Appropriate technology for production of purple sweet potato flour and product characteristics

Purple sweet potato (PSP) has an advantage because it contains anthocyanin pigments that can provide functional effects for the human body. The utilization of PSP in West Java Province has not been optimal; it is necessary to innovate process technology and appropriate equipment for processing PSP to increase the added value and economy. The objective of this research is to develop appropriate technological innovations for the production of PSP flour and its product characteristics and to test the performance of the drum dryer as the main supporting tool for the production of PSP flour. The methods used include: (1) the process of making PSP flour on a pilot plant scale with immersion in citrate acid and blanching (a), blanching treatment (b); (2) analysis of the characteristics of PSP flour; (3) feasibility analysis and techno-economics for production PSP flour. The results showed that a temperature of 120 °C and a drum rotation speed of 0.7 rpm were optimal conditions for the performance of the drum dryer when drying purple sweet potato paste from moisture content 65.59±2.77% to 5.42±1.17%; the measured drying capacity was 7.24±0.34 kg/hour. Characteristics of PSP produced moisture content 5.42–7.42%, ash 3.32–3.33%, carbohydrates 76.55–82.46%, fat 0.34–0.40%, protein 5.70– 5.82%, anthocyanin 2.7–3.32 mgCyE/g with colour analysis (L*) 29.913–31.372, the morphology of the granules with Scanning Electron Microscopy showed an even physical shape of the particles. Feasibility analysis obtained NPV of IDR 138,011,164; IRR of 41.03%; Net B/C of 1.17; and a payback period of 41 months. Based on these criteria, the purple sweet potato flour production business can run as long as the project runs according to the assumptions set.