田浩　張慧

【Abstract】Natural Lutein is one of the important yellow carotenoid at the same time is an important colorants and nutrients. In this paper, the overview of lutein industry were briefly reviewed, also introduced the function and application of lutein. Natural lutein is a natural pigment with a huge prospect of application in the future.

【Key words】Lutein; Carotenoid; Colorant; Antioxidant; ARMD

1Introduction of lutein

Carotenoids are yellow, red and orange pigments which are widely distributed in nature. Carotenoids are a class of terpenoid pigments with a 40-carbon backbone and a large conjugated double-bond system, which not only make carotenoids have characteristic colour, but also endow them with the function as antioxidants in disease prevention.

Lutein is a more polar kind of carotenoids, which mainly extracted from marigold, a kind economic crop widely cultivated in China. According to statistics, China product 800 million grams lutein, accounted for 85% of world output. So China is the biggest producing area of natural lutein.

Lutein insoluble in water, but soluble in most organic solvents like ethyl acetate, isopropyl alcohol, acetone, methylene chloride and so on. Lutein extracted from marigold mainly included marigold extract ointment (10%-25%), lutein ester powder (50%-70%), lutein crystal (above 80%).

Lutein is normally obtained from the petals of marigold after an extraction process by organic solvent which yields oleoresins with varying concentrations of lutein that range from 10% to 50%, mostly in the ester form, which is roughly a half if free lutein is considered. These concentrates are the product most commonly used for the formulation of food supplements. Lutein can be further purified by processes that involve saponification, further concentration, and a final recrystallization to its crystalline form. Crystalline lutein is, nevertheless, difficult to handle and, hence, is commonly sold as suspensions of the carotenoid in corn or soybean oils. These kind of purified extracts (content is above 70% or more) are commercial products. Pure free crystalline lutein is also available, most commonly in the form of microcapsule.

2Function and physiological activity

２．１Natural colorants

Lutein has the bright yellow as well as good dyeing ability. So it can be widely used in the dyeing of cakes, candies, condiment, pickles and animal feed, can dye nutrient ,sugar pills and capsules. In china, Lutein has been widely used as feed additives. In Europe and the US，lutein has been widely used in food industry as a safe and reliable colorant.

2.2Vision Protection

Lutein is important for macular protection in the retina, where the lacking easily leads to macular degeneration and blurred vision, to move forward a single step diminution of vision and myopia.

Age-related macular degeneration(ARMD) is the major cause of irreversible blindness in older men and women. It has been proved that the content of lutein and zeaxanthin in retina is inversely proportional to the risk of ARMD. It has been reported that the consumption of lutein and zeaxanthin leads to a 40 percent reduction in ARMD. Lutein and zeaxanthin accumulation has the capacity to absorb light in the blue wavelengths that impinge directly on the fovea of the retina, at the same time they can quench singlet oxygen, thus protecting the macular cells during a lifetime of oxidative stress. Lutein can't be synthesized by body, only be absorbed by diet. Experts suggest that one need take 6 mg lutein to protect ones eyes every single day.

２．３Antioxidant

Like most carotenoids, lutein has excellent or more antioxidant ability, which ability controls the activity of oxygen free radicals, thus protects the normal cells from damage. Lutein can inactivate singlet oxygen through physical or chemical quenching effect, thus protecting the body from harm, and strengthen the body's immune ability at the same time.

２．４Against cancer

Several studies show that lutein has inhibitory effect on many kinds of cancer, for example: breast cancer, prostate cancer, colorectal cancer, skin cancer, etc. Lutein taken in the dietary can not only inhibit swelling cancer also can even play a vital role in reduce the prevalence of tumors. Related authorities suggest 400 g ~ 600g fruits and vegetables should be took in per day, thus can make the relative risk of cancer decreased by 50%.

３Application and prospect

Natural lutein is excellent stain, but also excellent antioxidant. Marigold color can find application in coloring foods like edible oils, oleo-margarine, mustard, mayonnaise and other salad dressings, cakes, yogurt, ice cream, and dairy products. As nutrition enhancer and antioxidants, lutein is added to infant formula to assist the growth of vision, or is made into capsule to directly meet the needs of oxidation to maintain the body function normally. The application of microcapsule greatly expands the scope of application of lutein, by which lutein can be added to the beverage as the colorants and nutrients.

Natural lutein has a bright prospect with excellent biological activities, at the time China has a rich sources. So lutein industry has huge development potential and economic value in China. Serious attention should be give scientific research personnel to ensure we play an important role in the lutein industry.

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［責(zé)任編輯：劉帥］