Enhanced Lycopene Extraction from Tomato Peels by Optimized Mixed-Polarity Solvent Mixtures

Antonio Zuorro

doi:10.3390/molecules25092038

Abstract

Mounting evidence from clinical and epidemiological studies suggests that lycopene, the most abundant carotenoid in tomatoes, may be beneficial in the prevention or treatment of some important diseases. Ripe tomato peels are the richest source of lycopene, but the use of conventional solvent extraction methods without pretreatment of the plant material results in very poor recovery. The reason lies in the localization of lycopene in the plant tissue and the low permeability of the latter to solvent molecules. In this paper, a mixture design procedure was used to formulate solvent mixtures allowing the recovery of lycopene from non-pretreated tomato peels. Two ternary systems were investigated: (a) n-hexane–ethanol–acetone and (b) ethyl lactate–ethanol–acetone. Optimization of the ternary mixture composition led to a recovery of over 90% of the lycopene present in the peels. The high extraction efficiency was explained in terms of lycopene affinity combined with the ability to swell the plant material. A tomato oleoresin with high antioxidant activity and a lycopene content of about 13% (w/w) was also produced. Overall, the results indicate that highly effective solvents for direct recovery of lycopene from tomato peels can be easily prepared by a mixture design approach.

Highlights

Over the last decades, lycopene, the carotenoid pigment responsible for the deep red color of tomato fruits, has received increasing attention from the scientific community due to its reported beneficial effects
We present a different approach for the recovery of lycopene from tomato peels adequate pretreatments, such as those based on ultrasounds [21], microwaves [22] or enzymes [23], not subjected to any treatment
Results were expressed as μmol Trolox Equivalent Antioxidant Capacity (TEAC) per gram of dry sample using a calibration curve obtained with Trolox standards (0.05–50 μmol L–1 )

Summary

Introduction

Lycopene, the carotenoid pigment responsible for the deep red color of tomato fruits, has received increasing attention from the scientific community due to its reported beneficial effects. Results from epidemiological and clinical studies suggest that lycopene may provide protection against cardiovascular disease [1,2], cancer [3,4,5], and neurodegenerative disorders such as Alzheimer’s, Parkinson’s, and Huntington’s diseases [6,7]. The mechanisms by which lycopene exerts its action have not been fully elucidated, but it is generally believed that they are primarily related to its high antioxidant activity [8,9]. Mounting evidence supports the ability of lycopene to induce apoptosis, inhibit cell proliferation, and increase intercellular gap-junctional communication [10,11,12]

Objectives

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Results

Conclusion