ABSTRACT
Some heavy metals are dangerous to health and there is rising concern about the quality of foodstuffs in some parts of the world. Fish, particularly Tuna fish, can concentrate huge quantities of several metals from water and they even play a significant role in human nourishment. In this study, the concentrations of mercury and four trace metals in five brands of canned tuna samples purchased within the Tabriz city [Iran] were determined after digestion via the Association of Official Analytical Chemists techniques. A total of 40 samples were collected. Lead and cadmium levels were determined via graphite tube atomic absorption spectrophoto-metry, whereas nickel and tin levels were determined via flame atomic absorption spectrophotometry, and mercury levels were determined via hydride generation atomic absorption spectro-photometry. The ranges obtained for the elements were Pb [0.01-0.242], Ca [0.0-1.05], Ni [0.113-0.589], Sn [0.05-0.9], and Hg [0.1-0.205] mg/kg wet weight. The results showed that tuna fabricated and marketed in Tabriz [Iran] had safe level of heavy metals that were lower than the averages of EC/FAO/WHO levels for these toxic metals
Subject(s)
Animals , Food Preservation , Metals, Heavy , Spectrophotometry, AtomicABSTRACT
Lactobacillus acidophilus as a probiotic has more useful effects and low viability of this bacterium and other probiotics under hard acidic-bile conditions of digestive system and food products, have encouraged researchers to find methods to solve this problem. Microencapsulation as one of the newest methods has noticeable effects in this field. The aim of this study was to evaluate the morphological and protective characteristics of beads obtained from microencapsulation of Lactobacillus acidophilus. After activation of starter culture of la5 in MRS-broth medium, in order to purification bacteria was used centrifuge device with speed of 10000rpm for 10 minutes. Microencapsulation was done by calcium alginate and resistant starch with extrusion method. Morphology of beads was evaluated by optical microscope. The study of beads stability was done for 12 hours and the study of survival microencapsulated bacteria was done for 120 minutes within hydrochloric acid, phosphate buffer [0.1 mol] and digestive powder inclusion solution. A morphological characteristics of beads was indicated by optical microscope. These results showed that the strength of beads in various environments is different and in this regard physical tension is very important. Under unfavorable environmental conditions, microencapsulation with calcium alginate and resistant starch was played an important role in the protection of lactobacillus acidophilus. The survival rate of microencapsulated bacteria in all conditions was significantly higher than free bacteria [P <0/05]. Morphological characteristics and strength of beads had great importance in theirs protective function of probiotic bacteria. Microencapsulation with calcium alginate and resistant starch plays an important role in increasing the rate of lactobacillus acidophilus survival
ABSTRACT
Microencapsulation of probiotic cells is the newest method for increasing probiotics' survival in probiotic food products in gastrointestinal conditions and safely transferring them to the large intestine. The aim of this study was to investigate the effect of microencapsulation with calcium alginate and resistant starch on the lactobacillus acidophilus [La5], and the survival rate in simulated gastrointestinal juice conditions. Survivability of this bacteria was conducted in 0.6% bile salt solution and simulated gastric juice[PH1.55], followed by incubation in simulated intestinal juice with and without 0.6% bile salt. In this study the extrusion method was performed for the microencapsulation process. Data were analyzed using an independent t-test. Our results showed that survivability of microencapsulated cells in a simulated gastric juice condition, and also in simulated intestinal juice with and without 0.6% bile salt, is significantly more than free cells[p<0/05]