Cyclodextrins as nano-encapsulating agents for hydrophobic food ingredients

DOS SANTOS,; MAZZOBRE, MARÍA FLORENCIA

Viña del Mar, Chile

Congreso; TENTH INTERNATIONAL CONGRESSON ENGINEERING AND FOOD (ICEF10); 2008

1. Justification Cyclodextrins (CDs) are able to form inclusion complexes with hydrophobic molecules of suitable size and geometry. The molecular encapsulation of lypophylic nutritional ingredients in CDs allows to increase the stability of flavors, vitamins, dyes or lipids. 2. Objective The objective of this work was to compare the properties of a modified cyclodextrin, 2-hydroxypropil-â-cyclodextrin (HPBCD) with those of â-cyclodextrin (BCD). Particularly, sorption and thermal properties, and the ability to form inclusion complexes with hydrophobic compounds were studied. 2. Methods Terpenic alcohol (ATerp) and myristic acid (AMir) were selected as models of numerous  additives and nutritional flavors used both in food or pharmaceuticals. Inclusion complexes of ATerp/BCD, ATerp/HPBCD and AMir/HPBCD were prepared by co-precipitation in aqueous solutions, in 1:1, 1:2, 1:3 and 1:4 molar ratios. All systems were freeze-dried and equilibrated to different relative humidities. Sorption isotherms and thermal properties (by differential scanning calorimetry) were studied. 3. Results The structural modification of the BCD conferred properties of sorption, solubility, amorficity, and ability/capacity to form hydrates different from those from the original BCD. The presence of a well defined Tg allowed to confirm the amorphous characteristics of the CD studied and their complexes. Although the formation of the complex did not affect the sorption isotherms of the HPBCD, a decrease of the Tg values was observed which indicates that in the presence of ATerp structural modifications take place affecting the physical characteristics of the matrix. Thermal analyses showed that the inclusion of AMir in the HPBCD was not complete. As a difference  with the encapsulation of other compounds, greater inclusion of AMir was observed as the relative humidities and/or time of storage increased. It is interesting to emphasize that in addition to the hydrophobicity, the spatial structure of the binding molecule significantly affects the structure of the inclusion complex, the degree of encapsulation and delivery, and the interactions of the systems with water. 4. Significance to the food engineering field. These data would be useful for the selection of adequate storage conditions, shelf life  prediction or controlled delivery of ingredients in products formulated with cyclodextrins as nano-encapsulating agents.