## 5 Factors Affecting UV-C Process in Stimulation  
The efficiency of UV stimulation on crops is affected by factors, such as light source, product composition, flow profile, and geometric configuration. UV light has a great impact on the quality attribute of food in relation to wavelength, intensity, and exposure. Total dosage (energy per unit area) is the main factor determining fruit and vegetable responses to UV-C, but the intensity of the radiation (dose per unit time) may also determine treatment outcome. The degree to which the stimulation occurs by UV radiation is directly related to the UV dose. The UV-C dose (J\(\cdot\)cm\({}^{-2}\)) is expressed in terms of the UVC intensity flux (W\(\cdot\)cm\({}^{-2}\)) and exposure time (s), as calculated from the correlation presented in Equation (1). \[\text{Dose}=\text{UVC Intensity}\cdot\text{Exposure time} \tag{1}\]  
The UV-C intensity rate is the total amount of radiant flux passing from all angles through a unit area that is determined based on the location of the sample under exposure. However, the UV-C intensity is not equal to the amount of energy absorbed by the exposed sample. The effect of UV-C exposure time (20-40 min at 15 cm distance) on the defense response chemical content is well experimented with in recent research on bitter gourd resulting in a significant change in the quality attributes [135]. Distance from the source to the sample is an important factor that affects intensity flux and stimulation. The shorter the distance, the higher the radiant flux to effectively stimulate or disinfect the sample of the crop. This correlation is well described by the Equation (2) shown below [146; 147]. \[\text{UVC intensity}\left(r\right)=\left(\frac{P}{2\pi r}\right)\cdot e^{- \alpha.r} \tag{2}\]  
The UVC fluence rate at radial distance r from the lamp is proportional to \(P\), which is UV-C power emitted per unit arc length of the lamp, and \(\alpha\) is the absorption coefficient (cm\({}^{-1}\)). During UV-C irradiation into the sample, the performance of absorption to induce a change is also dependent on the composition of the food product. The surface of the food item determines the penetration ability of UV-C light. A higher value of \(\alpha\) leads to a decrease in the penetration ability of UV-C, resulting in the minimal effectiveness of the stimulation of UV-C dose [148]. Complete information and characterization of the absorptive characteristics of a sample are very important when estimating the required UVC dose. For example, in fruits, there is a presence of epicticular waves, which contain a microcrystalline structure. Exposure of fruit to UV-C changes the wax morphology, \begin{table}
\begin{tabular}{c c c c} \hline
**Commodity** & **Operating Condition** & **Key Finding** & **Reference** \\ \hline \multirow{4}{*}{**Mandarin (_Satsuma_)**} & \multirow{4}{*}{UV-C dose of 0.75, 1.5 and 3.0 kJ\(\cdot\)m\({}^{-2}\).} & Phenolic acids and antioxidant capacity & \\  & & were not significantly affected by UV-C & \\  & UV-C dose of 0.75, 1.5 and 3.0 kJ\(\cdot\)m\({}^{-2}\). & treatments, while 1.5 and 3.0 kJ\(\cdot\)m\({}^{-2}\) & \\  & & significantly increased flavonoids and & \\  & & total phenolics. 0.75 kJ\(\cdot\)m\({}^{-2}\) was infective & \\  & & to induce any change. & \\ \hline \multirow{4}{*}{**Garlic (_Danyang_)**} & \multirow{4}{*}{UV-C of 25 kJ\(\cdot\)m\({}^{-2}\), exposure time of 380 s.} & The UV-C treatment reduces microorganisms present and no significant differences in quality attributes, phenolic compounds, and antioxidants. & \\  & & The optimum dose of UV-C for enhancing total anthocyanin content was & \\  & & 3.0 kJ\(\cdot\)m\({}^{-2}\). & \\ \hline \multirow{2}{*}{**Fresh-cut Rocket Leaves**} & \multirow{2}{*}{UV-C dose at 1, 3 and 5 kJ\(\cdot\)m\({}^{-2}\).} & the highest accumulation of & \\  & & phytochemicals in mangoes exposed to & \\  & & 4.93 kJ\(\cdot\)m\({}^{-2}\). & \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._composition, and structure, eventually resulting in a change in surface permeability.