Using complexation for the microencapsulation of nisin in biopolymer matrices by spray-drying

- Nisin was complexed with pectin or alginate.
- The formed complexes were spray-dried to form microcapsules containing nisin.
- Complexation was able to protect the antimicrobial activity of nisin during spray-drying.
- Spray-drying process promoted the aggregation of nisin-pectin complexes and the dissociation of nisin-alginate aggregates.

The aim of this study is to investigate the potential of complexation to encapsulate nisin (5 g/L concentration) using spray-drying technique and to evaluate how complexation with pectin or alginate (2 g/L concentration) can preserve nisin structure and antimicrobial activity. Spray-drying of nisin-low methoxyl pectin or nisin-alginate electrostatic complexes has led to the microencapsulation of the peptide in different networks that were highly influenced by the polysaccharide type. Turbidity and particle size measurements indicated that while spray-drying promoted the aggregation of nisin-pectin complexes, it favored the dissociation of nisin-alginate aggregates to form individual complexes. Structural changes of nisin induced by complexation with pectin or alginate and spray-drying were studied by using UV-Vis absorption and fluorescence spectroscopy. The results showed that complexation with pectin or alginate preserved nisin structure as well as its antimicrobial activity during spray-drying.