SK Inc. said Friday it has injected an additional $55 million into a San Francisco-based alternative protein firm Perfect Day to wade further into the global alternative food market.

According to the holding firm of South Korea’s third-largest conglomerate SK Group, the investment was made together with STIC Investments, a leading private equity fund here. This is SK Inc.’s second investment in Perfect Day, after a 54 billion-won ($45.4 million) investment last year.

The investment will increase SK Inc.’s stake in Perfect Day and give it a seat on the board, though SK declined to give an exact amount for the stake, explaining only that it was less than 10 percent.

“As part of our environment, social and governance effort, we are investing in alternative food companies with core technologies. Through partnership with major food companies in Asia, SK Inc. will lead the highly promising Asian alternative food market,” a company official said.

Perfect Day is best known as the world’s first manufacturer of animal-free milk protein. The firm extracts protein genes from cows, mixes them with microorganisms and ferments them. The fermented protein is then used as an ingredient for ice cream, cheese, bread and protein shakes.

After its launch last year, Perfect Day’s ice cream brand Brave Robot received favorable feedback from customers, with its products available at more than 5,000 locations in the US. The company recently launched a new brand Modern Kitchen to offer different products, including cream cheese.