Physicochemical, Nutritional, Microbial, Sensory, and Antinutritional Evaluation of Tomato Ketchup Fortified with <i>Chlorella vulgaris</i> Protein Isolates

This study evaluated the effects of fortifying tomato ketchup with Chlorella vulgaris protein isolates (CPIs) on its nutritional, functional, microbial, and sensory properties. CPIs were extracted by isoelectric precipitation and dried using oven drying (OD) or vacuum drying (VD). Functional properties, antioxidant activity, amino acid composition, mineral content, physicochemical characteristics, antinutritional factors, microbial quality, and sensory acceptability were assessed. OD isolates exhibited higher protein solubility and DPPH radical scavenging activity (65.6%) than VD isolates (47.5%). CPIs fortification increased protein content from 1.6% in the control to 6.3% in the 13% CPIs formulation and significantly ( p < 0.05) enhanced essential amino acids, particularly leucine, lysine, valine, isoleucine, phenylalanine, and threonine. Potassium, sodium, magnesium, calcium, and iron contents were also improved. Antioxidant activity increased with CPIs inclusion, while antinutritional factors and microbial counts remained within safe limits. Sensory evaluation showed that 3–5% CPIs incorporation maintained acceptable quality. These findings demonstrate the potential of CPIs as sustainable ingredients for developing protein-enriched functional condiments.