Characterization and comparison of aroma profiles of orange pulp and peel by GC-MS/O, OAV, aroma recombination and omission tests

Citrus, as one of the most popular fruits in the world, besides their pulp, their peel has a unique flavor and rich value. Compared with pulp, the aroma of citrus peel is more intense and unique, and there are few comprehensive studies on the difference between citrus peel and pulp aroma properties. In this study, the aroma characterization of September Red navel orange (SRO) pulp (OPU) and peel (OPE) was investigated by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), odor activity value (OAV) determination and sensory analysis. Terpenes, alcohols, and aldehydes were found as the major volatile compounds in SRO, meanwhile, 23 key aroma components were detected, with 15 of them present in both OPU and OPE, and the concentration of the 15 substances in OPE was 1-1700 times higher than in OPU. The quantitative descriptive analyses (QDA) sensory analysis results showed there were six main fragrances present, with "fruity", "green", "floral", and "woody" significantly stronger (p<0.05) in OPE than in OPU. Finally, (E)-2-pentenal, ethyl butyrate, (E)-2-decenal, styrene, (Z)-3-hexen-1-ol, (Z)-2-hexen-1-ol, linalool, nerol, gamma-terpinene, and acetic acid were summarized as the key aroma compounds by aroma recombination and omission experiments. This study expands our knowledge of orange aroma characterization and not only provides theoretical basis for natural fruit flavor products, but also helps to promote the healthy development of the flavor industry.