文摘
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.
