Food Biotechnology
Dina Shahrampour; Morteza Khomeiri; Seyed Mohammad Ali Razavi; Mahboobeh Kashiri
Abstract
Introduction
Increasing public awareness of the impact of diet on health has increased the demand for healthy food products, especially probiotics. Probiotics are living and non-pathogenic microorganisms with beneficial effects on the host when consumed on a regular basis and sufficient amounts ...
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Introduction
Increasing public awareness of the impact of diet on health has increased the demand for healthy food products, especially probiotics. Probiotics are living and non-pathogenic microorganisms with beneficial effects on the host when consumed on a regular basis and sufficient amounts (106 cfu/gr or ml). A significant number of probiotics become inactive during various food processes (thermal, mechanical and osmotic stress), storage condition (exposure to oxygen, UV light and low or high temperature) or during interaction with food ingredients. In addition, the breakdown and passage of food through the digestive system can also affect the survival and ability of probiotics to form colony in the intestine. Therefore, it is a challenge for food manufacturers to maintain and deliver live probiotic cells in sufficient quantities via food product. On the other hand, the variety of probiotic food products in the market, especially in Iran, is low and is mainly limited to dairy products, fermented drinks and pickles. Bioactive edible films and coatings are defined as biopolymer-based structures that carry bioactive components such as vitamins, enzymes, peptides, etc, and slowly release them on the food surface during storage. Biopolymers such as polysaccharides, proteins, and lipids are used in the preparation of edible films and coatings. Trapping probiotic bacteria in the structure of edible films and coatings is a new approach that has been proposed to increase the survival of these microorganisms and to develop new probiotic products in the food industry.
Materials and Methods
In this study, an alginate-based probiotic bioactive film containing L. plantarum was fabricated after centrifuging of overnight culture of probiotic bacterium from MRS medium and adding the bacterial cells into film forming solution. The effect of bacterial addition on physical, mechanical and prevention properties of alginate film was evaluated. In addition, the effect of two temperatures 4 °C and 25 °C on the survival of embedded probiotic bacterium in the film structure during one month of storage was also investigated by microbial count assay on MRS agar medium. Then, the model food was covered with probiotic film and the survival of probiotic bacterium during storage at 4 °C was determined.
Results and Discussion
The results showed that the population of probiotic bacterium declined about 4.61% after drying of alginate film solution. Addition of probiotic bacterium to the alginate film increased the thickness, turbidity, and tensile strength of the film, while had no significant effect on solubility, water activity, Elongation (%) and microstructure of alginate film. In addition, the probiotic film containing bacteria had less Lightness (L*), and moisture content than the control film. Also, the incorporation of L. plantarum in alginate film could decrease the water vapor permeability (WVP) from 0.755 to 4.51 (×10-10 g m-1s-1pa-1). The total color difference (ΔE) of alginate film containing probiotic bacteria compared to control film without probiotic bacteria was 1.1. The SEM images were confirmed the proper and uniform distribution of probiotic L. plantarum cells on the surface of alginate film. The survival percentage of L. plantarum in alginate film after one month of storage at 4 °C and 25 °C was 96.84 and 47.29%, respectively. Also, the population of embedded bacteria in the film structure on the food model (sausage) surface after three weeks storage in refrigerator was in desired level of probiotic products (> 106 cfu / gr).
Conclusion
The viability of probiotic bacteria after the application of alginate film containing L. plantarum on the surface of food model (sausage) during cold storage remained at the optimal recommended level for three weeks. Therefore, alginate film is recommended as a suitable carrier for probiotic microorganisms to produce new functional products.
Roya Rezaei; Hadi Koohsari
Abstract
Probiotics are living microorganisms that provide beneficial effects when they are eaten with food. The probiotic dairy products raise the risks associated with increased cholesterol and lactose intolerance. In this research, fruit and vegetable juices of apple, banana, carrot and tomato were used as ...
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Probiotics are living microorganisms that provide beneficial effects when they are eaten with food. The probiotic dairy products raise the risks associated with increased cholesterol and lactose intolerance. In this research, fruit and vegetable juices of apple, banana, carrot and tomato were used as substrates for producing probiotic beverages and the viability of two LABs of L. acidophilus and L. plantarum in these products was investigated. Fruit and vegetable juices were inoculated with bacterial suspensions to obtain a concentration of 105 CFU/ml for each LAB. Samples were incubated at 37°C for 72 hours and at 24-hour intervals, pH levels and viable cell count in products were determined based on CFU/ml. Fermented products were transferred to the refrigerator and the viability of LABs was determined at 4°C for 4 weeks. The results show that, in all products, the pH decreased over time, so that there was a significant difference between the two examined bacteria during the experiment (P<0.05). Both LABs were able to grow well in products and to ferment the fruit and vegetable juices properly implying that all the beverages were able to provide suitable conditions for the growth of two strains of LABs. L. plantarum showed a higher viability in cold storage at 4°C. In general, considering the high growth rate of these bacteria in the products and pH reduction and their viability during cold storage at 4°C, fruit and vegetable juices of apple, banana, carrot and tomato can be a good substrate for producing non-dairy probiotic beverages.
