Thermal and light stability of anthocyanins from strawberry by-products non-encapsulated and encapsulated with inulin.

BACKGROUND

Strawberry by-products were explored as sources of anthocyanins for the extraction of natural colorants in the development of new value-added products for the food industry. For this purpose, the stability of strawberry anthocyanin extracts was evaluated for color and total anthocyanin content. The anthocyanins were encapsulated with inulin to protect them from processing at high temperatures and exposure to light. Microcapsules were obtained by two drying processes (spray and freeze drying) in order to study their use as coloring ingredients for their use in the food industry.

METHODS

Thermal (using the response surface methodology - RSM) and light stability tests were performed, simulating long-term processing and food storage. Antioxidant activity, total anthocyanin content and color analysis were quantified using several methods, and the microcapsules were characterized using scanning electron microscopy. Anthocyanins and their derivatives were identified by high resolution mass spectrometry.

RESULTS

The strawberry extracts showed high antioxidant capacity and total anthocyanin content. The RSM of the thermal stability test showed that temperature is the variable with the most significant effect on color stability and total anthocyanin content. The anthocyanins showed more stability at 50°C/60 min, 57°C/102 min, 93°C/18 min and with up to 8 days of light. Microencapsulation of the strawberry extracts with inulin obtained by spray and freeze drying improved the stability of anthocyanins. The spray drying process can offer better applications for the food industry due to the more regular shape of the microcapsules, which supports the potential use of strawberry by-products as coloring ingredients for application in the food industry.

CONCLUSIONS

This study can serve as a technical reference for the development of anthocyanin microcapsules with inulin from strawberry by-products obtained by spray drying, resulting in stable natural colorants to be used as ingredients in the food industry.