Ultimately, taste overrides many other considerations in the populace, and there are few flavour enhancers out there that have proven to be as effective as Glutamates. One of the most popular (and controversial) of these is MSG, or mono-sodium glutamate. Many foods are laced with this substance and it leads to people eating more of that food than they otherwise would, whatever the known nutritional deficiencies of that food.
Example? Well let's start with the Romans and one of their key delicacies, Garum. This was, in essence, 'fermented' salted fish. By fermenting, what is meant is that the fish was pretty much salted and then left in a bucket in the sun. I call that being left to rot more than left to ferment, but that's me. Personally, I don't find that all that much appealing, but it was eaten in volumes in the Roman Empire that required factories to produce the stuff. Believe it or not, it is still produced in certain quarters of Italy to this day, even though it is far less popular.
The point being, that if you add glutamates to your Soylent Green, all you do to keep selling it is emphasise the taste. This has been working for the snack food industry for decades. Most people today know that chips (for example) are not high in nutrition, yet demand for them is growing annually and they are very nearly a US$44bn dollar industry today.
Now, it is true that potato chips are not known to come from a dubious source, but taste is still a driving factor in their sales growth. Arguably, the same would be true of your Green product. Besides, even the name Green means it's good for the environment, right?
In any event, I recommend a two step process. First, make it taste really good; glutamates are good for that. Second, make that the thing you saturate the air waves with every chance you get. You might be surprised how little the source matters after that.
Want even more proof? Well, start watching what the Japanese are doing in creating artificial meat from human feces. If they can do it and make it a really salable commodity, then you will have your answer.