Alterations in the morphological, sugar composition, and volatile flavor properties of petai (Parkia speciosa Hassk.) seed during ripening.

Petai seeds are one of the well-known strong-smelling foods of the Southeast Asian region that have been harvested and commercially offered in different ripening forms. The current study focused on alterations in the size, color, sugar composition, and volatile flavor properties of petai seeds in the four ripening stages (unripe, mid ripe, ripe, and over-ripe). The ripening process was mainly indicated by the increase in size and weight as seed color turned paler and less greenish. The total sugar content gradually increased during ripening, and then elevated from 1.60 g/100 g (ripe seed) to the level of 2.82 g/100 g in the over-ripe seed. Ripening also altered the volatile flavor composition of petai seed, wherein the predominant aldehydes (hexanal and acetaldehyde) were decreased, and the sulfuric compounds (hydrogen sulfide, methanethiol, and 1,2,4-trithiolane) tended to increase. Additionally, gas chromatography-olfactometry (GC-O) analysis revealed alterations in the perceived odor strength and sensation of each volatile compound and demonstrated volatile flavor profiles, viz. detection percentages of volatile group odor strengths and descriptive odors, of petai seed. These results provide valuable information for monitoring alterations in the physical appearance, sugar composition, and aroma that represent the flavor quality in seasonal petai seed.