Heat treatment is the most successful process in inactivating microorganisms and enzymes in various food systems. Particularly, fruit drinks are commonly pasteurized and packaged to preserve them, extending their shelf life. Although widely applied, heat treatment deteriorates some nutrients and organoleptic properties of foods (Berk, 2018; Fellows, 2017; Hii, Tan, & Woo, 2023; Ramesh, 2020). Thus, alternative methods to preserve foods using the application of different physical principles become necessary. The application of conventional power ultrasound (20 kHz to 100 kHz) is considered an emerging food processing technology that has been used for degassing, extraction of flavorings, filtration, drying, freezing, alteration of enzyme activity, sterilization of equipment, mixing and homogenization, bactericidal action, among others. The major mechanical effect of power ultrasound (US) in liquid systems is the formation of cavitation bubbles, which collapse during the treatment, resulting in localized temperature and pressure increases denominated “hotspots” (Paniwnyk, 2014). Several studies have reported that when fruit and vegetable juices (such as orange, sweet lime, spinach, carrot, and mango) are treated by US, the ascorbic acid content, total phenolic content, scavenging activity, color, and volatile aroma compounds preserve better compared with those processed by thermal treatment (Aadil et al., 2015; Khandpur & Gogate, 2015; Wang, Liu, Xie, & Sun, 2020). However, ascorbic acid, color, and other juices' quality properties degrade as a function of acoustic energy density (Rojas, Kubo, Caetano-Silva, & Augusto, 2021; Zinoviadou et al., 2015) due to oxidative process (free radicals' formation) and temperature increase, depending on processing time (Lepaus et al., 2023). On the other hand, ultrasound can improve the stability of liquid particles due to its homogenization effect, which is associated with particle size reduction (Gomes, Costa, Rodrigues, de Castro, & Silva, 2022).

Short-wave ultraviolet light radiation (UVC, 254 nm) is an emerging non-thermal technology capable of inactive a wide range of microorganisms (Almazyad, 2022; Singh, Bhardwaj, Khatri, Kim, & Bhardwaj, 2021; Yemmireddy, Adhikari, & Moreira, 2022). However, its microbicidal action is limited by light penetration on treated materials. Thus, it is effective only on surfaces or clear liquids. UV light between 200 and 290 nm penetrates cell membranes to disrupt DNA molecules, delaying cell replication. Besides, hydrogen peroxide produced when applying UV light induces various chemical and physicochemical changes in the cell components with indirect lethal effects (Rahman, 2020). UVC radiation is commonly used to treat clear beverages as fruit juices without pulp, or in thin layer matrices to favor its effectiveness. In citrus juices, UVC radiation is recognized to preserve the nutritional and quality properties because low changes in ascorbic acid (17–35%) and color differences (0.7 to 1.1) have been reported in grapefruit and Navel orange juice (Gayán, Serrano, Monfort, Álvarez, & Condón, 2012; La Cava & Sgroppo, 2015; Pala & Toklucu, 2013); meanwhile, total phenolics content and antioxidant capacity remained similar to untreated orange juice (Pala & Toklucu, 2013). However, depending on the dose and specific nutrients, long treatments by UVC radiation may affect nutritional and quality properties. The unwanted effects were related to the radicals produced by the UVC via photocatalyst (Basak, Shaik, & Chakraborty, 2023), different photochemical reactions (Aghajanzadeh, Ziaiifar, & Verkerk, 2023), and aerobic oxidation. Selected studies on the sensory properties of apple juice, apple cider, orange juice, mango juice, and pineapple juice after UVC treatment showed better attributes or consumer preferences over thermal ones (Abdul Karim Shah, Shamsudin, Rahman, & Adzahan, 2016).

Orange juice has a high nutritional value owing to ascorbic acid, carotenoids, folic acid, potassium, magnesium, iron, and flavanons content and is mainly preferred as a fresh beverage by consumers (Gomes et al., 2022; Pala & Toklucu, 2013). The orange juice global market in 2024 is expected to reach 5.21 billion USD and grow in the next few years due to ongoing health and wellness trends; in 2023, North America was the dominant region in the orange juice market (Research and Markets, 2024). Ascorbic acid content and cloud stability are critical aspects of orange juice and are considered juice quality indicators due to their influence on juice appearance, flavor, and mouthfeel (Aghajanzadeh et al., 2023).

Mango (Mangifera indica) is one of the most important tropical fruits in the world due to its pleasant flavor and nutritional value. Mango contains abundant micronutrients such as vitamins, dietary fiber, and bio-compounds such as ascorbic acid, phenols, and carotenoids with antioxidant, hypoglycemic, and anti-cancer abilities (Wang et al., 2020). Consumers prefer fruit nectars over carbonated drinks because of their fruit content. North America was one of the most significant global nectar markets in 2019, and mango nectar is the fourth most important fruit in the nectar market (Knowledge Sourcing Intelligence, 2022). Regarding mango beverages, mango nectar is more popular than mango juice in North America as a convenience drink for consumers.

Ultrasound and UVC radiation as emerging technologies to preserve foods have been investigated in the last decades with relevant results and potential applications. Several researchers have focused on evaluating US or UVC to process fruit juices and establish the optimal conditions. Due to the limited effects of individual processes on microbial inactivation, the combination of the US plus UVC has been tested in non-clarified beverages. For instance, the effect of US, UVC, or US+UVC have assessed on orange, tangerine, or grapefruit juices (Aadil et al., 2015; Bazaraa, Eissa, Helmy, Ramadan, & Aboelhaggag, 2023; Char, Mitilinaki, Guerreno, & Alzamora, 2010; Gayán et al., 2012; Gomes et al., 2022; Kijpatanasilp, Shiekh, Jafari, Worobo, & Assatarakul, 2023; Taze, Unluturk, Buzrul, & Alpas, 2015; Valero et al., 2007), mango nectar or juice (Guerrero-Beltrán & Barbosa-Cánovas, 2006; Santhirasegaram, Razali, George, & Somasundran, 2015; Santhirasegaram, Razali, & Somasundran, 2015; Wang et al., 2020), strawberry juice (Tomadoni, Cassani, Viacava, Moreira, & Ponce, 2017), pomegranate juice (Alabdali, Icyer, Ozkaya, & Durak, 2020), and grape juice (Unluturk & Atilgan, 2014). However, selected characteristics related to sensory attributes, physicochemical properties, stability, and quality characteristics remain unclear for some beverages processed by this combined treatment, especially mango nectar. Moreover, few studies consider an optimum approach based on the balance of microbial safety and juice or nectar quality (nutritional and sensory attributes). Despite the impact of individual US or UVC processes has been studied in orange juice, few approaches have evaluated the combined technologies. Likewise, US+UVC treatments on mango nectar (one of North America's most popular fruit drinks) were scarcely reported, particularly their effect on sensory attributes. The key benefit of UVC and US as preservation technologies is that they produce higher-quality food with minimum nutrient depletion, whereas safety can be guaranteed. Moreover, UVC and US are recognized as sustainable technologies for reducing energy consumption and minimizing the environmental impact of food processing, additive-free, and clean labels (Islam et al., 2022; Radhakrishnan, Maqsood, & Siliveru, 2023). Therefore, this study aims to evaluate the inactivation efficiency of ultrasound, UVC radiation, and the combined US+UVC treatment on the total aerobic mesophilic bacteria and mold and yeast of orange juice and mango nectar, assessing their physicochemical and sensory properties after treatments. Furthermore, the microbial growth during storage at 4 °C for 12 days was also evaluated, together with the sedimentation index of orange juice during the storage period.