Fortification of dietary biopolymers-based packaging material with bioactive plant extracts

Due to the diverse functionality of plant extracts and their generally recognized as safe (GRAS) status for use in foods, their incorporation into dietary biopolymer-based packaging materials has recently elicited great interest for food applications. Polysaccharides (e.g., chitosan, alginate), proteins (e.g., soy and whey protein isolates, gelatine, zein) are among those well-studied promising edible polymer carriers used for delivering a variety of bioactive extracts including those from green tea, grape seeds, blueberry, and cranberry. The addition of plant extracts has proved to provide certain physicochemical modification or bioactivity of the above listed/materials, and thus could expand their overall applications. This review summarized the impact of plant extracts on the modification of the physicochemical characteristics (mechanical and sensory properties) of the biopolymer, carriers as well as the effectiveness of extracts' functionality (particularly antioxidant capacity and antimicrobial activities) on the resultant materials. Noticeably, various factors determine final results. The main factors include the origin of the extracts and the biopolymer carriers, polymer carriers/extracts composition, and material-forming processes used. Interactions between polymer carriers and extracts have been well recognized in explaining some of the above observations. Specifically, polyphenolic substances in extracts have been identified and proposed as being one of the key bioactive components, which can contribute to possible hydrogen bond involvement interactions. However, few studies have established the structural correlation between specific polyphenolic compounds and the polymer carriers. Proposed potential applications of the resulting materials are expected to be put into a wider commercial utilization in the future. (C) 2012 Elsevier Ltd. All rights reserved.