Supercritical CO2 Extraction of Phytocompounds from Olive Pomace Subjected to Different Drying Methods.

Olive pomace is a semisolid by-product of olive oil production and represents a valuable source of functional phytocompounds. The valorization of agro-food chain by-products represents a key factor in reducing production costs, providing benefits related to their reuse. On this ground, we herein investigate extraction methods with supercritical carbon dioxide (SC-CO2) of functional phytocompounds from olive pomace samples subjected to two different drying methods, i.e., freeze drying and hot-air drying. Olive pomace was produced using the two most common industrial olive oil production processes, one based on the two-phase (2P) decanter and one based on the three-phase (3P) decanter. Our results show that freeze drying more efficiently preserves phytocompounds such as α-tocopherol, carotenoids, chlorophylls, and polyphenols, whereas hot-air drying does not compromise the ß-sitosterol content and the extraction of squalene is not dependent on the drying method used. Moreover, higher amounts of α-tocopherol and polyphenols were extracted from 2P olive pomace, while ß-sitosterol, chlorophylls, and carotenoids were more concentrated in 3P olive pomace. Finally, tocopherol and pigment/polyphenol fractions exerted antioxidant activity in vitro and in accelerated oxidative conditions. These results highlight the potential of olive pomace to be upcycled by extracting from it, with green methods, functional phytocompounds for reuse in food and pharmaceutical industries.

Changes in stability, tocopherols, fatty acids and antioxidant capacity of sacha inchi (Plukenetia volubilis) oil during French fries deep-frying.

Sacha inchi (Plukenetia volubilis) oil (SI) is appreciated for its nutritional and sensorial characteristics. The aim of this study was to evaluate SI changes during French fries deep-frying at 170 °C or 180 °C up to 119 and 50 min, respectively; commercial soybean oil (SO) was tested as control. SI had high α-linolenic acid (53.8%), linoleic acid (33.4%) and total tocopherols (2540.1 mg/kg). During frying tocopherol content, oil stability and antioxidant capacity (ABTS, DPPH) decreased following zero-order kinetics; γ-tocopherol showed the strongest decrease. Notwithstanding the high SI unsaturation and the commercial antioxidant (TBHQ) in SO, SI showed slightly higher or similar hydrolysis (free fatty acids and diacylglycerols), similar primary (K232, oxidized-triacylglycerols) and lower secondary (K268, triacylglycerol oligopolymers) oxidation. Because of the high tocopherol content, SI showed lower degradation than SO. Thus, SI is suitable for short-term deep-frying; additionally, it may enhance the nutritional value and the flavour of fried foods.

Effects of storage on the oxidative stability of acorn oils extracted from three different Quercus species.

BACKGROUND: Acorn fruit and its components and by-products are receiving renewed interest due to their nutritional and phytochemical features. In particular, the oil extracted from acorns is recognized for having high nutritional quality and for being rich in bioactive compounds. Despite the growing interest, few papers are available that consider the evolution of acorn-oil characteristics during storage. Our aim was to investigate the storage-related changes in acorn oils extracted from three Quercus species grown in Algeria (Q. ilex, Q. suber, and Q. coccifera) 180 days after production, with a focus on polar and volatile compounds, not yet investigated. Basic quality parameters, phenolic content, antioxidant activity and induction time were also monitored. RESULTS: The oxidation markers (peroxide value and UV absorptions) increased during storage, whereas antioxidants decreased. A distinctive volatile profile was observed at the time of production, which underwent changes during storage. Polar compounds increased, whereas induction time decreased. The oil extracted from Quercus suber L. was the most affected by storage time. CONCLUSION: Floral and fruity volatile compounds detected in the oils' headspace could explain the pleasant flavor of acorn oils reported by other authors. As with other vegetable oils, storage depletes both volatiles and antioxidants and produces oxidation compounds, such as oxidized triacylglycerols. However, the acorn oils that were studied were quite stable under storage in the dark at room temperature for 6 months. © 2020 Society of Chemical Industry.

Functional compounds from olive pomace to obtain high-added value foods - a review.

Olive pomace, the solid by-product from virgin olive oil extraction, constitutes a remarkable source of functional compounds and has been exploited by several authors to formulate high value-added foods and, consequently, to foster the sustainability of the olive-oil chain. In this framework, the aim of the present review was to summarize the results on the application of functional compounds from olive pomace in food products. Phenolic-rich extracts from olive pomace were added to vegetable oils, fish burgers, fermented milk, and in the edible coating of fruit, to take advantage of their antioxidant and antimicrobial effects. Olive pomace was also used directly in the formulation of pasta and baked goods, by exploiting polyunsaturated fatty acids, phenolic compounds, and dietary fiber to obtain high value-added healthy foods and / or to extend their shelf-life. With the same scope, olive pomace was also added to animal feeds, providing healthy, improved animal products. Different authors used olive pomace to produce biodegradable materials and / or active packaging able to increase the content of bioactive compounds and the oxidative stability of foods. Overall, the results highlighted, in most cases, the effectiveness of the addition of olive pomace-derived functional compounds in improving nutritional value, quality, and / or the shelf-life of foods. However, the direct addition of olive pomace was found to be more challenging, especially due to alterations in the sensory and textural features of food. © 2020 Society of Chemical Industry.

The challenge of exploiting polyphenols from olive leaves: addition to foods to improve their shelf-life and nutritional value.

Olive leaves represent a waste from the olive oil industry which can be reused as source of polyphenols. The most representative phenolic compound of olive leaves is the secoiridoid oleuropein, followed by verbascoside, apigenin-7-O-glucoside, luteolin-7-O-glucoside, and simple phenols. The attention towards these compounds derives above all from the large number of studies demonstrating their beneficial effect on health, in fact olive leaves have been widely used in folk medicine in the Mediterranean regions. Moreover, the growing demand from consumers to replace the synthetic antioxidants, led researchers to conduct studies on the addition of plant bioactives in foods to improve their shelf-life and/or to obtain functional products. The current study overviews the findings on the addition of polyphenol-rich olive leaf extract (OLE) to foods. In particular, the effect of OLE addition on the antioxidant, microbiological and nutritional properties of different foods is examined. Most studies have highlighted the antioxidant effect of OLE in different food matrices, such as oils, meat, baked goods, vegetables, and dairy products. Furthermore, the antimicrobial activity of OLE has been observed in meat and vegetable foods, highlighting the potential of OLE as a replacer of synthetic preservatives. Finally, several authors studied the effect of OLE addition with the aim of improving the nutritional properties of vegetable products, tea, milk, meat and biscuits. Advantages and drawbacks of the different use of OLE were reported and discussed. © 2020 Society of Chemical Industry.

Antioxidant activity, tocopherols and polyphenols of acornoil obtained from Quercus species grown in Algeria.

Among the unusual vegetable fats, acorn oil has interesting nutritional and functional properties. Few studies are present in literature on acorn oil characterization and antioxidant activity evaluation while no studies are present regarding the analysis of the phenolic profile. The present study aims at investigating the content of hydrophilic and lipophilic phenolic compounds and pigments, as well as antioxidant properties and quality of the oil extracted from three Quercus species grown in Algeria. Oil yield, expressed as dry weight, was in the range 7.05-8.40%. Tocopherols contents were remarkable for the three species (539-676 mg kg-1), with (ß + γ)-tocopherols being the most abundant. Oils had also significant amounts of carotenoids (42-66 mg kg-1) and similar polyphenol patterns, but with a wide quantitative variability between species (195-436 mg kg-1). Twenty phenolic compounds were detected, 12 of which were tentatively identified. All of them were hydrolysable tannins derivatives (gallotannin or ellagitannin). Oils methanolic extracts had remarkable antioxidant activity; up to 3.34 and 3.79 µmol TE g-1 oil (DPPH and ABTS test, respectively). Quercus oil is a potential source of natural antioxidants, and it could be used as a new functional oil.