Characterization of phenolic compounds and aroma active compounds in feijoa juice from four New Zealand grown cultivars by LC-MS and HS-SPME-GC-O-MS.

Abstract

The phenolic compounds and aroma active compounds in feijoa (Acca sellowiana (O.Berg) Burret) juice from four New Zealand grown cultivars (Apollo, Unique, Opal Star, and Wiki Tu) were investigated. A high total phenolic content (maximum 1.89 mg GAE/mL juice) and significant antioxidant activities (maximum 14.66 mM Trolox/mL juice) were determined in feijoa juices. A total of 7 phenolic compounds from the screening of 29 standards were identified and quantified by LC-MS, with procyanidin B1 (209.78-511.07 μg/mL) and (+)-catechin (121.80-472.75 μg/mL) being the most abundant. Procyanidin B2 and quercetin-3-galactoside were reported in feijoa samples for the first time. The volatile compounds in feijoa juice were identified by HS-SPME-GC-MS, and 17 of the 63 identified compounds were not previously reported in feijoa samples. A total of 25 aroma active compounds were further identified by the olfactory test, and the esters and terpenes were the dominant compounds contributing to the aroma of feijoa juice. Methyl benzoate showed the characteristic "feijoa-like" aroma with a concentration of 13.62-52.62 μg/g juice. The aroma profile of feijoa juice from the four selected cultivars was established, and the "fruity" and "green, grassy & herbal" notes were the predominant attributes. Among the four selected cultivars, the Unique cultivar had the highest total phenolic content and antioxidant activities, while the Wiki Tu was the most aroma intensive. This study, first report on the phenolics and aroma compounds in feijoa juice with comparison of four cultivars, could be fundamental and essential to natural fruit juice industry and feijoa fruit investigation, as well as provided scientific evidence to local feijoa market and growers regarding cultivar selection.