Abstract:
Abstract: Lycopene is the pigment primarily responsible for the characteristic deep-red color of ripe tomato fruits, comprising approximately 80% to 90% of the pigments present. Early studies focused on other pro-vitamin A carotenoids (α-carotene, β-carotene), which were negligible. In recent years, increasing studies indicated that lycopene, with its acyclic structure and large array of conjugated double bonds carries many distinct biological and physicochemical properties. Lycopene is among the most efficient singlet oxygen quenchers of the natural carotenoids without pro-vitamin A activity. It acts as a natural antioxidant in human serum and other tissues to protect the oxidative damage of lipids, proteins, and DNA. Other evidence from epidemiological and animal studies supported the chemoprevention potential of lycopene and the reduction in chronic disease (including cancer) of lycopene metabolites. Lycopene, as a natural food additive, is given more attention due to extensive use and deep understanding of the natural ingredients in food. Therefore, adding lycopene to functional foods raises concerns about green and efficient extraction technology. Conventional solvent extraction (CSE) techniques used for the solvent extraction of natural products are associated with longer extraction times and use of large amount of organic solvents. However, ultrasound assisted extraction (UAE) can be effectively used to improve the extraction rate by increasing the mass transfer rates and rupturing cell walls due to the ultrasonic cavitation effect. Compared with other material pretreatment methods, lyophilization induces better retention of lycopene bioactivity from raw tomatoes. Superfine grinding, pertaining to cellular level pulverizing techniques, can be used to get fruit and vegetable powder with a small particle size and a large specific surface area. However, studies of freeze-drying application in combination with superfine pulverizing technology have not been reported in extraction of lycopene. Thus, in this paper, lyophilization and superfine grinding were applied for the preparation of red ripe tomatoes. Tomato powder, with a particle size interval of < 74 μm, was selected as the extraction material by using standard sieve. The effects of liquid-to-material ratio, ultrasonic temperature, ultrasonic power, and ultrasonic time on the extraction yield of lycopene were studied by single-factor tests. Response surface methodology was used to optimize UAE conditions of lycopene from lyophilized tomato powder. On the basis of the optimum process, a comparison of efficiency with CSE was studied. The results showed that the best extraction conditions for lycopene were as follows: the liquid-to-material ratio was 41:1 mL/g, the ultrasonic temperature was 55℃, the ultrasonic specific power was 18 W/g and the ultrasonic time was 15 min. In the validation test, the average extraction yield of lycopene was 1.82 mg/g with an ultrasonic time of 10 min. The measured value was consistent with the predicted value, which was 1.83 mg/g. The reliability of the model was proved. Compared to CSE, the extraction yield of lycopene of UAE was 1.82 ± 0.05 mg/g, which was increased by 6.04%; the extraction time was 15 min, which was reduced by 92.47%. The paper provides a reference for the high effective extraction of lycopene and comprehensive utilization of the tomato.