Feijoa or pineapple guava (Acca sellowiana) is a native fruit species from the Southern region of Brazil. Several studies have reported various biological activities of feijoa, including antimicrobial, antioxidant, antitumor and anti-inflammatory properties, attributed to its composition rich in important bioactive compounds, such as polyphenols, flavonoids, vitamin C and dietary fibers. Nevertheless, peels represent about 60% of total fruits weight, which are discarded during industrial processing or consumption of whole fresh fruits. To the best of our knowledge, no previous studies focusing on the monosaccharide composition of its by-product to be used as an ingredient in food formulation were reported. The hypothesis of our study is that the feijoa peel flours can be considered promising functional food ingredients. Samples were separated into two groups, which samples were composed only of mesocarp (FPF1) and samples were used epicarp and mesocarp (FPF2). Each sample was evaluated and compared in relation to the determination of the neutral monosaccharide composition and uronic acids, analyzed by liquid-gas chromatography. The main components were glucose (43.3% in FPF1 and 34.4% in FPF2) and xylose (33.9% in FPF1 and 37.4% in FPF2), followed by uronic acid (9.1% in FPF1 and 12.5% in FPF2). The neutral monosaccharide composition suggests the presence of cellulose, xyloglucans, glucomannans, and pectin. The differences in the levels of rhamnose, arabinose, and uronic acid indicated that a higher amount of pectin is present in the epicarp peel compared to the mesocarp. The results indicated that the main contribution to the high glucose content of feijoa peel flours is due to the cellulose and its related to the high content of insoluble dietary fiber in the samples. Studies have shown that polysaccharides founded in the samples possess biological and pharmacological activities, including the modulation of the immune response, antitumor, anti-glycemic and suppress the progression of diabetes.