Nano/microencapsulation of anthocyanins; a systematic review and meta-analysis

Anthocyanins, a kind of phenolic compounds are present in plant kingdom. They exhibit biological activities such as anti-inflammatory and anti-cancer properties as well as imparting colors to various plants. The objective of this review is to provide a systematic evaluation of the evidence and a meta-analysis of published researches on the nano/microencapsulation of anthocyanins. A comprehensive literature search was conducted for articles published in 2016 to 2019 on PubMed, Web of Sciences and Scopus databases. Overall 45 eligible articles (51 cases; some authors studied 2 or more encapsulation methods) with appropriate data were included in the statistical analysis. In the current work, based on the technique and equipment applied for the formulation of micro/nanoencapsulation systems, the anthocyanin-loaded nano/microcarriers were classified into five main classes: (a) spray dried particles (spray-drying); (b) freeze-dried particles (freeze-drying); (c) lipid-based particles (emulsification and liposomal encapsulation); (d) electrospun fibers and electrosprayed particles (electrohydrodynamic encapsulation); and (e) nano/micro-gels (gelation). Based on the results from the meta-analysis, the studied technique for encapsulation of anthocyanins can be ordered as: spray-drying (33.33%), freeze-drying (27.08%), gelation (20.83%), lipid-based particles (14.58%) and electrohydrodynamic processes (4.17%). In addition, carbohydrates such as maltodextrin (19.56%) and gums (15.22%) have been the most frequently used biopolymers for encapsulation of anthocyanins in the selected studies.