Optimization of Roasting Conditions of Salak Seed as Coffee Substitute and Its Physicochemical Properties

The growing attention towards utilizing salak seeds as a substitute for coffee has increased due to the presence of caffeine and its health-enhancing properties. The present study aimed to determine the optimum roasting conditions for salak seed coffee (SSC) with high total phenolic content (TPC) and desirable lightness (L*) using response surface methodology (RSM). Regular SSC was produced at optimal roasting temperature and time of 189.36 °C and 39.54 min, respectively. An instant SSC was produced by hot water extraction at 90∘C of regular SSC, followed by freeze drying. Physicochemical and antioxidant properties of regular and instant SSC were compared. The moisture, TPC, pH, and solubility of instant SSC were significantly higher (p < 0.05) than those of regular SSC. Furthermore, instant SSC appeared to be lighter than that of regular SSC. TheIC50 of instant SSC was 0.23 mg/mL, indicating higher antioxidant capacity than that of regular SSC (0.37 mg/mL). There was no significant difference (p > 0.05) in terms of caffeine content between regular and instant SSC. The total number of volatile compounds identified in instant and regular SSC was 140 and 65, respectively. The quantitative descriptive analysis (QDA) results showed that the intensity for all the sensorial attributes (e.g. colour, nutty flavour, bitterness, aftertaste and body) tested was higher in instant SSC. The retention of flavor compounds, enhanced solubility and antioxidant capacity of instant SSC indicated that the commercialization of SSC as a coffee substitute is promising.