Edible Films Based on Black Chia (<i>Salvia hispanica</i> L.) Seed Mucilage Containing <i>Rhus microphylla</i> Fruit Phenolic Extract

• Main Authors: Ana V. Charles-Rodríguez, Luz L. Rivera-Solís, Joana T. Martins, Zlatina Genisheva, Armando Robledo-Olivo, Susana González-Morales, Gustavo López-Guarin, Dolores G. Martínez-Vázquez, António A. Vicente, María L. Flores-López
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: Coatings
• Subjects: Black chia seed; mucilage; <i>Rhus microphylla</i> fruit; phenolic extract; edible films
• Online Access: https://www.mdpi.com/2079-6412/10/4/326

Functional films based on black chia (<i>Salvia hispanica</i> L.) seed mucilage (BCm) containing <i>Rhus microphylla</i> (Rm) fruit phenolic extract were built and characterized. A hydro-alcohol extract (HAE) of Rm was incorporated as the bioactive agent due to its noteworthy phenolic profile, and good antioxidant and antifungal activities. The effects of the BCm concentration (0.2% and 0.4%, w/v), HAE incorporation, and their interaction with glycerol (1.0%, w/v) and calcium chloride (0.05%, w/v) on the films’ physicochemical properties were evaluated. The filmogenic solutions successfully fitted to the Herschel–Bulkley model (<i>R²</i> < 0.999), exhibiting a pseudoplastic and shear thinning character, typical of polymer solutions. Interestingly, their rheological properties were not (<i>p</i> > 0.05) changed by the HAE addition, but their surface tension was enhanced (<i>p</i> < 0.05), which could favor their coating ability. The polyanionic nature of the systems (zeta potential-Zp values from −26.9 to −33.3 mV) allowed them to interact with Ca²⁺ cations, thus forming stable and resistant films. All the films showed low water solubility (15.0% to 22.3%) and high permeability (3.7 to 4.0 × 10⁻¹⁰ g m⁻¹ s⁻¹ Pa⁻¹), as well as high biodegradability (moisture content from 66.0% to 80.9%); although the moisture content was reduced (<i>p</i> < 0.05) with HAE addition. The combination of higher BCm ratio and HAE addition (BCm0.4+Rm) led to a more resistant, thick, opaque, and dark film compared with the others obtained. This study reveals the BCm-based films’ potential, highlighting those with HAE, representing a novel alternative to improve the quality of food products.