Electronic nose discrimination, analytical identification, and sensory confirmation of flavor impact components in citrus juices

Orange and grapefruit juices were evaluated for flavor characteristics using sensory techniques and compared with results from three different electronic noses. Volatile components were extracted from juices using both solid phase microextraction (SPME) and liquid-liquid extraction. Volatiles were characterized by gas chromatography-olfactometry (GCO) and identified by GC and mass spectrometry (MS).; A 12 metal oxide sensor ENose utilizing multivariate statistical analysis (MVSA) could distinguish between 26 different grapefruit juice cultivars. A 12 organic polymer sensor ENose exhibited some success in discriminating between orange juices (OJ) exposed to different heat treatments (unpasteurized, heated to 96°C for: 8 seconds, 120 seconds, and in excess of 180 seconds) but was less successful in discriminating between OJ from different cultivars. A 32 organic polymer sensor array ENose utilizing MVSA could differentiate between unpasteurized OJ (UPOJ) stored for 0, 3, 6, 9, and 12 days at 2°C. Results from Canonical discriminant analysis of ENose data were similar to that from sensory panel, and from headspace GC data from the identical UPOJ stored for different times.; Headspace aroma components from UPOJ and heat abused early-mid season OJ were extracted using SPME and analyzed using GCO. Eighteen aroma peaks were common to both heat treated and UPOJ. Six aroma active peaks were observed in only UPOJ headspace. Five different aroma components were observed in heat abused juice. GCO analysis of liquid-liquid extracts from unpasteurized and severely heated Valencia juice found 23 aroma peaks common to both samples, but found 17 peaks only in UPOJ, and 2 peaks only in the heat abused sample.; Recombination of 8 intense aroma contributors of UPOJ, plus 4 additional components reported in OJ, added to model juice solutions did not differ significantly (p <.05) in orange aroma and flavor from an UPOJ previously frozen.; The primary source of linalool, a major flavor impact compound, in Valencia orange juice was from the peel oil which is typically introduced during juice extraction. Highest concentrations of linalool were found in juices which experienced the most peel maceration during extraction.