Hello, I am a small scale popcorn producer. My popcorn is already poped and packed in a bag like crips. It is not the microwave oven popcorn. The product is similar to Butterkist popcorn (you can check it on Google). Recently, I am getting more request for the product, so I am considering preservatives so I it can increase the shelf life and thus produce in mass quantity. I do not know which preservative is best for preserving popcorn. I have checked the ingredient of Butterkist and they said "preservative free". But I know clearly that something must be added to increase the shelf life. While my product remain crispy and tasty for 3-4 weeks,after which it start to lose its crispness. But Butterkist popcorn last 1-2 years. Please I want you all to advice me on what to do. Thanks in advance.