Are olive pomace powders a safe source of bioactives and nutrients?

Abstract

BACKGROUND The olive oil industry generates significant amounts of semi‐solid wastes, namely olive pomace. Olive pomace is a by‐product rich in high‐value compounds (e.g. dietary fibre, unsaturated fatty acids, polyphenols) widely explored to obtain new food ingredients. However, conventional extraction methods frequently use organic solvents, while novel eco‐friendly techniques have high operational costs. The development of powdered products without any extraction step has been proposed as a more feasible and sustainable approach. RESULTS The present study fractionated and valorized the liquid and pulp fraction of olive pomace obtaining two stable and safe powdered ingredients, namely a liquid‐enriched powder (LOPP) and a pulp‐enriched powder (POPP). These powders were characterized chemically, and their bioactivity was assessed. LOPP exhibited a significant amount of mannitol (141 g kg−1), potassium (54 g kg−1) and hydroxytyrosol derivatives (5 mg g−1). POPP exhibited a high amount of dietary fibre (620 g kg−1) associated with a significant amount of bound phenolics (7.41 mg GAE g−1 fibre DW) with substantial antioxidant activity. POPP also contained an unsaturated fatty acid composition similar to that of olive oil (76% of total fatty acids) and showed potential as a reasonable source of protein (12%). Their functional properties (solubility, water‐holding and oil‐holding capacity), antioxidant capacity and antimicrobial activity were also assessed, and their biological safety was verified. CONCLUSIONS The development of olive pomace powders for application in the food industry could be a suitable strategy to add value to olive pomace and obtain safe multifunctional ingredients with higher health‐promoting effects than dietary fibre and polyphenols. © 2020 Society of Chemical Industry

Study of olive pomace antioxidant dietary fibre powder throughout gastrointestinal tract as multisource of phenolics, fatty acids and dietary fibre

“…The amount of dietary fibre, its composition (neutral sugars, uronic acids, TPC and individual phenolics) and AOX measured after SGD are presented in Fig. 1, together with the previous results of dietary fibre profile of POPP obtained using the AOAC (Association of Official Analytical Chemists) method (Ribeiro, Oliveira, Coelho, et al, 2020). The comparison between the results achieved using the AOAC methodology and SGD allowed to understand the possible effects of digestion in POPP dietary fibre content and composition, but also to estimate their potential beneficial effects on human health.…”

“…RI higher than 100% was registered. A liberation of compounds from POPP by the action of pH and digestive enzymes; and chemical Ribeiro, Oliveira, Coelho, et al (2020); *2 mg galacturonic acid equivalents (GUAE)/ g fibre DW. Results are the means of three determinations ± standard deviation.…”

“…The pulp-enriched powder (POPP) obtained in our previous study revealed a rich composition in DF (68.14 ± 0.54 g/100 g DW), mainly insoluble dietary fibre (IDF) (52.17 ± 0.01 g/ 100 g DW), but also a significant amount of free phenolic compounds (extractable) and bound phenolic compounds linked to the lipids, proteins and dietary fibre (Ribeiro, Oliveira, Coelho, et al, 2020). POPP also exhibited a high level (about 19 g/ 100 g DW) of unsaturated fatty acids (UFAs), principally in monounsaturated form (>16%), but also in polyunsaturated form (>1%) Oleic acid was the UFA detected in higher amount followed by linoleic acid (Ribeiro, Oliveira, Coelho, et al, 2020). Both these UFAs are known for their beneficial effects on the reduction of cholesterol and triglycerides (Lopez-Huertas, 2010).…”

“…Both these UFAs are known for their beneficial effects on the reduction of cholesterol and triglycerides (Lopez-Huertas, 2010). Regarding POPP bound phenolics, it was estimated that more than half of its total bound phenolics (≈ 54%) were linked to dietary fibre (Ribeiro, Oliveira, Coelho, et al, 2020). In literature, the bound phenolic compounds have been described as significant contributors of the health-related properties attributed to dietary fibre, due to its capacity to pass through the gastrointestinal tract almost intact reaching the colon linked to dietary fibre (González-Sarrías, Espín, & Tomás-Barberán, 2017;Liu, Jia, Chen, Wan, Dong, Nie, Xie, & Yu, 2019).…”

“…In our previous work, the complete chemical characterisation of POPP was achieved showing that POPP is an attractive add-value powdered product with the advantage of retaining several functional compounds, namely UFAs, dietary fibre and phenolics (Ribeiro, Oliveira, Coelho, et al, 2020). The retention of these functional compounds together could interact with each other synergically ascribing multifunctional properties to food (García-Lomillo, González-SanJosé, Del Pino-García, Rivero-Pérez, & Muñiz-Rodríguez, 2014;Saura-Calixto, 1998).…”