Doctor of Philosophy / Department of Animal Sciences and Industry / Terry Houser / One experiment was conducted to determine the collagen and adipocyte characteristics in pork belly fat with different iodine values (IV) and if these factors contribute to belly firmness. An additional two experiments were conducted to create an objective method to score bacon distortion during cooking and to determine how IV and cooking method contribute to bacon distortion. Experiment 1 sorted pork bellies (n=72) into three IV categories: High 76.5 g/100g, Intermediate 70.5 g/100g, and Low 64.9 g/100g. Belly characteristics and firmness were measured before processing into bacon. After processing, 3 bacon slices were selected from the belly and analyzed for histochemistry and collagen analysis. No differences were observed between belly characteristics, while High IV bellies showed softer bellies. Adipocyte characteristics remained unchanged between IV groups. High IV bellies showed greater amounts of collagen. Experiment 2 cooked bacon slices (n=585) on three different appliances (griddle, microwave, and oven) and scored the resulting distortion using a subjective scale. Raw and cooked bacon characteristics were measured to determine which response variables contributing to distortion. Bacon slices were removed from 6 different locations within each belly sampled. Two distortion measurements were created to objectively describe distortion response (crest frequency and bacon distortion index. Subjective distortion scores, crest frequency, bacon distortion index, and raw and cooked bacon characteristics were shown to change between locations of the belly. Accuracy of predictive equations developed to predict distortion scores were low. Experiment 3 evaluated how IV interacts with cooking methodology to influence cooking characteristics, fat quality and distortion of bacon. Bacon slices (n=300) were organized into two IV categories, Low (61.52 to 65.54 g/100g) and High (78.83 to 85.34 g/100g) and cooked using three different appliances (oven, microwave, and griddle). Bacon from the Low IV group had the greatest amount of fat. Cooking bacon on a griddle showed the greatest distortion scores, while the oven produced bacon with the lowest distortion scores. Bacon with higher IV produced bacon with increased distortion scores. Bacon from the High IV group showed smaller cooked dimensions than the Low IV bacon. Neither cooking method nor IV level affected the cooked fatty acid composition.

Master of Science / Department of Animal Sciences and Industry / Terry A. Houser / The objectives of this study were to determine the impact of 0 and 20% dried distillers grains with soluble (DDGS) and increasing levels of glycerol (0, 2.5 and 5%) in grow-finishing rations on bacon quality and to determine the relationship between belly firmness and slicing yield for commercially produced bacon. A total of 84 barrows (PIC, initially 31.03 kg) were fed corn-soybean meal-based diets organized in a 2 x 3 factorial with primary effects of DDGS (0 or 20%) and glycerol (0, 2.5, or 5%) as fed. Belly length was measured from flank end to blade end. Belly thickness was measured at eight locations evenly spaced around the perimeter of the belly. Belly firmness was measured by centering bellies perpendicularly (skin side up and skin side down) over a stainless steel smokestick and measuring the flex between the edges on the ventral and dorsal edges of the belly. Bellies were injected at 12% of the skinned belly weight resulting in a final concentration of 1.74% salt, 0.5% sugar, 0.3% sodium phosphate, 120 ppm sodium nitrite, and 500 ppm sodium erythorbate in the bellies. Bellies were cooked to an internal temperature of 53oC, chilled, pressed and sliced for evaluation. Belly slice yield was calculated by determining the yield of #1 type bacon slices. Proximate analysis and fatty acid analysis were evaluated by taking every 10th bacon slice beginning from the caudal end to make a composite sample for each belly. Iodine value was calculated using the resulting fatty acid content results. Twenty bacon slices were removed from the belly one-third the length of the belly from the cranial end for sensory analysis and cooking yields. Sensory characteristics were evaluated on an 8-point scale for brittleness, bacon flavor intensity, saltiness and off-flavor. There were no significant DDGS x glycerol interactions on any parameters measured (P > 0.08). Inclusion of 20% DDGS in pig diets decreased belly firmness (P < 0.04) as measured by the belly flop fat side down method. Twenty percent DDGS decreased the percentage of myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, vaccenic acid, total saturated fatty acids, and total monounsaturated fatty acids (P < 0.01). In contrast, 20% DDGS increased the percentage of linoleic acid, α-linolenic acid, eicosadienoic acid, total polyunsaturated fatty acids and decreased unsaturated: saturated fatty acid ratios, polyunsaturated: saturated fatty acid ratios, and iodine values (P < 0.01). Statistical correlation analysis of belly processing characteristics showed that by increasing belly weight there will be an increase in smokehouse yields (R = 0.81), increasing smokehouse yields will increase slice yield (R = 0.71), increasing belly thickness results in firmer bellies (R = 0.94) and increasing belly firmness will increase slice yields (R = 0.60). Fatty acid content did not correlate with any belly processing characteristic (R < 0.50). Iodine values were highly correlated with Total MUFA (R = 0.83) Total PUFA (R = 0.79), Total TFA (R = 0.75), and UFA: SFA ratio, and PUFA: SFA ratios (R = 0.83). The inclusion of 0, 2.5 and 5% glycerol in swine diets did not affect any measured parameters in this study. In conclusion, feeding DDGS at a level of 20% decreased belly firmness and changed the fatty acid profile; however, it did not affect belly processing or sensory characteristics. Glycerol fed at 2.5 or 5.0% did not affect belly quality, fatty acid profile, or sensory characteristics of bacon.