[jsmatula]

I have a problem which may prove to be challenging for me and maybe someone here may be able to help.  I have a need for a process in which I can produce an edible covering though it need not be flavored just wont kill people if they accidently eat it, the covering will need to be paper like or plastic like but I would need it to quickly evaporate under only a moderate amount of heat such as direct sunlight or a small flame.  the evaporation would need to be under 45 secs as to "reveal" what is underneath it.  I have but high school chemistry knowledge and only what I can remember of that.  I know im asking something pretty specific but I didn't know where else to start.

[Furanone]

Hi Jsmastula,

Welcome to the Chemical Forums!

I will try to help if I can but what you may ask may not be entirely possible but perhaps something close could be achieved.

First, when you say you desire a plastic or paper-like film (in texture) as an edible covering then this would be a polymeric material meaning very large molecules made from chains of monomeric (single) units. For plastics it is typically a synthetic chemical (polystyrene with styrene the repeating unit, polyethylene, polypropylene, etc.). For paper, it is typically cellulose which is arguably the most abundant molecule on earth (which is chains of the sugar monosaccharide glucose). Since they are polymers they usually can form strong films. However, when you say you desire for this material to evaporate with heat or when holding a candle to it, the problem with polymers is that they are too large molecules to have a boiling point and they will decompose first (chemically burn and turn to smoke) before ever evaporating. So maybe you mean that you desire that they melt with heat or when holding a candle to the edible film. If this is the case this is then perhaps possible; however, your film will need to have a high enough water or other edible plasticizer content (ethanol, propylene glycol) to allow melting since a completely dry film will decompose first with high enough heat.

Therefore, one suggestion would be to use gelatin (a protein which is also a polymer of chains of amino acids) with some clouding agent added such as brominated vegetable oil or a food coloring. Then with heat the gelatin would melt (and drip) off the product and gelatin has minimal flavor so would not impact flavor much, but since you would require a fairly high amount of water, the water content after melting may make product soggy in texture. One way around this is to seek out a product called "gelatin hydrolysate" which is much smaller chains of gelatin protein so that in order to form the same strength gel/film as regular gelatin, a much higher amount of powder (and thus lower amount of water) must be added. It would also melt faster with applying heat, give less of a residue on the food it was coating, and would be more antimicrobial so yeast./molds/bacteria would have less chance to grow on it thus allowing the food to store longer in refrigerator. Another interesting thing about gelatin is that its melting temperature can be controlled very precisely to a set temperature based on its ratio of hydroxyproline-to-proline amino acids -- more hydroxyproline will increase hydrogen bonding and thus increase the meting temperature. Cold water fish will have lower amounts of hydroxyproline since it would solidify in the arctic waters (in form of collagen), so mixing fish gelatin with animal gelatins can give you a gelatin blend that melts at the exact temperature you desire. Of course experiments would be required to optimize this.

Another possibility is using Carnauba wax as a coating. This is used on many candies, chocolates (so M&M's don't melt in your hands) and even fruits (shiny red apples) as an edible coating to help protect the product. The Carnauba wax coating is very thin so light can pass through it revealing the food on the other side, but at a greater thickness it would scatter light enough to look white or at least hazy. However, at this thickness it could also impact the sensory attributes of the edible product underneath even after melting it off (eg. make it taste like the candle you are using to melt the edible coating).

Maybe this is not what you want but at least it gives you a starting point and some things to think about.