Impact of Preharvest and Postharvest on Color Changes during Convective Drying of Mangoes

Abstract

The purpose of this study was to evaluate the impact of the harvest stage, ripening conditions and maturity on color changes of cv. ‘Cogshall’ and cv. ‘Kent’ variety mangoes during drying. A total of four harvests were undertaken, and the fruits were ripened at 20 and 35 °C for five different ripening times at each temperature. At each ripening time, mangoes were dried at 60 °C/30% RH/1.5 m/s for 5 h. A wide physico-chemical and color variability of fresh and dry pulp was created. The relationships according to the L*, H* and C* coordinates were established using mixed covariance regression models in relation to the above pre- and postharvest (preprocess) parameters. According to the L* coordinate results, browning during drying was not affected by the preprocess parameters. However, dried slices from mangoes ripened at 35 °C exhibited better retention of the initial chroma, and had a greater decrease in hue than dried slices from mangoes ripened at 20 °C. However, fresh mango color, successfully managed by the pre- and postharvest conditions, had more impact on dried mango color than the studied parameters. The preprocess parameters were effective levers for improving fresh mango color, and consequently dried mango color.

Impact of Special Drying Schemes on Color Stability of Mangoes with Different Maturity Degrees

“…The color of the mangoes’ flesh has also changed during ripening, with a significant decrease in L* and H*, without reaching stabilization. However, this would not have been long in coming, as the values of the color indexes reached were close to the optima at 20 °C described by Diop et al [ 3 ]. The evolution of the physicochemical parameters and their timing were similar to those reported by Noiwan et al [ 27 ] on the Nam Dok Mai variety.…”

“…However, in mango-drying units, the raw material comes from various origins in terms of varieties, maturity degrees and other pre- and postharvest parameters influencing mango composition [ 15 ]. This latter factor, as documented by Diop et al [ 3 ], causes differences in the content of substrates involved in color degradation reactions. In this case, the increase with the maturity degree of the contents of reducing sugars [ 16 ] and amino acids [ 17 ], which are the substrates of the Maillard reaction, and that of the carotenoid contents, leads to more intensive oxidation during convective drying [ 18 ].…”

“…The L*, a* and b* data were converted into L*, H* and C*. The C*-based color alterations are not presented, due to the fact that this index is not a good predictor of changes in carotenoid contents for the Cogshall variety [ 23 ], nor for browning or color alterations during drying [ 3 ].…”

“…As with the orange sweet potato [ 2 ], the color observed is the result of an accumulation of reactions progressing as the fruit matures, from paring–cutting and racking, drying and then storage. Diop et al [ 3 ] showed that a “good drying procedure” caused very little alteration to fresh mango pulp color, regardless of its color or its origin. Production unit operators often point out that this is not the case under real conditions, in particular with the presence of overly dark products.…”

Laser light backscattering image to predict moisture content of mango slices with different ripeness during drying process

“…However, because of the difference in external conditions such as the growth environment, the quality of mango itself, such as color, polyphenol and carotenoid content, and so forth, would be uneven, it is difficult to obtain a relatively uniform sample during drying (Diop et al, 2021). One of the primary factors that cause inconsistent in dried products is the difference in maturity.…”