# Table Olive Flours\": An Ingredient Rich in Bioactive Compounds?
## 4 Discussion  
In general, flours with distinct colors and nutritional characteristics were obtained when different natural table olives were used. Concerning the fat content of the flours, as mentioned before, the lowest value corresponded to the \"green table olive flour\", and no significant differences were detected between the flours obtained from turning color and black table olives. This fact is related to the maturation process of the fruits. During this process, some biochemical changes occurred, and the amount of fat increased [30]. Identical results were mentioned by [PERSON] & [PERSON] [31], who indicated a lower fat content in green olives compared to black olives. On the contrary, the crude protein and carbohydrate contents decrease as the olives ripen due to this oil increase. Regarding the ash content, the \"green table olive flour\" had the highest value. This mineral content is expected to be mostly due to the salt used for olive curing. Since green table olives presented higher moisture and the brine used always had the same salt concentration, the amount of salt will be higher after removing the water to express the results in dry weight. Consequently, the ash will be higher in the green table olives. Regarding fatty acids and tocopherols, the olives' ripeness influences the profile and content of these compounds. The \"green table olive flour\" had the highest percentages of oleic acid (C18:1) and MUFA. On the contrary, the \"black table olive flour\" had the highest percentages of linoleic acid (C18:2) and PUFA, and the more mature the olives are, the fewer tocopherols their flours will have. The total phenolic contents varied between 247 and 404 mg/100 g d.m., in line with the values reported by [PERSON] et al. [4] (87-460 mg/100 g d.m.) for Portuguese table olives. These results are similar to those reported by [PERSON] et al. [11], who also detected a decline in total phenolics during the maturation process of cv. Cobrancosa. As mentioned before, of all the compounds identified, hydroxytyrosol was the major compound in all \"table olive flours\", suggesting that table olives are generally good sources of this phenol. Similar results for table olives were reported by [PERSON] et al. [32], [PERSON] et al. [8] and [PERSON] et al. [4]. According to these authors, hydroxytyrosol is the phenolic compound that exists in more significant quantities in table olives. Its accumulation comes from the hydrolysis of oleuropein and hydroxytyrosol-4-\(\beta\)-glucoside, phenolic compounds that decreased during the fermentation and storage time [32]. Hydroxytyrosol is a compound with antioxidant and antimicrobial properties, and is already recognized by the FDA as a safe compound, designated as GRAS (Generally Recognized as Safe) [33]. The \"green table olive flour\" was the one with the highest amounts of this compound, followed by the \"turning color table olive flour\" and, finally, the \"black table olive flour\". Concerning tyrosol, similar to hydroxytyrosol, the amount of both compounds decreases as the olive matures. Tyrosol was also detected by [PERSON] et al. [32] when studying the fermentation of naturally black olives. Tyrosol also has antioxidant activity, and is an anti-arrhythmia agent [33]. Luteolin stood out as the third major compound, with the \"green and turning color table olive flours\" showing the highest values. Luteolin is a flavonoid, with antioxidant and anti-inflammatory potential, as well as apoptosis-inducing and chemo preventive activities [33]. Oleuropein was not detected since, during fermentation, it is known that this phenol decreases with time, being converted in hydroxytyrosol [32]. Oleuropein is responsible for the bitter taste of unprocessed olives and, to become edible, the fruits need to lose, at least partially, their natural bitterness. Consequently, it is expected that oleuropein might not be found in processed fruits. [PERSON] et al.