Abstract
Aristotelia chilensis is a plant rich in phenolics and other bioactive compounds. Their leaves are discarded as waste in the maqui berry industry. A new application of these wastes is intended by the recovery of bioactive compounds using pressurized hot water extraction with conventional or microwave heating. Both technologies have been selected for their green character regarding the type of solvent and the high efficiency in shorter operation times. Extractions were performed in the temperature range 140–200 °C with a solid/liquid ratio of 1:15 (w:w). The extracts’ total phenolic content, antioxidant capacity, and saccharides content obtained with both heating methods were measured. Additionally, the thermo-rheological properties of the gelling matrix enriched with these extracts were analyzed. Optimum conditions for lyophilized extracts were found with conventional heating, at 140 °C and 20 min extraction; 250.0 mg GAE/g dry extract and 1321.5 mg Trolox/g dry extract. Close to optimum performance was achieved with microwave heating in a fraction of the time (5 min) at 160 °C (extraction), yielding extracts with 231.9 mg GAE/g dry extract of total phenolics and antiradical capacity equivalent to 1176.3 mg Trolox/g dry extract. Slightly higher antioxidant values were identified for spray-dried extracts (between 5% for phenolic content and 2.5% for antioxidant capacity). The extracts obtained with both heating methods at 200 °C contained more than 20% oligosaccharides, primarily glucose. All the formulated gelling matrices enriched with the obtained extracts displayed intermediate gel strength properties. The tested technologies efficiently recovered highly active antioxidant extracts, rich in polyphenolics, and valuable for formulating gelling matrices with potential applicability in foods and other products.
Highlights
Aristotelia chilensis, commonly known in South America as maqui, is a native tree of the subantarctic forests of Chile and Argentina, growing at 2500 m above sea level and reaching approximately 4–5 m height [1]
The selected green technologies use water as the only solvent, and due to operation under pressurized conditions, they reduce energy consumption and solvents and prevent toxic effluents formation, being strategies much more sustainable with the environment. Both PHWE heating methods tested in this research are appropriate for recovering phenolic compounds with antiradical properties from maqui leaves
These extraction technologies allowed adding value to A. chilensis leaves from maqui industrial discards by recovering antioxidant soluble extracts
Summary
Aristotelia chilensis, commonly known in South America as maqui, is a native tree of the subantarctic forests of Chile and Argentina, growing at 2500 m above sea level and reaching approximately 4–5 m height [1]. It produces succulent berries, which have been applied throughout civilizations to prepare medicines, foods, and colorants. Infusions of maqui leaves that are highly antioxidant and rich in phenolic compounds [2] were used by ancient cultures to treat several ailments, such as diarrhea, throat infections, and mouth ulcers [3] Nowadays, these infusions are still used as a natural muscle relaxant or as an analgesic [1].
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