Indones. J. Chem., 2021, 21 (4), 1057 - 1062 Siti Susanti et al. 1057 NOTE: Comparing the Chemical Characteristics of Pectin Isolated from Various Indonesian Fruit Peels Siti Susanti 1* , Anang Mohamad Legowo 1 , Nurwantoro 1 , Silviana 2 , and Fahmi Arifan 3 1 Food Technology Division, Department of Agriculture, Faculty of Animal and Agricultural Sciences, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia 2 Department of Chemical Engineering, Faculty of Engineering, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia 3 Diploma Program of Chemical Engineering, Faculty of Vocational School, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia * Corresponding author: email: sitisusanti@live.undip.ac.id Received: September 16, 2020 Accepted: February 9, 2021 DOI: 10.22146/ijc.59799 Abstract: The Indonesian pectin manufacturing industry is underdeveloped, and pectin is imported to meet its increasing demand; we attempted to isolate pectins from various fruit peels, such as orange peel (OP), papaya peel (PP), mango peel (MP), watermelon peel (WP), and chayote peel (CP) and investigated their chemical characteristics (equivalent weight of the extracted pectins and their moisture, ash, methoxyl, and galacturonic acid (GA) contents). Acid extraction, purification, precipitation, and drying processes were used to process the isolated pectins. We examined their chemical properties for conformance to quality standards advised by the International Pectin Producers Association (IPPA). The moisture (except OP pectin) and ash contents (except PP pectin) of the extracted pectins were within the limit set by IPPA. However, the equivalent weight (W eq) of any of the isolated pectins did not satisfy IPPA standards. The methoxyl contents of the pectins isolated from OP, WP, and CP satisfied IPPA standards. High methoxyl pectins were isolated from PP and MP. The galacturonic acid contents of the isolated pectins were higher than the acceptable limit of the GA level. Thus, OP, PP, MP, WP, and CP are potential sources of pectin. Keywords: natural source; chemical; pectin; fruit peels ■ INTRODUCTION Pectin is a polysaccharide and a functional ingredient utilized in the food and pharmaceutical industries. Natural pectin can be isolated from the cell walls of different plant parts [1]. The fruit peel, which is considered a waste product in the food and fruit-based industries, is also a source of natural pectin [2]. Pectin is used as a stabilizer in food and has emerged as an important ingredient used in the food industry. The last decade has seen a growing interest in Indonesian culinary. This has resulted in a gradual increase in the demand for pectin [3]. Unfortunately, pectin is still imported into Indonesia as the pectin manufacturing industry in Indonesia is still undeveloped. However, a huge amount of waste that can be potential sources of pectin is generated each year by the fruit industries present in the country [3]. The utilization of fruit peels as sources of pectin is still in its nascent stage. The peels of various indigenous fruits (such as banana, durian, grapefruit, and papaya peels) can be potential sources of natural pectin [4]. Various extraction and isolation methods for obtaining pectin have been reported. The isolation methods employed can potentially influence the yield and chemical characteristics of pectin. This study outlined the procedure to isolate pectin from various fruit peels (mango, orange, papaya,