The plant-based beverage (PBB) market is among the fastest-growing segments of the food industry, driven by demand for ethical, environmental, and health-conscious dairy alternatives. However, commercial PBBs often rely on additives to mimic milk’s sensory and functional properties, raising concerns about ultra-processed formulations. This study aimed to develop and characterize eight minimally processed PBBs representing different categories (carob, tiger nut, cashew, sesame, rice, lucuma, beetroot, and tomato), with bovine milk as a reference, to explore fermentation as a strategy to enhance antioxidant properties without additives. The beverages were prepared by mixing water with a single food matrix, which was heat-treated (95 ºC, 10 min) and fermented with either Lactiplantibacillus plantarum WCFS1 (10⁶ CFU/mL) or commercial kefir grains (5 g/L). Fermentation was carried out at 30 ºC for 24 h, followed by storage at 4 ºC for two weeks, during which the progress of fermentation was monitored and total polyphenols, TEAC, and ORAC were analyzed to assess antioxidant capacity. All fermented beverages exhibited microbial growth and pH reduction, indicating successful fermentation, with a variable impact on antioxidant potential. For future in vitro studies, tomato has been selected for its antioxidant properties, leading to different modulations of the three indicators (polyphenols, TEAC, and ORAC) when comparing different microbiological starter cultures.