Turning to Olives for Anthocyanin’s Which May Prevent Oxidative Stress

06/11/19:   With the incidence of diseases becoming more and more abundant, there is a need for consumers to look for foods that are healthier choice options in the daily diet.

Have you ever thought about olives as a means of getting your daily hit of antioxidants which in turn helps to prevent daily oxidative stress?

The latest research out of Italy shows results reported in this work to strongly support the possibility to use the table olive as a functional food.

The study looked at different varietals which many in the study are also grown in Australia and included:

  • Cellina di Nardo (CdN)
  • Kalamata (grown in Australia)
  • Leccino (grown in Australia)
  • Empeltre
  • Ogliarola
  • Blanqueta
  • Hojablanca (grown in Australia)

It was demonstrated that the full maturation of olives is the best harvest time to obtain a table olive with a high content in phenolic compounds, anthocyanins, and other health valuable compounds.

Total phenolic contents (mg GAE/g DW) in seven commercial black table olives.

Researchers noted “In fact, to assess whether and how the phenolic components vary during maturation, the phenolic content was studied during different ripening stages. The results showed an increase in the total quantity of polyphenols in relation to the stage of maturation that in the later stages of ripening a two-fold intensification of total phenolic compounds was observed. This data is in accordance with the values reported by other researchers. The same researchers observed that phenolic fraction in fresh pulp is about 2% of the total weight of the pulp and detected a similar value in fully ripened CdN olives where the phenolic fraction represents the 1.6% of the pulp total weight.”

“The qualitative analysis of phenolic compounds during maturation demonstrated a great variation of the phenolic composition during ripening.  In particular, from Stage 4, olives start to accumulate anthocyanins, so that at Stage 7, the anthocyanin level reached 4.62 g/kg, an increase in anthocyanins matching to the progress of fruit ripening.   In comparison, another study reported the anthocyanin content of fresh blueberries contained 3.2g/kg of anthocyanin level in late-ripening blueberries.

In fact, the anthocyanin biosynthesis starts when the oleuropein decreases as a direct result of an increase of the enzymatic activity of phenylalanine-ammonium lyase during drupe maturation.  The anthocyanin content found in CdN olives is higher than the number of anthocyanins present in most of the other commercial olive fruits, as reported by a study conducted on several Italian cultivars.  The black olives of Frantoio, a cultivar widespread in Tuscany and Australia, has a number of anthocyanins equal to 1.25 g/kg of fresh pulp; Ciliegino olives have an even lower quantity of phenolic compounds: 0.50 g/kg of fresh pulp.” said Researchers.

This research is important because it exposes a potential new way for marketing of black table olives to consumers about daily anthocyanin intake for good health by adding olives to the daily diet.

_____________________________________________

Antioxidant Activity and Anthocyanin Contents in Olives (cv Cellina di Nardo) during Ripening and After Fermentation

Abstract

The olive tree “Cellina di Nardò” (CdN) is one of the most widespread cultivars in Southern Italy, mainly grown in the Provinces of Lecce, Taranto, and Brindisi over a total of about 60,000 hectares.  Although this cultivar is mainly used for oil production, the drupes are also suitable and potentially marketable as table olives.  When used for this purpose, olives are harvested after complete maturation, which gives to them a natural black color due to anthocyanin accumulation. This survey reports for the first time on the total phenolic content (TPC), anthocyanin characterization, and antioxidant activity of CdN olive fruits during ripening and after fermentation. The antioxidant activity (AA) was determined using three different methods. Data showed that TPC increased during maturation, reaching values two times higher in completely ripened olives.  Anthocyanins were found only in mature olives and the concentrations reached up to 5.3 g/kg dry weight. AA was determined for the four ripening stages, and was particularly high in the totally black olive fruit, in accordance with TPC and anthocyanin amounts.  Moreover, the CdN olives showed a higher TPC and a greater AA compared to other black table olives produced by cultivars commonly grown for this purpose. These data demonstrate the great potential of black table CdN olives, a product that combines exceptional organoleptic properties with remarkable antioxidant capacity.

Results
The effects of water regimes on the plant water status, photosynthetic performance, metabolites fluctuations and fruit quality parameters were evaluated. All DIS treatments enhanced leaf tissue density, RDI and SDI generally did not affect leaf water status and maintained photosynthetic machinery working properly, while SDIAF treatment impaired olive tree physiological indicators. DIS treatments maintained the levels of primary metabolites in leaves, but SDIAF plants showed signs of oxidative stress.

Moreover, DIS treatments led to changes in the secondary metabolism, both in leaves and in fruits, with increased total phenolic compounds, ortho-diphenols, and flavonoids concentrations, and higher total antioxidant capacity, as well higher oil content.

Phenolic profiles showed the relevance of an early harvest in order to obtain higher oleuropein levels with associated higher health benefits.

Conclusion
Different treatments (or curing methods) that are necessary to remove the bitterness of the raw olive and to stabilize them to obtain edible table olives, causing a loss in phenolic substances which also results in a loss of anthocyanins and antioxidant activity. However, CdN black table olives were the richest in polyphenols, consequently possessing the best antioxidant activity among the analyzed black table olives and among other black table olives reported in literature.  Moreover, it is plausible that regular consumption of CdN table olives can give real returns in terms of prevention of oxidative stress.

Authors:  Alessio Aprile,,  Carmine Negro,  Erika Sabella,  Andrea Luvisi,  Francesca Nicolì,  Eliana Nutricati,  Marzia Vergine,  Antonio Miceli,  Federica Blando,  and Luigi De Bellis

  • Department of Biological and Environmental Sciences and Technologies (DiSTeBA), Salento University, Via Prov. le Lecce-Monteroni, 73100 Lecce, Italy;
  • Institute of Sciences of Food Production (ISPA), National Research Council (CNR), Research Unit of Lecce, Via Prov. le Lecce-Monteroni, 73100 Lecce,

Read the full study at Antioxidants MDPI

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