Techno-economic Analysis: Antioxidant-Rich Natural Colorant Production from Dragon Fruit Peel

In this study, the economics of the various way production of natural colorant has been evaluated, specifically related to the effect of the drying methods: spray drying and freeze-drying. It has been found in this study that, the manufacturing costs of the food colorant in the form of extract, spray-dried powder, and freeze-dried powder were USD 6.01/kg, USD 29.89/kg, and USD 56.6/kg total solid content, respectively. The economic parameters consist of NPV, DPBP, PVR, and IRR of powder production using spray drying method were USD 1,989,412.68, 4.3 years, 3.31 and 20.6%, respectively, while that of using freeze-drying were USD 2,156,866.29, 7.27 years 1.78, and 8%. It is also known that drying using spray drying shows better economic parameters than freeze-drying. The sensitivity analysis of powder production using the spray drying method shows that the selling price parameter is a parameter that has a significant effect on the economics of production activity, followed by the cost of peel and cost of labor.


Introduction
Dragon fruit (Hylocereus undatus) is a fruit that belongs to the Cactaceae family. Dragon fruit plant is originally from Mexico, Central America, North America and is now widely cultivated in Indonesia. Indonesia has great potential for the dragon fruit business [1]. Dragon fruit flesh is mostly consumed and utilized in fresh form or juice, while dragon fruit peel (30-35% of the total weight) is often disposed of as waste. Dragon fruit peel contains antioxidants that can reduce the body's cholesterol levels [2]. Red dragon fruit peel (Hylocereus polyrhizus) contains betacyanin, which is widely used as an antioxidant and natural colorant [3]. A previous study reported that dragon fruit peel has greater antioxidant potential when compared to the antioxidant content contained in the flesh [4]. This antioxidant content in dragon fruit peel may protect human bodies from the dangers of free radicals.
Betacyanin can be produced from dragon fruit peels by extraction. This extract can be consumed or used directly in the food processing process. However, betacyanin extract in liquid form has a limitation in transportation and storage flexibility, and also shelf life. Processing of liquid extracts into powder can increase its shelf life, minimize transportation cost, and also making it easier to apply as a mixture of food products. One of the methods for making extract powder is drying using a spray dryer. Spray drying is a method of drying liquid extracts into powder which is widely applied in the industry [5]. Freeze drying is another drying method for turning liquid extracts into powder. The advantage of freeze-drying is that the sample is in a frozen condition so that it may avoid degradation of the temperature-sensitive components (e.g. protein, flavor, and color). The production of extract powder from dragon fruit peel has economic potential. To determine the production process to be carried out, it is necessary to assess which process is the most economical to avoid the risk of loss and to achieve optimum profit. Achieving these objectives can be done through analytical studies using methods of economic approaches that are commonly used. To answer this problem, this study was conducted to determine the feasibility of the production process with different drying methods: spray drying and freeze-drying. The cost of manufacturing of the powder will also be compared with that in the form of extract.

Methods
The economics that is evaluated in this study is influenced by production costs and revenue from the selling of natural colorant powder dragon fruit peel extract. The economic evaluation was carried out using experimental data obtained from previous studies included yield, powder moisture content, optimal extraction time, the solvent mass fraction (water) remaining in the residue, and ambient air humidity [14].
The production cost of dragon fruit peel extract powder was calculated using the approach existing method proposed [10]. Cost of Manufacturing (COM) was calculated as a function of Fixed Capital Investment (FCI), labor wages (COL), utility costs (CUT), water treatment costs (CWT), and raw material costs (CRW). FCI is calculated using the cost correlation method approach [11,10] for each equipment. The process flow used in powder production using the spray drying method consists of three extractors, one reservoir, 3 extraction tanks, one mixing tank, 5 centrifugal pumps, one compressor, one indirect heater, one filter press, and one spray dryer and for powder production. For the freeze-drying method, a process production consists of three extractors, one reservoir, 3 extraction tanks, one mixing tank, 5 centrifugal pumps, one filter press, one freezer, and one freeze dryer are used. The PFD (Process Flow Diagram) process is shown in Figure 2.1.

Production cost
The production costs are calculated using the methodology proposed [10]. Production costs (COM) are a function of investment costs (FCI), operational labor costs (COL), utility costs (CUT), water treatment costs (CWT), and raw material costs (CRM), which can be determined using the following eq.
Industrial-scale process units and laboratory-scale operating units with constant solvent, solids ratio value, temperature, pressure, and maceration extraction time are assumed to have the same performance. The efficiency values for pumps, fans, indirect heaters are assumed to be 75%, 70%, and 85%, respectively. Efficiency values are obtained from the literature of [10], [12]. CWT is neglected because the process produces the main residue which is non-toxic and can be used for fertilizing crops, put into the soil, or commercialized as a by-product.

Cost of labor (COL).
Operational labor costs in this study covering the total costs incurred to pay the salaries of all factory operators in one year are determined using the existing approach proposed [10]. The calculation of the number of operators required to run and control the process activities per shift is done using the following equation.
The maximum labor cost using the maximum labor wage in Indonesia, namely in Karawang Regency, is IDR 4,594,325 / month or 327 USD / month. The lowest minimum wage in Indonesia is in

Cost of raw material (CRM)
The raw material costs in the production of extract powder consist of components of the cost of purchasing dragon fruit peel and water. The maximum price used for dragon fruit peel is Rp 3,000 per kg, and the minimum price for dragon fruit peel is Rp. 0, with the possibility that the peel is a waste from other industrial processes. The cost of purchasing water is obtained from the market price of reverse osmosis water in certain areas. The minimum price for reverse osmosis water in Indonesia is Rp. 210,526.3 / kL or 8.58 USD / kL, and the maximum price for reverse osmosis water is Rp. 263,157,895 / kL or 18.74 USD / kL.

Cost of utility (CUT)
The utility costs for powder production in this study consist of electricity and natural gas costs. Electricity costs include all costs that need to be paid to run all process units that require electrical energy. The cost of electricity is determined through the basic electricity tariff by PLN at the industrial use scale set by the Indonesian Ministry of Energy and Mineral Resources. The minimum tariff used is Rp. 997 per kWh which is the basic tariff for industrial-scale electricity in Indonesia in 2020, and taking into account inflation of 5%, the maximum value is set at Rp. 1,046 per kWh. Natural gas in Indonesia is supplied by PGN (Perusahaan Gas Negara). The minimum price is set at USD 6 per mmbtu based on the 2020 SKK Migas, and the maximum price is set at USD 10 based on the price of natural gas in Medan.

Fixed Capital Investment.
The Fixed Capital of Investment in this study includes the costs incurred to purchase all process equipment for the manufacture of dragon fruit peel powder. The calculation of the cost of purchasing equipment to be purchased is carried out using the correlation cost method with references to [10], [13], [11].

Revenue
Revenue is obtained from selling powders. The price of powders on the market can vary due to several factors, such as purity, antioxidant content, market trends, and so on. In this study, the selling price used is 36.3 USD/kg.

Production cost
3.1.1. Liquid extract production cost. The cost of producing the liquid extract in this study is calculated from the cost of the extraction and filtering processes. The extraction operating conditions used are the optimum operating conditions of previous research in the form of extraction time of 60 minutes, the solvent in the form of desalinated water, and the ratio of solvent to solids ratio is 3 [14].   Table 3.1, the required manufacturing cost (COM) per kg of total solid content dragon fruit peel extract solids is 6.01 USD. CRM in this study gave the most significant proportion of COM with a percentage of 67.50%. The next largest proportion is COL with a percentage of 36.6%. COL and CRM which have the largest contribution to COM are in line with the study reported [15] in a study of Jussara pulp extraction using ultrasound-assisted and agitated bed-extraction technology and also reported [16] on the production of orange peel extract powder using the microwave-assisted extraction method and IOP Publishing doi:10.1088/1757-899X/1143/1/012041 5 the spray drying method. FCI in the production of liquid extract ranks third with a percentage of 14.48%. This condition occurs because the process of making liquid extracts is simple and is operated in-room operating conditions so that high technology is not required. CUT has the smallest percentage of 5.09% because the tools used for the extraction process are relatively simple and require relatively low energy.
3.1.2. Production cost of spray-dried dragon fruit peel extract. The powder production cost for the spray drying method in this study is calculated from the total cost of processing the peel until the powder is obtained. Table 3.2 presents the COM value along with the percentage of FCI, COL, CRM, CUT against COM for powder production with operating conditions of 170 o C and a total powder production of 20.9 tons of powder/year. Based on Table 3.2, the production cost of spray-dried powder is 29.89 USD/kg powder. CRM in this study gave the most significant proportion of COM with a percentage of 47.32%. CRM that has the greatest contribution to COM is in line with the study reported [15] in a study of Jussara pulp extraction using ultrasound-assisted and agitated bed-extraction technology and also reported on the research [16] on the production of orange peel extract powder using the microwave-assisted extraction method and the spray drying method. The next largest proportion is FCI with a percentage of 31.21%. The secondlargest proportion is FCI (31.21%) where this trend is in line with the economic evaluation of orange peel extract spray drying. It was reported that the proportion of FCI to COM for the production of orange peel extract powder was 34.6% for the variation of the solvent to orange peel ratio of 14, which is the largest proportion to COM [16]. This condition is due to the high costs incurred for the procurement of a spray dryer. CUT ranks third with a percentage of 15.21%. CUT is dominated by the need for the drying process in the form of electricity and natural gas, which is large in the spray drying process as well as the consumption of electricity by the main and other supporting equipment in the production process. The large energy consumption of the spray dryer was reported [12] in a study on the energy consumption of industrial spray dryers. In his report, he wrote, based on a survey of 32 spray dryers with an average evaporation capacity of 67.8 tons of water per hour, an average heat input of 333.3 GJ per hour was required. The smallest percentage is owned by COL, which is 6.26% due to the low wages of labor in Indonesia when compared to the wages of workers in the US as in [15].

Production cost of freeze-dried dragon fruit peel extract.
The cost of powder production using the freeze-drying method in this study is calculated from the total cost of processing the peel to obtain the powder. The processes involved include extraction, filtering, and drying using freeze-drying. Table  3.3 presents the COM values along with the percentage of FCI, COL, CRM, CUT against COM powder production with total powder production of 20,889 tons of powder/year.   Table 3.3, the COM per kg of powder is 55.60 USD. The FCI in this study provided the most significant proportion of COM with a percentage of 52.70%. This trend is in line with the economic evaluation of orange peel extract spray drying. It was reported that the proportion of FCI to COM for the production of orange peel extract powder was 34.6% for the variation of the solvent to orange peel ratio of 14, which is the largest proportion to COM [16]. A similar condition was also reported by [22] in an economic evaluation study on the reduction of fat content in annatto fruit seeds using supercritical carbon dioxide. The large FCI value is due to the purchase value of the expensive freeze dryer. The investment value of the freeze dryer was also reported [23] on the research of the investment value of various drying methods. The second-largest proportion is CUT (37.85%). CUT is dominated by the need for the drying process in the form of freeze-drying and refrigerator electricity. Freeze-drying requires a lot of energy, which is an obstacle to the application of this drying method to many materials [24]. CRM ranks third with a percentage of 5.78%. The small percentage of CRM is because the raw materials for production are relatively cheap. Dragon fruit peel is a waste from the production of other factories and the extraction process in this study uses water solvents that are widely available in Indonesia at relatively cheap prices. The smallest percentage is owned by COL, which is 3.68%, this is due to the low labor wages in Indonesia when compared to the wages of workers in the US as in research [15].

Comparison of production costs (COM/kg solid content) liquid extract, powder from the spraydried, and freeze-dried extract.
. The graph presented in Figure 3.2 shows the COM for powder is greater than liquid extract. There is an increase in COM from liquid extract production to powder production from spray drying 4 times. Meanwhile, the increase in COM from liquid extract production to freeze-drying production is 7.5 times. Spray drying and freeze-drying provide substantial COM additions. The process increases the values of FCI, CUT, and COL which contribute to COM computation. However, the conversion to powder provides significant mechanical and economic advantages, where the powder has better stability, longer shelf life, and lower storage requirements and distribution costs [25]. In the production process using a spray dryer and freeze dryer, the FCI value increased significantly due to the cost of purchasing the main equipment in the form of a spray dryer and other companion tools such as the inlet air heater and pump set. CUT also increases due to the need for electricity as the main energy for the spray dryer, and the need for gas supply to heat the inlet spray dryer air supply. COL increases along with the addition of processes requiring an increase in the number of workers.
The spray drying method is the cheapest and most effective method among other microencapsulation methods because it is suitable for continuous operation, provides convenience in the aspects of transportation and distribution, thereby reducing storage and transportation costs [26]. The resulting product stability is the same as it had when it is made. The drying process to powder reduces the moisture content significantly where the extract powder from spray drying has a moisture content of 0.08. A very large reduction in moisture content due to the drying process inhibits microbial growth and results in longer shelf life. Besides, the range of distribution of powders is wider than that of liquid extracts. The product in the form of a liquid extract has a low shelf life and stability, which hinders the distribution process over long distances.

Economic Analysis and Sensitivity Analysis of Drying Powder Production (Spray Drying and
Freeze Drying) Dragon Fruit Peel Extract Assumptions and the basis for the economic feasibility of operating a factory are evaluated using the net present value [20]. In this study, the feasibility of economic analysis methods is sought including NPV (Net Present Value), DPBP (Discounted Payback Period), IRR (Internal Return Ratio), PVR (Present Value Ratio). Making cash flow refers to the book Analysis, Synthesis, and Design of Chemical Process [10]. The assumptions and bases used are summarized in Table 3.4. This study aims to analyze the production economics of both powder manufacturing methods. The results of a further analysis can be used to compare and get an overview of the two most economical methods. The economic analysis of the spray-dried extract production gives a Discounted Payback Period (DPBP) value of 4.3 years, which shows that it takes 4.3 years after start-up to return fixed capital investment. A positive Net Present Value (NPV) indicates that the factory is profitable [28]. The Present Value Ratio (PVR) shows that the amount of incoming or outgoing costs is 3.3 times the costs incurred and shows that the factory operation provides a profit of 3.3 times the investment value. The Internal Rate of Return (IRR) value shows a positive value above the bank interest discount rate of 6%. In the investment criteria, the IRR must be greater than the OCC or opportunity cost of capital so that the IOP Publishing doi:10.1088/1757-899X/1143/1/012041 8 investment plan is feasible to implement [28]. So that with an IRR that is far above the discount rate, investment in production is feasible. This can be caused by the relatively low COM, which is 29.89 USD, and because the high purity causes the selling price in the big market. The selling price is a component that greatly influences the factory's annual revenue. Revenue is known to be one of the main contributors affecting the economy of production activity.
The economic analysis on Freeze-dried extract production gives a DPBP value of 7.27 years, NPV is positive, PVR is 1.78, and IRR is 8.7%. The Internal Rate of Return (IRR) value shows a positive value above the bank interest discount rate of 6%. In the investment criteria, the IRR must be greater than the OCC or opportunity cost of capital so that the investment plan is feasible to implement [28].

Sensitivity Analysis Spray Dried and Freeze-Dried Extract.
Sensitivity analysis is carried out to observe the impact of changes in several economic parameters on NPV so that it can be found that the most significant parameters affect the profitability of a plant [21]. Therefore, in this case, the sensitivity analysis is determined by projecting COL, CW (Cost of Water), COE (Cost of Electricity), COP (Cost of Peel), and selling price. The value of each factor will be varied with a relative change range of 5%. The results of the analysis of the impact of parameter changes on the NPV on spray-dried and freezedried extract shown in freeze-dried extract.
Sensitivity analysis for the spray-dried extract production provides that the selling price aspect is the aspect that has the most significant influence on NPV. Therefore, this uncertainty needs to be minimized, among others, by negotiating with the buyer. The trend found is in line with a research report on the economic analysis of citrus peel extract powder using the spray drying method [17]. It was reported that selling price is the most influencing aspect of the economics of powder production. Sensitivity analysis for the freeze-dried extract production also provides that the selling price aspect is the aspect that has the most significant influence on NPV. Therefore, this uncertainty needs to be minimized, by negotiating with the buyer.

Conclusion
The production cost of dragon fruit peel liquid extract (COM/kg dry solids) is USD 6.01, the production cost of dragon fruit extract powder using spray drying and freeze-drying methods is USD 29.89 and USD 55.6, respectively. The increase in the production cost of liquid extract for powder is 4 times using the spray drying method and 7.5 times using the freeze-drying method. The economic parameters of powder production using spray drying method are obtained NPV, DPBP, PVR, IRR respectively USD 1,989,412.68, 4.3 years, 3.31, and 20.6%. Whereas economic parameters of powder production using freeze-drying are obtained NPV, DPBP, PVR, IRR respectively 7.27 years, USD 2,156,866.29, 1.78, and 8%. It is also known that drying using spray drying shows better economic parameters than freezedrying. The sensitivity analysis of powder production using the spray drying method shows that the IOP Publishing doi:10.1088/1757-899X/1143/1/012041 9 selling price parameter is a parameter that has a significant effect on the economics of production activity followed by COP and COL.