Aroma composition changes in early season grapefruit juice produced from thermal concentration.
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.
Lin
Jianming
J
Citrus Research and Education Center, University of Florida, Lake Alfred, Florida 33850, USA.
Rouseff
Russell L
RL
Barros
Sandy
S
Naim
Michael
M
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