Studies On The Properties And Applications Of Hypocrellin

Hypocrellins are main active components in Shiraia bambusicola which had been used as an orally taken folk medicine for several centuries in China. Hypocrellins are naturally occurring hydrophobic perylenequinone pigments with bright red color and excellent tinting strength. It has great potential to be used as natural colorant in food industry. The stabilities and antimicrobial activities of hypocrellins were studied in this research. Hypocrellin/HP-β-CD inclusion complex was prepared in order to improve the water solubility of hypocrellin. The effect of dietary hypocrellins supplementation on egg quality and functional properties are also investigated. The dissertation is a fundamental research for application of hypocrellins in food industry.The parameters of extracting process were obtained by the monofactrorial tests. The optimal parameters were 1 gram of material powder immersed in 30 mL absolute ethanol at 60℃for 2h. The extracting rate of hypocrellins under these parameters was 4.45mg/g dry material. There are 3 main pigment components in hypocrellins extract. The major components was hypocrellin B （67%）, followed by hypocrellin A （～25%） and hypocrellin C （～8%）.Value of pH was a significant factor on the stabilities of hypocrellins. Hypocrellins has bright red color with excellent stabilities to heat and irradiation in acidic circumstances. The color of hypocrellin turned to green and the stabilities to heat and light were decreased in alkaline conditions. Metal ions such as Mg²⁺,Pb²⁺,Mn²⁺ , Ca²⁺ hardly affect the stabilities of hypocrellins. Zn²⁺ and Na+ had copigmentation effect on hypocrellins. Fe²⁺, Fe³⁺, Al³⁺ and Cu²⁺ could affect the color and stabilities of hypocrelins. Hypocrellins were resistant to hydrogen peroxide and soium pyrosulfite, but was sensitive to sodium sulfite. No significant influences of food additives in common use, such as ascorbic acid, sodium benzoate, potassium sorbate, cane sugar, glucose and citric acid, on the stabilities of pigment were observed. The oxidative stability of vegetable oil was not affected by hypocrellins in dark place. Hige dose of hypocrellins will decrease the oxidative stability of vegetable oil under illumination. Therefore, when hypocrellins were used as oil colorants, the products should be stored in dark place.Hypocrellins possessed excellent photodynamic antimicrobial activities against Gram-positive bacteria, however, the antimicrobial activities against Gram-negative bacteria were not obvious. The irradiation time and oxygen play important roles in the antimicrobial activities of hypocrellins. Antimicrobial activities of hypocrellins against both Gram-positive and Gram-negative microorganisms were enhanced when Ca²⁺ or Mg²⁺ was employed or in acidic circumstances. A loose binding has been established between hypocrellins and the organisms. Hypocrellins maintains a photodynamic activity in terms of both types I and II reactions. The ractive oxygen speices produce by hypocrellins could cause the injuries of cell wall and membrane. The permeability of membrane was enhanced. Consequently, the leakage of intracellular contents appeared to be the major cause of microorganism inactivation upon photodynamic antimicrobial process of hypocrellins.Hypocrellins supplementation of poultry feed significantly improve the color of egg yolk and increase the concentration of hypocrellins deposited in egg yolk. The content of hypocrellins deposited in egg yolk increased with the increasing of feed time and hypocrellins dosages added to the diet. The content of hypocrellins deposited in egg yolk decreased sharply when the layers were feed by basal diet. Besides egg yolk color, short-term hypocrellins supplementations of poultry diet dose not influence the productive performance of layers and qulity, functional properties and strorage stabilities of eggs. The highest hypocrellins content in tissues samples was measured in ovary, followed by liver. The hypocrellins contents in heart, lung, gizzard and breast muscles were much lower. Moreover, hypocrellins content in ovary and liver were increased significantly with the increasing of hypocrellin added to the diet. By contrast, no significant differences of hypocrellins content in heart, lung, gizzard and breast muscle were observed in all supplementation diet groups.Hypocrellins and HP-β-CD can form inclusion complex with possible stoichiometry of 1:1. The inclusion process was an exothermic and enthalpy-driven process accompanied with a negative entropic contribution. FT-IR, DSC, TG and spectroscopic studies comfirm the formation of inclusion complex and presume that the aroma rings of hypocrellins were embedded in the cavity of HP-β-CD. The formation of inclusion complex can significantly increase the solubility and the thermal decomposition start temperature.