## 1 Introduction  
Food is a natural material susceptible to various physical, chemical, enzymatic, and biological changes during handling, preparation, and storage [1]. These alterations can significantly affect the food's sensory properties and suitability for consumption. The action of microorganisms and enzymes primarily causes these changes [2]. To stabilize foodstuffs and mitigate the adverse effects of microbial and enzymatic activity, the food industry employs various preservation techniques, often in combination. Conventional methods include thermal processing, such as refrigeration, freezing, blanching, heating, drying, pasteurization, and sterilization [3]. In contrast, non-thermal food processing techniques, which operate without heat, include high pressure processes (HPPP), ultrasound, cold plasma, pulsed electric fields (PEF), and supercritical carbon [4]. These innovative non-thermal technologies can be utilized to create products with specific forms and properties and are helpful in general food processing and the pre-processing of raw materials. These methods are particularly effective when mass transfer within the raw material is crucial, such as drying, pressing, extraction, or osmotic dehydration [5]. Ultrasound refers to sound waves with frequencies above 16 kHz, typically ranging from 20 kHz to 10 MHz, beyond human hearing. It propagates through elastic media, causing longitudinal displacement and creating alternating areas of compression and rarefaction [6; 7]. Two standard ultrasound pre-treatment techniques are ultrasonic water baths and sontrodes. Effective sonication requires samples to be fully immersed in a liquid medium at a typical material-to-liquid ratio of 1:4 [8; 9]. This process occurs at room temperature, facilitating mass transfer between the raw material and the medium. In ultrasonic baths, transducers convert electrical energy into sound energy, generating high-intensity waves at frequencies from 20 to 40 kHz for durations of five to 30 min. The sontrode method delivers sonic waves directly into the liquid, operating at frequencies of 20 to 24 kHz, making it more suitable for small volumes due to rapid temperature increases [8; 9; 10]. Ultrasound impacts vegetable quality, affecting texture, color, taste, and nutrition. For instance, [PERSON] et al. [11] reported that ultrasound damaged cell wall structuresin peppers, enhancing diffusion. Meanwhile, [PERSON] et al. [12] noted that ultrasound delayed tomato softening and improved the preservation of texture and color. [PERSON] and [PERSON] [13] found that sonicated green asparagus stored at 4 \({}^{\circ}\)C retained higher levels of total soluble solids (TSS) and vitamin C, attributed to cavitation effects on enzyme activity. Additionally, the combination of ultrasound and ultraviolet radiation increased the nutritional content in tomatoes [14]. Ultrasound pre-treatment of beetroots resulted in notable color changes without significant pigment loss [15]. Recent research has extensively explored the role of ultrasound as a pre-treatment in various food processing methods, including drying, extraction, crystallization, filtration, and freezing. However, its influence on lactic fermentation is less discussed. Recent research can enhance the growth of microorganisms during fermentation by increasing the availability of essential nutrients [7], which is attributed to cell structure modification and improved mass transfer [16; 17]. Still, its effects on lactic fermentation are less explored. Ultrasound can enhance microbial growth during fermentation by improving nutrient availability and mass transfer due to cell structure modification [18]. However, it can also cause damage to microorganisms through cavitation. [PERSON] et al. [19] used ultrasound (50 W, 30 kHz) on mandarin juice, finding increased _L. reuteri_ cell counts after fermentation. The highest viable cell counts and increase in antioxidant capacity were observed after 5 min.