Novel Approaches to Spontaneous and Controlled Fermentation of Romanian Small Autumn Watermelon (Citrullus lanatus)

Romanian small autumn watermelon (Citrullus lanatus), late-harvested at the end of October, is a valuable vegetal source of natural carbohydrates, carotenoids, vitamins (especially A and C), fibers, and minerals, and, above all, it provides hydration while being low in calories. To extend the period during which Romanian small autumn watermelon can be consumed and its associated health benefits, the present study aims to preserve these fruits through spontaneous and controlled fermentation. The conditions were identical in both fermentation routes: a room temperature of 21 ± 1 °C for 4 days, followed by 17–18 °C in the dark thereafter. Several physical, chemical, and microbiological investigations were conducted at 7-day intervals over the 63 days of storage. The study revealed several advantages of controlled fermentation: a rapid decrease in pH, a uniform lactic acid concentration, an improved phytochemical profile, and better preservation of color and texture. Controlled fermentation of vegetables offers greater predictability, safety, and consistency than spontaneous fermentation, making it suitable for industrial application.