## 4 Discussion  
Empirically, Indonesians use longevity spinach in their meals with quantities ranging from 5 to 8 leaves or a mass equivalent 10-16 g once per day. Considering the acceptable daily intake for longevity spinach extract and its water content, 300 mg of longevity spinach extract powder is equivalent to 16 g of fresh longevity spinach [38,39]. Therefore, the product was planned to be eaten once a day by individuals in Jakarta and its satellite cities. Indonesia's capital city area was chosen because of its upper-middle class population, which is the biggest in Indonesia. Middle-to-upper socioeconomic groups were chosen because this group was considered to have a greater awareness of the importance of maintaining health to stay productive without any significant complications, especially during the pandemic [40]. In Jakarta, 250,000 citizens suffer from diabetic disease, of which only a quarter use herbal supplements in addition to conventional medicines [36,41]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Plant Summary** & **Value** \\ \hline Total capital expenditure (USD) & 598,127.77 \\ Operational cost (USD/year) & 819,735.03 \\ Revenues (USD/year) & 1,928,217.68 \\ Batch size (kg) & 0.251 \\ Batch quantities/day & 15 \\ Feedstock (kg/day) & 720 \\ Conversion (\%) & 0.52 \\ Production rate (bottles/year) & 26,082 \\ Payback period (months) & 17 \\ IRR (after taxes) (\%) & 91.65 \\ NPV (at 9.95\% interest) (USD) & 3,972,653,13 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Economic summary of longevity spinach extract production. Considering the growth of the herbal industry of 9% per year, the market share was fixed to 5625 diabetic citizens who would use the supplement [42]. Indonesia, as a tropical and biodiverse country, serves as a region of maximum potential in this feasibility study. With the advantage of being a maritime country, Indonesia has a strategic location for developing industry because products can be shipped in two opposite directions at the same time [43]. The Indonesian government has executed an integrated port network plan for international purposes, which has opened a bigger market [15]. Thus, Jakarta not only serves as the highest-value market but also is a major supply chain point for the global market. The longevity spinach manufacturing plant would also need sustainable feedstock. The longevity spinach can be cultivated optimally in low terrain at a maximum of 1250 m above the sea surface. The cultivation process also requires moderate water intake, at about 1500 to 3000 mm rainfall intensity per year [44]. Most areas in Southeast Asia concur with those requirement conditions, while other sub-tropical areas such as South China and Eastern Australia must build closed farms with a constant water supply in their low terrains [13; 45; 46]. It is important to meet these requirements so the longevity spinach can achieve the greatest phytochemical composition [14]. It is calculated that 1000 m\({}^{2}\) of farm area will produce 450 kg of longevity spinach per year, so the extraction plant would need around 500 hectares of land for cultivation purposes [44]. Longevity spinach extract has high anti-hyperglycemic activity, with more than 40% effectiveness [38]. The previous research also used dried leaves as the feedstock and drinking water as the solvent. However, from research on the isolated compounds no more than 30% effectiveness was found for each phytochemical compound [47; 48; 49]. Thus, the higher effectiveness in longevity spinach extract as compared to the isolated compounds can be considered as due to the synergetic activity between those compounds. Moreover, the main phytochemical compound of the longevity leaf extract is p-hydroxycinnamic acid, which has immunomodulatory potential. Based on a study by [PERSON] et.al, p-hydroxycinnamic acid can induce splenocytes proliferation at 80%, with decreasing values at increasing concentrations [50]. As shown by the economic assessment, the operational expenditure was greater than the capital expenditure.