RESUMEN

Traditional pressing is of low efficiency (< 80 %). A highly efficient sesame oil extraction technique was discovered via micro-hydration of sesame paste (φ = ∼ 75 %) and then agitation with a yield of âˆ¼ 95 %. However, the extraction mechanism is still unknown. To uncover this, microscopic imaging was used, and it found that agitation progressively increased the droplet size of micro-hydrated paste (φ = 74.5 %) from an initial size of < 4 µm. As agitated for 20 min, almost 85 % (v/v) of oil was over 20 µm, which was linearly and positively correlated (R2 > 0.96) with oil yield. Increase in droplet size was due to droplet compression, film rupture, and droplet coalescence. The coalescence frequency based on agitation time followed an exponent curve (R2 > 0.97). This coalescence might be related to the decreased water relaxation time and increased paste viscosity. This study, for the first time, found the oil droplet coalescence in hydrated sesame paste (φ = 74.5 %) during agitation, thereby successfully extracting oil at room temperature. The findings of this work can be a starting point for research on micro-hydration extraction for oil-containing materials from a packing density of oil droplets point view.

Asunto(s)

Sesamum , Aceite de Sésamo , Fenómenos Químicos , Viscosidad

RESUMEN

Micro-hydrated trimethylamine oxide (TMAO) has been investigated using a range-separated-hybrid functional including empirical dispersion correction. Electrophilic and nucleophilic sites on TMAO and water clusters have been identified using the molecular electrostatic potential (MESP). The nature of the chemical bonding in the different isomers of the micro-hydrated complexes has been investigated with the topological analysis of the electron density (QTAIM) method. For complexes containing one to four water molecules, the strongest intermolecular interactions consist in hydrogen bonding between the oxygen atom of the TMAO and hydrogen atoms of water molecules. From five water molecules, interactions between water molecules become the main source of stabilization of the most stable isomer. From four stationary points corresponding to the 1:1 (TMAO:H2O) complex, we determined the minimum distances between water molecules and central TMAO allowing the latter molecule to be encapsulated within a water clathrate-type cage. Optimization of TMAO encapsulated within two water cages (512 and 51262) suggests that only in the case of the 512 62 water cage the insertion of TMAO, the preservation of the hydrogen bonding between water molecules is energetically favorable. The interaction energy between one inserted TMAO and the 512 62 water cage was calculated to be around 150 kJ/mol with respect to the ground state of two partners. This result suggests that a thorough investigation of mono-hydrated complexes may be particularly relevant to identify the most suitable water cage for encapsulating a given solute.