Elsevier

Food Chemistry

Volume 173, 15 April 2015, Pages 943-950
Food Chemistry

Extraction of lycopene from tomato processing waste: Kinetics and modelling

https://doi.org/10.1016/j.foodchem.2014.10.127Get rights and content

Highlights

  • Inexpensive food industry by-product was used for lycopene extraction.

  • Kinetic study was performed very accurately by using ‘continuous measurement’.

  • Mathematical models were used to understand physicochemical behaviour of extraction.

  • Optimal condition for lycopene extraction is determined.

Abstract

Lycopene, a nutraceutical compound, was extracted from tomato processing waste, an abundantly available food industry by-product in Italy. The extraction kinetics was mathematically described using the first order kinetic model, the mass transfer model and Peleg’s model to understand the physicochemical behaviour of the extraction. Samples were extracted using acetone/n-hexane mixtures at different ratios (1:3, 2:2 and 3:1, v/v) and at different temperatures (30, 40 and 50 °C) and simultaneously analysed using UV–VIS spectrophotometry. The lycopene yield was in the range 3.47–4.03 mg/100 g, which corresponds to a percentage recovery of 65.22–75.75. All kinetic models gave a good fit to the experimental data, but the best one was Peleg’s model, having the highest RAdj2 and the lowest RMSE, MBE and χ2 values. All the models confirmed that a temperature of 30 °C and solvent mixture of acetone/n-hexane 1:3 (v/v) provided optimal conditions for extraction of lycopene.

Introduction

Lycopene, a bright red pigment, belongs to the carotenoid family and has received great interest due to its various biological activities. Lycopene acts as a potent antioxidant and contributes towards reducing the risk of chronic diseases by protecting cells against oxidative damage (Rao & Agarwal, 1999). Epidemiological and case-control studies as well as research on cell cultures and animals have shown that increased dietary consumption of tomatoes and tomato products containing lycopene is associated with decreased risk of prostate and breast cancer (Chalabi et al., 2006, Holzapfel et al., 2013). Studies have also revealed its protective effect on cardiovascular (Arab & Steck, 2000) and coronary heart diseases (Clinton, 1998). It inhibits low-density lipoprotein oxidation and helps to reduce cholesterol levels in the blood (Rao & Agarwal, 1999). Lycopene exhibits anti-inflammatory activity by inhibiting the activation of inducible nitric oxide synthase proteins (Rafi, Yadav, & Reyes, 2007). In the food industry, lycopene from tomato products is used as a food additive to enhance storage stability, nutritional properties and health benefits (Østerlie & Lerfall, 2005).

Though lycopene is found in watermelon, pink grapefruit, guava, and rosehip, the richest source is tomato. Not only can it be extracted from fresh tomato, but adequate quantities can also be obtained from tomato processing waste or tomato pomace (Zuorro, Fidaleo, & Lavecchia, 2011). The wet pomace contains about 33% seed, 27% skin and 40% pulp, whilst the dried form contains about 44% seed and 56% skin and pulp (Perretti et al., 2013). The lycopene content present in the skin fraction of tomato pomace is about 5 times higher than in the pulp (Papaioannou & Karabelas, 2012).

Italy produces about 38% of the tomatoes grown in the European Union, over 4 million tons annually, roughly 90% of which is intended for processing (Global Agricultural Information Network). According to the World Processing Tomato Council (WPTC), Italy produces about 200,000 t of tomato processing waste annually, whilst the worldwide production is more than 1,200,000 t (Zuorro et al., 2011). At present, the tomato processing waste is either discarded or used as animal fodder, but its abundance in lycopene makes it a promising prospect as a sustainable, alternative and low-cost source of this nutraceutical compound.

Lycopene is more commonly extracted with organic solvents such as hexane, acetone, ethanol, chloroform, petroleum ether, etc. (Berg et al., 2000, Naviglio et al., 2008, Sadler et al., 1990, Xu and Pan, 2013). Since lycopene extracted using hexane/acetone or hexane/ethanol is more stable than that extracted using methanol or dichloromethane (Taungbodhitham, Jones, Wahlqvist, & Briggs, 1998), a solvent mixture consisting of hexane/acetone, hexane/acetone/ethanol is often used (Lin and Chen, 2003, Taungbodhitham et al., 1998). Recently, several advanced methods to extract lycopene from tomato have also been described, amongst them supercritical fluid extraction (Zuknik, Nik Norulaini, & Mohd Omar, 2012), ultrasound assisted extraction (Eh & Teoh, 2012), ultrasound-microwave extraction (Lianfu & Zelong, 2008), and enzyme assisted extraction (Zuorro et al., 2011) etc.

The kinetic description of solid–liquid extraction helps to design, optimise and simulate the extraction processes and to manage time and energy. In this study, we have modelled lycopene extraction from tomato processing waste, and examined the effects of two independent variables, namely temperature and solvent composition, on the kinetics of extraction.

Section snippets

Materials

Tomato processing waste devoid of seeds was obtained from Pezziol SPA, Parma, Italy. The average particle size and water content of the sample were ⩽0.5 mm and 35%, respectively. HPLC grade acetone, n-hexane, methanol and acetonitrile were purchased from Sigma–Aldrich, USA. Lycopene standard of HPLC grade (⩾95%) and solid sodium chloride (NaCl) (⩾99.5%) were obtained from Sigma–Aldrich, USA. Milli-Q ultrapure water with a resistivity of 18.3  cm was used in all the steps (Millipore, Germany).

Lycopene extraction and analysis

Lycopene extraction

The focus of the study was to obtain some reliable data on the extraction of lycopene from tomato processing by-products and to find the closest mathematical model that best fits to the lycopene extraction data set. Tomato processing waste devoid of seeds was used as raw material. The seed portion was avoided to prevent fatty acid contamination during the process of extraction. Several experiments were conducted as a function of two independent variables namely, temperature and solvent

Conclusions

Kinetic modelling was used to optimise the extraction of lycopene from tomato processing waste. The results demonstrated that the process variables, namely temperature and solvent composition have a strong effect on the extraction efficiency. Based on the models investigated, the best operational conditions for the extraction of lycopene were the lowest temperature (30 °C) and a solvent mixture containing the highest quantity of n-hexane (acetone/n-hexane 1:3, v/v). Peleg’s model appears to

Acknowledgements

The authors of this manuscript are thankful to Prof. Giorgio Mancini, Department of Physics, University of Camerino, Italy for assisting in mathematical modelling.

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