Active Poly (Lactic Acid) Films with Rice Straw Aqueous Extracts for Meat Preservation Purposes

Abstract

Aqueous extracts from rice straw (RS), using ultrasound-assisted reflux heating extraction (USHT) and subcritical water extraction (SWE), under two process conditions (160 °C, 7 bars; and 180 °C, 11 bars), were obtained and characterised as to their phenolic content and antioxidant and antimicrobial capacities. These extracts were incorporated (6% wt.) into poly (lactic acid) (PLA) films by melt blending and compression moulding that were characterised as to their structural and functional properties and their capacity to preserve fresh pork meat, as vacuum thermo-sealed bags, throughout 16 days of cold storage. The extracts slightly reduced the extensibility, resistance to break, and water barrier capacity of the PLA films but enhanced their oxygen barrier capacity and the UV light-blocking effect. The films with RS extracts were effective at preserving meat quality parameters, inhibiting microbial growth, meat oxidation, discolouration, and weight loss. The SWE extract obtained at 180 °C was the most effective at obtaining active films for meat preservation, exhibiting the greatest antioxidant and antibacterial activity. Therefore, the green SWE technique is useful for obtaining active extracts from RS, allowing for its valorisation in the development of biodegradable active materials useful to preserve food quality.