Effect of pre-treatments on solar drying kinetics of red seedless grapes (cv. Monukka)

• Autor(a) principal: Ramos, Inês N.
• Data de Publicação: 2014
• Outros Autores: Brandão, Teresa R. S., Silva, Cristina L.M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.14/17599
• topic: Pre-treatments; Solar drying; Kinetics; Modeling; Raisins

Two di erent pre-treatments were applied to grapes prior to drying in a mixed mode solar dryer. Grapes were blanched in water and in a 0.1% sun ower oil water emulsion, both at 99 C and for approximately 15 seconds. Several models were tested to t the experimental data of drying curves but the normalized Newton model gave the best t results. Samples blanched in hot water or in the 0.1% edible oil emulsion had faster drying rates than untreated samples. Contrary to what was expected, pre-treating with the 0.1% edible oil emulsion did not increase the drying rate to a higher extent than blanching. Pre-treatments did not give a noteworthy di erence in the total drying time. However, they had an important role in accelerating initial drying rates, thus preventing moulds and bacterial growth and consequently increasing farmers' income.