Microwave vs. conventional extraction of pectin from Malus domestica 'Falticeni' pomace and its potential use in hydrocolloid-based films

Conventional extraction (CE) and microwave-assisted extraction (MAE) were compared in terms of efficiency and quality of pectin in two separate processes aimed to extract pectin from Malus domestica 'Falticeni' apple pomace. A similar extraction yield in a shorter extraction time was observed for the microwave-assisted procedure as compared to CE, while the galacturonic acid content and the degree of esterification of pectin were similar for both methods. Apple pectin extracted from this plant source by both methods had high galacturonic acid content, degree of esterification and molecular weight. Considering the high efficiency of microwave-assisted extraction and the composition of the obtained pectin, microwave-assisted apple pectin extracted under optimal conditions was used to produce edible films in combination with hydroxypropyl methylcellulose (HPMC). Films formulated with pectin from microwave extraction had significant lower oxygen permeability as compared to plasticized pure HPMC films, which makes microwave extracted pectin suitable for film-forming applications in which a good barrier to oxygen is required.