For many of us, Thanksgiving is a meat-lovers' paradise: there's turkey on the menu, of course, plus various servings of sausage, ham, bacon, duck or beef.
In recent years, scientists have tried replicating the taste of meat in order to come up with plant-based substitutes that will either be healthier or more environmentally conscious, while maintain the salivating savory flavors that carnivores love.
But challenges remain. The molecular structure of meat is complicated to reproduce in the lab, explained Mark Post, professor of physiology at Maastricht University in the Netherlands, and inventor of the in-vitro meat that debuted in London in 2013.
"Taste comes from proteins, sugars and aromatics in fat tissue," Post told Discovery News in an e-mail. "It is very complex and incompletely understood. There are likely up to 800 components in the protein and fat fraction that contribute to the taste."
Post's laboratory is one of several around the world trying to come up with a meat substitute. Impossible Foods, a startup in Redwood City, Calif., is promising a cheeseburger using "plant blood" by 2016; Hampton Creek, which is selling eggless plant-based mayo and cookies; and Beyond Meat, which uses a mixture of peas and plants to form a protein substitute.
These new products are going in a different direction than Tofurky, which has been selling its popular soy-based turkey since the mid-1990s.
"Soy, for instance, has a slightly bitter taste which is difficult to mask," Post said. "Other plant proteins such as lupine and pea-proteins seem to be easier to handle in that respect."
It's not just taste, but texture that is hard to mimic, said Janeal Yancey, professor of meat science at the University of Arkansas.
"There are the proteins that contribute to texture, but you also have connective tissue, or gristle, that contributes to the mouthfeel, or texture experience," Yancey said.
That mouthfeel changes with the way the meat is cooked, and how much "char," or carbonization, is present.
To our prehistoric forebears, protein was the most expensive nutrient in our diet. "You risked your life to hunt and harvest protein," Yancey said. "Our bodies are made to crave protein. It provides satiety that allows us to fill full and feel satisfied."
Meat-lovers got some bad news earlier this month, when the World Health Organization warned people that processed meat -- like sausage, bacon, hot dogs and red meat -- posed an increased cancer risk.
Eating more turkey may help, since poultry wasn't on that WHO red list.
Food scientists say the difference between turkey and beef is the melting point of the fat in each.
"Since the turkey fat is more oily and less solid in your mouth, it's more effective at delivering fat soluble flavor compounds," said Edward Mills, associate professor of meat science at Penn State's meat laboratory.
In other words, turkey is softer than beef.
As for when a meat or poultry substitute will be available that gives us the same flavor as beef, poultry or pork?
"We will continue to make progress in that direction," Mills said. "I'm not sure we will know when we get there. It strikes me that there will always be some degree of difference that is not identical."