Pink Guava Puree (PGP) factory produces tons of residues from its unit operation [refiner (R),
siever (S), and decanter (D)]. These residues represent a waste of nutrients and can contribute
to environmental problem. However, it can benefit related industries if the properties of the
residues are known. Thus, this research aims to determine the compositions of the residues
from PGP processing factory in order to evaluate possible value-added by-product and energy
sources. The residues from each unit operation were being tested for proximate composition,
dietary fibre components, pH value, emulsifying activity (EA) and emulsifying stability (ES),
carbon-to-nitrogen (C/N) ratio, and sugar analysis. The sugar content was analysed using High
Performance Liquid Chromatography (HPLC-RI detector). Results showed that the residues
have good composition of carbohydrate (11.82–12.18%), and thus potential as carbon source
and can be a good substrate for fermentation. These residues may also benefit the food industry
as a good source of dietary fibre (18.63–29.86%). The pH value for these PGP residues is 4;
thus they were considered as acidic food by-product. The low pH value also contributed to the
low EA and ES value other than the low content of protein in the sample. C/N ratio for PGP
residue from R (46:1) is the lowest compared to the C/N ratio from S (84:1) and D (115:1). The
amount of sugars detected in the PGP residues in descending order were fructose > glucose >
sucrose.