Polyphenol Profile in Manzanilla Table Olives As Affected by Water Deficit during Specific Phenological Stages and Spanish-Style Processing

Abstract

Reducing water consumption on agriculture is a worldwide goal toward sustainability. In this scenario, two experiments of regulated deficit irrigation (RDI) were carried out on olive trees, cultivar Manzanilla. With regard to experiment A, three RDI techniques were applied during the olive pit hardening period (stage II), while in experiment B, two RDI treatments were applied during the rehydration phase (stage III). Table olives under RDI are so-called hydroSOStainable. The effect of water deficit and Spanish-style processing was studied on the polyphenol profile, antioxidant capacity, and total polyphenol content (TPC) of both raw olives (RO) and table olives (TO). The TPC decreased after processing of TO. It could be due to osmotic mechanisms. However, many individual polyphenols, such as oleuropein (main polyphenol) or oleoside diglucoside, increased their concentrations in hydroSOStainable TO. Additionally, the TPC content was correlated to the phenological stage of the fruit when the stress is applied. A moderate stress during pit hardening and an intense stress during the rehydration phase were the treatments that best improved the polyphenol profile.

Impact of Gastrointestinal In Vitro Digestion and Deficit Irrigation on Antioxidant Activity and Phenolic Content Bioaccessibility of “Manzanilla” Table Olives

“…A high proportion of table olive polyphenols are very susceptible to chemical degradation when they are submitted to the acidic conditions of digestion [15]. It was formerly described the polyphenolic profile of hydroSOStainable table olives of the current research [3], and it was found an increase of oleuropein, comselogoside, and verbascoside on A1 treatment as compared with control, as well as an increase of elenoic acid glucoside, oleuropein, and comselogoside regarding RDI treatments of experiment B. Beside this increases, it was previously reported that only 25% of oleuropein (one of the most important polyphenols in table olives) was stable during digestion, as well as only 20% of comselogoside and elenoic acid derivatives [15]. Flavonoids, verbascoside, and hydroxytyrosol derivatives also presented a small TPC bioaccessibility in a research conducted with three table olives cultivars [14].…”

“…Field characteristics of both experiments could be found in the work by Sánchez-Rodríguez and Cano-Lamadrid et al [3]. Climatic conditions could be considered equal for both experiments because only 10 km separated the farms.…”

“…Flavonoids, verbascoside, and hydroxytyrosol derivatives also presented a small TPC bioaccessibility in a research conducted with three table olives cultivars [14]. Flavonoids are not very soluble in either organic or aqueous solvents and are usually present in foods in combination with sugars in the form of glycosides [16], so it is possible that higher concentrations that were found on RDI table olives on some flavonoids such as luteolin [3] would probably not have been extracted from the olive pulp during the in vitro digestion simulation.…”

“…Nowadays, regulated deficit irrigation (RDI) strategies are being implemented on olive tree orchards with the main purpose of saving water. Additionally, moderate RDI strategies are being investigated in table olives due to their "potential" effect on enhancing the accumulation of bioactive compounds and improvement of the intensity of key sensory attributes; these special table olives are known as hydroSOStainable [3].…”

Table Olives: An Overview on Effects of Processing on Nutritional and Sensory Quality

“…Results showed that olives grown under moderate irrigation stress had the highest content of PUFA, and in particular, linoleic acid. The same research group [24] carried out a study by applying a similar irrigation experimental plan and evaluated its influence on the phenolic profile of Spanish style Manzanilla olives. Results evidenced that a moderate level of irrigation increased the amounts of some polyphenols in table olives, especially those of compounds with health promoting activities, such oleuropein and oleoside diglucoside.…”