I spent a considerable amount of time and $ on this a few years ago. Bought a digital PH meter, a bunch of steaks, citric acid and began testing. My intention was to create a backcountry kit with a collapsible spray bottle (you could fill from a stream/pond), foil wrapped citric acid packages mixed with the proper ratio for the collapsible spray bottle and sell it for less than 20 bucks. I tested and tested different citric acid to water ratios on beef in 110*+ temps for weeks. I did the testing in the middle of my barn intentionally. Surrounded by horses and way more flies than you find in the backcountry. I was able to find a good ratio over time and eliminate any larvae spawn for up to a week inside the meat. Any more time and the natural oils/liquids in the steaks were gone. basically air dried beef. Visually I was able to keep the beef appealing for quite some time. I never did cook or consume it. By the time I got to sourcing and pricing the kit I lost hope. It would have had to be over seas sourced and needed over a couple hundred thousand bucks to get production costs low enough to be in the $20 retail range. I cant imagine the taste of the meat would be effected seeing is how the citric acid basically creates an external layer on meat that will be disposed of (shaved) once it gets home or to the butcher shop for processing. Minimal meat penetration with the citric acid. In layman terms it creates a lemon peel flavor seal over the meat that bugs do not like and keeps them from attacking the meats. I photographed and video the whole process and it was a fun experiment. I planned to patent it as well, after researching the topic it was originally published by a gentleman in Alaska so it limited patent rights. I reached out to him but he has no interest in patenting or signing papers so I could patent the idea. We talked for hours and he is a great guy! If you get a chance to google search Larry Bartlett (I believe) he has a few great articles floating around on the subject. I still have the PH meter in the garage, kinda limited buyers when I tried to resell it.. I will try to find the research and follow up with what I found to be the best citric acid/water ratio.
I ordered the citric acid kit from Caribou Gear when I bought some of their game bags a few years ago. (Great bags by the way). It was just a small packet of powder and a pump bottle that you mix before using. I used it 3X on different hunts, and only used it to keep flies off of the meat while I was deboning at the kill site. I had spread out a lightweight plastic sheet to put the meat to cool, and the flies showed up like vultures. The spray worked well, and I didn't notice any taste on the meat later. On a muzzy elk hunt, I had suggested the spray to the other guys I went with, and one of them bought bulk citris spray (2 lbs.), and when he used it for his elk, it didn't keep the flies off at all.
I've had this kit with me for the last dozen hunts, and used it 3X. Cheap and lightweight insurance and well worth it if needed.