Layla Zaghari; Alireza Bassiri; Somaye Rahimi; Ali Zonousi
Abstract
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 ...
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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
Layla Zaghari; Alireza Bassiri; Somaye Rahimi; Ali Zonousi
Abstract
Intoduction: Probiotics are defined as essential live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The range of beneficial properties reaches from lowering cholesterol to preventing cancer. The most important probiotic microorganisms belong to the group ...
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Intoduction: Probiotics are defined as essential live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The range of beneficial properties reaches from lowering cholesterol to preventing cancer. The most important probiotic microorganisms belong to the group of lactic acid bacteria. Lactobacillus reuteri which naturally occurs in the human intestine possess probiotic properties with good colonization potential. The development of probiotic foods presents many challenges, particularly with respect to the stability of the bioactive compounds during processing, storage and passage through acidic gastric environment. Therefore, it is a great challenge to bring the probiotics into a stable form, which guarantees, that the microorganisms reach their target location, the human intestine, in an adequate amount. Microencapsulation helps improve survival probiotic bacteria from environmental stresses. In most studies, probiotic bacteria are entrapped in a gel matrix of natural biological materials such as alginate, or gellan. The core and wall solutions are turned into drops of the desired size by employing an emulsion method. The main problem in the probiotic entrapment approach is that gel bead entrapment technologies generally stabilize the bacteria in liquid products and are difficult to scale up. In order to extend the shelf life of encapsulated probiotics, a glassy state form of the embedding matrix is required. This can be achieved by employing such as air-suspension fluidized-bed coating. In the present research, an air-suspension fluidized-bed technique for generation of core and shell microcapsules containing probiotic Lactobacillus reuteri cells and the efficacy of shellac and sodium alginate at different concentrations on viability of capsules in simulated gastrointestinal conditions was evaluated.
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 bottomspraying atomizer. The growth curve of lactobacillus reuteri were determined by measuring the optical density (turbidity) at 600 nm to estimate the time when the growth curve enters a stationary phase in which bacteria develop a general stress resistance and are thus more resistant to various types of stresses. 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. Several different solutions of Lactobacillus reuteri were prepared and evaluated for percentage survival during the coating. The solution containing Lactobacillus reuteri (6–12 g/100 g solution), maltodextrin (4–7 g/100 g solution) and sorbitol (4–7 g/100 g solution) concentrations was spray-coated at three inlet temperatures: 37, 47 and 62°C onto and absorbed by the inert carrier microcrystalline cellulose to produce nonagglomerating dry coated. For the coating processes an aqueous shellac solution at 3 concentrations (16, 17 and 18% (w/v)), containing plasticizers in the ratios of 95 + 5 and an aqueous sodium alginate solution at 3 concentrations (0.5, 1 and 1.5% (w/v)), were used. Simulated gastric juice was prepared fresh daily containing 3.2 mg of pepsin, 1 ml of NaCl solution (0.5%) and acidified with HCl (1.2 M) to pH 1.5 ± 0.5. Tolerance to gastric juice was examined by placing freshly prepared cells in a tube containing sterile simulated gastric juice for 1 h and incubated at 37°C for 2 h. To characterize the morphology of the MCC particles coated with the different matrix formulations, SEM images were taken. 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
Javad Mahdizadeh Moghadam; Somaye Rahimi
Abstract
Introduction: Pumpkin is one of the agricultural products that despite its very low price, is known as a rich source of carotenoids with high antioxidant activity. Iran is one of the good producers of pumpkin at the world with fifth rank which is cultivated at provinces like Mazandaran, Guilan, Khorasan, ...
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Introduction: Pumpkin is one of the agricultural products that despite its very low price, is known as a rich source of carotenoids with high antioxidant activity. Iran is one of the good producers of pumpkin at the world with fifth rank which is cultivated at provinces like Mazandaran, Guilan, Khorasan, and Hamedan and so on extensively. Pumpkin is almost available for entire the year but many of them is spoiled and perished because of low storage equipments; on the other hand, unfortunately this valuable vegetable which is full of many types of carotenoids with high nutritive values, is not consumed by most of Iranian peoples, because of its low sensory properties such as no pleasant taste or odor; whereas it is used at many cuisines at other countries, especially North America. The pumpkin carotenoids contain natural pigment, beta- carotene and lycopene which can be used as natural colorant at food processed products or dietary supplements. Nowadays, the positive health effect of carotenoids such as improvement of eyesight, fetus growth, prevention from cardiovascular disease and cancer, maintenance of skin health and whole of body, anti blood hypertension and cholesterol is known, well, hence it must more be emphasized at household food basket. There are many researches about extraction of carotenoids form tomato, carrot, yeast and so on, but studying the pumpkin carotenoids was done less. Generally, due to the hydrophobic characteristic of carotenoids and their little solubility at water, organic solvents such as hexane are applied for their extraction, which some researches had been done about its solubility at different organic solvents, yet. Materials and methods: In this research the ripped pumpkins (Curcurbita moschata) were cultivated at private farm at Khorasan were rinsed and chopped to same cubes. Then, pumpkin cubes were peeled off and the seeds were removed. For extraction of carotenoids, the pumpkin specimens prepared at four states of raw (mashed pumpkin), cooked (mashed pumpkin), dried (40 C) (powder) and dry powder of cooked pieces (40 C). Carotenoids were extracted from pumpkin samples by various organic solvents such as hexane, acetone, ethanol, at different volume ratio of them like 1:1(v) and 1:1:1(v). When the pumpkins became colorless, the extract had been evaporated at a vacuumed rotating evaporator to gain a thick extract without any solvent. The extract had been gathered and stored at black bottles and refrigerator to minimize the side effects of light and heat on nutritive characteristics of carotenoids. The total carotenoids content of the pumpkin extracts was measured by spectrophotometric method at 480 nm according to beta- carotene. The antioxidant activity of the extracts was calculated on the basis of DPPH scavenging activity of the samples at 517 nm. The project was done on a complete random design and one-way ANOVA and Duncan test were used for statistical data analysis and clearance the significant difference among treatments at 95% confidence level. Results & Discussions: Statistical analysis of the results showed that various organic solvents, their volume ratio and also various state of pumpkin specimens had a significant effect on the carotenoid extraction from pumpkin samples (p
