abductive iterative design approach contextualized within the creation of new food products, services and business models and their associated emotional attachments. This paper concludes by outlining what EFD can offer to reorient food systems to successfully promote healthy eating.
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The Australian Nutrition Foundation (ANF) was one of the first community service organisations to work with food industry , having pioneered the concept of corporate membership since its inception in 1982. ANF has worked closely and successfully with industry - the development of the ANF Food Selection Guidelines for Children and Adolescents is one example of this collaboration. While the guidelines were initially developed for use in school canteens, they can be used in a range of institutions where caterers wish to have tender specifications for purchase of healthy food for children and adolescents.