| Citrus is one of the major fruits in worldwide, with bright colour, delicious taste, pleasant flavor and aboundant nutrients. There are plenty citrus fruits resources in China with first cultivated area and first outcome of whole world, it would be meaningful for the exploration of citrus processing. The studies in our lab showed that there are abundant carotenoids in the citrus peels. Carotenoids are the principal pigments of citrus peels and the content and profile differ in different species and tissues. Carotenoids not only can present the color of citrus peels, but also play an important role in health care such as antioxidation activities and the relationship between the structure and bioactivies are rare and unsolved. So it has very important strategic significance to make comprehensive studies on carotenoids of citrus peels, besides we have excellent research traditions in this area.The objective of this study was to gain optimum extraction conditions of carotenoids from citrus peels cultivated in Hubei Province, and the relationship between the major carotenoids, and antioxidant activity in vitro were also observed. In this study, modern apparatus means of chromatogram and spectrum and the chemical analysis are used to investigate carotenoids in citrus peels and the major content of cartenoids in citrus peels were also observed. The food and feed processing technologies are used to realize the functional of carotenoids in citrus peels in ducks feeding experiment. The results are as follows:1Optimization of ultrasonic-assisted extraction of carotenoids from citrus peelsUltrasonic technique was employed to extract carotenoids from citrus peels. Single factor experiments were studied including ultrasonic power, extraction time, the number of extraction of liquid ratio, temperature, drying method, mesh and so on. The optimum extraction conditions by single factor experiments were as follows:petroleum ether:acet-one=2:1, material to liquid ratio1:50, temperature of40℃, extraction of the number of6 times, extraction time6min, ultrasonic power270W, mesh100～120head, the average rate is82.4±1.2%.Three-factor three-level Box-Behnken design was applied to evaluate the effects of three independent factors,(the number of extraction, extraction time and extraction temp-erature) on the extraction rate of carotenoids. After optimizing the combination different factors by computer, the optimizing range of three factors for extraction of carotenoids fr-om citrus peels were confirmed:the number of extraction (3～4), extraction time (5～8min), and extraction temperature (35～45℃), the results would provide technical basis for yield of carotenoids from citrus peels, the average rate is80%～90%.2Variety carotenoids composition and its content in citrus peelsβ-carotene, lycopene, zeaxanthin and lutein content in China that belong to various citrus types were determined by using HPLC. Variety of citrus peels use different HPLC analytical methods.The results shows that in citrus peels, the major carotenoids were lutein and zeaxan-thin.Lycopene is primarily existed in red grapefruit. It is implied that citrus peels is a go-od sources of natural carotenoids.3Antioxidative activities of carotenoid extracted from citrus peels in vitroCarotenoids in citrus peels are natural source of the byproducts of citrus industry. The scavenging effects of carotenoids in citrus peels on free radicals were studied. To study the antioxidant effect of carotenoids in citrus peels, the contents of MDA in tissue of liver and mitochondria of liver were studied by TBA assay in vitro, and the hemolysis extent of blood cells and scavenging activity of free radicals of DPPH and ABTS were al-so detected by spectrophotometric methods. The results are as follows:Miyagawa and Va-lencia Orange right from the oxidation of red blood cells were the best, followed by Guo-qing NO.1. The effect on the H2O2-induced liver homogenate lipid peroxidation reaction, the red grapefruit was the best, followed by Jin Cheng and Valencia. On H2O2-induced lipid peroxidation reaction of liver homogenates were significantly better than the effect of BHT. The inhibition effect on red grapefruit, Guoqing NO.1and Miyagawa to the liv-er mitochondria lipid peroxidation reaction was not significantly different, and the effect was significantly better than BHT. Guoqing NO.1and Valencia were the best when cleari-ng the DPPH free radical, and followed by blood orange. And the ability of carotenoids clearing the DPPH free radicals was significantly better than BHT. The effects in clearing ABTS free radicals, the Jincheng was the best, followed by Valencia and Miyagawa.And the ability of citrus peel carotenoid clearing the ATBS free radicals was significantly better than BHT.4The ducks feeding experiments of carotenoid extracted from citrus peelsIn ducks feeding study,β-carotene and lycopene are detected through the liquid phase analysis of carotenoids in red grapefruit peels. By external standard method calculation,β-carotene and lycopene content are9.58±0.91μg/g and10.11±1.01μg/g separately.Carotenoids did not significantly affect egg production, egg weight and yolk weight. After the feeding which is rich in β-carotene and lycopene, the a*values and b*values have improved significantly in egg yolk. In addition, Roche color values of the yolk also improved. Also, β-carotene and lycopene can be enriched in the liver, serum, small intestine and yolk of the laying duck. As there is no significant difference in the two kinds of carotenoid content in the small intestine, it may reflect the composition of carotenoids in the feed. In other tissues, because of the dynamic transformation of the carotenoids, the content of the two carotenoids are different. In addition, we can also know that the liver and egg yolk are the main enrichment organizations for the laying ducks.Carotenoids can increase the activity of the superoxide dismutase and catalase in the liver of laying duck, at the same time, it can reduce the content of MDA in the liver. However, carotenoids reduce the activity of glutathione peroxidase in the liver. These results suggest that the carotenoids have a function of regulate the hepatic antioxidant enzyme system in vivo. Because antioxidant enzyme system show different fuctions in the antioxidant role, the carotenoids also show differences in the process of regulation.The distribution of different carotenoids in different parts of the tissues by the means of the uptake and transformation in the laying duck, then add a specific carotenoid to make the Poultry Products meet the human needs of nutrition and health and the commercialization. It can provide a theoretical basis for food production and development of the citrus peel carotenoids. |
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