Sequential phenolic acid co-pigmentation pretreatment and contact ultrasound-assisted air drying to intensify blackberry drying and enhance anthocyanin retention: A study on mass transfer and phenolic distribution

Wenjin Gong; Dandan Li; Yue Wu; Sivakumar Manickam; Xun Sun; Yongbin Han; Yang Tao; Xiaoli Liu

doi:10.1016/j.ultsonch.2021.105788

Sequential phenolic acid co-pigmentation pretreatment and contact ultrasound-assisted air drying to intensify blackberry drying and enhance anthocyanin retention: A study on mass transfer and phenolic distribution

Ultrason Sonochem. 2021 Dec:80:105788. doi: 10.1016/j.ultsonch.2021.105788. Epub 2021 Oct 14.

Authors

Wenjin Gong¹, Dandan Li¹, Yue Wu², Sivakumar Manickam³, Xun Sun⁴, Yongbin Han¹, Yang Tao⁵, Xiaoli Liu⁶

Affiliations

¹ College of Food Science and Technology, Whole Grain Food Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China.
² Sonochemistry Group, School of Chemistry, The University of Melbourne, Parkville, Victoria 3010, Australia.
³ Petroleum and Chemical Engineering, Faculty of Engineering, Universiti Teknologi Brunei, Bandar Seri Begawan BE1410, Brunei Darussalam.
⁴ Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan 250061, China.
⁵ College of Food Science and Technology, Whole Grain Food Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China. Electronic address: yang.tao@njau.edu.cn.
⁶ Institute of Agro-product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.

Abstract

In this work, the spraying of ethanol solution containing phenolic acid (ferulic acid or caffeic acid) was performed before subjecting to contact ultrasound-assisted air drying of blackberry. The mass transfer modeling results revealed that sonication intensified both internal water diffusion and external water exchange during drying, and ethanol pretreatment enhanced the effective diffusivity of water. Compared with air drying alone, the drying time for sequential ferulic acid pretreatment and drying with sonication was shortened by 89.2%. Owing to the co-pigmentation between phenolic acid and anthocyanins, the retention of anthocyanins was significantly enhanced after dehydration. At the end of drying, the total anthocyanin contents in the ultrasound-dried samples pretreated with ferulic acid and caffeic acid were 25.3% and 10.5% higher than the sonicated samples without pretreatments, respectively. Furthermore, drying simultaneously with sonication promoted the preservation of non-anthocyaninic soluble phenolics including catechin, phloretic acid, rutin in blackberry compared to air drying alone. Besides, bound phenolics in blackberry were less influences by the applied dehydration treatments. This study demonstrates that the combination of phenolic acid co-pigmentation pretreatment and ultrasound drying could be a promising method to protect anthocyanin pigments during dehydration of berry fruits.

Keywords: Anthocyanins; Blackberry; Bound phenolics; Phenolic acid co-pigmentation; Soluble phenolics; Ultrasound drying.