Effects of Different Pretreatment Methods on Quality Characteristics of Freeze-dried Blueberry Powder

Abstract

In order to explore the effects of different pretreatment methods (breaking skin, beating pulp, filtering, etc.) on the quality of blueberry powder, vacuum freeze-drying technology was used to prepare blueberry powder, and its physical properties, active components and antioxidant capacity were determined. Meanwhile, the main groups were analyzed by Fourier transform infrared spectroscopy. The results were as follows: The physical properties and antioxidant capacity of blueberry powder prepared by different pretreatment methods were different. Through infrared spectroscopy, the main groups of the three blueberry powders did not change significantly. The whole fruit powder (WP) had good dispersity and the highest contents of total phenol (5.48 mg/g) and anthocyanin (0.69 mg/g), and the strongest antioxidant capacity. Fruit pulp powder (PP) had the lowest water content (5.47%) and the highest solubility (71.38%). Fruit juice powder (JP) had the lowest average particle size (98.62 μm) and the highest glass transition temperature (43.71 ℃). Although WP had lower solubility, it had the strongest antioxidant capacity and could be used for processing nutritional fortifier. PP and JP had good physical properties and high solubility. Besides direct consumption, they could also be pressed for tablet processing or used as raw materials for further processing of solid drinks. The three kinds of blueberry powder had its own advantages and could be developed according to the actual situation.

Keywords

• blueberries
• fruit powder
• beating pulp
• vacuum freeze drying
• antioxidant capacity