Impact de deux procédés technologiques (jus et confiture) et du séchage sur les polyphénols et les caroténoïdes de l’abricot.

Abstract

Apricot is considered to be a good source of polyphenols and carotenoids. Currently, there is considerable interest in these biologically active components due to their antioxidant properties. However these compounds are very unstable species undergoing many reactions during food processing. These changes have significant effects on the nutritional and technological food quality. As such, it is essential to know the impact of transformation and preservation processes on these compounds. The aim of our work is to follow the evolution of polyphenols and carotenoids durring apricot processing to juice and jam, and after drying (traditional and in oven). Juice and jam samples were taken at an industrialist specialising in different fruits products, mainly apricot. So to apply a traditional drying diagram, a survey was conducted among farmers practising traditional drying in Bordj Bou Arreridj and M’sila region. The monitoring of some physico-chemical parameters (humidity, acidity, pH, Brix and ash) showed a significant effect of different processes on the evolution of these parameters. The quantification of carotenoids and polyphenols (totals polyphenols, flavonoids and tannins) was conducted by Spectrophotometric method. Carotenoids have shown fragility during studied processes, where more than 60% have been degraded during juice process, more than 70% during jam process, 67% after traditional drying and 44% after drying in oven. However the effects on polyphenols were not uniform, for juice and jam process. Bleaching step led to a significant increase in phenolic content. On the other hand, refining, cooking and pasteurisation has led to decline remarkably this content. Overall, the juice process has preserved the polyphenols content, however the jam process caused a decrease in the order of 5%. Similarly a decrease of 15% has been reported after traditional drying. Also an increase of 4% was recorded after drying in oven. The antioxidant activity of phenolic extracts was evaluated by the DPPH test. A positive correlation was found between the evolution of polyphenols and antioxidant activity for juice and jam processes but it is negative for the traditional drying.