As seen in the movie Food Inc., the low-grade trimmings come from the most contaminated parts of the cow and were once only used in dog food and cooking oil. But because of BPI’s treatment of the trimmings — simmering them in low heat, separating fat and tissue using a centrifuge and spraying them with ammonia gas to kill germs — the United States Department of Agriculture says it’s safe to eat.
Fortunately, given the lack of beef cattle on Mars it’s not something that Amber would have to be concerned about eating.
Back in the real world, however, I can see this revelation potentially harming the prospects for true synthetic meat. Should synthetic meat ever prove practical it will be deliberately conflated with pink slime by “pure” food advocates, crusading vegans, anti-corporate activists, and (ironically) live-raised meat producers in an effort to make it an object of disgust and thereby poison any market for it. Assuming synthetic meat would be safe to consume, the environmental and humane benefits will be ignored because (respectively) it isn’t real meat, it is real meat, someone might make a profit on it, and someone else might make a profit on it.
Like GMO foods in In the Shadow of Ares, it might be something that we’ll have to wait for Loonies and Martians to perfect and bring to market, out of local necessity.