## 3 Results and Discussion
### Variabilities of the Raman Band Intensities  
Since the maturation process of tomatoes has been studied intensely [30; 31; 39], 30 hot peppers were compared to the same number of tomatoes. Each species was represented by 10 fruits of the categories immature, maturing and fully matured fruits, see Table 1. The categories were related to green, orange and red fruits, respectively. A comparison of the intensity values revealed a higher carotenoid content within the peppers than within the tomatoes, which might be due to the higher water content of tomatoes, thus a lower carotenoid concentration. The intensity also increased along with the ripening process from green to red. Both green hot peppers and green tomatoes showed low variations within their sample group of 10. The variations increased significantly during the ripening process. This was explained as due to the fact that fruits of the category orange showed features of different stages of ripeness. The discoloration played an additional role, as the green chlorophyll masked the red caroten and hence led to an obvious lower concentration of the caroten. Hence, the standard deviation of orange and red peppers was almost as large as the mean of all samples in this category. Since the inter-fruit variation appeared somewhat large, the intra-fruit variability was investigated. Five different measuring locations were defined on single fruits. A ripe pepper was compared with a red tomato, i.e., a ripe tomato, see Table 2. Each test point was examined as a triple measurement using the same parameters. The carotenoid concentration was not found significantly different for the two fruits at the distinct measuring locations. The intra-fruit variation proved comparable to the inter-fruit variation within a color category as shown in Table 1. This is an important finding since an automated analysis would not necessarily have to pay attention and aim for a specific test point. It should hence be sufficient that the laser beam would be focused on an intact area of the fruit surface. For a potential field application, the influence of the \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Species** & \multicolumn{2}{c}{**Peppers**} & \multicolumn{2}{c}{**Tomatoes**} \\ \hline
**Color** & **Green** & **Orange** & **Red** & **Green** & **Orange** & **Red** \\ \hline
**Mean value** & \(3.6\times 10^{2}\) & \(2.1\times 10^{3}\) & \(7.5\times 10^{3}\) & \(1.2\times 10^{2}\) & \(3.2\times 10^{2}\) & \(5.5\times 10^{2}\) \\
**Std. deviation** & \(9.3\times 10^{1}\) & \(2.0\times 10^{3}\) & \(4.9\times 10^{3}\) & \(6.2\times 10^{1}\) & \(1.0\times 10^{2}\) & \(1.9\times 10^{2}\) \\
**Minimum** & \(2.2\times 10^{2}\) & \(2.8\times 10^{2}\) & \(1.6\times 10^{3}\) & \(2.1\times 10^{1}\) & \(1.6\times 10^{2}\) & \(2.2\times 10^{2}\) \\
**Maximum** & \(5.9\times 10^{2}\) & \(9.4\times 10^{3}\) & \(1.8\times 10^{4}\) & \(2.3\times 10^{2}\) & \(5.1\times 10^{2}\) & \(1.0\times 10^{3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Inter-fruit variations of the Raman band intensities at 1500 cm\({}^{-1}\) within 10 fruits of each category (green, orange and orange/red, red, see below) and species. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Species** & **Pepper** & **Tomato** \\ \hline
**Color** & **Red** & **Red** \\ \hline
**Mean value** & \(1.3\times 10^{4}\) & \(6.5\times 10^{2}\) \\
**Std. deviation** & \(1.8\times 10^{3}\) & \(2.2\times 10^{2}\) \\
**Minimum** & \(1.1\times 10^{3}\) & \(3.8\times 10^{2}\) \\
**Maximum** & \(1.8\times 10^{4}\) & \(1.1\times 10^{3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Intra-fruit variations of Raman band intensities at 1500 cm\({}^{-1}\) measured as triplicates on 5 spots each on a hot pepper and tomato. test location on the fruit surface on the maturity index to be calculated was furthermore verified. Figure 4 shows the results of triple measurements carried out at five points using the handheld spectrometer (blue) and the benchtop spectrometer (orange).