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Thermal stabilities of lycopene and β-carotene in pink grapefruit juice and tomato pulp
19th International Conference on Food Processing & Technology
October 23-25, 2017 | Paris, France

Fatmagul Hamzaoglu, Hanim Sevindik, Mehmet Ozkan and Meltem Turkyilmaz

Ankara University, Turkey

Posters & Accepted Abstracts: J Food Process Technol


Thermal stabilities of lycopene and β-carotene in tomato pulp (TP) and pink grapefruit juice (PGJ) were studied at various temperatures. The juice samples were heated in water (80 and 95°C) or oil baths (110°C) and the samples were taken from the baths at regular time intervals. Heated and cooled tubes were analyzed for lycopene and β-carotene contents by HPLC. The thermal degradation of lycopene and β-carotene in both TP and PGJ were fitted to first-order reaction model. Kinetic data showed that thermal degradation rates of lycopene and β-carotene increased with increasing temperature. For example, t1/2 values at 80°C of lycopene (7.4 h) and β-carotene (46.8 h) in TP were 1.85 and 1.71 times higher than t1/2 values at 110°C. Higher t1/2 values indicated that thermal stabilities of lycopene (32.2-76.9%) and β-carotene (58.8%) in PGJ were much higher than those in TP. On the contrary, lycopene and β-carotene in PGJ were more sensitive (30.7-43.7%) to temperature change than in TP, as indicated by higher Q10 and activation energy values (Ea) at 80�??110°C. CIE model L*, a*, b*, C* and h° values were also determined for color changes in TP and PGJ during heating. As the heating temperature and time increased, redness decreased (41.3-55.5%) in both samples. High correlations were found between a*(r=0.934) and h°(r=0.978) values and lycopene content of both TP and PGJ during heating. Furthermore, high correlations were found between the decrease in β-carotene content and increase in both b*(r=-0.971) and h° (r=-0.997) values of TP, while the similar high correlation was only found between β-carotene content and h°(r=0.981) values of PGJ. In conclusion, to protect the lycopene and β-carotene in PGJ and TP, low process temperature should be preferred. To determine changes in contents of lycopene and β-carotene in PGJ and TP, reflectance color values could be used.

Biography :

Fatmagul Hamzaoglu completed her undergraduate studies in the Department of Food Engineering at Ankara University in 2013 and obtained Master of Science degree in the same department in 2016. She is currently working on her PhD in the same department since 2016.