| Astaxanthin is the highest-grade carotenoid-synthesized product.It has superb antioxidant and other biological functions.It can be used not only as an aquaculture feed additive,but also in medical?fatigue relief?,health food,cosmetics and other industries.Great application potential.In this paper,Haematococcus pluvialis is used as the raw material,the extraction process of astaxanthin is optimized,and the astaxanthin oleoresin is purified and crystallized by cleaning-crystallization method,and combined with thin layer chromatography,electron microscopy scanning,XRD diffraction and nuclear magnetic technology The crystals were characterized and analyzed;and the stability,antioxidant,bacteriostatic and digestibility of astaxanthin crystals were further studied.The main experimental results are as follows:1.To extract astaxanthin from Haematococcus pluvialis by grinding and breaking walls and constant temperature stirring,the extraction rate can reach 92%.Taking astaxanthin oleoresin as the research object,the crystallization purification process of astaxanthin was established.Through single factor and response surface experiments,the crystallization purification conditions of astaxanthin were finally determined as follows:material-liquid ratio1:40,saponification solution concentration 0.03 mol/L.The saponification time was 11 h,the saponification temperature was 4?,the number of cleaning times was 6 times,and the freeze-drying time was 72 h.The crystal purity was 98.9%after testing.The characterization of high-purity astaxanthin crystals was characterized,and the purity of the astaxanthin crystals obtained by the experiment was similar to that of the astaxanthin standard.The shape of the astaxanthin crystals was determined by scanning electron microscopy.Shape or flower shape,the particle size is 17-57?m;the crystallinity of the astaxanthin obtained by the experiment is confirmed by XRD diffraction,and the diffraction peak is the strongest when 2?is 16.28°;the structure of the astaxanthin obtained by the experiment is determined by nuclear magnetic analysis The type is all-trans astaxanthin.2.Using astaxanthin oleoresin as a control,the effects of temperature,light,acid-base concentration,pH,oxidant and reducing agent,metal ions,and sucrose on the crystal stability of astaxanthin were investigated.The results show that the temperature is higher than 40?can affect the stability of astaxanthin crystals,higher than 50?can affect the stability of astaxanthin oleoresin;direct sunlight and indoor scattered light irradiation damage the crystals of astaxanthin oleoresin and astaxanthin The strongest effect,UV irradiation and incandescent lamp only have a certain damage to astaxanthin crystals,and the best preservation effect of astaxanthin in dark conditions;astaxanthin crystals are very stable under alkaline conditions and are easily destroyed under strong acid conditions,Astaxanthin oleoresin is unstable to alkaline substances and strong acids;oxidants have a greater impact on the stability of astaxanthin oleoresins and crystals than reducing agents;astaxanthin oleoresins and crystals should be avoided with Al3+,Ag+,Fe3+,Cu2+Contact;high-concentration sucrose solution has a certain destructive effect on astaxanthin crystals,and has no effect on astaxanthin oleoresin.3.Using vitamin E as a control,the antioxidant activity of astaxanthin crystals was studied.The results show that the astaxanthin crystals have a clearing effect on DPPH free radicals,ABTS free radicals,and hydroxyl free radicals.By calculating the IC50 value,it reflects that the astaxanthin crystal can scavenge the three free radicals in order of DPPH free radical>ABTS free radical>hydroxyl free,and at the same time,the ability to scavenge DPPH free radical,ABTS free radical and hydroxyl free radical respectively It is 4.3,2.6,186.3 times of vitamin E.Astaxanthin's ability to reduce iron ions is significantly greater than that of vitamin E,and as the sample concentration increases,astaxanthin has a more advantageous effect on iron ion reduction.4.The inhibitory effects of astaxanthin crystals and astaxanthin oleoresin on Escherichia coli,Escherichia coli K12,Staphylococcus aureus,Bacillus subtilis,Candida albicans,yeast and Aspergillus flavus were studied by agar plate punching.The results show that astaxanthin crystals have an inhibitory effect on Gram-negative bacteria,Gram-positive bacteria and fungi.Among the selected strains,Candida albicans has the strongest inhibitory effect;Lan-positive bacteria and mold have an inhibitory effect.Through the measurement of the conductivity and soluble protein content of Candida albicans culture solution,it is concluded that the inhibition effect of astaxanthin crystals on Candida albicans is achieved by destroying the permeability of its cell membrane. |
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