Simultaneous extraction and nanoemulsification of lycopene from tomato waste: optimization and stability studies of lycopene nanoemulsions in selected food system

Lycopene is a very valuable pigment in tomato processing wastes with great antioxidant activities. However, like other carotenoid pigments it suffers from low water solubility, little bioavailability and less structural stability. In present study, it was hypnotized that the simultaneous extraction and size reduction of lycopene from tomato waste using nanoemulsion systems, can give the most desired nano-sized lycopene with increased water-solubility and chemical stability. Thus, lycopene nanoemulsions were prepared from tomato processing waste, and the effects of extracting solvents, emulsifiers, co-emulsifiers, as well as ultrasonic and microwave pretreatments were evaluated on mean particle size, size distribution, lycopene content, antioxidant and antimicrobial activities of obtained lycopene nanoparticles. Moreover, the chemical stability of lycopene nanoparticles diluted in grape juice as model food systems and in deionized water as a control were evaluated. It was concluded that using saponin as emulsifier, glycerol as co-emulsifier, ethyl acetate as solvent, and applying ultrasound irradiation as pretreatment process for 5 min, gave the product with the most desired characteristics, as particle size of 91.62 ± 3.327 nm, PDI of 0.210 ± 0.008, lycopene load of 101.47 ± 2.578 µg/g, DPPH radical scavenging of 97.15 ± 2.578%, and S. aureus and E. coli growth inhibition zone diameters of 27.2 ± 0.36 and 4.1 ± 1.15 mm, respectively. Furthermore, beside a high physical stability of optimum lycopene nanoemulsion, it showed a good chemical stability in selected food systems compared to the control. Consequently, it can be concluded that the obtained nanoemulsion technique can be a promising technique for isolation and size reduction of lycopene from tomato industrial wastes, for food formulation uses.