COTYLEDON STRUCTURE OF RAW, SOAKED AND RO ASTED ALMOND (PRUNUS-AMYGDALUS L.)

The microstructure of the sweet almond (variety Marcona) and the most important microstructural changes caused after roasting (150 degrees C , 45 min) and soaking (H2O and NaCl 5%, 24 h) were studied by scanning electron microscopy (SEM). The majority of the cotyledon tissue is ma de up of rather large, nearly isodiametric parenchyma cells with a thi ck cell wall; the cell-to-cell junctions are characterized by a distin ct middle lamella. The cytoplasmatic membrane delimits the cellular co ntent, protein bodies and lipid bodies being the major components. A c ytoplasmic network consisting of the membranous system structured as h exagonal cells extends throughout each parenchyma cell, and surrounds the major components. The parenchymatic tissue is surrounded by a laye r of epidermic cells and tegument. After roasting, the cellular organi zation is lost and the cytoplasmic network surrounding the lipid bodie s and protein bodies is altered; the heat destroys some middle lamella e of cell-to-cell junctions; the cytoplasmic compartimentalization of the oil is lost in most cells and the oil drops coalesce; protein bodi es are distended and aggregated; other thermal modifications of roasti ng included pitting and pock marking of the epidermis and protein bodi es, caused by the escape of steam and ail. Soaking in water did not ca use drastic changes in structure; the most significant modification wa s an alteration of the cytoplasmic network and membrane; soaking in 5% NaCl also produced a partial disolution of protein bodies.