Lactic Acid Fermentation of Tomato: Effects on cis/trans Lycopene Isomer Ratio, β-Carotene Mass Fraction and Formation of L(+)- and D(–)-Lactic Acid

Elena Bartkiene^1*, Daiva Vidmantiene², Grazina Juodeikiene², Pranas Viskelis^2,3 and Dalia Urbonaviciene<sup>2,3

1</sup>Lithuanian University of Health Sciences, Veterinary Academy, Department of Food Safety and Quality, Tilzes str. 18, LT-47181 Kaunas, Lithuania
²Kaunas University of Technology, Department of Food Technology, Radvilenu str. 19, LT-50254 Kaunas, Lithuania
³Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Kauno str. 30, LT-54333 Babtai, Kaunas District, Lithuania

Article history:
Received January 30, 2013
Accepted July 24, 2013

Key words:
tomato, lactic acid fermentation, lycopene, ß-carotene, L(+)/D(–)-lactic acid

Summary:
Fermentation of tomato pulp by the bacteriocin-producing lactic acid bacteria (Lactobacillus sakei KTU05-6, Pediococcus acidilactici KTU05-7 and Pediococcus pentosaceus KTU05-8) was applied as a preservation method for the production of tomato products. The changes in L- and D-lactic acid contents during fermentation of different tomato varieties (Ronaldo and Cunero) were analysed. Additionally, the effects of lacto-fermentation on the cis/trans lycopene ratio, ß-carotene content, and their relation to colour characteristics of fermented tomato products were investigated. Mass fractions of L- and D-lactic acid in the fermented tomato products varied from (4.25±0.04) to (7.19±0.08) mg per 100 g, and from (4.05±0.05) to (6.34±0.04) mg per 100 g, respectively. Fermentation with P. acidilactici or L. sakei culture resulted in the the decrease of D-lactic acid content by 43.6 and 37.7 %, respectively, compared to spontaneous fermentation. The fermentation with P. pentosaceus or L. sakei increased the content of lycopene on average from 3.70 to 5.68 mg per 100 g, and ß-carotene from 0.89 mg per 100 g (in Cunero var.) and from 0.28 mg per 100 g (in Ronaldo var.) to 1.14 mg per 100 g. Fermentation of tomato with selected lactic acid bacteria resulted in a greater lycopene bioavailability accompanied by an increase in cis-lycopene isomer content.

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