Dear All,
I am studying about antimicrobial activity of protein based edible films. I am dissolving protein extracts in water at 4% concentration with 1.6 g glycerol, then adjusting pH 12, and heating 95 oC for 1 hour. After cooling to room temperature, 1 mL essential oil and 0.25 g Tween 80 is added to solution, and then, homogenized at 14.000 rpm for 3 min. When air bubles cleared from solution with a vacum pump, it is pouring into petri dishes for drying at 38 oC overnight. Dried films hold into a desicator with 58% relative humidity. Then, films are cut 10 mm diameter circular shape, and placed on Nutrient agar inoculated with microorganisms. After just 2 or 3 min, films are melting and becoming fluidized. Water solubility of films are approximately 40% of dry weight basis.
I attached a figure for illustration more detaily.
How can I fix this problem? How can I make antimicrobial activity analysis of films?
Please help.
Thanks.
Hi Furkan
Do you buffer your pH or is it the original pH 12 that you adjusted at the beginning?
What kind of oil your are using? Is it possible that you get a saponification at high pH?
Do you observe this effect only on agar? Are your films stable outside the exsicaror?
Dear Höger,
Thanks for your answer.
I am adjusting pH 12 with 5 M NaOH for the best protein solubilisation.
I am using Thyme, Clove and rosemary essential oils obtained from Clavenger hydrodistillation.
I did not observe this effect on agar, and my films are stable at 58% relative humidity.
Hi Furkan,
did you try to increase the amount of glycerol? instead of 40%,@ you can use 50%.
and why you use pH 12 and heating processes together?
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