Apple pomace, a by-product of the cider production, has been studied as a potential source of polyphenols, compounds of great interest for the industry. Ultrasound has been used to improve extraction efficiency in terms of time needed and total polyphenol content. A preliminary study has been first investigated to optimize ethanol proportion of aqueous extractant (50%, v/v) and solid/liquid ratio (<15%, w/v). A response surface methodology has then been used to maximize total polyphenol content of extracts and investigate influence of parameters involved in extraction procedures for both total polyphenols content and composition of extracts. Optimal settings reached from a central composite design were applied for ultrasound-assisted extraction and were compared to conventional procedure: yields were increased by more than 20%. Ultrasound-assisted polyphenols extraction from apple pomace appears to be a relevant, rapid, sustainable alternative to conventional procedure, and that scale up of the process is possible.

State of the Art. Chemical rules available to modify target compounds and/or create new crystal structures with respect to a predicted route are strongly attractive for solid-state chemists. Unfortunately, in this field, the rational design of new structural types remain rarely reliable, leading to a number of exceptional cases or unpredicted behaviors. Especially, several "exotic" structural types appear of great interest, but paradoxically often do not fit predictive criteria. Here, we report the modification of the stacking of anionic layers among the wide series of hexagonal perovskite oxides, using the selective substitution of oxide for monovalent anions.At the basis of the search for original electronic and magnetic behavior, a number of studies focus on the prospecting for new complex structural types within "hot" topics such as cobaltite (strong competition between magnetic ground states, attractive thermoelectricity, 1 superconductivity, 2 etc.). In the field of perovskite-related oxide materials, the calculation of the well-known Goldschmidt tolerance factor (t) remarkably well anticipates possible distortion from the 3C ideal cubic-type. 3 However, it mostly concerns compounds built on the stacking of ideal [AO 3 ] anionic layers, and as a matter of fact depends on both the ionic radii of A, O and B, the interstitial cation. As soon as deficient anionic layers are involved, the stacking type gets ruled out by a number of hardly estimable parameters. The examination of the BaCoO 3-δ series exemplifies well this inability for structural prediction. For δ ) 0, the 2H form is stabilized where the hexagonal (h) packing of every layer is predicted by t > 1. Two additional forms have been reported so far, the 5H form for δ ≈ 0.26 4 and the 12H form for δ ≈ 0.4. 5 In both of them, oxygen-deficient [BaO 3-x ]layers still respect the h packing and create trimers or tetramers of facesharing octahedra. However, in between them, lacunar cubic (c) [BaO 2 ] layers create isolated tetrahedra, leading to (hhhcc′c) 2 and (hhcc′c) sequences in the 12H and 5H polymorphs, respectively, where c/h and c′ denote [BaO 3 ] and [BaO 2 ] layers, see images a and b in Figure 1.The basis of our work comes from the simple comparison between these two structural types and the modified structures reported for the 5H BaFeO 2.8 and BaFeO 2.65 with the (chchh) stacking sequence. 6 They both contain octahedral trimers isolated by Fe 2 O 7 pairs of corner-sharing tetrahedra at both sides of the h [BaO 2 ] layer. However, the orthorhombic distortion reported in ref 6b for the latter remains unclear as compared to the hexagonal form for the former. 6a In these compounds, the central h [BaO 2 ] layer contains an underbonded O 2-anion pentacoordinated by Ba 2+ cations, i.e., the valence-bond sums (BVS) are -0.63 and -0.46, respectively, instead of -2 using O'Keefe data. 7 It strongly suggests the likely presence of a monovalent anion, with regard to a more favorable BVS. At this point, it is noteworthy that OH -and Cl -are involved during t...