Researchers increase red bell pepper carotenoid solubility for food and beverage applications

Researchers from Brazil’s Federal University of Fluminense studied​ how to enhance the solubility of capsanthin and capsorubin, the two main carotenoids in sweet bell peppers, to enable their use as a natural food and beverage color or as an ingredient for functionality.

“Consumption of a balanced diet rich in carotenoids has been associated with the prevention of diseases such as cancer in several tissues and macular degeneration,”​ they wrote, citing research published in the journal Molecules ​in 2012​ and Vision Research ​in 2010​.

“However, their low water solubility and instability in front of light, thermal treatment and oxygen hinder their utilization in food or pharmaceutical formulations,”​ they added.

Broaden applications​

The researchers previously found that sweet bell pepper carotenoid in beta-cyclodextrin was efficient to mix in with yogurt, but not when applying it to liquid bases for beverages. “This finding led to the search for alternatives that besides protecting the guest molecules, make possible the application of complex in water-based foods,” ​they wrote.

They hypothesized that carotenoids will be more water soluble when complexed with 2-hydroxypropyl-beta-cyclodextrin (2-HP-beta-CD), a water-soluble modified cyclodextrin. According to the researchers, the FDA classified native cyclodextrins​ (including beta-cyclodextrin) as Generally Recognized as Safe, while the EU’s guideline says that beta-cyclodextrin is allowed as food additive with an ADI of 5 mg/kg/day.

 “The aim of this investigation was to prepare inclusion complexes between red bell pepper pigments and 2-HP-beta-CD using four different mass ratios (1:4, 1:6, 1:8 and 1:10) through ultrasonic homogenization,”​ they added.

Study procedure​

Using red bell pepper purchased from a market in Rio de Janeiro, the scientists ground it in an industrial blender and extracted the pigments by maceration in a solvent mixture of ethyl alcohol and distilled water.

Then, the extract was saponified, washed, and carotenoid pigments were dissolved in HPLC grade acetone. The extract was then dispersed in ethanol, and 2-HP-beta-CD was dissolved in 45 ml solution of ethanol and water. The two were mixed using an ultrasound probe in the four different ratios.

Observations​

Researchers observed that, after molecular inclusion of red bell pepper pigments, samples had a minimum aqueous solubility of 8.00 mg/mL and the maximum 16.55 mg/mL, indicating an increase of 320-660 times the solubility of extract, which they concluded as a demonstration of the carotenoids’ increased solubility.

“In previous work of our research group, the difficulty of incorporating the red bell pepper:β-cyclodextrin complex in water-based media was observed,”​ the researchers said. “Samples easily precipitated, limiting the possibility of incorporation in various foods, especially beverages.”​

“Solubility data obtained in this study expands the applicability of carotenoids in a wide variety of foods such as desserts, juices, teas, soft drinks, jellies, candy, popsicles, soluble powders, among others,” ​they added.

Source: ​Food Chemistry​
Published online ahead of print, doi:10.1016/j.foodchem.2016.03.122
Increasing solubility of red bell pepper carotenoids by complexation with 2-hydroxypropyl-β-cyclodextrin​
Authors: Nicolly de Lima Petito, Daiana da Silva Dias, Valéria Gonçalves Costa, Deborah Quintanilha Falcão, Kátia Gome de Lima Araujo