CONICET | Buscador de Institutos y Recursos Humanos

Abstract. There was studied the effect of different pre treatments on the time of drying of fresh fruits of rose hip (Rose rubiginosa). We used fresh fruit preserved at 2ºC and 90 % of relative humidity up to use. The rose hip fruits were submitted to the following pre treatments: chemical (dip in NaOH´s solutions and ethyl oleate with K2CO3) and mechanicals (to effect slightly deep cuts in the cuticle of the fruits and manual punctures of 1,0 mm in the surface of the fruits). Drying was carried out in an experimental equipment with a standard condition: air 70ºC, 5 m/s and 5 % of relative humidity, comparing with samples without treatment. In all cases, the pre treatments decrease drying times significantly (26-58 %) when they are compared with the samples without treating. The pre treatments with NaOH decrease the time very little, whereas ethyl oleate (this treatment darkens the product and an undesirable aroma leaves them as residue) and the treated ones with longitudinal cuts reduce it practically to the half. In agreement to the results, the best is the pretreatment of mechanical punctures that reduce drying time by about 58%. Key words: fruits - drying times - pre treatments.