Résumé
Omega-3 fatty acids [FAs] have been shown to prevent cardiovascular disease. The most commonly used omega-3 fatty acids like eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA] are highly vulnerable to oxidation and therefore, have short shelf life. Recent advances in nanoliposomes provided a biocompatible system for stabilizing omega-3 FAs. Several methods could be implemented to prepare nanoliposomes. To the best of our knowledge, the performances of these methods in preparation omega-3 FAs have not been examined. Nanoliposomes were prepared by thin film hydration followed by one of the following methods: 1- extrusion, ultrasonic irradiation; 2- bath sonication; 3- probe sonication; or 4- combined probe and bath sonication. The size of liposomes obtained from methods 1 to 4 were 99.7 +/- 3.5, 381.2 +/- 7.8, 90.1 +/- 2.3, and 87.1 +/- 4.10 nm with zeta potential being -42.4 +/- 1,7,-36.3 +/- 1.6, -43.8 +/- 2.4, and 31.6 +/- 1.9 mV, respectively. The encapsulation efficiency [EE] for DHA was 13.2 +/- 1.1%, 26.7 +/- 1.9%, 56.9 +/- 5.2% and 51.8 +/- 3.8% for methods 1 to 4, respectively. The corresponding levels for EPA were 6.5 +/- 1.3%, 18.1 +/- 2.3%, 38.6 +/- 1.8%, and 38 +/- 3.7%, respectively. The EE for DHA and EPA of liposomes for both methods 3 and 4 increased significantly [p<0.05]. Propanal, as the major volatile product formed during liposomal preparations, amounts from 81.2 +/- 4.1 to 118.8 +/- 2.3 microg/Kg. The differential scanning calorimetry [DSC] study showed that DHA and EPA influence the phase transition temperature of small unilamellar vesicles [SUVs] of dipalmitoyl phosphatidyl choline [DPPC]. Transmission electron microscopy [TEM] images of liposomes stained with uranyl acetate showed that the liposomes were spherical in shape and maintain high structural integrity. In conclusion, probe ultrasound of pre-formed liposomes facilitates significant loading of DHA and EPA into the nanoliposomal membrane
Résumé
Pomegranate fruit is a rich source of bioactive compounds. The serious concern over unprocessed fruit juices is microbial contamination, which effectively inactivated by thermal processing, but it significantly affects juice functional compounds. Therefore, the effect of gamma irradiation and ultrasonic on inoculated microbial to pomegranate juices was studied. Two pomegranate cultivars were purchased from the Agricultural Research Center of Saveh, and their juices were extracted by a manual device and immediately centrifuged. Then the studied microorganisms were resuspended in sterile pomegranate juices. The juices were continuously sonicated at amplitude levels of 50, 75 and 100% and times of 0, 3, 6, 9, 12 and 15 min at temperature of 25 +/- 1 C. Irradiation treatment was also carried out at various doses of 0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3 kGy. The results showed that lower amplitude levels [50 and 75%] did not inactivate E. coli and S. cerevisiaesignificantly [<1.5 log reduction], while at 100% amplitude level for 15 min, their population reduced by 3.47 and 1.86 log cfu/mL, respectively. Gamma irradiation treatment at 1 kGy also reduced E. coli by 6.66 log cfu/mL, whereas at 3 kGy it reduced S. cerevisiae by 5.08 log cfu/mL. The low-dose gamma irradiation could potentially inactivate the studied microorganisms compared to the sonication, which had less destructive effects on their populations. Further research is needed to determine the effect of these methods on other fruit juices for industry purposes