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

[Detection of aflatoxin M1 in spray dried and lyophilize bovine colostrum products]

Aflatoxin M[1] [AFM[1]] is an important mycotoxin frequently found in milk and dairy products. Dairy products and colostrums may be contaminated by aflatoxin M[1] when dairy cattle have fed with aflatoxin B[1]-contaminated feeds. This study was undertaken in a dairy farm around Tehran province to determine the presence and level of aflatoxin M[1] [AFM[1]] in spray dried and lyophilized colostrums samples. In this study, 25 spray dried and lyophilized colostrums samples were analyzed using competitive ELISA for determining the presence and levels of AFM[1]. AFM[1] was found in 76% of the colostrums samples. The range of contamination level was 16 ng/l to 1176 ng/l, [mean values was 213.37 ng/l]. Ninety two percent of the contaminated samples exceeded the maximum acceptable levels [50 ng/l, EU standard] and 8% exceeded 500 ng/l. Due to human health hazard and high occurrence of AFM[1] in colostrums samples, monitoring programs should be more extensive and frequent in Iran