Thesis (M.S.)--Ohio University, March, 2006. / Title from PDF t.p. Includes bibliographical references (p. 67-75)

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This study determined the impact of starches on the properties of low fat rennet curd as measured by microstructural and instrumental analysis. In experiment 1, 17 starches were initially screened for swelling power, impact of curd yield at 5 g/L and 10 g/L in milk, and settling in rennet-induced partially acidified low fat curd. Starches examined were narrowed down to five in experiment 2; they included: modified waxy corn starch, waxy rice starch, instant tapioca starch, dextrin, and a modified tapioca starch. These starches were added to skim milk to make rennet-induced partially acidified milk gels. Gels were made by adding starch to skim milk, heating to gelatinize starch, followed by addition of rennet and glucono-delta-lactone (GDL) to induce gelation. Once gels were set they were cut and centrifuged to sediment the curd. The amount of starch lost in whey was quantified to estimate starch retention in the curd. Confocal laser scanning microscopy was used to determine starch impact on curd microstructure. Curds yields were 13.1%, 18.4%, 20.7%, 21.5%, 23.5%, and 13.2% for control gel, and gels containing waxy corn, waxy rice, instant tapioca, modified tapioca and dextrin starches, respectively. Estimated starch retentions in the curds were 71%, 90%, 90%, 21%, and 1% for these curds. Waxy corn, waxy rice, and instant tapioca starches have the potential to improve the texture of low fat cheese because they are retained well in the protein network during coagulation and concentration of the milk proteins, and they generate interruptions in curd network that may help limit extensive protein-protein interactions. Modified tapioca starch causes the protein structure of the curd to be very loose, but it was not retained optimally in the curd. Also, because there were few distinct starch particles in the modified tapioca curd network, it is likely that when it is subjected to all the cheesemaking steps the same loose protein structure would not be observed. Dextrin was not retained well in the curd, nor did it disrupt the protein network, making it unsuitable for use in low fat cheese. In experiment 3, low fat cheddar cheeses were made with waxy corn starch, waxy rice starch, modified tapioca starch, and instant tapioca starch. Modified tapioca starch did not increase the moisture content of the cheese. Waxy corn starch, waxy rice starch, and instant tapioca starch all increased the moisture content of the cheeses significantly. However, when moisture contents of cheeses were over 61%, the body of the cheese visibly softened during storage, making the cheese very pasty. When starch-containing cheeses had moisture levels lower than that, the curd did not knit together well.

This thesis investigates whether fats, akin to other taste stimuli, exhibit sensory properties such as mixture interactions. In order to determine gustatory, rather than tactile or olfactory effects, viscosity-controlled emulsions of deodorised oils were used as the base to which taste stimuli were incorporated and presented to a panel of trained assessors. In preliminary qualitative assessments, panellists described the 10% olive oil emulsion as saltier, stronger, fattier and having a more lingering aftertaste than the non-oil control, suggesting that oil modulates taste duration as well influencing taste intensity and/or perceived quality. Panellists were unable to rate the oil/fat taste per se with any degree of certainty hence further experiments examined the effect of oil on the perception of taste mixtures. In mixture interaction experiments, the addition of oil did not result in mixture suppression or enhancement for sweet, salty, sour or bitter while it significantly enhanced umami. To determine the locus of interaction, when MSG and oil were presented to each side of the tongue separately, the enhancement effect disappeared indicating a peripheral mechanism of interaction, similar to the attenuation of chilli burn by oil. In contrast, suprathreshold sucrose sweetness was enhanced by the contralateral presentation of oil, indicating sensory processing at a higher locus. Furthermore, the addition of oil significantly reduced bitterness in a caffeine-MSG mixture. Since earlier experiments did not indicate any interaction between oil and bitterness, the decrease in the perceived bitterness of this binary mixture is attributed to an increase in umami which is likely to have suppressed bitterness, the perceptually dominant component in this mixture. These findings suggest a gustatory role for fats in modulating the taste profile of mixtures, in particular, enhancing total taste intensity, prolonging taste duration, and enhancing umami. A taste receptor-based model of fat perception provides for an orosensory mechanism capable of signalling the arrival of the most energy-dense nutrient, essential fatty acids and fat-soluble vitamins. The chemosensory signal may also be the basis for hedonic responses with subsequent implications for intake.

This study investigated the use of extrusion technology and fat replacers to produce high protein, low fat Cheddar cheese. In chapter 3, four different fat replacers were tested at the highest concentration level of each, as recommended by the manufacturers for low fat cheese, to investigate the change in cheese texture and optimize extruder conditions. In addition, the press time/pressure combinations of the extruded cheeses were optimized. The fat replacers and extruder conditions that were effective in improving the texture of low fat cheese were then used in chapter 4. In chapter 4, three fat replacers were used at three different concentrations (lowest, middle and highest) as recommended by the manufacturers for replacing fat in cheese. The fat replacers were microcrystalline cellulose (MCC 1) (0.125%, 1.06% and 2%), whey protein concentrate (WPC 2) (0.50%, 0.75% and 1%) and whey protein concentrate (WPC 1) (0.40%, 2.20% and 4%). These fat replacers were effective in improving the texture of low fat cheese as determined from the results of chapter 3. The extruded cheese samples with and without fat replacers were analyzed for texture at three different time periods (1 day, 1 week, and 1 month). None of the fat replacers used were effective in improving the texture of low fat cheese significantly. Since none of the treatments statistically improved the texture of low fat cheese, in the next part of the study, extrusion alone and WPC 1 at the middle concentration were then used to produce low fat cheese with high protein content by blending low moisture aged Cheddar cheese and nonfat cheese. Extrusion of cheese blends with or without fat replacer yielded cheese with high protein level. It was concluded from the study that the fat replacers we used were not effective in improving the texture but extrusion of aged Cheddar cheese with nonfat cheese can yield high protein cheese.

This research examines the effect of a nutrition education intervention to change attitudes and other factors associated with eating breakfast and consuming low-fat dairy and whole-grains. Adolescents (n = 106) 11 to 15 years old were recruited from afterschool programs in Los Angeles County, California. Participants in the treatment group (n = 57) met once weekly for 60 minutes during seven weeks. The curriculum focused on changing attitudes, subjective norms, and perceived behavioral control toward eating breakfast along with including low-fat dairy and whole grains. The first three lessons focused on basic nutrition concepts. The later lessons focused on identifying barriers and overcoming barriers, goal-setting, and identifying methods to stay motivated. Questionnaires were administered at baseline and post-intervention. Data were analyzed using SAS statistical analysis program (v. 9.2). Eighty-eight percent of participants were Hispanic, 55% were girls, and mean age was 12 years. One-hundred six adolescents completed the questionnaire at baseline and 75 completed it at post-intervention. Cronbach alpha statistic for subjective norms and attitudes toward eating breakfast, consuming low-fat dairy and whole-grains were 0.67 and higher for each dependant variable. Intention was significantly predicted by attitudes, subjective norms, and perceived behavioral control; however, as these models do not differentiate change, additional models were run with interactions between group (treatment versus control) and the change variables. Significant changes in perceived behavioral control were observed among participants in the treatment group regarding drinking skim milk, 1% milk, and 2% milk respectively (p < .05; p < .001; p < .001) and attitude (p < .05). No change was observed in breakfast eating or consumption of wholegrains

Thesis (M. App. Sc.)--University of Queensland, 2002. / Includes bibliographical references.

Dehulled black beans were micronized at 90⁰C, 100⁰C, 110⁰C, 120⁰C, 130⁰C and 140⁰C; milled to flour and tested for lipoxygenase activity. Non micronized black bean flour was higher in lipoxygenase activity than flours at ≥120ºC (p=≤0.05). Micronized (100⁰C, 110⁰C, 120⁰C) and non micronized black bean flour was added to low fat beef burgers (6%). C18:3 was significantly higher in the black bean flour samples (raw and cooked). Whole wheat flour had the highest amount of C18:2 in all samples (p= ≤0.05). The all beef control was significantly higher in Newton value, drip loss, cook loss and percent shrinkage compared to burgers with binders (p= ≤0.05). Ninety-three participants participated in an consumer sensory panel. Results showed higher acceptability of micronized burgers compared to all beef or whole wheat flour controls. This study demonstrated incorporation of black bean flour into low fat beef burgers can improve their physical, chemical and sensory properties.

Thirty-seven overweight/obese (BMI: 25-35 kg/m2), premenopausal women that were randomly assigned to either an ad libitum low-carbohydrate (LC) (20% CHO, 30-40% protein, 30-40% fat), or an ad libitum low-fat (LF) (55-60% CHO, 15-20% protein, 20-25% fat) diet.All subjects were given weekly menus matching their assigned macronutrient requirements to aid in meal planning and dietary compliance. Baseline and post-diet measures included height, weight, body composition (DXA), blood lipids [total cholesterol (TC), HDL, LDL, and triglycerides (TG)], and plasma insulin levels. There were no significant group differences in any of the above-listed variables prior to the study. Nineteen women completed the 6-wk study (LC=11, LF=8). Compliance to the diets was adequate as indicated by weekly 24-hr recalls and daily urinary ketone levels. Both groups lost a significant amount of weight and body flat, (P<0.05); and weight and body fat losses were not significantly different between the groups. All groups experienced similar decreases in TG, TC, LDL, HDL, and insulin levels. These results indicate a LC diet is no more effective than a LF diet in promoting favorable changes in body weight, body composition, blood lipids and insulin levels. / Department of Family and Consumer Sciences

Dehulled black beans were micronized at 90⁰C, 100⁰C, 110⁰C, 120⁰C, 130⁰C and 140⁰C; milled to flour and tested for lipoxygenase activity. Non micronized black bean flour was higher in lipoxygenase activity than flours at ≥120ºC (p=≤0.05). Micronized (100⁰C, 110⁰C, 120⁰C) and non micronized black bean flour was added to low fat beef burgers (6%). C18:3 was significantly higher in the black bean flour samples (raw and cooked). Whole wheat flour had the highest amount of C18:2 in all samples (p= ≤0.05). The all beef control was significantly higher in Newton value, drip loss, cook loss and percent shrinkage compared to burgers with binders (p= ≤0.05). Ninety-three participants participated in an consumer sensory panel. Results showed higher acceptability of micronized burgers compared to all beef or whole wheat flour controls. This study demonstrated incorporation of black bean flour into low fat beef burgers can improve their physical, chemical and sensory properties.