Osmo-air dehydration treatments are widely applied to fruits in order to prolong shelf-life, reduce packaging and logistic costs, and to improve both sensory and nutritional quality of the end products. In this work osmo-air dehydration was applied to blueberries (Vaccinium corymbosum), a fruit that is gaining increasing attention due to its high content of dietary antioxidants, which have been proven to be associated with a reduced risk of heart disease, cancer, and other chronic diseases. In particular, the aim of this study was to investigate the performance of NIR spectroscopy as a tool for monitoring blueberry osmo and air drehydration processes. Blanched blueberries were dipped in sucrose and fructose+glucose osmotic solutions for 24 hours, and the osmotic exchanges were determined by mass balances (water loss, solid gain, sugar intake, changes in total phenolics and anthocyanins); NIR spectra were collected in order to study molecular modifications due to the osmotic treatments. Untreated and infused berries were subsequently air-dried at 70°C to final moisture content of 10-14%. During drying chemical, nutritional and structural changes were monitored and NIR spectra were acquired on whole berries, using an optic probe working in diffuse reflectance. Spectral data were standardised, transformed into first derivative and processed by using Principal Component Analysis. Results show that NIR spectroscopy was able to follow the osmotic and the air-drying processes and to discriminate untreated and osmo-dehyrated berries. Spectral differences reflect the main molecular modifications associated with water absorption bands due to OH stretch + OH bending and sugar absorption bands due to CH stretch + CH bending, OH stretch + OH bending. In order to investigate the variation of main constituents (sugars and water) involved in the osmo-dehydration process, two-dimensional correlation analysis of spectral data was also carried out.
Application of near infrared spectroscopy for monitoring osmo-air dehydration processes of blueberries / N. Sinelli, G. Giovanelli, A. Brambilla, E. Casiraghi - In: Book of abstract[s.l] : Leibniz-Institut fur Agrartechnik Potsdam-Bornim, 2009. - pp. 19-28 (( Intervento presentato al 5. convegno International Symposium on Food Processing, Monitoring Technology in Bioprocesses and Food Quality Management tenutosi a Potsdam (DE) nel 2009.
Application of near infrared spectroscopy for monitoring osmo-air dehydration processes of blueberries
N. Sinelli;G. Giovanelli;A. Brambilla;E. Casiraghi
2009
Abstract
Osmo-air dehydration treatments are widely applied to fruits in order to prolong shelf-life, reduce packaging and logistic costs, and to improve both sensory and nutritional quality of the end products. In this work osmo-air dehydration was applied to blueberries (Vaccinium corymbosum), a fruit that is gaining increasing attention due to its high content of dietary antioxidants, which have been proven to be associated with a reduced risk of heart disease, cancer, and other chronic diseases. In particular, the aim of this study was to investigate the performance of NIR spectroscopy as a tool for monitoring blueberry osmo and air drehydration processes. Blanched blueberries were dipped in sucrose and fructose+glucose osmotic solutions for 24 hours, and the osmotic exchanges were determined by mass balances (water loss, solid gain, sugar intake, changes in total phenolics and anthocyanins); NIR spectra were collected in order to study molecular modifications due to the osmotic treatments. Untreated and infused berries were subsequently air-dried at 70°C to final moisture content of 10-14%. During drying chemical, nutritional and structural changes were monitored and NIR spectra were acquired on whole berries, using an optic probe working in diffuse reflectance. Spectral data were standardised, transformed into first derivative and processed by using Principal Component Analysis. Results show that NIR spectroscopy was able to follow the osmotic and the air-drying processes and to discriminate untreated and osmo-dehyrated berries. Spectral differences reflect the main molecular modifications associated with water absorption bands due to OH stretch + OH bending and sugar absorption bands due to CH stretch + CH bending, OH stretch + OH bending. In order to investigate the variation of main constituents (sugars and water) involved in the osmo-dehydration process, two-dimensional correlation analysis of spectral data was also carried out.
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