# Table Olive Flours\": An Ingredient Rich in Bioactive Compounds?
## 4 Discussion
[8] also did not find oleuropein when studying 25 samples of tables olives (Spanish-style green olives in brine, Greek-style naturally black olives in brine, and Kalamata olives in brine) purchased in Greece, as well as [PERSON] et al. [4] when studying Portuguese table olives. However, as can be seen by observing Table 3, it was found that an oleuropein derivative was detected in the \"green table olive flour\", neither being seen in the \"turning color table olive flour\" nor in the \"black table olive flour\". On the contrary, chlorogenic acid, verbascoside, and one of its derivatives were only detected and quantified in the \"turning color\" and \"black table olive flours\". In the \"black table olive flour\", they were found in more significant quantities. However, it was only in chlorogenic acid that a significant difference was observed between the two flours. Verbascoside was also only quantified by [PERSON] et al. [11] in mature fruits of cv. Cobrancosa, while in immature fruits, this compound was not detected, in line with our results. [PERSON] and [PERSON] [7] suggested that the formation of verbascoside may also be related to the partial degradation of eleuropein, which could explain the later appearance of this compound in olive fruits. Furthermore, [PERSON] et al. [30] also referred that verbascoside formation is metabolically linked to the conjugation of hydroxytyrosol with caffe acid. In the present work, it was stated that when the concentration of hydroxytyrosol decreased with the ripening stage, the verbascoside increased. Rutin and apigenin were the compounds detected in smaller quantities. Nevertheless, both compounds have interesting health properties. Rutin is a vasoprotective, and apigenin has a biological activity to inhibit tumor growth, as well as chemopre activity [33]. In general, regarding the sum of identified phenolic compounds, the sequence obtained was as follows: \"green table olive flour\"? \"turning color table olive flour\"? \"black table olive flour\". However, all of the \"olive flours\" produced in the present work showed phenolic compounds with biological properties that are very important for human health. Regarding the antioxidant activity, it was stated that the total reducing capacity increased as the olive ripeness increased. These results may be due to the fact that this test evaluates the presence of compounds with reducing ability, such as sugars, organic acids or peptides, and is not only specific for phenolic compounds. Other substances may be present in the table olives, which may have reducing properties. Concerning the blocking effect of DPPH free radicals, the highest values were obtained in \"green table olive flour\". Thus, it was found that as maturation increases, the blocking effect of DPPH free radicals decreases, indicating that the antioxidant capacity assessed by the sequestration of these free radicals was more significant in lower ripening states, that is, in the \"green table olive flour\". This is in line with [PERSON] et al. [11], who also indicated a lower antioxidant potential evaluated by the DPPH method with increased maturity in olives of cv. Cobrancosa. The same trend was observed for the ABTS** free radical scavenging activity. These results may also be related to the lower content of Vitamin E (tocomberols) in the \"black table olive flour\", as Vitamin E is recognized as a powerful antioxidant in olives. Vitamin E has an important role in the preservation of lipid moiety. After performing a PCA, the \"table olive flours\" were discriminated into three groups based on the physicochemical and antioxidant properties. Group I (\"green table olive flour\") corresponded to the samples with higher C18:1 and MUFA proportions, and with the highest DPPH and ABTS** free radical scavenging activities, corresponding to a high antioxidant activity. This fact was probably due to the higher contents in hydroxytyrosol, tyrosol and \(\gamma\)-tocopherol.