_Applied_  
_sciences_  
_Article_  
**A One-Pot Ultrasound-Assisted Almond Skin**  
**Separation/Polyphenols Extraction and its Effects on**  
**Structure, Polyphenols, Lipids, and Proteins Quality**  
**[PERSON] 1,2, [PERSON] 3, [PERSON] 4, [PERSON] 5, [PERSON] 2, [PERSON] 1,* and [PERSON] 2,*()**  
1 Department of Biology, Faculty of Science Dhar El-Mahraz, University Sidi Mohammed Ben Abdellah, P.O. Box 1796, Fez 30050, Morocco; [EMAIL_ADDRESS]  
2 INRAE, Avignon University, UMR 408, Green Extraction Team, F-84000 Avignon, France; [EMAIL_ADDRESS]  
3 College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China; [EMAIL_ADDRESS]  
4 INRAE, Avignon University, UMR408, Securite et Qualite des Produits d'Origine Vegetale, F-84914 Avignon, France; [EMAIL_ADDRESS]  
5 INRAE, Unite de Pathologie Vegetale, F-84140 Avignon, France; [PERSON]
* Correspondence: [PERSON]SS] (A.R.); [EMAIL_ADDRESS] (F.C.)  
Received: 9 May 2020; Accepted: 20 May 2020; Published: 24 May 2020  
**Featured Application: In the 21 st century, we have to meet the challenges of green food processing to secure food production, reduce by-products, and protect both the environment and consumers. Ultrasound has been used as a non-thermal processing technique at the same time for processing (skin separation) and extraction (polyphenol extract). This new process to obtain peeled almonds reduces by-products and produces high value extract rich in polyphenols. The results of this investigation pave the way for the set-up of an industrial application of ultrasound to almond processing but also open up the way for combined utilization of ultrasound.**  
**Abstract:** Almond skin is an important by-product in the almond processing industry, rich in potentially health-promoting phenolic compounds. The objective of this present study is to separate the skin from the almond and extract its polyphenol contents using Ultrasound-Assisted Extraction (UAE) at room temperature. Optimization was performed according to a two-variable central composite design (CCD), and the optimum combination of ultrasonic intensity and extraction temperature was obtained through multi-response optimization: ultrasonic intensity (UI), 9.47 W.cm\({}^{-2}\); and temperature, 20 \({}^{\circ}\)C for an extraction time of 20 min. Under the above-mentioned conditions, total phenolic content was 258% higher with UAE than silent experiment. Mathematic modelling and microscopic investigations were achieved to enable understanding physical and structural effects of ultrasound on almond skins and comprehension of the mechanism behind the enhancement of mass transfer phenomena. Scanning Electron Microscopy (SEM) showed different acoustic cavitation impacts including fragmentation, sonoporation, and erosion. Extracts were analyzed by ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS), identifying a combination of flavanols, flavanones and non-flavonoids. UAE shows no negative effect on almond proteins and lipids when compared to natural almonds (NS).  
**Keywords:** Ultrasound; green food processing; extraction; almond; skin; microscopy; polyphenols; lipids; proteins