افزايش مدت ماندگاري و كاهش ميكرو ارگانيسم هاي مضر صنايع لبني با استفاده از بسته بندي هاي با تكنولوژي هاي نانويي

Increase shelf life and reduce harmful microorganisms using nano-technology in the Dairy industry

بيوفيلمها تجمعات پيچيدهي ميكروبي متصل به سطوح غيرزنده و زنده هستند كه در يك ماتريكس اگزوپلي ساكاريدي محصور شدهاند. امروزه استفاده از فناوريهاي نوين بيشترين رقابت را در صنايع غذايي ايجاد كرده است. بنابراين به كارگيري بسته بنديهاي ضد ميكروبي حاوي نانو ذرات ميتواند رشد ميكروارگانيسمهاي نامطلوب غذايي را در محصولات فساد پذير كاهش دهد. هدف از اين پژوهش بررسي اثر ضد باكتريايي نانو ذرات اكسيد روي و ميباشد. فعاليت ضد Aspergillus flavus و قارچ S.aureus ،E.coli دي اكسيد تيتانيوم و نقره بر باكتريهاي اندازه گيري شد. روش كنگورد آگار، روش لولهاي و ((MTP بيوفيلمي مواد مورد تست به روش ميكروتيتر پليت ميكرو پليت جهت تاييد تشكيل بيوفيم استفاده شد. قطر نانو ذرات در حدود 30 الي 93 نانومتر بود. نتايج نشان دهنده ارتباط معنيدار بين غلظت نانو ذرات و نوع ميكروارگانيسم است. در حضور تابش نور در غلظت 1 گرم بر ليتر از نانو از خود نشان داد. با افزايش S.aureus حساسيت بالايي نسبت به باكتري E.coli ذرات در زمان 60 دقيقه، باكتري به طور قابل ملاحظه اي كاسته شد. اثر ضد S.aureus و E.coli غلظت نانو ذرات اكسيد روي، از رشد هر دو باكتري قارچي نانو ذرات دي اكسيد تيتانيوم در حضور تابش نور قابل ملاحظه بود و تمامي نتايج با پژوهشهاي قبلي تطابق داشت. نتايج نشان داد كه نانو ذرات نقره فعاليت ضد بيوفيلمي دارند. بنابراين از خواص ضد ميكروبي اين نانو ذرات ميتوان در بسته بندي محصولات لبني استفاده نمود.

Biofilms are complex communities of microorganism s attachedto an abiotic and living surfaces and enclosed in an exopolysaccaride matrix. The use of new technologies has created the most competition in food industry. The use of antimicrobial packaging containing nanoparticles, can reduce the growth of food undesirable microorganisms in addition to food safety against environmental factors, specially in putrefying food. The purpose of this research is to investigate the antimicrobial activity of zinc Oxide and Titanium Dioxide nanoparticles on E.coli, S.aureus and Aspergillus flavus. Suspension of nanoparticles with different concentrations was prepared. Bacterial suspensions S.aureus and E.coli diluted 10-6 and 10-3 for A.flavus dilution was prepared. 1 ml of bacterial suspension and 1 ml of different concentrations of nanoparticles and 20 ml of sterile broth culture for each organism in glasses were poured. Two glass control of nanoparticles were both lacking. One of the glasses, put in the dark, and the other was placed under uv radiation. All glasses during 0, 20, 40 and 60 minutes were irradiated with a C uv lamp. Check the dates mentioned, the glasses 1 mL of the suspension was removed and the plates were poured Pour plate method. The agar plates were added to the melt and all plates and depending on the type of microorganisms, E.coli and S.aureus at 37 ° C for 24 h and A.flavus at 25 ° C for 72 h incubated respectively. Inhibition zone diameters, minimal inhibition concentration (MIC) and fractional inhibitory concentration index were determined to confirm antibacterial susceptibility and synergistic effects. Antibiofilm activity of tested materials was evaluated with MTP assay. Congo Red Agar, tube method and MTP was used for conform to detect biofilm production. Diameter of about 92 and 30 nanometers of ZnO , TiO2 and Ag nanaparticles was confirmed by SEM and XRD. The results show asignificant relationship between the concentration of microorganisms. The presence of UV radiation exposure in the a concentration of 1 gram per liter at 60 minutes, the E.coli compared to S.aureus showed high sensitivity. So that, the growth of both bactery was decreased by increasing the ZnO nanoparticles concentration and the reduction of S.aureus and E.coli growth. The result of this study demonstrated that nanoparticles ZnO and TiO2 has a strong antimicrobial effect. The results indicated that nano-Ag infusion also had antibiofilm activity. The antimicrobial properties of nanoparticles can be used in the packaging of dairy products, especially milk and cheese.