## 3 Results and Discussion
### Characterization of Basil Pesto Samples
#### 3.2.1 Physicochemical and Microbiological Aspects
The main aspects highlighted during the storage of basil pesto samples are the color variation (an increase in browning) and the flavor variation (generation of off flavors). The panelists defined the fresh and enriched samples (F and F+) as more acceptable for color and flavor where the basil flavor and intense green were the prevalent factors. However, the thermal-treated samples (P and P+) showed a decrease in the same parameters. The differences between fresh and pasteurized samples are evident. Color changes were due mainly to oxidative processes: phenolic compound oxidation, chlorophyll degradation, non-enzymatic browning, etc. During the storage time, a decrease in the intense green color and an increase in the oxidate green color were highlighted (Figure 6). These results can be correlated with the colorimetric analysis reported in Table 3, where a* chromatism varied during storage, resulting in browning of the same samples, in particular P and P+. The microbiological stability of basil pesto sauce can be affected by different variables such as pH, a\({}_{w}\), moisture content, and eventually, the applied thermal treatments. For this reason, it is necessary to prevent the germination of spores by creating a suitable substrate that inhibits spore growth, with a low pH. Acidity regulators are typically added to commercial sauces, however, the addition of these often affects the organoleptic properties of the treated foods. As previously described by [PERSON] et al. [34], the ethyl acetate extraction of OMMW makes it possible to obtain a phenolic extract characterized by a polymeric fraction which exhibits a marked antimicrobial property. In order to inhibit the growth of microorganisms and endogenous enzymes in vegetable-based products, pasteurization heat treatment is industrially used with the aim to stabilize the products [35]. During storage, the enumeration of aerobic mesophilic microorganisms was below the detection limit (<105 CFU g\({}^{-1}\)) for pasteurized samples. The combination of thermal treatment and phenolic enrichment enabled inhibition of the growth of yeast and molds unlike the untreated samples. According to [PERSON] et al. [36], the application of heat treatment (pasteurization) and the presence of polyphenols in olive oil byproducts improve fungistatic and bacteriostatic properties. No aerobic mesophilic microorganism count was verified for fresh pesto samples with phenolic extract, but values ranging between 0.30 and 2.60 log10 CFU g\({}^{-1}\) for molds were observed during storage. Based on these outcomes, the microbiological stability of the samples could be considered satisfactory. Figure 5: Sensorial evaluation of basil pesto at 1 st time of storage. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & **Days** & **F** & **F+** & **P** & **P+** & **Sign. ** \\ \hline \multirow{6}{*}{**L\({}^{\star}\)**} & 1 & 42.09 \(\pm\) 1.09 \({}^{\text{ABa}}\) & 43.33 \(\pm\) 1.52 \({}^{\text{ABb}}\) & 41.42 \(\pm\) 1.03 \({}^{\text{B}}\) & 42.74 \(\pm\) 0.88 \({}^{\text{AB}}\) & **\(\ast\ast\)** \\  & 7 & 39.50 \(\pm\) 1.38 \({}^{\text{CB}}\) & 42.47 \(\pm\) 0.90 \({}^{\text{Bab}}\) & 40.33 \(\pm\) 1.06 \({}^{\text{C}}\) & 44.33 \(\pm\) 1.25 \({}^{\text{A}}\) & **\(\ast\ast\)** \\  & 15 & 39.04 \(\pm\) 1.46 \({}^{\text{CB}}\) & 41.89 \(\pm\) 1.02 \({}^{\text{Rb}}\) & 40.14 \(\pm\) 0.98 \({}^{\text{C}}\) & 44.03 \(\pm\) 1.78 \({}^{\text{A}}\) & **\(\ast\ast\)** \\  & 30 & 40.12 \(\pm\) 1.17 \({}^{\text{BB}}\) & 42.53 \(\pm\) 0.75 \({}^{\text{ABb}}\) & 40.52 \(\pm\) 1.42 \({}^{\text{B}}\) & 42.78 \(\pm\) 1.28 \({}^{\text{A}}\) & **\(\ast\ast\)** \\  & 60 & 38.99 \(\pm\) 0.90 \({}^{\text{CB}}\) & 42.85 \(\pm\) 1.09 \({}^{\text{ABb}}\) & 41.83 \(\pm\) 1.18 \({}^{\text{B}}\) & 43.09 \(\pm\) 0.86 \({}^{\text{A}}\) & **\(\ast\ast\)** \\  & 90 & 39.34 \(\pm\) 1.58 \({}^{\text{BB}}\) & 43.28 \(\pm\) 0.53 \({}^{\text{Aa}}\) & 41.72 \(\pm\) 2.14 \({}^{\text{A}}\) & 43.27 \(\pm\) 0.96 \({}^{\text{A}}\) & **\(\ast\ast\)** \\  & **Sign. ** & **\(\ast\ast\)** & **\(\ast\)** & **n.s. ** & **n.s.