Abstract
Spirulina (Arthrospira platensis) is a protein- and antioxidant-rich microalga, but its use in beverages is limited by sensory acceptance. Four juices (apple, sour cherry, tomato, and celery) were initially tested with added blue and green spirulina (0.8% and 1.6% w/w). Based on preliminary acceptability scores, only sour cherry and tomato juices were selected for further analyses. Blue spirulina enrichment increased protein (from 0.80 to 1.36 g/100 g in sour cherry; 0.89 to 1.52 g/100 g in tomato), fat (0.05 to 0.21 g/100 g; 0.09 to 0.25 g/100 g), and energy (259 to 279 kJ/100 g; 140 to 170 kJ/100 g). Antioxidant activity improved significantly, with DPPH IC(50) reduced from 260 to 135 mg/mL (sour cherry) and from 268 to 171 mg/mL (tomato). Colour analysis confirmed a shift from red to blue hues (a* from 15.2 to 3.7 in sour cherry). Data were statistically processed using ANOVA followed by Tukey's HSD test, while sensory data were additionally evaluated by PCA and GPA to identify product-specific differences. These results confirm that spirulina-enriched sour cherry and tomato juices are nutritionally enhanced functional beverages, though sensory off-notes remain a challenge for consumer acceptance.