Encapsulation of green tea extract in nanoliposomes and evaluation of its antibacterial, antioxidant and prebiotic properties

Background: The application of natural compounds including green tea extract [GTE] in food and pharmaceutical industries is limited. Encapsulation in nanoliposomes could be used as a delivery system to protect these compounds during processing and storage

Objective: In this study encapsulation of green tea extract in nanoliposomes and evaluation of its antibacterial, antioxidant and prebiotic properties were evaluated

Methods: GTE was encapsulated in liposomes by thin film layer method and reached to nanoscale with sonication. The prebiotic activity of 1% nanoliposomal GTE was evaluated on the growth of lactobacillus casei and bifidobacterium lactis in MRS broth medium. Furthermore, the antioxidant activity of nanoliposomal GTE was estimated by DPPH assay. The antibacterial activity of nanoliposomal GTE against Bacillus cereus [ATCC11778], Salmonella typhimurium 138 phage type 2, E. coli O[157]: H[7] and Listeria monocytogenes [ATCC19118] was determined using well diffusion technique

Results: The mean diameter of nanoliposomes was about 44.7 +/- 1.9 nm and had 0.203 +/- 0.014 polydispersity index. Entrapment efficiency of nanoliposomal GTE under the optimum conditions was 97%. Antibacterial activity of GTE was significantly increased after encapsulation in nanoliposomes. The strongest antibacterial activity of nanoliposomal GTE was seen against listeria monocytogenes with an inhibition zone of 16.2 mm while E. coli was the most resistance strain with an inhibition zone of 14 mm. Furthermore, the antioxidant activity of GTE was significantly increased after nanoliposome encapsulation since the IC[50] value of nanoliposomal GTE was decreased to 1.78 microg ml[-1]. Moreover, addition of 1 % nanoliposomal GTE enhanced the growth rate of Lactobacillus casei and Bifidobacterium lactis to a significant extent

Conclusion: Nanoencapsulation effectively enhanced beneficial properties of GTE

Antibiotic residues and aflatoxin M1 contamination in milk powder used in Tehran dairy factories, Iran

The presence of aflatoxin M1 [AFM1] and antibiotic residues in milk and milk products is a public health concern. Milk and milk powder have the potential for introducing AFM1 and antibiotic into human diet. In recent years, milk powder has been used on a large scale in dairy factories. Consequently, antibiotic residues and aflatoxin contamination control in these products has gained importance. The aim of this survey was to determine the level of beta-lactam and tetracycline antibiotic residues and also AFM1 contamination of milk powder used in Tehran dairy factories. During 12 months [September 2011 to September 2012], 240 samples of milk powder were collected from ten Tehran dairy factories. All samples were analyzed for the presence of AFM1 using ELISA technique. In addition, antibiotic residues were determined by BetaStar Combo test, a rapid assay for both beta-lactam and tetracycline antibiotics. The samples depicted positive results i.e. 30% and 17.5% for beta-lactam and tetracycline antibiotics, respectively. Also, AFM1 was found in 155 cases [64.6%] with an average concentration of 29.85 +/- 18.99 ng/ L. The results showed the milk powder used by dairy factories is safe in respect of AFM1 contamination and antibiotic residues in Tehran

[Coliform bacteria removal from contaminated water using nanosilver]

Although silver can be used as an effective water disinfectant, it has some disadvantages such as its high costs and darkening of the skin and mucous membrane due to long-term exposure to high silver concentrations. Nanotechnology can solve such problems through reduction of silver content. The aim of this study was to evaluate the effect of nanosilver on removing the coliform bacteria from contaminated water. This bench-scale experimental study was carried out in a batch system on artificially contaminated water samples prepared by adding 5 ml effluent to 60 liters of tap water. In each run, the nanosilver suspension [30-180 microgL-1] was added to 6 containers [500 ml] of contaminated water and then a sample was taken every 20 minutes for a 100-minute period and tested for coliform according to the standard methods book. Results revealed that the coliform bacteria removal significantly increased with increasing the contact time of nonosilver [P=0.001], but there was no significant correlation between the nanosilver concentrations and coliform removal [P=0.6]. The maximum coliform removal [92.41%] was achieved within 100 minutes contact time for 60 microgL-1 of silver. Although nanosilver treatment is effective in removing coliform from contaminated water, further researches are required to study the efficacy of drinking water disinfection

[Comparing the effect of electrochemical process and Alum coagulation in removing turbidity and coliform bacteria from the synthetic wastewater]

Nowadays, 1.1 billion people in the world do not have access to a safe and adequate water supply. So, seeking more efficient water treatment methods are a critical need. This study designed to compare the effects of the electrochemical process [EP] and Alum coagulation on turbidity and coliform bacteria removal from the synthetic wastewater [SW]. This experimental study was conducted on five SW samples in a batch system. First, the optimum Alum dosage and pH were determined by Jar-test. Thereafter, samples were subjected to coagulation and 10 samples were taken before and after the process. The EP was accomplished on each five SW samples. In each run, a 600 mA DC was applied on 1700 ml of SW using aluminum electrodes for 1 hour and one sample was taken every 10 minutes [35 samples]. The turbidity and most probably numbers of total coliforms were confirmed and the fecal coliforms as well as the heterotrophic plate count [HPC] were determined for all samples according to the standard methods book instructions [21st edition]. The optimum Alum dosage and pH range for coagulation were 16mg/L and 7 pH units, respectively. Using coagulation, the removal efficiencies for the total, confirmed and fecal coliforms were 80.57%, 48.89%, and 65.59%, respectively. Moreover, the removal efficiencies for HPC and turbidity were 89.92% and 91.11%, respectively. The EP not only removed 100% of the coliforms, but also reduced both HPC and turbidity to 91.05% and 96.31%, respectively. The EP is more effective than Alum coagulation in the removal of turbidity and bacteriological indicators from the synthetic wastewater