Guest–Host Inclusion Complexes of β-Cyclodextrin With Commercial Oil–Soluble Copper Chlorophyll and Natural Chlorophyll Recovered by Enzyme-Assisted Extraction

Abstract

Natural green pigments, with their numerous and attractive shades, represent valuable ingredients in food preparations. However, scarce solubility and stability of chlorophyll under use conditions limit its potential application, despite the widespread availability of natural sources. Therefore, this work aimed to produce a food-grade inclusion complex, by simple mixing, based on chlorophyll (Chl) and β-cyclodextrin (β-CD), able to preserve the pigment stability and green nuance at different storage conditions (temperature: 4°C, 25°C, and 40°C in the dark or under UV-light). After assessing the most suitable stoichiometric inclusion ratio between the pigment contained in the commercial preparation [E141(i)] and the β-CD (1:1), simple mixing was employed as a solvent-free, time-saving technique to encapsulate chlorophyll (recovered from spinach by enzyme-assisted extraction). Two innovative inclusion complexes were prepared using wet pellet (Chl_pellet/β-CD) or freeze-dried powder (Chl_freeze-dried/β-CD), showing a powder recovery of 90.4% and 100%, inclusion efficiency of 92% and 96%, and loading capacity of 1.4% and 2.5%, respectively. The presence of β-CD increased the solubility (+59% and +66% for Chl_pellet and Chl_freeze-dried) and stability of the pigment, especially under the most critical conditions (40°C, UV; degradation rate constant varied from 0.025 [Chl-free] to 0.021 [Chl_freeze-dried/β-CD] days⁻¹ and from 0.31 [Chl-free] to 0.23 [Chl_pellet/β-CD] days⁻¹). Chl_pellet/β-CD and Chl_freeze-dried/β-CD better retained greenness than the free pigment, both in the dark and under UV-light, especially at low temperature. Overall, the current research expands the understanding regarding easy and prompt techniques for Chl encapsulation in β-CDs as a promising strategy for its potential application in the food industry.