Effect of Spanish style processing on the phenolic compounds and antioxidant activity of Algerian green table olives

Abstract

SUMMARY:The study was carried out on seven Algerian olive cultivars to report the effect of Spanish style processing on individual and total phenolic compounds and the changes that occur in antioxidant capacity. The results indicate that the treatment leads to losses in phenolic contents which are cultivar dependent. Sigoise is the least affected variety (12.25%) and Azzeradj from Seddouk the most affected one (94.80%). The phenolic profile shows drastic changes after processing. Hydroxytyrosol is dominant in processed olives (14.42-545.42 mg·100 g −1 ) while oleuropein is the major phenolic compound in fresh olives (994.27 mg·100 g −1 ). As a consequence to the loss in phenolic content, substantial reductions in the antioxidant activities of the extracts are noted. They are estimated to be 13.12-92.75% in scavenging activity against the DPPH radical, 37.78-93.98% in reducing capacity, 59.45-97.94% in the hydrogen peroxide radical and 7.26-51.66% in the inhibition bleaching of β-carotene. Among the processed varieties, only Sigoise presented a positive value of RACI (relative antioxidant capacity index). KEYWORDS: Antioxidant activity; Phenolic compounds; RACI; Spanish style processing; Table olivesRESUMEN: Efecto del procesamiento sobre el contenido fenólico y la actividad antioxidante de aceitunas verdes de mesa argelinas. El estudio se llevó a cabo con siete variedades de aceitunas argelinas y se investigó el efecto de la elaboración al estilo español sobre los compuestos fenólicos individuales y totales; así como los cambios que se producen en la capacidad antioxidante. Los resultados obtenidos muestran que el procesamiento conduce a pérdidas en el contenido fenólico, lo cual es dependiente de la variedad. Sigoise es la variedad menos afectada (12.25%) y Azzeradj de Seddouk la más (94.80%). El perfil fenólico muestra cambios drásticos después de su procesamiento. El hidroxitirosol es el polifenol predominante en aceitunas procesadas (14.42-545.42 mg·100 g −1 ), mientras que la oleuropeína es el compuesto fenólico mayoritario en las aceitunas frescas (994.27 mg·100 g −1 ). En consonancia con la pérdida en estos polifenoles, se detectaron reducciones sustanciales de la actividad antioxidante de los extractos. Se estima en 13.12 a 92.75% la actividad de eliminación de radicales DPPH 37.78-93.98% en la reducción de la capacidad, 59.45 a 97.941% en el radical peróxido de hidrógeno y 7.26-51.66% en la inhibición de blanqueo del β-caroteno. Entre las variedades procesadas, sólo Sigoise presentó un valor positivo de RACI (Indice Relativo de Capacidad Antioxidante).

Comparative Study on Chemical Composition of Green and Black Table Olives Brines of the Endemic ′′Sigoise′′ Cultivar: Recovery of high‐Added Values Compounds

“…It is noteworthy that our results go in contrast with the data set formed by [42] which indicate a decrease in flavonoids at the level of the black stage of maturity for the studied varieties, including Sigoise, whose results are similar to those of Bouaziz et al [43] This variation can be ascribed to treatment styles, successive washes and the physiology of the drupe (thickness and texture of the pulp). [44] According to our study, the total sugar content of green olive brines is lower than that of black olive brines, which may be assigned to the enzymatic activity of the hydrolysis of oleuropein and ligstroside in sugar and the elenolic acid during the fermentation stage. Therefore, the formed the glucose is exploited as substrate by the fermentable bacteria present in the brines of the green olives.…”

“…This variation can be ascribed to treatment styles, successive washes and the physiology of the drupe (thickness and texture of the pulp) [44] …”

Data_Sheet_1.docx

“…The brine samples showed an average total phenols concentration of 1,821 ppm (Table 2) although the antimicrobial phenolic compounds were not detected. The phenolic content of olives is drastically affected by the alkaline treatment and the successive washing stages during the elaboration as Spanish-style table olives (Medina et al, 2008;Mettouchi et al, 2016;Ait Chabane et al, 2019). In addition, the LAB population showed values below 2.85 log CFU/ml in some specific samples (Table 3), and the high concentration of NaCl of the initial brines could also inhibit the growth of them in favor of yeasts (Arroyo-López et al, 2012).…”

“…The increasingly restrictive new environmental policies applied in many countries have forced table olive producers to eliminate the second wash in this type of elaboration, replacing it with a single one, although more intense (12-15 h), to reduce the volume of wastewaters (Sánchez-Gómez et al, 2006). However, Algerian regulations seem to be more flexible in this regard, and factories continue to carry out two washes (Mettouchi et al, 2016). Another trend currently carried out in many factories is to perform a controlled fermentation.…”