Molecular Docking Comparative Analysis of Ascorbic Acid, Citric Acid, and Acetic Acid as Browning Inhibitors of Pineapple Fruit (Ananas comosus) Nareswari Nestiti (a*), Bambang Dwi Argo (a), Inggit Kresna Maharsih (a), Rini Yulianingsih (a)
a) Department of Biosystem Engineering, Faculty of Agricultural Engineering, Universitas Brawijaya
Jalan Veteran, Malang 65145, East Java, Indonesia
*nareswarin[at]student.ub.ac.id
Abstract
Pineapple (Ananas comosus) will turn into brownish color through a fruit maturity phase due to the browning reaction. Browning reaction is color changing process of food from its original color to a darker color by the presence of quinone compounds. Polyphenol oxidase (PPO), Phenylalanine ammonia-lyase (PAL), and Peroxidase (POD)- generally cause browning process in pineapple. Meanwhile- ascorbic acid, citric acid, and acetic acid proven as browning inhibitor compounds in food industry. Molecular docking simulations had not been carried out to determine the binding energy (∆-G) and inhibition constant (Ki) between PPO, PAL, or POD- with ascorbic acid, citric acid, and acetic acid as browning inhibitors in previous studies. Molecular docking carried out to determine the best interaction between ligands (ascorbic acid, citric acid, and acetic acid) and the receptor which represented by enzymes (PPO, PAL, POD) in this study. This research obtained the best type of browning inhibitor for each enzyme. The best browning inhibitor for POD enzymes is acetic acid with a ∆-G value of -4.03 kcal/mol and a Ki of 1.103 mM. The best browning inhibitor for PAL enzymes is ascorbic acid with a ∆-G value of -5.9 kcal/mol and a Ki of 0.047 mM. The best browning inhibitors for PPO enzymes were ascorbic acid and citric acid with ∆-G value of -5.4 kcal/mol and a Ki of 0.109 mM. Ascorbic acid is the main inhibitor of PPO due to more bond interactions discovered compared to PPO and citric acid interactions.
