TAHITI LIME POSTHARVEST AND NON-DESTRUCTIVE ASSESSMENT OF ESSENTIAL OILS BY NIR SPECTROSCOPY

Tahiti lime trees were sprayed with bioregulators to evaluate their effect on fruit abscission, postharvest life, and terpene content. The amounts per tree used were: 40 mg active ingradient (a.i.) aminoethoxyvinylglycine (AVG), 0.6 mg eq. kinetin of an Ascophyllum nodosum extract (AN) per tree, 3.4 mg a.i. of a hydrolyzed shark tissue emulsion (AHS), 0.04 mg a.i. of a fertilizer containing triacontanol and brassinolide (TB), 24 mg gibberellic acid 3 (GA3), 3.5 ng gibberellic acid 4/7 (GA_4&7), and a combination of GA₃+GA_4&7 treatments. To assess the effect of biorregulators on fruit quality near infrared spectroscopy (NIRS) was used as a non-destructive, real-time analysis to evaluate the terpene content in essential oils of the fruit peel without solvent extractions within three days of harvest. Postharvest quality trait changes in intact limes stored at 10°C and 85% relative humidity were monitored during eight weeks after harvesting. The GA treatments resulted in fruits whose color took longer to change from green to yellow after harvesting. Trees treated with AVG, GA_4&7 and GA₃+GA_4&7 produced fruit with significantly more juice than other trees. AVG-, AHS- and AN-treated trees had higher fruit retention rates and yielded the most fruits for six weeks at the beginning of the harvesting season. NIRS revealed C-H stretch bands that confirmed the presence of terpenes in Tahiti lime flavedo analyzed directly on the fruit peel, and strongly suggests a directly proportional relation between terpene content and fruit maturity. A calibration model for quantification of terpenes in lime peel by NIRS is in development.