title: Aroma composition changes in early season grapefruit juice produced from thermal concentration.
abstract: Differences in aroma components and total volatiles between a single unpasteurized Marsh grapefruit juice and its 65 Brix concentrate reconstituted to 10 Brix were examined using GC-olfactometry (GC-O) and GC-FID. Total volatiles (FID) in the reconstituted concentrate were reduced to less than 5% of initial values, but 57% of total aroma (GC-O) remained. Forty-one aroma-active compounds were observed in unpasteurized single strength juice, whereas 27 components were found in the unflavored reconstituted concentrate. Aroma-active compounds were classified into grapefruit/sulfury, sweet/fruity, fresh/citrusy, green/fatty/metallic, and cooked/meaty groups. Five of six components in the sweet/fruity and 14 of 18 green/fatty/metallic components survived thermal concentration. However, only 4-mercapto-4-methyl-2-pentanone in the grapefruit/sulfury group, and linalool and nootkatone from the fresh/citrusy group, were found in the reconstituted concentrate. Methional was the only aroma compound in the cooked/meaty category found in both juice types. beta-Damascenone and 1-p-menthen-8-thiol were found only in the reconstituted concentrate. 4-Mercapto-4-methyl-2-pentanol was found for the first time in grapefruit juice.
authors.affiliation: Citrus Research and Education Center, University of Florida, Lake Alfred, Florida 33850, USA.
authors.forename: Jianming
authors.initials: J
authors.lastname: Lin
authors.forename: Russell L
authors.initials: RL
authors.lastname: Rouseff
authors.forename: Sandy
authors.initials: S
authors.lastname: Barros
authors.forename: Michael
authors.initials: M
authors.lastname: Naim
mesh_terms: D001628:Beverages / Q000032:analysis*; D002849:Chromatography, Gas; D002957:Citrus / Q000737:chemistry*; D005511:Food Handling; D006358:Hot Temperature; D009812:Odorants / Q000032:analysis*; D012621:Seasons; D014835:Volatilization