UVM Theses and Dissertations
Format:
Print
Author:
Walsh, Helen
Dept./Program:
Nutritional and Food Sciences
Year:
2009
Degree:
MS
Abstract:
Consumption of functional food products, such as those containing prebiotics and probiotics has been recognized as an important factor in lowering risk of high cholesterol, intestinal cancer and other gastrointestinal diseases. The purpose of this study was to produce an oat-based, symbiotic yogurt-like food incorporating oats, sugar and inulin with pre-polymerized whey protein isolate (PWPI) as the gelling agent and probiotics L. acidophilus, L. casei and Blfidobacterium. Preliminary trials assessed factors which were important to the stability and quality of the product; addition level of PWPI and inoculant, and the incubation time required. These trials resulted in an optimized product suitable for further study. A series of trials was carried out using products, both with and without (F and C respectively) inulin, mineral and vitamin fortification.
Chemical analysis determined the protein, fat, dietary fiber and ash content. The structure of this product was assessed by pH and viscosity measurement as well as by use of scanning and electron microscopy. The formulations were studied over a 9 week shelf-life for changes in pH, viscosity and survivability of the probiotics. At the end of the study the levels of probiotics; L. casei, at 4.8 x 10⁶ cfu/g (F), 4.3 x 10⁶ cfu/g (C) and Bifidobacteria, at 3.1 x 10⁶ cfu/g (F), 3.17 x 10⁶ cfu/g (C), were at therapeutic levels, however L. acidophilus showed rapid decline over the first 3 weeks. Difference in probiotic survival between formulations was only significant for L. acidophilus (P> 0.05).
A lowering of both viscosity and pH was significant (P <0.05) and a significant difference in the case of pH (P <0.0001) between fortified and control samples was also seen. Scanning and electron microscopy of samples revealed that the prepolymerized whey protein isolate played a major role in the structure of the gel. The fortified product was further assessed for organoleptic quality. Organoleptic trials showed that the product was 'fair' for all attributes and consumers showed a preference for addition of flavorings similar to those used in oatmeal breakfast foods.
Chemical analysis determined the protein, fat, dietary fiber and ash content. The structure of this product was assessed by pH and viscosity measurement as well as by use of scanning and electron microscopy. The formulations were studied over a 9 week shelf-life for changes in pH, viscosity and survivability of the probiotics. At the end of the study the levels of probiotics; L. casei, at 4.8 x 10⁶ cfu/g (F), 4.3 x 10⁶ cfu/g (C) and Bifidobacteria, at 3.1 x 10⁶ cfu/g (F), 3.17 x 10⁶ cfu/g (C), were at therapeutic levels, however L. acidophilus showed rapid decline over the first 3 weeks. Difference in probiotic survival between formulations was only significant for L. acidophilus (P> 0.05).
A lowering of both viscosity and pH was significant (P <0.05) and a significant difference in the case of pH (P <0.0001) between fortified and control samples was also seen. Scanning and electron microscopy of samples revealed that the prepolymerized whey protein isolate played a major role in the structure of the gel. The fortified product was further assessed for organoleptic quality. Organoleptic trials showed that the product was 'fair' for all attributes and consumers showed a preference for addition of flavorings similar to those used in oatmeal breakfast foods.