tə fˈɔːɹm ɐ stˈeɪbəl fˈoʊm ænd ɪmˈʌlʃən, ɐ sˈɜːfæktənt, sˈʌtʃ ɐz lˈɛsɪθˌɪn, mˈɑːnoʊɡlˌɪsɚɹˌaɪdz ɔːɹ pɹˈoʊtiːnz, mˈʌst biː pɹˈɛzənt tə ɹᵻdˈuːs ðɪ ˌɪntɚfˈeɪʃəl tˈɛnʃən bᵻtwˌiːn ðɪ ˈɛɹˈɔɪl fˈeɪz ænd ðɪ ˈeɪkwɪəs fˈeɪz.
To form a stable foam and emulsion, a surfactant, such as lecithin, monoglycerides or proteins, must be present to reduce the interfacial tension between the air-oil phase and the aqueous phase.