## 4 Conclusions  
In the current study, we systematically compared the physical properties, phenolic retention, and volatile profile of three types of mandarin powders that are derived from the whole fruit juices (A3 & RS3), the flavedo-removed fruit juices (A2 & RS2), and the peel-removed fruit juices (A1 & RS1). Overall, the A3 and RS3 powders had a higher yellow colour than the other powders (A2 & RS2 and A1 & RS1). For density, solubility, and water activity, no significant differences were observed between the mandarin powders that were prepared from the whole fruit juices (A3 and RS3) and the flavedo-removed fruit juices (A2 & RS2). Regarding the microstructure of powders, the whole fruit juice powder exhibited a relatively severer winkled surface with deeper indentations and bigger bulges. Furthermore, the wall materials showed a satisfactory protection effect on individual phenolic compound, and a significantly higher amount of total phenolic compounds was observed from the powders that were produced from whole fruit juices (A3, 1023 \(\mu\)g/100 mg vs. A2, 809 \(\mu\)g/100 mg vs. A1, 653 \(\mu\)g/100 mg; RS3, 314 \(\mu\)g/100 mg vs. RS2, 179 \(\mu\)g/100 mg vs. RS1, and 146 \(\mu\)g/100 mg). After spray drying, volatile compounds with pleasant odours (D-limonene, \(\beta\)-myrcene, and \(\alpha\)-pinene) were well retained in the particles, whereas the unpleasant notes from off-odor compounds (\(\alpha\)-terpineol and terpinene-4-ol) were sufficiently masked. The whole fruit powders had a significantly higher content of total volatile compounds (A3, 775,558 \(\mu\)g/L vs. A2, 125,617 \(\mu\)g/L vs. A1, 12,590 \(\mu\)g/L; RS3, 865,023 \(\mu\)g/L vs. RS2, 286, 763 \(\mu\)g/L vs. RS1, 22,902 \(\mu\)g/L). This research provided an environment-sustainable method for efficiently utilising bioactive compounds from whole mandarin fruits, meanwhile minimising the by-products generation during mandarin fruit processing.  
The following are available online at [[https://www.mdpi.com/2304-815/10/1/123/s1](https://www.mdpi.com/2304-815/10/1/123/s1)]([https://www.mdpi.com/2304-815/10/1/123/s1](https://www.mdpi.com/2304-815/10/1/123/s1)), Figure S1: Mandarin fruits anatomy. Figure S2: Mandarin juice preparation. Table S1: Calibration curves for the quantification of aroma compounds in mandarin juices and microcapsules. Table S2: Accuracy and precision of the quantification method of phenolic compounds.  
Conceptualization, S.Y.Q., Y.S. and Q.L.; methodology, S.Y.Q., Y.P., X.C., J.L.H.T., P.T., and Y.Z.; formal analysis, J.L.H.T., X.C.; investigation, J.L.H.T., X.C., P.T.; writing-original draft, X.C.; writing-review & editing, S.Y.Q. and Y.P.; supervision, S.Y.Q.; project administration, Y.S., and S.Y.Q. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the University of Auckland (New Zealand), the National Key Research and Development Programme of China (2017 YFD0400701-1) and Hunan Province Key Research and Development Programme of China (2019 NK2041).  
Not applicable.  
Data Availability Statement: Data is contained within the article or Supplementary Material.  
We acknowledge the China Scholarship Council (P.R. China) for awarding a PhD scholarship to the first author ([PERSON]) and the technician support given by [PERSON] and [PERSON].  
The authors declare no conflict of interest.