Thesis (Ph. D.)--University of Wisconsin--Madison, 1955. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The effects of deep fat frying and oven baking on mass transfer (moisture loss and oil uptake), color and textural characteristics of chicken nuggets were studied. Deep fat frying was performed at three oil temperatures, namely 150, 170 and 190°C. The frying times were 1, 2, 3 and 4 min. Oven baking was accomplished at three temperature levels: 200, 220, and 240°C, and the baking times were 10, 15, 20 and 25 min. / Moisture content of the breading portion of the fried chicken nuggets decreased following a typical drying curve and ranged from 0.90 to 0.22 g/g (db), while the moisture content of the core portion of the chicken nuggets decreased almost linearly and ranged from 1.96 to 1.4 g/g (db). Fat contents of the breading and core portions increased linearly with time. Generally, frying temperature significantly affected the moisture contents of the breading and core. It also affected the fat content of the core but not that of the breading. (Abstract shortened by UMI.)

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 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 Oil samples were withdrawn at different times and analyzed for colour, free fat acid (FFA) content, viscosity and dielectric properties.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.

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Frying oil is a heat and mass transfer medium, which affects the quality of food. The reaction mechanisms in deep-frying oils are mainly thermal oxidation, hydrolysis, and polymerization, which result in lipid deterioration. Addition of synthetic or natural antioxidants can effectively slow down lipid deterioration during deep-frying. Total polar components, polymerized triglycerides, p-anisidine value, acid value and iodine value are reliable indicators for assessing oil degradation during frying. Color darkening of deep-frying oils is one of apparent changes during deep-frying and is closely associated with the levels of decomposition compounds in the frying oils. However, the evidence of the relationship between color and deep-frying oil quality indicators are scanty. The main objective of this thesis is to develop a model for rapid assessment of oil quality during 30-hour deep-frying processes using oil color and quality as indicators. Significant color changes (p < 0.05) were observed in soybean oil as compared to canola and sunflower oil during 30-hour deep-frying trials. Canolol-enriched frying oils showed the highest color values before deep-frying, but the final results showed the least color changes (p < 0.05) during the 30-hour deep-frying trials. The highest percentage of total polar components (15.55 %), polymeric triglycerides (9.3 %), and p-Anisidine value (62.34) were found in TBHQ-enriched deep-frying oil samples in soybean oil. The highest acid value (3.06 mg KOH/100g) was found in canolol-enriched frying oil samples in canola oil. Rosemary and canolol-enriched deep-frying oil samples showed significant effect (p < 0.05) on color changes while reducing formation of total polar components, polymeric triglycerides, and aldehydes during the 30-hour deep-frying study. Significant correlations (p < 0.05) were found between color and oil quality indicators in all of the deep-frying oil samples; significant regression (p < 0.05) models are expressing the level of oil deterioration from color (light-dark, red-green, yellow-blue) in deep-frying oils. Overall, this study established several models using color as an indicator aiming to rapidly assess deep-frying oil quality. / October 2016

Color formation in oils during frying is one of the most noticeable degradation reactions that occur in the frying oil. Degradation reactions cause formation of products that positively and negatively impact the nutritional and sensory qualities of both the food being fried and the frying oil. The origins of these pigment forming reactions in the oil and the factors affecting these reactions are not well understood. Assessments of the mechanisms, the components involved and external conditions affecting oil darkening were conducted. The effect of basic food ingredients, commercially sold and laboratory formulated breading and battering, preformed lipid hydroperoxides and phospholipids on color formation and oil degradation of the frying oil were investigated. Protein products, specifically whey protein, caused both the fastest darkening and thermo-oxidative deterioration of the frying oil. This breakdown was aided further through the addition of minor food materials such as glucose and amino acids as well as lipid hydroperoxides in concentrations greater than 5 % of the frying oil. Nonenzymatic browning is the main reaction causing color formation in the frying oil and utilizes carbonyls from the food product such as starches, sugars and lipid oxidation products as starting materials alongside amino groups from proteins and amino acids. Breading ingredients contributed to oil color formation due to particles from the food crust breaking off into the frying oil to further accelerate browning reactions. Increasing the temperature of the frying oil provided additional stimulus for color forming and thermo-oxidative reactions to progress at a faster rate. / xv, 184 leaves : ill. ; 29 cm