Functional Yogurt: Enhancing Color Stability, Functional Quality, and Storage Life With Malabar Spinach (Basella alba L.) Fruit

Abstract

Malabar spinach (Basella alba L.) is a leafy green vegetable rich in betalains, and is found in its fruit. It is also rich in bioactive and antioxidant compounds. This study investigated the potential use of malabar spinach fruit extract (MSFE) at four concentrations (T₀ = 0 μL (control), T₁ = 500 μL, T₂ = 1000 μL, and T₃ = 2000 μL) in yogurt as a natural colorant during 21 days of refrigerated storage. The pH and syneresis of the MSFE-containing yogurt significantly decreased (p < 0.05). Moreover, the total soluble solids, viscosity, and titratable acidity increased (p < 0.05) in a dose-dependent manner and maintained a similar pattern upon storage. Furthermore, compared with the control yogurt, the MSFE-treated yogurt exhibited higher total phenolic content (29.97 mg GAE/100 g DM, T₃) and total flavonoid content (6.72 mg QE/100 g DM, T₃) as well as increased antioxidant activity (15.47%, T₃). Higher MSFE levels significantly reduced (p < 0.05) the initial total plate count from 520.5 × 10⁶ CFU/g (T₁) to 118.7 × 10⁶ CFU/g (T₃). However, bacterial proliferation led to an increase in the total plate count during storage. MSFE significantly enhanced (p < 0.05) yogurt color properties, with T₃ resulting in the highest betalain content (2.776 mg/L). The betalain content slightly decreased (p < 0.05) after 14 days but regenerated by the end of the storage period. Nevertheless, MSFE exhibited acceptable color stability over a wide pH range during storage. These findings suggest that MSFE is a viable natural colorant for yogurt, offering improved nutrition and consumer appeal, which was further confirmed by principal component analysis (PCA).