Take a look:

Adding Molecules to Food, Pros and Cons: A Review on Synthetic and Natural Food Additives. http://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12065/abstract

Simply you can use spice oil as it has antimicrobial effects.

you can use chitosan or bacteriocins production from lactic acid bacteria

Hi Bhaghat YB,

I suggest to use for red and blue fruits. These are rich in flavonoids that show high antioxidant potential. Furthermore, there are studies that show flavonoids as antimicrobials.

Good Luck in your research.

moringa oleifera powder has been used sucessfully as antimocrobial agent and it is biodegradeable and safe. Also ginger, garlic play similar role

Do not forget egg white, which contains lysozyme.

In some cases propolis alcoholic extract could be useful.

Hi Bhagath YB,

bio edible potential antimicrobial agents (safe for consumption) are numerous and I suggest some lactic acid bacteria with antibacterial activity occurs.

Several works are published and show the antibacterial effect.

Regards.

Dilmi Bouras A.

Muchas hierbas y especias contienen aceites esenciales a los que se les han atribuidos propiedades antimicrobianas con uso potencial en alimentos, por ejemplo: ajo, cebolla, romero, salvia, cilantro, perejil, orégano, laurel, albahaca, hierbabuena y tomillo entre otros. 

Hello.

I'm not a specialist, but I suggest honey.

Article there http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3609166/

Regards.

Hello

Some lactic acid bacteria strains have proven antimicrobial potential. Ex .: Lactobacillus acidophilus, Bifidobacterium, Lb bulgaricus ...

Regards