# Effects of Drying Methods and Temperatures on the Quality of Chestnut Flows
## 4 Conclusions  
The aim of the present study is to evaluate the effect of drying methods and temperature on the chemical and health quality of chestnut flour. Based on the results obtained, it is possible to conclude that the flour produced with fruits dried with woody fire by the traditional \"metato\" method has a polyphenol content and an antioxidant power lower than the other flours. This is probably due to the highly-fluctuating temperature behavior of the traditional method. Conversely, in the flours dried with hot air at a constant temperature of 40 \({}^{\circ}\)C or 70 \({}^{\circ}\)C, the polyphenol content is kept higher. In fact, the greater or lesser activity of enzymes that promote the oxidation of polyphenols may depend on the temperature and the stability to which they are subjected. The content of sugars is similar to the flours obtained by hot air, both at 40 \({}^{\circ}\)C and 70 \({}^{\circ}\)C. On the contrary, the traditionally dried flour shows a total absence of galactose. Furthermore, traditionally dried flours contain some potentially toxic volatile molecules (furfural, guaicaol, and o-cresol). This rings the first alarm bell, since the presence of such compounds in high concentrations can be toxic to human health. In the future, to establish the toxicity level of chestnut flours, \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**1-Octen-3-ol**} & \multicolumn{2}{c}{**Furfural**} & \multicolumn{2}{c}{**Guaicaol**} & \multicolumn{2}{c}{**O-Cresol**} \\ \hline  & **RT** & **Area** & **RT** & **Area** & **RT** & **Area** & **RT** & **Area** \\ \hline Traditional non-defective & 22.003 & 1,298,711 & 22.926 & **3,288,748 \({}^{\star}\)** & 32.584 & **8,686,673 \({}^{\star}\)** & 35.439 & 836,714 \\ \hline Traditional defective & 22.001 & 640,837 & 22.922 & 53,749 & 32.582 & 4,408,542 & 35.435 & **2,602,744 \({}^{\star}\)** \\ \hline Hot air 70 \({}^{\circ}\)C non-defective & 21.999 & 431,202 & 22.922 & 438,989 & 32.584 & 1,097,308 & 35.437 & 334,842 \\ \hline Hot air 40 \({}^{\circ}\)C defective & 22.003 & **5,320,343 \({}^{\star}\)** & 22.924 & 585,345 & 32.586 & 678,755 & 35.435 & 177,180 \\ \hline Hot air 70 \({}^{\circ}\)C non-defective & 22.001 & 259,093 & 22.926 & 251,179 & 32.586 & 2,334,425 & 35.435 & 728,489 \\ \hline Hot air 40 \({}^{\circ}\)C defective & 22.001 & 609,126 & 22.928 & 1,590,987 & 32.584 & 3,752,913 & 35.435 & 1,416,660 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The retention time (RT) and area of four molecules detected in examined flours in Figure 5. The values in bold correspond to the largest areas of each column. Asterisks indicate a significative difference (\(p\)-value \(\leq\) 0.01) from the mean of the areas of all flours for each relevant peak. Figure 5: Chromatograms of 8 flours (representative of 2 years) distinguishable with different colors: light blue and blue for traditionally dried non-defective, black for traditionally dried defective, green and red for 70 \({}^{\circ}\)C hot air-dried non-defective, purple for 70 \({}^{\circ}\)C hot air-dried defective, brown for 40 \({}^{\circ}\)C hot air-dried non-defective and pink for 40 \({}^{\circ}\)C hot air-dried defective. The relevant peaks are circled and numbered from 1 to **4: 1** for 1-octe-3-ol, **2** for furfural, **3** for guaicaol (phenol, 2-methoxy), and **4** for o-cresol (phenol, 2-methyl). more detailed analyses on the exact content of toxic compounds could be performed. For the parasitized flours, the content of sugars and biomolecules is higher with respect to the healthy ones. Polyphenols and antioxidants in general are secondary metabolites for plant defense and sugars often act as substrates for the latter. Hence, in adverse conditions, the production of these metabolites is enhanced. Despite being beyond the scope of the present study, the aroma of the parasitized flours highlights the presence of a musty character; therefore, the positive higher content in polyphenols does not correspond to a likewise positive organoleptic profile.