This dataset compiles the data generated in the research project investigating the formation and characterization of lupin protein–proanthocyanidin complexes and their application as multifunctional emulsifiers in high internal phase emulsions (HIPEs). The study was conducted through laboratory-based experimentation, including the preparation of protein–polyphenol complexes, formulation of model emulsions, and a wide range of physicochemical, rheological, and microscopic analyses. The dataset includes raw experimental spreadsheets, organized laboratory notebook records, detailed protocols for the preparation of complexes and emulsions, and files generated from analytical instrumentation (e.g., spectroscopy, particle size analysis, zeta potential, microscopy, and rheometry), along with consolidated tables that supported data interpretation. These files contain replicated measurements, intermediate calculations, formulation conditions, and instrumental parameters used throughout the project. No interviews, surveys, or bibliographic surveys were used as primary sources; all data originate from laboratory experiments. The dataset was structured through systematic organization, standardization, consistency checks, and compilation of all information required for the reproducibility of the experiments. This dataset also contains the results of the characterization of lupin protein and lupin protein–grape seed extract (GSE) complexes used to stabilize high internal phase emulsions. Here you will find results from zeta potential measurements. New results will be added as the research project progresses. Samples are labeled as LP (lupin protein) and LP-GSE (lupin protein–grape seed extract complexes), tested at different NaCl concentrations (0–200 mM) or pH values (3.5–6.5). For example, the sample named LP_100 mM refers to a lupin protein dispersion containing 100 mM NaCl, whereas LP-GSE_pH3.5 refers to a lupin protein–grape seed extract complex dispersion prepared at pH 3.5.