Encapsulation and Stabilization of β-Carotene in Amaranth Matrices Obtained by Dry and Wet Assisted Ball Milling

Abstract

Amaranth starchy fractions have recently awakened interest from the industry, mainly due to its potential functional characteristics. The encapsulating efficiencies of starch-enriched fraction (SEF) and native starch (NS) obtained, respectively, by dry and wet assisted ball milling were studied. The effects of high impact milling, gelatin addition, and storage temperature (5–45 °C, 45 days) on the retention of β-carotene were investigated. Significant effects of both milling and amaranth protein present in SEF matrix on emulsification and subsequent retention of β-carotene were found. Ball milled SEF matrix showed the best encapsulation performance, with up to three times of total β-carotene content in comparison with the NS-containing matrices. Degradation of surface and encapsulated β-carotene followed a first-order kinetic model and was strongly influenced by storage temperature. The activation energy of surface β-carotene degradation doubled that of encapsulated β-carotene (86 vs. 48 kJ/mol, respectively). This difference indicates that encapsulated β-carotene is more stable to temperature changes than surface β-carotene and revealed the protective capability of the SEF matrix even at high temperatures. The color coordinates a* and L* for samples stored at 25 and 45 °C positively correlated with the remaining β-carotene, revealing the potentiality of color measurement as an adequate index of β-carotene retention. The starch-enriched amaranth fraction modified by high impact milling showed a high technological potential as an encapsulating agent and its own protein content served as a good emulsifier-stabilizer.