Pulsed electric fields assisted extraction of carotenoids from tomato by-products

Tomato fruit is among the most widely consumed vegetables in the world and represents an important source of many traditional nutrients and a predominant source of several carotenoids. Within the class of carotenoids, lycopene is the most abundant and represents more than 80% of total tomato carotenoids content. Tomato by-products, namely peel and seeds, account for about 10-40% of the millions of tons of tomato fruit processed every year to produce different type of products. This by-product, thus, represents a cheap and reach source of the above mentioned bioactive compounds. They are traditionally recovered by extraction with solvents which is a time consuming process and requires large quantities of solvents. This study was conducted to evaluate the effect of pulsed electric field (PEF) treatment for enhancing carotenoids extraction from tomato by-product resulting from the production of tomato sauce. The process was based on the application of moderate electric fields (1-5 kV/cm) and low total specific energy input (1-20 kJ/kg) to the tomato peels. The cell disintegration index (Zp) was used to identify the PEF processing conditions for the pre-treatment of the tomato peel before the carotenoid extraction. The optimal PEF processing and extraction conditions were defined, and the extraction yield of carotenoids was determined. Results showed that, compared to the untreated sample, significantly higher amounts of total carotenoids, lycopene and antioxidant activity were detected in the extracts from PEFtreatment samples. The antioxidant capacity of the extracts obtained from tomato peel was correlated with the carotenoid concentration. The results of this study indicate that the utilization of PEF technology as pre-treatment of tomato by-products before the carotenoid extraction could add new value to the tomato processing chain, improving economic performance and decreasing waste problems.