Optimization and bioactive evaluation of corn silk incorporated carrot banana smoothie using d-optimal mixture design

Abstract

Corn silk (CS), the long, silky fibers surrounding corn kernels, is recognized for its diuretic, anti-inflammatory, and antioxidant properties, and is beneficial for managing conditions such as cystitis, gout, and obesity. This study aimed to evaluate the functional properties and shelf-life of a CS-incorporated carrot-banana smoothie. CS was analyzed for its proximate composition, antioxidant activity, and techno-functional properties, revealing low moisture (3.43±0.27 %), high ash (4.67±0.12 %), and protein (9.82±0.1 %) contents. It presented a high total phenolic content (TPC) (115.37±0.19 mg GAE/100g ), total flavonoid content (92.69±0.23 mg QE/100g ), and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) activity (49.67±0.68 %), alongside significant ascorbic acid levels (123.12±0.66 mg/100g ). Using a Design expert (d-optimal design, 17 smoothie formulations were tested, with the optimized solution containing 6.84 g corn silk powder, 28.15 g carrot, and 35 g banana. This formulation achieved desirable properties, including total soluble solids (17.36±0.05 °Brix), pH (4.00±0.08), DPPH (47.89±0.16 %), and TPC (52.26±0.21 mg GAE/100g ), and was well-received in sensory evaluations. Shelf-life analysis over 12 days revealed significant decreases in pH, total soluble solids, DPPH, and TPC, with increases in yeast and mold counts, while Escherichia coli was undetected. The smoothie was deemed nutritious and safe for consumption for up to six days.