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Edible Bioplastic Films

by Sarah

 

I’m trying to create bioplastic film bags flavored with fruits to hold sandwiches. I have been using starch and agar recipes on this site and substituting puree for water but my biggest problem is whenever I put any kind of food with moisture (even bread) inside, it absorbs a lot of the moisture. I have tried adding a little bit of sunflower oil to make it less likely to do this as well as pectin as an emulsifier (although I’m not sure if it would count as one) and this does help a little bit but not to the level I’d hope. I would really love to get close to the shine of traditional plastic bags as well as the flexibility and tensile strength. Tensile strength and flexibility I managed to solve by adding agar but when it’s on something with a little bit of moisture this sort of disappears and it becomes mushy. I also want to make the bag more transparent like plastic. Basically, I am trying to get as close to traditional plastic as possible (Although I know this is difficult with starch) but with edible materials.

Comments (1)

  1. Green Plastics says:

    Developing plastics for food packaging is tough! As you have discovered, you have to pay attention to what people in the industry call the “barrier properties” of the plastic: moisture barrier and odor barrier in particular. In commercial materials, these properties are often achieved with very thin coatings applied to the plastic.

    If you are interested in an in-depth discussion of how some people in the industry solve this problem, there are many examples in the “Green Plastics” book: you can just look in the index under “coatings” to see some of the places the book talks about this topic.

    As an example, here is an excerpt from page 141 in the book: “Additives or coatings are commonly used with synthetic plastics, and can be developed for bioplastics as well when needed. Naturally occurring substances with potential use as biodegradable, moisture-proof coatings are oils, waxes, and even shellac… The base cellulose sheet in cellophane, although insoluble in water, absorbs and loses moisture readily; it is not a good moisture barrier. Cellophane is made moisture-proof with a coating of nitrocellulose-wax blend.”

    I hope this is able to give you some ideas!

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