Optimisation of Sucrose-Free Hard Candy Enriched with Piper retrofractum Vahl Extracts Using Response Surface Methodology (RSM)

Javanese long pepper (Piper retrofractum Vahl) is a local herbal plant that is rich in bioactive compounds such as flavonoids, polyphenols, and other active components. The main bioactive compound is piperine which is associated with therapeutic potential. Therefore, this research aims to develop an optimum formulation of sucrose-free hard candy with the addition of Piper retrofractum Vahl extracts obtained based on the results of previous research. The optimum results were determined using Response Surface Methodology (RSM) with Box-Behnken Design through the four stages in Design Expert 13 software. This was followed by optimisation of the free-sucrose hard candy manufacturing process with the addition of Piper retrofractum extract at (5-10) g and xylitol (10-30) g to produce 16 combinations. The parameters observed were percentage of antioxidants, solubility time, pH, and RGB colour. The results showed the optimum condition to be 10 g of extract and 30 g of xylitol which produced a D value of 0.746. Moreover, the responses obtained at the conditions included 55.718% antioxidant, 12.073 min of solubility time, pH 3.228, and RGB colour values of 60.821.