Impact of Pretreatment Solutions on the Physicochemical and Microbiological Properties of Dried Tu Quy Mango (Mangifera indica L.)

Tu Quy mango (from Ben Tre, Vietnam) is known for its delicious taste; however, fresh mangoes have a limited shelf life. Although drying helps extend the shelf life of mangoes, the drying process can lead to undesirable changes, such as darkening and reduced biological activity. This study investigated the effects of pretreatments, specifically potassium metabisulphite (PMS), citric acid (CA), and ginger powder extract (GE), on the proximate composition, physical and chemical properties, biological activity, and microbiological quality of dried mango products derived from Tu Quy mango. The results showed that the pretreatments significantly reduced the moisture content and color change of the dried mango slices (p < 0.05). The physical and chemical properties, rehydration characteristics, and firmness of the dried mango slices remained unaffected by the pretreatments. The pretreatment solutions increased the osmotic pressure, created an acidic environment, inactivated enzymes, and limited the oxidation of the mango slices during dehydration. A one-way ANOVA followed by Tukey’s test at a significance level of 0.05 was employed to evaluate differences among pretreatment solutions. GEs significantly influenced the biological properties of the dried mango slices. Mango slices soaked with GE showed significantly higher retention of polyphenols and carotenoids (p < 0.05), with values of 171.96 ± 7.73 mg GAE (gallic acid equivalent)/100 g DW (dry weight) and 3.89 ± 0.09  μg/g DW, respectively. No differences were found in flavonoids and ascorbic acid contents among pretreatment methods. The DPPH, ABTS free radical scavenging, and FRAP iron reduction abilities of dried mango slices pretreated with CA solution and GE did not differ. However, GE significantly reduced (p < 0.05) the total aerobic microorganisms, molds, and yeasts of dried mango slices. This study demonstrates that GE is more effective than the two pretreatment solutions (PMS and CA) in enhancing the biological activity and microbiological quality of dried mango.