افزايش پايداري حرارتي باكتري پروبيوتيك لاكتوباسيلوس پلانتاروم A7 براي توليد نان پروبيوتيك با استفاده از تكنيك ريز پوشاني

چكيده انگليسي :

Enhancement of heat stability of Lactobacillus plantarum A7 to produce probiotic bread using microencapsulation method Hajar Yousefi Yousefi shokouh@yahoo com March 5 2013 College of Agriculture Department of Food Science and Technology Isfahan Universiy of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Sabihe Soleimanianzad soleiman@cc iut ac ir Mohammad Shahedi shahedim@cc iut ac ir Abstract Probiotic foods are defined as those that contain a single or mixed culture of probiotic microorganisms that affect beneficially the consumer s health by improving their intestinal microbial balance These include metabolism of lactose control of gastrointestinal infections suppression of cancer reduction of serum cholesterol and immune stimulation To achive the beneficial effects a minimum of 6 Log of alive bacteria should be in food Today most probiotics available are dairy based but cereals can prove to be a healthier option for developing non diary probiotic foods since they can overcome some of the disadvantages associated with dairy products like lactose intolerance allergy and the impact in cholesterol levels Main problem in preparing baked food probiotic is the processing temperature and its effect on microorganisms survival One of the methods for improving probiotic survival against environmental stress is microencapsulation In this study to evaluate the protective effect of microencapsulation against baking heat Lactobacillus plantarum A7 was encapsulated by emulsion method with 1 and 2 corn starch 0 5 1 and 2 sodium alginate and 2 gum arabic The encapsulated and non encapsulated bacteria were mixed with bread constituents and the dough baked in the oven at 180 C for 20 minutes To evaluate the dough and bread pH containing probiotic bacteria pH was measured before and after the leavening in dough and after baking in bread After baking live probiotic bacteria were counted and the microcapsule formulation that kept the highest number of alive bacteria was selecetd as the optimum treatment Then size and surface morphology in this treatment was evaluated by particle size analyzer and scanning electron microscopy The texture of the breads were evaluated immediately 24 and 48 hours after baking using penetration test Encapsulation yield was 20 70 44 6 and increasing of sodium alginate concentration in this regard has significant effect p 0 05 Measuring of the pH after leavening showed that dough has been fermented and the pH in all treatment has been reduced Also the pH values in the baked breads were in the range of 5 6 indicated the bread can be a suitable carrier for microcapsule The number of viable bacterial cells after baking showed that the microencapsulation could increase the number of alive bacteria in bread 1 2 log in comparison to the non encapsulated bacteria The microcapsule made with 2 corn starch and 2 sodium alginate had the highest number of alive bacteria after baking The average size of microcapsule was 329 85 29 45 Bm It seems that the hydrocolloids used in microencapsulation and residual oils from emulsification step is resulted in to soft breads production In conclusion microencapsulation could conserve the number of alive bacteria up to the 10 5 cfu g of the bread To get 107cfu g of alive bacteria in baked bread some more investigation are needed Keywords Probiotic bread Microencapsulation Emulsions Heat stability Lactobacillus plantarum A7

يوسفي كوپايي، هاجر

افزايش پايداري حرارتي باكتري پروبيوتيك لاكتوباسيلوس پلانتاروم A7 براي توليد نان پروبيوتيك با استفاده از تكنيك ريز پوشاني

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