*Corresponding author. Email: reknasugiyana@yahoo.com eISSN: 2550-2166 / © 2020 The Authors. Published by Rynnye Lyan Resources FULL PAPER Food Research 4 (6) : 2224 - 2232 (December 2020) Journal homepage: http://www.myfoodresearch.com Optimization of protein and tannin extraction in Moringa oleifera leaf as antioxidant source 1,* Wahyuni, R., 2 Wignyanto, W., 2 Wijana, S. and 2 Sucipto, S. 1 Department Food Science and Technology, Faculty of Agriculture, Yudharta University, Purwosari, Pasuruan, East Java, Indonesia 2 Department of Agro Industrial Technology, Faculty of Agricultural Technology, Brawijaya University, Malang, East Java, Indonesia Article history: Received: 23 June 2020 Received in revised form: 16 July 2020 Accepted: 9 August 2020 Available Online: 3 October 2020 Keywords: Moringa leaf, Extraction optimization, Total protein, Total tannin, Antioxidant activity DOI: https://doi.org/10.26656/fr.2017.4(6).293 Abstract Moringa oleifera contains high nutritional and bioactive compounds that have the potential as a source of antioxidants. The main objective of this study was to obtain optimal conditions in the extraction process of Moringa leaf, maintain protein and antioxidant activity, and reduce tannin. It is carried out through the response surface method which consists of two factors. The first factor (X 1 ) was the extraction temperature (°C) which contains three levels, namely 70, 80, and 90°C. The second factor (X 2 ) was time (mins) consisting of three levels, namely 5, 10, and 15 mins. The parameters in this study were total protein, antioxidant activity, and total tannin. The results revealed that the optimum condition for Moringa leaf extraction is found to be temperature 80.54°C and a time of 12.19 mins. In that treatment, the total protein is 17.4594%, antioxidant activity is up to 10.2629 µg/mL, and tannin is 7.853% with the desirability of 0.792 or 79.2%. 1. Introduction Moringa oleifera is a well famous plant cultivated in hot up to tropical climates, such as Indonesia (Mendieta et al., 2013). Organic moringa cultivation in Indonesia has been carried out in several regions such as Blora, Central Java, Gunung Kidul, Yogyakarta, Poteran Island, Sumenep Regency, and NTT Province. One of the parts of the moringa plant that can be utilized is the leaf, where the production of wet leaves is around 5-6 tons/ hectare (Krisnandi, 2015). Moringa leaf contains fiber, protein, fat, minerals such as Ca, Mg, P, K, Cu, Fe, S, Vitamins: A (Beta- carotene), B-choline, B1-thiamine, riboflavin, nicotinic acid, ascorbic acid, acid Amino: Arginine, Lysin, Tryptophan, Phenylalanine, Threonine, Leucine, Methionine, Isoleucine, Valine, Phytochemicals: tannin, sterol, saponin, terpenoid, phenolic, alkaloid, flavonoid, quercetin, isoleucine, valine, phytochemicals: tannins, sterols, saponins, terpenoids, phenolics, alkaloids, flavonoids, quercetin, isoleucine, violins, phytochemicals: tannins, sterols, saponins, terpenoids, phenolics, alkaloids, flavonoids, quercetin, isoucercitins, caemferothosrays, glycothiocytes, glycotosicans (Gopalakrishnan et al., 2016). Besides, the iron content in moringa leaf is also higher than other vegetables, which is 17.2 mg/100 g (Yameogo et al., 2011). In general, all parts in the moringa plant have several functions, namely as hypolipidemic, antiatherosclerotic, prevention of cardiovascular disease (Chumark et al., 2008), anti-diabetic, inflammation, anemia, and immune system booster because moringa is rich in nutrients, essential amino acids, vitamins, minerals, and 40 natural antioxidants sources (Mahmood et al., 2010). Nowadays, most research on the use of moringa leaf tend to be directed to the use of natural antioxidants. The antioxidant activity of moringa leaf extract, both young and old, is very effective to prevent oxidative damage of the main biomolecules (Shahriar et al., 2012). This is because the phenol content in a leaf is much higher compared to pods and seeds, so the use of moringa leaf as a source of natural antioxidants is highly recommended (Wangcharoen et al., 2011). Apart from being a source of antioxidant, the leaf also has a function as anti-inflammatory, anti-pain (Upadhye et al., 2011), anti-ulcer (Das et al., 2011), and as an antimicrobial and wound healing (Moyo et al., 2012). In addition to its advantages, moringa has weaknesses, including having a low protein digestibility which is 56.1±8.9% and there are anti-nutritional substances namely tannins, saponins, and trypsin inhibitors. Production protein concentrates is