Processing effects on lycopene content and antioxidant activity of tomatoes

Area of Science:

• Nutritional biochemistry
• Food science
• Antioxidant research

Background:

• Tomato consumption is linked to reduced cancer risk, with lycopene identified as a key antioxidant.
• Understanding the stability of carotenoids and other bioactive compounds during tomato processing is crucial for preserving health benefits.
• Previous research highlights lycopene's role, but the contribution of other tomato constituents to antioxidant activity remains to be fully elucidated.

Purpose of the Study:

• To quantify four carotenoids (trans-lycopene, phytofluene, phytoene, zeta-carotene) in raw tomatoes and processed products.
• To assess the impact of tomato processing on carotenoid levels, particularly lycopene.
• To evaluate the antioxidant activity of tomato fractions and identify the contributing compounds.

Main Methods:

• Carotenoids were quantified in raw tomatoes, hot break tomato juice, and final paste from two processing plants over two years.
• Lycopene and other carotenoid losses were calculated based on processing stages and initial tomato Brix levels.
• Antioxidant activity was determined using free radical and singlet oxygen quenching assays on different tomato fractions (aqueous, methanol, hexane).

Main Results:

• Lycopene losses during processing into paste ranged from 9% to 28%, influenced by the initial Brix level of raw tomatoes.
• Other carotenoids (phytofluene, phytoene, zeta-carotene) showed no consistent changes during processing.
• Significant antioxidant activity was observed in the hexane fraction (rich in lycopene) and the methanol fraction (containing phenolic antioxidants like caffeic and chlorogenic acid).

Conclusions:

• Tomato processing, particularly concentration to paste, leads to significant lycopene degradation.
• Polyphenols present in tomatoes, in addition to lycopene, contribute significantly to the overall antioxidant capacity of tomato products.
• Both lycopene and polyphenols may play vital roles in the observed health-protective effects associated with tomato consumption.