SAN FRANCISCO (Reuters) - Plant-based burger maker Impossible Foods on Wednesday announced a partnership with major meat supplier OSI Group [OSIGP.UL], a longtime producer of patties for fast-food chains, as it ramps up to meet demand from consumers and restaurants including Burger King.

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Burger King started offering the Impossible Whopper in April in 59 stores in and around St. Louis, and is expected to launch nationally, which would put the plant-based Whopper on the menu in about 7,000 Burger Kings.

The partnership between the vegan burger maker and one of the biggest meat suppliers comes as young, environmentally conscious consumers are feasting on plant-based patties and sausages.

“We got ourselves into a supply-demand imbalance in which we frankly just did not anticipate the level of demand that came from consumers,” Sheetal Shah, Impossible Foods’ senior vice president of product and operations, said.

Shares of rival vegan burger company Beyond Meat Inc BYND.O are up over 700% percent since it went public in May. Beyond Meat earlier this week forecast its revenue would rise over 170% in 2019.

Privately-held OSI, based in Aurora, Illinois, has been supplying McDonald's Corp MCD.N for about six decades and has 65 facilities in 17 countries.

Shah said California-based Impossible Foods and OSI will both be investing in OSI facilities to produce the plant-based burger patties and that multiple facilities in the Chicago area will start supplying Burger King and eventually other customers as well. The investment details were not disclosed.

When asked if Impossible would be serving McDonald’s too, Shah declined to comment on customers, but said: “I see no reason why we shouldn’t be able to go anywhere and everywhere.”

When it comes to plant-based meat substitutes, “Its time and place is right now,” Kevin Scott, senior executive vice president for OSI North America, told Reuters. “The work that’s been done in the sector on our behalf and other manufacturers and companies like Impossible Foods are really narrowing that gap to a point of overall consumer acceptance.”

Just three months after its IPO, Beyond Meat this week said it was raising more funds in a stock offering to expand its manufacturing facilities, which are also stretched by booming demand.

Smelling the sizzling opportunity, major meat packers like chicken producer Perdue Foods and Canadian packaged meat producer Maple Leaf Foods Inc MFI.TO have also launched vegan meat substitute products.