The relationships between moisture loss and oil uptake and their effects on porosity, pore size distribution and pore structure during deep-fat frying of chicken breast meat were investigated. Chicken meat samples were deep-fat fried in an industrial fryer. The frying oil temperatures were 170, 180 and 190°C and samples were fried for times ranging from 5 to 900 s.

The purpose of this study was to investigate the quality of frying oil in eight randomly selected restaurants in Umeå. A further aim was to examine the techniques and control methods the various restaurants used. The methods used to answer the purpose was questionnaires, answered by the chefs, which was used to examine the procedures used in the handling of frying oils. To investigate the quality of the frying oils two types of quick tests were used, a Oxifrit-test and a TPM-test. The results showed that all food businesses had developed procedures for the handling of frying oils. Procedures for intermittent usage, change of frying oil, monitoring of the oil, cleaning and handling of frying oils after use existed at the eight restaurants. According to the recommendations of the Deutsche Gesellschaft für fettwissenschaft the observed routines does not meet all the criteria to achieve a good quality of frying oil, and therefore needs improvements. However the Oxifrit-test and TPM-test showed that the frying oils generally archive a good quality in the selected restaurants. There were only three restaurants where the oil should have been replaced. Further improvement of procedures might help to improve the quality of frying oil.

The goal of this research was to investigate the influence of the degree of hydrogenation of frying oil on quality and textural changes in chicken nuggets during deep-fat frying. Thermal stabilities of the frying oils were also studied. The frying oil consisted of blends of hydrogenated and non-hydrogenated oils mixed at different ratios. Physical and textural attributes of the products, as well as the moisture and fat contents, were measured at various frying times. Oil samples were withdrawn at different times and analyzed for colour, free fat acid (FFA) content, viscosity and dielectric properties. Physical and textural properties of chicken nuggets were influenced by frying time and the degree of oil hydrogenation. The experimental data, for changes in the properties of both flying oil and fried product, was adequately described using first order reaction kinetics. Increasing frying time decreased product lightness whereas chroma and hardness values increased. Frying in oils with higher degrees of hydrogenation resulted in products with lighter and harder (more crispy) texture. Products fried in non-hydrogenated oil absorbed more oil but also retained more moisture compared to samples fried in hydrogenated oil. The rate of change in the colour parameters of oils was observed to increase with increasing frying time and the degree of hydrogenation. The chroma values of the oils increased when frying time increased and degree of hydrogenation decreased. The viscosity of oil tended to increase with increasing degree of hydrogenation. The FFA content and dielectric constant of the frying oils correlated with frying time and degree of hydrogenation.

Thesis (Ph.D.). / Written for the Dept. of Bioresource Engineering, Macdonald College of McGill University. Title from title page of PDF (viewed 2008/08/04). Includes bibliographical references.

p. 1-105 / Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-04-08T20:52:19Z No. of bitstreams: 1 Dissertacao Fabiana Curvelo.pdf: 3183264 bytes, checksum: d6fda0ec04c18450142264589452880c (MD5) / Approved for entry into archive by Rodrigo Meirelles(rodrigomei@ufba.br) on 2013-04-09T13:24:30Z (GMT) No. of bitstreams: 1 Dissertacao Fabiana Curvelo.pdf: 3183264 bytes, checksum: d6fda0ec04c18450142264589452880c (MD5) / Made available in DSpace on 2013-04-09T13:24:30Z (GMT). No. of bitstreams: 1 Dissertacao Fabiana Curvelo.pdf: 3183264 bytes, checksum: d6fda0ec04c18450142264589452880c (MD5) Previous issue date: 2010 / O Objetivo do presente trabalho foi avaliar a qualidade do óleo de palma bruto e daquele empregado na fritura de acarajés, consumidos na cidade de Salvador-Bahia. Metodologia: para avaliação das técnicas de fritura aplicou-se questionário semi estruturado a 149 baianas de acarajé distribuídas pelos 12 distritos sanitários da referida cidade. Com base nestes, foram coletados os 15 principais óleos empregados na fritura dos bolinhos e 149 amostras daquele empregado na fritura. A avaliação das características físico-químicas dos óleos incluiu: compostos polares totais (%), acidez (% de ácido palmítico), índice de peróxido (mEq/kg), índice de refração (40 ºC) e medidas de cor (CIELAB). Resultados: na matéria prima foi observado que 73,33 % e 46,66 % das amostras apresentaram acidez e compostos polares, respectivamente, superiores ao limite estabelecido; o índice de peróxidos variou entre 0,5-4,5 mEq/kg e refração entre 1,4500-1,4590. Óleos contendo somente a fração oleína apresentaram-se mais luminosos e vermelhos em relação àqueles contendo ambas as frações. A avaliação das técnicas de fritura demonstrou que a maioria das baianas emprega mistura de oleína + estearina, repõe o óleo de fritura e utilizam equipamentos inadequados ao processo. Os dados físico-químicos do óleo da fritura indicaram elevada acidez, decréscimo do índice de refração, compostos polares e peróxidos dentro da normalidade, cor vermelha pouco expressiva. Conclusões: observou-se elevada heterogeneidade entre os óleos estudados e comprometimento da qualidade dos mesmos, embora se tenha observado boa estabilidade térmica. Recomendam-se ações educativas no setor e melhoria da matéria prima inicial para garantir um produto de qualidade. / Salvador

Frying in vegetable oil is a popular cooking and food processing method worldwide; as a result, the oils used for frying are widely consumed by the general public and it is of practical importance to better understand their health impacts. To date, the effects of frying oil consumption on human health are inconclusive, making it difficult to establish dietary recommendations or guidelines. Here we show that dietary administration of frying oil, which was prepared under the conditions of good commercial practice, exaggerated dextran sodium sulfate (DSS)-induced colitis in mice. In addition, to explore the potential compounds involved in the actions of the frying oil, we isolated polar compounds from the frying oil and found that administration of the polar compounds also exacerbated DSS-induced colitis in mice. Together, our results showed that dietary administration of frying oil exaggerated development of inflammatory bowel disease (IBD) in mice, and this effect could be mediated by the polar compounds in the frying oil.

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Deep-frying is now a popular cooking method all over the world due to its low cost and time-saving property. It also provides special and likeable flavor, helps prolong shelf lives of commercial products, and offering food products of stable quality. However, by- products formed during the frying process, such as malonaldehyde, were shown to be harmful to human health. Such compounds can be taken in when having fried foods, potentially inducing or promoting some diseases. However, there is limited research studying the direct effects of frying oil consumption on cancer. In order to have a better understanding of the effects on cancer by frying oil, we used a well-established AOM/DSS- induced colon cancer animal model to study the impact by frying oil. After 10-week treatment with diet containing deep-frying oil (3.8% in diet) or with un-oxidized oil (10% in diet), the mice showed enhanced tumorigenesis in colon, where the total tumor burden significantly increased (4.5 ± 1.9 mm2 for the treatment group, compared with 0.5 ± 0.5 mm2 for the control group, P < 0.05). Also, the expression of pro-inflammatory and pro- tumorigenic cytokines (Mcp-1, Inf-γ, Il-6, Il-1β, Myc, Axin2 and Vegf) were increased in the mice treated with frying oil diets. Together the results showed that consumption of deep-frying oil promoted the colorectal cancer in mice, providing more detailed information for health instruction.

No description available.