POSTHARVEST RIPENING BEHAVIOR OF NINE THAI MANGO CULTIVARS AND THEIR SUITABILITY FOR INDUSTRIAL APPLICATIONS

Genome-wide transcriptome analysis uncovers gene networks regulating fruit quality and volatile compounds in mango cultivar 'Tainong' during postharvest

Mango is one of the most economically important fruit; however, the gene regulatory mechanism associated with ripening and quality changes during storage remains largely unclear. This study explored the relationship between transcriptome changes and postharvest mango quality. Fruit quality patterns and volatile components were obtained using headspace gas chromatography and ion-mobility spectrometry (HS-GC-IMS). The changes in mango peel and pulp transcriptome were analyzed during four stages (pre-harvesting, harvesting, maturity, and overripe stages). Based on the temporal analysis, multiple genes involved in the biosynthesis of secondary metabolites were upregulated in both the peel and pulp during the mango ripening process. Moreover, cysteine and methionine metabolism related to ethylene synthesis were upregulated in the pulp over time. Weighted gene co-expression network analysis (WGCNA) further showed that the pathways of pyruvate metabolism, citrate cycle, propionate metabolism, autophagy, and SNARE interactions in vesicular transport were positively correlated with the ripening process. Finally, a regulatory network of important pathways from pulp to peel was constructed during the postharvest storage of mango fruit. The above findings provide a global insight into the molecular regulation mechanisms of postharvest mango quality and flavor changes.

Storage Time as an Index for Varietal Prediction of Mango Ripening: A Systemic Approach Validated on Five Senegalese Varieties

Mangifera indica species presents a wide varietal diversity in terms of fruit size and morphology and also of physicochemical and organoleptic properties of the pulp. In Senegal, in addition to the well-known export varieties, such as 'Kent', local varieties have been little studied particularly during ripening. This study aims to propose prediction models integrating variables deduced from varietal characteristics. Five mango varieties ('Diourou', 'Papaye', 'Sierraleone', 'Boukodiekhal' and 'Sewe') endemic to Senegal were characterized at harvest and followed during ripening storage. Caliber parameters were determined at green-mature stage as well as storage (25 °C) weight losses. Considering the 'ripening storage time' (R_ST) variable as ripeness level index, intra-varietal prediction models were built by multi-linear regression (R² = 0.98) using pulp pH, soluble solid content (SSC) and Hue angle. In addition to these physicochemical parameters, variety-specific size, shape and weight loss parameters, were additional variables in multi-linear models (R² = 0.97) for multi-varietal prediction of R_ST. Results showed that storage time, which was the most influential factor on the pH, SSC and Hue, can be used as a response for varietal prediction of mango ripening. As a decision support tool, theses statistical models, validated on two seasons, will contribute to reduce post-harvest losses and enhance mango value chain through a better ripening process monitoring.

Automatic Classification of the Ripeness Stage of Mango Fruit Using a Machine Learning Approach

Most mango farms classify the maturity stage manually by trained workers using external indicators such as size, shape, and skin color, which can lead to human error or inconsistencies. We developed four common machine learning (ML) classifiers, the k-mean, naïve Bayes, support vector machine, and feed-forward artificial neural network (FANN), all of which were aimed at classifying the ripeness stage of mangoes at harvest. The ML classifiers were trained on biochemical data and then tested on physical and electrical data.The performance of the ML models was compared using fourfold cross validation. The FANN classifier performed the best, with a mean accuracy of 89.6% for unripe, ripe, and overripe classes, when compared to the other classifiers.

Developing an Automatic Color Determination Procedure for the Quality Assessment of Mangos (Mangifera indica) Using a CCD Camera and Color Standards

Color is one of the key sensory characteristics in the evaluation of the quality of mangos (Mangifera indica) especially with regard to determining the optimal level of ripeness. However, an objective color determination of entire fruits can be a challenging task. Conventional evaluation methods such as colorimetric or spectrophotometric procedures are primarily limited to a homogenous distribution of the color. Accordingly, a direct assessment of the mango quality with regard to color requires more pronounced color determination procedures. In this study, the color of the peel and the pulp of the mango cultivars “Nam Dokmai”, “Mahachanok”, and “Kent” was evaluated and categorized into various levels of ripeness using a charge-coupled device (CCD) camera in combination with a computer vision system and color standards. The color evaluation process is based on a transformation of the RGB (red, green, and blue) color space values into the HSI (hue, saturation, and intensity) color system and the Natural Color Standard (NCS). The results showed that for pulp color codes, 0560-Y20R and 0560-Y40R can be used as appropriate indicators for the ripeness of the cultivars “Nam Dokmai” and “Mahachanok”. The peels of these two mango cultivars present two distinct colors (1050-Y40R and 1060-Y40R), which can be used to determine the fruit maturity during the post-ripening process. However, in the case of the cultivar “Kent”, peel color detection was not an applicable approach for determining ripeness; thus, the determination of the pulp color with the color code 0550-Y20R gave promising results.

Ripening quality of Dusehri mango in relation to harvest time

The effect of different harvesting time on ripening quality of mango cv. Dusehri was investigated under sub-tropics of northwestern India. Fruits were harvested at 101, 106 and 111 days after fruit set (DAFS) and kept at 25 °C in temperature controlled chamber for ripening. Fruits were analyzed periodically for physico-chemical characteristics at the time of harvest (0 h) and after 72, 96 and 120 h of ripening period. With advancement in ripening period, an increase in physiological loss in weight, soluble solids content (SSC), sensory quality rating, β-carotene and pulp colour development of mango fruits was recorded. While a decline in fruit firmness and titratable acidity (TA) was observed with ripening period. Fruits picked at 111 DAFS recorded highest SSC (8.01%), sensory rating (4.67), β-carotene (0.427 mg/100 g) vis-à-vis lowest fruit firmness (15.3 lbf) and TA content (1.56%). The luminosity of fruit pulp decreased with the storage period. The redness and yellowness of the fruit pulp represented by a* and b* values, respectively increased with delay in harvesting period. The rate of ripening was rapid in late harvested fruits as compared to early harvested fruits. After 96 h of ripening period, fruits harvested at 111 DAFS showed very much desirable quality whereas fruits harvested at 101 DAFS showed moderately desirable quality. Results showed that harvesting of mango fruits can be extended to 111 days and such fruits attained optimum ripening quality after 96 h at 25 °C.

Processes involving selective precipitation for the recovery of purified pectins from mango peel

Three methods for the recovery of purified pectins from directly dried mango peel were developed, using selective precipitation of mango pectin in propan-2-ol (IPA) of adequate volume concentrations for purification. Yields, composition, macromolecular and gelling properties of the resultant pectins were compared. Effluent analyses proved postextractive removal of fruit exudate arabinogalactans. The recovery processes involved (A) washing of raw-pectin powder in IPA of defined volume concentration, (B) fractional alcoholic precipitation of dissolved raw pectin, or (C) selective pectin precipitation from the hot-acid extract of mango peel in adequately diluted IPA. High galacturonic acid contents (≥ 721g/kg) and intrinsic viscosities (≥ 320mL/g) enabled ∼2.2-fold gelling capacities compared to raw mango pectin, which resulted from the standard procedure mimicking industrial pectin recovery from established sources. Removal of the predominant impurities (coextractable exudate arabinogalactans, ash) diminished the yields to ∼49% of the raw-pectin yield. Technical feasibility of the proposed procedures was discussed.

Impact of the stage of ripening and dietary fat on in vitro bioaccessibility of beta-carotene in 'Ataulfo' mango

Pulp from "slightly ripe", "moderately ripe", or "fully ripe" mangoes was digested in vitro in the absence and presence of processed chicken as a source of exogenous fat and protein to examine the impact of stage of ripening of mango on micellarization during digestion and intestinal cell uptake (i.e., bioaccessibility) of beta-carotene. The quantity of beta-carotene transferred to the micelle fraction during simulated digestion significantly increased as the fruit ripened and when chicken was mixed with mango before digestion. Qualitative and quantitative changes that occur in pectin from mango pulp during the ripening process influenced the efficiency of micellarization of beta-carotene. Finally, the uptake of beta-carotene in micelles generated during simulated digestion by Caco-2 human intestinal cells confirmed the bioaccessibility of the provitamin A carotenoid in mango.