Proteomic analysis and physicochemical, antioxidant, and sensory characteristics of three wild and two commercial prickly pears fruits from Mexico

Abstract

Opuntia ficus-indica is the most domesticated plant species between the Opuntia genus. However, Mexico presents the highest richness of wild Opuntia species. In these areas, it represents an important food resource of arid and semiarid areas. Although several investigations have tried to elucidate the process of domestication of these species through the study of changes at the molecular level in the cladodes, it is still unknown what characteristics are favored in the fruits. To find additional comprehensions about these molecular changes, a proteomic analysis, as well as a study of physicochemical, antioxidant, and sensory characteristics of three wild prickly pears (O. macrocentra, O. phaeacantha, and O. engelmanii), and two commercial prickly pears (O. ficus-indica) fruits were carried out. Protein identification of pulp tissue determined by a gel-free shotgun (nanoLCMS/ MS) strategy showed a wide variation in the number of proteins identified in each species. Only 28 proteins were common among the five species, 39 proteins were uniques and common to wild species, and 175 proteins to the commercial ones. Identified proteins were classified by the biological interest mainly in carbohydrate metabolism, stress responses, and transport. Pulp, peel, and the seed of fruits of wild prickly pears showed the lowest pH values, as also the highest titratable total acidity, antioxidant capacity, and total phenolic, flavonoid, protein, lipid, ash, carbohydrate, and fiber contents. Furthermore, O. engelmanii showed a tendency to present the highest betacyanins, betaxanthins, and betalains contents. Sensory profiles of wild species were characterized by higher color, smell, and an acidic taste compared with the commercial varieties. Therefore, fruits of wild prickly pears could be proposed as an important nutritional source with biological interest for the food and pharmaceutical industry.