Optimization of Sweet Leaf ( <i>Sauropus androgynus</i> L. Merr)–Amaranth ( <i>Amaranthus hybridus</i> L.) Vegetable Leather With Carrageenan and Sorbitol

Vegetable leather is an emerging preservation strategy that extends shelf life, reduces postharvest losses, and provides a convenient format for nutrient-rich vegetables. Sweet leaf (<i>Sauropus androgynus</i> L. Merr.) and amaranth (<i>Amaranthus hybridus</i> L.) are rich in bioactive compounds, making them promising raw materials for functional vegetable leather. This study optimized vegetable leather formulation by evaluating the effects of carrageenan, sorbitol, and sweet leaf-amaranth ratios on mechanical and physicochemical properties. Response surface methodology (RSM) with a D-optimal design was applied using Design Expert 13.0.12 software. Factors tested included carrageenan concentration (0.5%-2.5%), sorbitol concentration (1%-13%), and sweet leaf-amaranth ratios (25:75, 50:50, and 75:25). Optimization results identified the optimal formula as 0.877% carrageenan, 1% sorbitol, and a 25:75 sweet leaf-amaranth ratio, with a desirability value of 0.864. The optimized product exhibited tensile strength of 6.08 N/mm², elongation of 6%, solubility of 92.77%, moisture content of 10.93%, and ash content of 3.11%. Functional analysis of the optimized product showed a chlorophyll content of 9.35 ± 0.35 mg·L^-1 and antioxidant activity of 76.0 ± 0.02% inhibition. Sensory evaluation indicated neutral to slightly favorable acceptance, with overall acceptability of 5.1 ± 0.90 on a seven-point hedonic scale. These results confirm that the optimized sweet leaf-amaranth vegetable leather has promising functional and consumer attributes in addition to desirable physicochemical properties.