HIGH-PRESSURE HOMOGENIZATION AND pH-SHIFTING MODULATE THE TECHNO-FUNCTIONAL PROPERTIES OF LUPIN PROTEIN ISOLATE (Lupinus albus)

Lupin protein isolate (LPI) is a promising plant-based ingredient due to its nutritional and functional properties, relevant to the food and beverage industry. High-pressure homogenization (HPH), combined with pH-shifting, has emerged as an effective approach to improve the techno-functional performance of plant proteins. This study evaluated the effects of HPH (50, 100, and 150 MPa) and different pH levels (2, 7, and 11) on the structural and techno-functional properties of LPI. Control samples were maintained at atmospheric pressure (0.1 MPa) under the same pH conditions. All treatments were performed in duplicate, freeze-dried, and analyzed in triplicate. Data were evaluated using ANOVA and Tukey’s test (p < 0.05). The LPI obtained presented a high protein content (86.21%) with a marked reduction in lipids and carbohydrates. Color variation was more pronounced at extreme pH values: pH 2.0 promoted darkening and stronger tones, while pH 11.0 led to pigment degradation and color attenuation. Neutral pH (7.0) provided greater chromatic stability, which is desirable for food applications. HPH and pH significantly influenced emulsifying properties. At pH 2.0, 150 MPa resulted in the highest values, with an Emulsifying Activity Index (EAI) of 27.3 m²/g and Emulsion Stability Index (ESI) of 104.1 min. At pH 7.0, 100 MPa achieved optimal performance (EAI 24.9 m²/g, ESI 88.1 min), while at pH 11.0, 50 MPa yielded the highest ESI (106.3 min). These outcomes demonstrate the potential of LPI to form stable emulsions applicable in products such as mayonnaise and meat analogues. Foaming properties were also modulated. Foaming capacity (FC) improved at all pH levels compared with controls, reaching 83% at pH 2.0 (50–100 MPa), 84% at pH 7.0 (50 and 150 MPa, vs. 63% control), and 80% at pH 11.0 (50 and 150 MPa). However, higher pressures in acidic media reduced FC due to aggregate formation. Foam stability (FS) was highest at pH 2.0 (96–100%), but decreased significantly under pressure at neutral and alkaline conditions, dropping from 96% (control) to 72–82% (pH 7.0) and from 99% to 87–88% (pH 11.0) after 60 min. In conclusion, HPH combined with pH-shifting effectively enhances the techno-functional properties of LPI, particularly emulsification and foaming behavior. These findings support its potential as a versatile, sustainable ingredient for innovative food formulations.