Sweeping-frequency ultrasonic preprocessing improves removal rate and stability of pigment removed from okra powders by different drying and sieving methods

AbstractDecolorization is a necessary step before the extraction of okra pectin, and the reapplication of removed pigment will benefit hierarchical utilization of resources. Based on sweeping-frequency ultrasonic preprocessing (SFUP), effects of drying methods (hot air drying (HD), freeze-drying (FD)), sieves (of 60, 80, and 120 mesh) on removal rate and stability of okra pigment (OPI) were investigated. Color deepening caused by the formation of enzymatic products within 1 h of OPI degradation was explained. The extracted OPI was finally applied to noodles to check its stability further. Results showed that compared with non-ultrasonic treatment, SFUP increased removal rate of OPI with the maximum value of 49.32%, and further enhanced the stability of OPI when applied to noodles. OPI through sieves of 80 mesh owned brighter color and more excellent stability, and colored noodles with OPI through SFUP and FD had a small total color difference and strong stability.Keywords: Sweeping-frequency ultrasonic preprocessingdrying methodsifted okra powderpigment Ethical statementThe research does not involve animals or Humans, sensory evaluation and/or customer testing. Informed consent was obtained from all individual participants included in the study.Disclosure statementNo potential conflict of interest was reported by the authors.Author contributionsLei Zhang: Data curation, Writing-original draft, Funding acquisition. Ao Zhang, Shanshan Zhou, Qianqian Wang, Zhenyuan Hu, Chenglin Li and Yang Hu: Investigation, Data curation, Writing-original draft. Haile Ma and Cunshan Zhou: Supervision.Data availability statementThe data that support the findings of this study are available upon reasonable request.Additional informationFundingThis work was supported by the National Natural Science Foundation of China (31801599); Scientific Research Project of College Students of Jiangsu University (21A299, J21AE0134); Innovation Training Program for College Students of Jiangsu University (202110299889X). Heartfelt thanks also should be expressed to Wahia Hafida and Xue Wang for supporting this work.