نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم و صنایع غذایی، سازمان پژوهشهای علمی و صنعتی ایران، تهران.
2 گروه صنایع غذایی و تبدیلی، پژوهشکده فناوریهای شیمیایی، سازمان پژوهشهای علمی و صنعتی ایران، تهران.
3 گروه مهندسی زراعی، پژوهشکده کشاورزی، سازمان پژوهشهای علمی و صنعتی ایران، تهران.
چکیده
در این تحقیق از کیتوزان، کلریدکلسیم و صمغ عربی به‌ترتیب در غلظت‌های (5/0، 1 و 5/1 درصد)، (5 درصد) و (5/1، 3 و 6 درصد) (وزنی/ حجمی) برای ریزپوشانی لایهدوم گرانول‌های حاوی لاکتوباسیلوس روتری، استفاده شد. زنده‌مانی نسبی باکتریهای ریزپوشانی شده با کیتوزان و صمغ عربی در غلظت‌های به‌ترتیب 1 و 6 درصد (وزنی/ حجمی) پس از آزمون حرارتی (دمای 80 درجه سانتی‌گراد به مدت 15 دقیقه)، به‌ترتیب (31/7 و 7/3 درصد) و پس از آزمون حرارتی (دمای 80 درجه سانتی‌گراد به مدت 30 دقیقه)، به‌ترتیب (63/0 و 31/0 درصد) بود که افزایش معنیداری نسبت به دیگر نمونهها و شاهد نشان داد. تاثیر زمان پوشش‌دهی (45 و90 دقیقه) بر زنده‌مانی نسبی باکتری (%) پس از آزمون حرارتی، نشان داد که نمونههای پوشش‌دهی شده با محلول کلریدکلسیم با غلظت 5% (وزنی/ حجمی) به مدت 90 دقیقه، پس از آزمون حرارتی (دمای 80 درجه سانتی‌گراد و زمان 15 دقیقه)، 9% بود که به‌طور معنیداری، دارای زنده مانی بالاتری نسبت به سایر نمونهها میباشند. با افزایش زمان پوشش‌دهی، قطر میکروکپسولها افزایش و میزان انتقال حرارت به قسمت مرکز هسته کاهش یافته و زنده‌مانی باکتری افزایش می‌یابد. میزان زنده‌مانی باکتری در نمونه ریزپوشانی شده با کلریدکلسیم 5 درصد (وزنی/ حجمی)، 1 و 24 ساعت پس از پخت در نان به‌ترتیب (56/0 و 52/0 درصد) بود که نسبت به نمونه ریزپوشانی شده با کیتوزان 1 درصد به‌طور معنیداری به‌ترتیب (47/0 و44/0) افزایش نشان داد. تعداد باکتریهای زنده در هر دو پوشش 1 و 24 ساعت پس از پخت، بیش از 106 CFU/g)) بود.
کلیدواژه‌ها
عنوان مقاله [English]
Developing probiotic bread using Lactobacillus reuteri part 2: Evaluation of fluidized bed double microencapsulation on thermal stability of Lactobacillus reuteri
نویسندگان [English]
- Layla Zaghari 1
- Alireza Bassiri 2
- Somaye Rahimi 2
- Ali Zonousi 3
1 Student of Food Science and Technology, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran.
2 Food Technology and Processing Faculty, Department of Chemical Technologies, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran.
3 Biosystems Engineering Faculty, Department of Agricultural Research, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran.
چکیده [English]
Intoduction: Probiotic products have been used worldwide in the last decades. They are significantly gaining popularity and their consumption is associated with increasing levels of health-consciousness. Probiotics can be defined as microbial cells that have a beneficial effect on the health and wellbeing of the host. In this sense different probiotic products have appeared on the market with different formulations and applications. Bread is the major type of bakery products and a staple food in most part of the world. Despite attempts to develop functional breads containing viable microorganisms, this has not been fully developed yet because of the high temperature during baking process. Viability of probiotic bacteria in the product at the point of consumption is an important consideration for their efficacy, as they have to survive during the processing and shelf life of food. Lactobacillus reuteri which naturally occurs in the human intestine possess probiotic properties with good colonization potential. The main purpose of probiotic encapsulation is to protect cells against an unfavorable environment, include high processing temperatures and storage. The fluid bed encapsulation process consists of spraying a coating solution into a fluidized bed of solid particles. After several cycles of wetting–drying, a continuous film is formed. The main parameters affecting the process are flow-rate and pressure of the spraying liquid, composition and rheology of the coating solution, flow-rate and temperature of the fluidizing air. Double microencapsulation for probiotics by air-suspension fluidized-bed coating is a good alternative method to achieve greater resistance to high temperatures during bread baking. The aim of this study was to evaluate the survival of Lactobacillus reuteri that had been double layered using chitosan, calcium chloride and Arabic gum for microencapsulation and which had been exposed to bread baking conditions.
Materials and Methods: Pure freeze-dried Lactobacillus reuteri PT-1655 were obtained from Persian Type Culture Collection (Tehran, Iran) and were activated by inoculation in the MRS broth at 37°C for 36-48 h. The air-suspension process was performed in a Wurster coater system with a bottom spraying atomizer. In various pretests, the fluidization pressure, the atomization pressure and the spraying rate of the microencapsulation process were varied to examine their influence on process conditions, especially on the particle development. In this study, chitosan, calcium chloride and Arabic gum at concentrations (0.5, 1 and 1.5% w/v), 5% w/v and (1.5, 3 and 6% w/v) were used as second layer in double microencapsulation, respectively. Heat resistance of unencapsulated and double encapsulated microorganisms was determined by placing in an oven which was preheated to 80°C for 15 and 30 minutes. The prepared dough after adding of unencapsulated and double encapsulated bacteria was shaped into loaves of 50 g each, placed in aluminum pans, and baked in a preheated oven at 180°C for 20 min and 70 – 80% relative humidity and then cooled at room temperature. The temperature during baking process was checked by putting a thermocouple at the crumb center. The viability of bacteria at controlled conditions was measured after 1 and 24 h after baking process. Experimental data have been represented as the mean with standard deviation (SD) of different independent determinations. The significance of differences was evaluated by analysis of variance (ANOVA). Differences were considered statistically significant at p
کلیدواژه‌ها [English]
- Lactobacillus reuteri
- double microencapsulation
- fluidized bed coater
- thermal stability
- probiotic bread
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