Novel nondestructive technique to determine optimum harvesting stage of ‘Ataúlfo’ mango fruit

Authors: OSUNA-GARCIA, JORGE - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP); OLIVARES-FIGUEROA, JESUS - Autonomous University Of Nayarit; TOIVONEN, PETER - Agri Food - Canada; PEREZ-BARRAZA, HILDA - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP); Goenaga, Ricardo; GRACIANO-CRISTOBAL, MARIA - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)

Submitted to: Advances in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2021
Publication Date: 7/10/2021
Citation: Osuna-Garcia, J.A., Olivares-Figueroa, J.D., Toivonen, P.M., Perez-Barraza, H., Goenaga, R.J., Graciano-Cristobal, M.J. 2021. Novel nondestructive technique to determine optimum harvesting stage of ‘Ataúlfo’ mango fruit. Advances in Agriculture. 12:2349-0837. https://doi.org/10.24297/jaa.v12i.9069.
DOI: https://doi.org/10.24297/jaa.v12i.9069

Interpretive Summary: Mexico is one of the main mango-exporting countries in the world. During 2019, about 78.7 million ten-pound boxes were marketed, mainly to the USA and Canada. The most important variables used to determine optimal harvest time are pulp color and total soluble solids, both of which use destructive and labor intensive techniques. Recently, some countries have started to use a minimum dry matter content (DM) to determine optimum fruit harvesting time. In Australia, Kensington Pride, Calypso and Honey Gold varieties are harvested when fruit have a minimum of 15% DM. For varieties grown in Mexico, there is no standards for DM content at harvest time. A portable spectrometer was validated to determine optimum harvesting stage of ‘Ataúlfo’ using dry matter and skin color as fruit indicators. To build the model, samples were collected in the following stages: Unripe; Green Mature 1; Green Mature 2; Green Mature 3; and, Fully mature. Fruit were scanned with a near infrared spectrometer using three temperatures (15, 25, and 35 °C). Skin color (‘a’ value) was measured with a Minolta 400 colorimeter. DM was attained in a conventional oven by drying samples for 72 h at 60 °C. The best model linearity was obtained using skin color ‘a’ (R2 = 0.98), whereas for DM the R2 was only 0.70. For the first validation, the best predicted value was skin color ‘a’ with an R2 = 0.9144, followed by DM with an R2 = 0.7056. On the second validation, the adjusted predicted value for skin color ‘a’ had an R2 = 0.8798, while DM had an R2 = 0.4445. When comparing NIR versus Heat Units Accumulation, in Nayarit, ‘Ataúlfo’ skin color average difference between the spectrometer vs the colorimeter was only -0.04. For ‘Ataúlfo’ from Sinaloa, skin color average difference was only -0.06, but the correlation was higher (R2 = 0.90). In conclusion, measuring skin color with the NIR spectrometer has potential as a nondestructive technique to determine the optimum harvesting stage of ‘Ataúlfo’ mango.

Technical Abstract: A portable spectrometer was validated to determine optimum harvesting stage of ‘Ataúlfo’ using dry matter and skin color as fruit indicators. To build the model, samples were collected as follows: a. Unripe; b. Green Mature 1; c. Green Mature 2; d. Green Mature 3; and e. Fully mature. Fruit were scanned with a near infrared spectrometer at three temperatures (15, 25, and 35 °C). Skin color (‘a’ value) was measured with a Minolta 400 colorimeter. DM was attained in a conventional oven by drying samples for 72 h at 60 °C. Model was built and validated three times. The best model linearity was obtained on skin color ‘a’ (R2 = 0.98), whereas for DM the R2 was only 0.70. For the first validation, the best predicted value was skin color ‘a’ with an R2 = 0.9144, followed by DM with an R2 = 0.7056. On the second validation, the adjusted predicted value for skin color ‘a’ had an R2 = 0.8798, while DM had an R2 = 0.4445. When comparing NIR versus Heat Units Accumulation, in Nayarit, ‘Ataúlfo’ skin color average difference between the spectrometer vs the colorimeter was only -0.04. For ‘Ataúlfo’ from Sinaloa, skin color average difference was only -0.06, but the correlation was higher (R2 = 0.90). In conclusion, measuring skin color with the NIR spectrometer has potential as a nondestructive technique to determine the optimum harvesting stage of ‘Ataúlfo’ mango.