## 3 Results and Discussion
### Effect of Storage on Fatty Acids and Volatile Composition of Negroamaro GPF
The heatmap shown in Figure 5 illustrates the changes in the amounts of different volatiles at T0_4 \({}^{\circ}\)C or T6_25 \({}^{\circ}\)C relative to T. Alcohols and esters, the two main groups of molecules identified, showed significant changes from T0 to T6 at either temperature. Among aldehydes C6-C10, heptenale, 2-octenale, benzaldehyde, 2-nonenale and 2-phenylacetaldehyde increased during storage and with increasing temperature as previously reported [40]. The increase in the concentrations of alcohols and aldehydes could be associated with variation in the percentage of mono and polyunsaturated fatty acids detected. The formation of ketones, 2-phenylethylalcohol, 2-pentylfuran and some hydrocarbons seems to depend on both time and temperature. The two factors, time and temperature, led to a significant increase in alcohols and esters, the latter associated with  
Figure 4: Principal Component Analysis of volatile compound concentrations detected in GPF stored for six months at 4 \({}^{\circ}\)C and 25 \({}^{\circ}\)C in the dark. PCA biplots on the PC1-PC2 plane combining score plots of major volatiles variables and the final sampling of GPF stored at 4\({}^{\circ}\)C (T6) and at 25 \({}^{\circ}\)C (T6). sensory notes of fruitiness, while no significant variation was found of the remaining of molecules detected [43]. Figure 5: Heatmap of volatile compounds. The evaluation of the volatile component, aldehydes were detected after six months of storage at the both temperatures, which could accompany the rancidity process of the GPF mostly at 25 \({}^{\circ}\)C. The concentrations of these compounds suggest a start of production of the volatile component, which is generally very subjective in individual perception. Color Profile and Moisture Percentage of Negroamaro Flour Pomace after Six Months of Storage at Different Temperatures  
GFP color is a quality parameter that affects both the appearance and consumer perception. \(L^{*}\), \(a^{*}\) and \(b^{*}\) (see Materials and Methods section) values of GPF at T0 and T6 samples stored at 4 \({}^{\circ}\)C and 25 \({}^{\circ}\)C in the dark and air conditions, are shown in Table 3. GPF samples showed positive \(a^{*}\) and \(b^{*}\) values, indicating that a GPF is more red than green and more yellow than blue, respectively. Table 3 showed that storing pomace flour during six months lead to a significant increase of \(L^{*}\), \(a^{*}\) and \(b^{*}\) values. On the other end storage of pomace flour for six months at 4 \({}^{\circ}\)C does not effect \(L^{*}\), \(a^{*}\) and \(b^{*}\) values. Increase of \(L^{*}\), \(a^{*}\) and \(b^{*}\) values suggests that storage at 25 \({}^{\circ}\)C of GPF leads to a mild whitening and an intensification of red and yellow color. This effect could be a direct consequence of the initial anthocyanins degradation in grape pomace during the storage at 25 \({}^{\circ}\)C [44,45]. With regards to the percentage of moisture, no significant differences were found between sampling time nor storage temperature (Table 3). Moisture content of food ingredients affect physical and chemical aspects related to freshness and stability during long term storage. Moreover, even slight deviations from a defined standard can adversely affect the physical properties of a food. Interestingly, in the case of wheat flour, fluctuation in moisture content during storage may be associated with changes in flavonoids and antioxidant activity [46].