Hi there I am excited to find your site...I make small batches of organic dog treats for sale and I need help determining which natural food preservative I can use in order to preserve and extend shelf life without refrigeration. Can I use dry milk in place of liquid? Citric Acid powder? Don't worry, I also bake and cook for my family and am sure that I'll have tons of questions for "human Food" as I go along!! any help would be greatly appreciated!