Comparative analysis of composition and hygroscopic properties of infrared freeze-dried blueberries, cranberries and raspberries

Abstract

The nutrient and antioxidant content in blueberries were significantly higher than cranberries and raspberries, except crude fiber. Fourier infrared spectroscopy was used to characterize quantitatively the differences in the composition of the tissues of three berries viz., blueberries, cranberries, and raspberries. The three berries have 10 characteristic common peaks in the 400–4000 cm⁻¹ range. The specific differences in three berries were characterized by comparing the relative absorption intensities and the second derivative spectra. The results of the comparison of the relative absorption intensity showed that there were significant differences between the values of three berries at the two peak positions of A₃₄₀₆/A₂₉₂₇ and A₁₀₅₇/A₂₉₂₇. Furthermore, thermogravimetric (TG) analysis was employed to establish for the three berries’ TG% and DTG thermal analysis map. While the dynamic vapor sorption was used to measure for infrared freeze-dried samples of the berries the moisture content, the results showed that the adsorption isotherm of berries was III, and there was a moisture sorption hysteresis.

Keywords:

• Berries
• nutrient
• FTIR
• thermogravimetric
• adsorption
• desorption

Acknowledgements

We acknowledge financial supports from the National Key R&D Program of China (Contract No. 2017YFD0400901), Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX20_1957), Special funds for Taishan Industry Leading Talents Project, the 111 Project (BP0719028), Jiangsu Province Key Laboratory Project of Advanced Food Manufacturing Equipment and Technology (No. FMZ202003), all of which enabled us to carry out this study.