Using pulsed magnetic fields to improve the quality of frozen blueberry: A bio-impedance approach

Author(s)

Arteaga, Hubert ; Silva, Ana Carolina de Sousa ; Tambelli, Caio Eduardo de Campos ; Souto, Sergio ; Costa, Ernane Jose Xavier

• Document type: Journal article
• Source: LWT-FOOD SCIENCE AND TECHNOLOGY; v. 169, p. 11-pg., 2022-10-03.

Abstract

Freezing assisted by pulsed magnetic field (PMF) is an emerging technology that could be used in food preser-vation. This paper evaluates how PMF-assisted freezing affects the preservation of blueberry and its bioactive compounds. Blueberries were subjected to 8 PMF-assisted freezing treatments: T1 (36.8 mT/30 Hz), T2 (36.8 mT/60 Hz), T3 (36.8 mT/90 Hz), T4 (36.8 mT/20 Hz), T5 (44.7 mT/30 Hz), T6 (44.7 mT/60 Hz), T7 (44.7 mT/ 90 Hz), and T8 (44.7 mT/120 Hz). In treatment T9 (control), the blueberries were subjected to conventional freezing to-35 degrees C; T10 represents fresh blueberries. Compared to conventional freezing (T9), PMF-assisted freezing (T1 to T8) gave different parameters of temperature, nucleation time, degree of supercooling, and phase change time. The parameters achieved with T7 evidenced better behavior: smaller crystals were formed, allowing the cellular structure to be preserved, as confirmed by the electrical parameters (Re, Ri, and Cm) ob-tained from electrical impedance data. Moreover, T7 preserved anthocyanins and polyphenols, promoting the highest antioxidant capacity among the blueberries subjected to PMF-assisted freezing. Meanwhile, conventional freezing and PMF-assisted freezing reduced the polyphenol oxidase and peroxidase activities. In conclusion, at the laboratory level, PMF-assisted freezing preserves the blueberry cellular structures and bioactive compounds. (AU)

• FAPESP's process: 18/05871-3 - Development of equipment and methodology to evaluate the effect of pulsed magnetic fields on food freezing.
• Grantee: Ernane José Xavier Costa
• Support Opportunities: Regular Research Grants