After Katie and Justin Silpe welcomed their second child, Katie returned to work while Justin took over responsibility for feeding their baby, using thawed breast milk from a supply that Katie had frozen. But time and again, their daughter refused to drink it.

The Silpes were not the only parents whose babies rejected breast milk that had been frozen — likely due to changes in taste and smell.

Justin, a molecular biologist, brought a sample of Katie’s breast milk to molecular biologist Bonnie Bassler’s lab at Princeton University, where he discovered that freezing not only altered the texture and flavor but also diminished the milk’s nutritional value.

After extensive testing, he identified a combination of three natural, infant-safe ingredients — in both powder and liquid forms — that, when added to fresh breast milk, could maintain its flavor and nutritional value even after freezing.

Justin co-founded PumpKin, dedicated to breast milk science, which is perfecting the breast milk additive at the Princeton Innovation Center Biolabs. Through the state’s Maternal and Infant Health R&D grant program, the PumpKin team recently received a grant from the New Jersey Economic Development Authority to support its research and development.

Since human milk varies greatly, Justin says the goal is to gather as many diverse samples as possible. PumpKin is seeking just over 100 donated breast milk samples to help finalize the additive before putting it on the market.