The functional food market has been rapidly growing for the past years but the development of new products is still imperative due to the increasing demand for healthy, high quality foods associated to changes in consumers‟ life-style. Incorporation of probiotics into cereal-based products is therefore desirable since it can combine the healthy formulation of a cereal mixture, the added value of prebiotic ingredients, and the beneficial effects of the probiotic bacteria. Encapsulation tecnhiques have been recently applied to protect probiotic cells from storage conditions in order to increase shelf-life of probiotic products and to overcome other technological hurdles such as the food production stresses. The aim of this research study was to evaluate the maintenance of viability of encapsulated probiotics in a cereal bar after food processing and during storage. A cereal mixture was used to prepare cereal bars using a high-shear granulator and the baking process was optimized in terms of textural and physical properties by monitoring the water activity (aw), moisture content (MC) and texture (bending force) of individual bars exposed for 10 and 15 minutes to 160 ºC. The probiotic strain Lactobacillus casei 01 was encapsulated in Ca-alginate beads and added to the cereal bar to a final concentration of 109 CFU.g-1 of product, followed by honey topping. The cereal bar was dried in an oven at 80 °C, 120 °C and 160 °C for 10 minutes. Viability above 108 CFU.g-1 was found at 80 and 120 °C, the latter with 0.81 ±0.33 log loss relative to the initial concentration (IC) of probiotics in the cereal bars. Despite some evidence of stickiness, quantitative evaluation showed no significant changes (p > 0.05) for water activity, moisture content and texture of the cereal bars dried at 120 °C. Probiotic viability on the cereal bars by 14 days of storage at 4 °C and 20 °C was 7.50 ±0.55 and 6.72 ±0.27 log CFU.g-1, respectively. Two other probiotic strains, Bifidobacterium animalis Bb12 and Lactobacillus acidophilus L10, were studied with oven drying at 120 ºC, and similar viability log loss was observed. This study indicated that it is feasible to incorporate probiotic bacteria into a cereal bar product, but further studies are required to determine the product shelf-life, viability during gastrointestinal passage and to assure probiotic functionality.
Date of Award | 3 Nov 2011 |
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Original language | English |
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Awarding Institution | - Universidade Católica Portuguesa
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Supervisor | Ana Maria Gomes (Supervisor), Maria José Sousa Gallagher (Co-Supervisor) & Teresa M. Barbosa (Supervisor) |
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- Mestrado em Microbiologia
Incorporation of probiotics in cereal bars: technological viability and stability
Henriques, S. M. D. S. (Student). 3 Nov 2011
Student thesis: Master's Thesis