Valorization of Beetroot Waste via Subcritical Water Extraction for Developing Active Food Packaging Materials

Area of Science:

• Agricultural Science
• Food Science
• Materials Science

Background:

• Valorization of agricultural waste, specifically beet root leaves and stems (BLS), is crucial for sustainable practices.
• Active compounds with antioxidant properties can be extracted from plant biomass.
• Polymer films are used for food packaging to extend shelf life.

Purpose of the Study:

• To extract active compounds from BLS using subcritical water extraction (SWE).
• To incorporate these extracts into thermoplastic starch (TPS) and polylactic acid (PLA) films.
• To evaluate the antioxidant properties and effectiveness of these films in preserving sunflower oil.

Main Methods:

• Subcritical water extraction (SWE) of BLS at 150 °C and 170 °C.
• Incorporation of extracts (6% wt.) into TPS and PLA polymer matrices.
• Characterization of extracts (total phenols, betalains, radical scavenging capacity) and films (color, UV-blocking, oxygen permeability, water vapor permeability).
• Assessment of sunflower oil oxidation protection.

Main Results:

• High extraction yields (60-67%) and significant antioxidant activity (total phenols: 51-73 mg GAE·g^-1, EC₅₀: 30-22 mg mg^-1 DPPH) were obtained.
• Higher extraction temperature (170 °C) increased phenolic content and antioxidant capacity.
• Films exhibited color and UV-blocking properties.
• Extracts reduced oxygen permeability (OP) in PLA films but increased it in TPS films.
• PLA films with extracts significantly protected sunflower oil from oxidation, linked to reduced OP.

Conclusions:

• SWE is effective for extracting bioactive compounds from BLS.
• BLS extracts can be used to create antioxidant polymer films.
• PLA films incorporated with BLS extracts show promise for protecting sunflower oil against oxidation, especially due to reduced oxygen permeability.