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The effect of hydrothermal treatment of two-phase olive waste (alperujo) on the solubilization of hydroxytyrosol was studied. Different conditions of saturated steam were assayed. A high amount of hydroxytyrosol was solubilized and increased with increasing steaming temperature and time, reaching 1.4-1.7 g/100 g of dry alperujo. The effect of acidic (H(2)SO(4)) and basic (NaOH) catalysts was also evaluated. Acid-catalyzed treatment was more effective at milder conditions, whereas the alkali-catalyzed conditions were not very suitable. In the present study, the extracted hydroxytyrosol was purified by means of a new, simple, and inexpensive chromatographic system, under international patent application (PCT/ES02/00058). From 1000 kg of alperujo, with 70% humidity, can be obtained approximately 4.5-5 kg of hydroxytyrosol. After a purification process, at least 3 kg of hydroxytyrosol, at 90-95% purity, would be obtained. The purified compound was identified by HPLC/UV and (1)H and (13)C NMR analyses, and its antioxidant activity was tested on refined olive oil without antioxidants by Rancimat method. The oxidative stability of refined olive oil was increased by a factor of 1.71 in the presence of 100 ppm of hydroxytyrosol.

Asparagus (Asparagus officinalis L.) by-products, which represent around 50% of the processed vegetable, are a potential source of dietary fibre. The way that these byproducts are treated affects the composition and functional properties of fibre-rich powders. Factors such as treatment intensity, solvent, and drying system were studied. Only the more soluble components (soluble sugars, uronic acids and proteins) showed significant differences. All the fibre-rich powders had a high concentration of TDF (62-77%). The IF/SF proportion decreased with the severity of treatment, and increasing in this way the physiological quality of the fibre. Functional properties-water holding capacity (WHC), oil holding capacity (OHC), solubility (SOL), and glucose dialysis retardation index (GDRI)-varied according to the obtaining procedure. WHC and GDRI were higher in intensely extracted fibres, due to the effect of thermal processing. WHC had similar values (11-20 mL water/g powder) than those described for other agricultural by-products, but OHC and GDRI were much higher (5-8 mL oil/g powder and 25-45%, respectively). These properties make fibre-rich powders from asparagus by-products a valuable source of dietary fibre to be included in the formulation of fibreenriched foods.