The formation and stability of milk foams are governed by milk proteins that adsorb at the air-water (AW) interface to form viscoelastic films capable of entrapping air and maintaining foam structure. Foam quality is a defining attribute of many dairy-based coffee beverages (e.g., cappuccinos, lattes, macchiatos), where stable foams prolong the release of coffee aroma and enhance sensory perception. However, poor foaming remains a recurring issue in the preparation of such beverages when using pasteurized fresh milk rather than barista formulations enriched with stabilizers, such as protein concentrates. This problem has been attributed to lipolysis, the enzymatic hydrolysis of triglycerides into free fatty acids (FFAs), monoacylglycerols (MAGs), and diacylglycerols (DAGs). Among these products, FFAs have been extensively regarded as key contributors to milk foam destabilization. However, previous studies have primarily focused on rancid milk, characterized by elevated FFA levels (>3.8 mmol/100 g fat), even though poor foaming has also been observed in non-rancid milk. This suggests that other lipolytic products may also influence foaming behavior, yet the role of sub-rancid lipolysis remains largely unexplored. This study investigates how limited lipolytic activity alters the composition of surface-active lipids and consequently affects the interfacial and foaming properties of milk. Cow milk was incubated with 1(3)-regiospecific Aspergillus niger lipase at concentrations ranging from 0.2 to 200.0 mU/mL at 37 °C for up to 180 min. Foaming properties were assessed following steam injection using a commercial espresso machine, while interfacial rheological properties (dilational elastic and viscous moduli, ε’ and ε’’) were analyzed via pendant drop tensiometry. The relative proportions of FFAs, MAGs, and DAGs were quantified by gas chromatography. The absence of lipolytic rancidity was verified through pH monitoring and FFA quantification by attenuated total reflectance Fourier-transform infrared spectroscopy. At early stages of lipolysis, the accumulation of FFAs and DAGs corresponded with reductions in ε’ and foaming capacity, indicating that these products disrupted the formation and stability of protein films at the AW interface. As lipolysis progressed, increasing MAG concentrations partially counteracted these effects, resulting in improved foaming properties. This improvement coincided with an increase in ε’, suggesting the formation of a more elastic and cohesive interfacial film, likely arising from cooperative interactions between MAGs and milk proteins. At higher lipase concentrations (≥ 20.0 mU/mL), excessive MAGs again reduced ε’ and impaired foam stability, likely due to protein displacement from the AW interface. Across all treatments, milk pH remained stable and FFA levels (0.68–2.10 mmol/100 g fat) were below the rancidity threshold, confirming that the observed changes in interfacial and foaming properties were driven by interactions between proteins and lipolytic products rather than acidification. These findings reveal that even mild lipolysis can substantially modify the interfacial structure and foaming performance of milk through compositional shifts among lipolytic products. Understanding the functional balance between MAGs, DAGs, and FFAs provides mechanistic insight into the variability of foaming capacity observed under non-rancid conditions.