## 3 Results
### Bioaccessibility and Shelf-Life Study of the Functional Beverage
The functional beverage, during storage at all temperatures, exhibited similar rheological behavior to control apple juice, which remained almost stable throughout storage. The initial viscosity of functional beverage was slightly increased, at 4.88 cP, compared to the control, at 2.72 cP (due to the presence of the o/w nanoemulsion with MDD 307 \(\pm\) 15 nm and 19.7 \(\pm\) 1.77 cP). The initial viscosity of the functional beverage was higher (4.88 cP) than the control (2.72 cP) due to the addition of the o/w nanoemulsion characterized by a MDD of 307 \(\pm\) 15 nm and a viscosity of 19.7 \(\pm\) 1.77 cP at 25 \({}^{\circ}\)C. The slight increase in the functional beverage's viscosity is attributed to the presence of nanoemulsion, which alters the structural density and increases resistance to flow. The nanoemulsion droplets interact with the beverage matrix, creating a more cohesive structure that slows down molecular movement, thereby increasing the overall viscosity. During storage at 4, 10, 25, and 40 \({}^{\circ}\)C, the functional beverage displayed similar rheological behavior to the control apple juice, remaining mostly stable throughout shelf-life. Microbiological analysis of the beverage samples stored at 4, 10, 25, and 40 \({}^{\circ}\)C was also performed. The results of the microbiological analysis showed that, at time 0 of storage, the Total Viable Count (TVC) was below the detection limit (<1 log CFU/mL) in all beverage samples studied and remained below the detection limit in all samples stored at 4 and 10 \({}^{\circ}\)C at the end of the beverage shelf life (50% lycopene reduction). Acceptable Total Viable Count (TVC) levels in fruit juices can vary depending on the regulatory standards of different countries. Generally, TVC levels are used to assess the microbiological quality and safety of the juice. The European Commission (EC) Regulation No 2073/2005 on microbiological criteria for foodstuffs suggests that fruit juices should have a TVC of less than 10\({}^{4}\) CFU/mL (colony-forming units per milliliter) at the end of their shelf life [69]. Similarly to the TVC, the growth of yeasts/molds and of _Enterobacteriaceae_ spp. was below the detection limit in all samples at the end of beverage shelf life for all examined temperatures. _Enterobacteria_ are considered hygiene indicators, and their absence in all beverage samples suggests proper handling and production processes, during which hygiene conditions were adequately maintained, leading to inhibition of the growth of  
Figure 6: Deterioration of lycopene concentrations in the functional beverage during storage as a function of temperature (4, 10, 25, and 40 \({}^{\circ}\)C). the studied microorganisms. The results of the microbiological analysis showed that all microorganisms studied remained below the detection limit in all samples stored at 4, 10, 25, and 40 \({}^{\circ}\)C throughout the respective storage period. It is evident that the packaging of the final product was performed under aseptic conditions, indicating that, in all stages of the preparation of the final product, the hygiene conditions were adequate. The results of the current study indicate that refrigeration is recommended for long-term storage of this product, as it can help slow down lycopene degradation. Implementing refrigeration, therefore, not only extends the microbiological shelf life but also ensures that the product retains its nutritional value over an extended period, making it more appealing and beneficial for consumers. This is particularly important for products rich in antioxidants like lycopene, as their effectiveness can diminish rapidly at higher temperatures. However, the sensory attributes of the beverage (flavor, mouthfeel, visual appeal) may be altered if the emulsion destabilizes or if chemical reactions occur. As a result, even in the case where microbiological quality is preserved, the sensory characteristics should be monitored, as they impact consumer acceptance.