Nutracêuticos: Licopeno -isolamento, isomerização, separação e estudo de estabilidade em produtos industrializados

• Autor(a) principal: Santos, Gilmar dos
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal Fluminense (RIUFF)
• Texto Completo: https://app.uff.br/riuff/handle/1/17574
• topic: Nutracêutico; Carotenóide; Licopeno; Goiaba; Cromatografia líquida; Estabilidade estrutural - Licopeno; Isomerização; Suco de goiaba - Carotenóide; Nutraceutical; carotenoid; lycopene; guava; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA

It has been proven that food containing high levels of the carotenoid lycopene is effective against some diseases due to the strong antioxidant character of this compound. Therefore, such food is considered as a nutraceutical nutrient with pharmaceutical properties. Lycopene is the major carotenoid present in fruits such as tomatoes, watermelon and guavas, and is responsible for their red colour. Because of its anticarcinogenic and anti-atherogenic activity, a lot of work about lycopene in tomatoes and tomato-based products has been done, but very little in guava. Even in the case of tomato-based products, there is still lack of understanding about the effect of storage on lycopene loss , and existing work is controversial. In the present work, different HPLC methods have been compared, using different stationary and mobile phases, with the purpose of separating a mixture of carotenoids extracted from tomatoes and isomerized with light and iodine solution. Only one of the methods was effective to resolve the two main lycopene isomers present in the extract, with the following chromatographic conditions: column- C30 Prontosil 200A 3μm, 250 x 4 mm; mobile phase- methanol (A), acetonitrile (B) and MTBE (C), isocratic elution 50%A, 50%C from 0 to 25 min, then gradient until 0%A, 37%B and 63%C from 25 to 40 min. An original ultrasonic micro-extraction method has been developed for extraction of carotenoids from fruit juices and pulp, using hexane, acetone and ethanol as solvents and BHT as antioxidant. The method, applied to commercial guava juices and pulp, was as precise as others int the literature, allowed complete recovery of lycopene. The main components of the extracts all-trans-lycopene and all-trans---carotene were quantified by comparison with standards and identified by their UV/VIS absorption spectra. Minoritary components were tentatively identified by comparison of spectra and absortion máxima with the ones found in literature. The effect of storage of the products on carotenoid content was studied, at 25 °C (guava juice in transparent PET and tetrapack packagings), 35°C (guava juice in transparent PET and tetrapack packagings) and frozen guava pulp ( - 18 °C). During 60 days, juices and pulp were sampled 4 times (T0= initial, T1= 14 , T2= 35 e T3= 60 days). In all conditions, carotenoids were stable in both juices. Statistical treatment of the concentrations found for all-trans-lycopene e all-trans--carotene were done by analysis of variance, and when there was significant difference, the Tuckey test was applied. No statistically significant changes with time were observed for lycopene in both juices, in both temperatures studied. There was significant lycopene loss in frozen pulp about 25 % in the end of the period studied. The presence of aditives and the kind of processing may have been the reasons for higher stability of lycopene in the juices than in the frozen pulp. The analysis of colour revealed a slight darkening of the products (L* index), and no change in intensity of the red colour (a* index).