Characterization of protein in royal jelly

• Main Authors: Lee, An-Ling, 李安玲
• Other Authors: Jiing-chuan Chern, Hwei- mei Wen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/86137229555815118452

碩士 === 國立屏東技術學院 === 食品技術研究所 === 85 === The objective of this study was to analyze the nutritional composition and to characterize the protein fraction in royal jelly . To assure the quality of royal jelly, an index of freshness was tried to be established in this study.The proximate analysis showed the content of moisture, crude protein, fat, ash and nitrogen-free extract in royal jelly was 68.4, 14.8, 3.4, 1.3 and 18.1 %, respectively. The major components of nitrogen-free extract were mainly glucose(6.4 %) and fructose(4.9 %). Vitamin analysis revealed that fresh royal jelly was rich in vitamin B complex, but it did not have any vitamin A, C and E. Fresh royal jelly also contained abundant minerals, such as Na, K, Ca, Mg, P, Cu, Fe and Mn.The total nitrogen content of fresh royal jelly was 2.5 %, which was mostly derived from protein nitrogen. Analyzed by amino acid analyzer, the content of free amino acid and total amino acid in protein hydrolysate was found to be 0.68 and 14.63 %, respectively.To characterize the protein, royal jelly was dissolved in 0.1M phosphate buffer(pH 7.0), then proceed centrifugation, ammonia sulfate precipitation and dialysis to separate the protein into water soluble and water insoluble fractions. Water soluble fraction accounts for more than 60 % of the total protein in royal jelly, and was further investigated by DEAE-Sephacel, SDS-PAGE and capillary gel electrophoresis (CGE). By DEAE-Sephacel, two fraction peaks were identified and collected from water soluble protein, whereas, in SDS-PAGE, four protein bands were well separated of which the molecular weight was estimated to be 65000, 54000, 42000 and 34000, respectively. However, by CGE, only three protein peaks with molecular weight of 110000, 92000 and 65000 were detected, respectively. Apparently, further studies were required to elucidate the different results observed by SDS-PAGE and CGE to estimate the molecular weight of protein in royal jelly.To study the temperature effect on the freshness, royal jelly was stored at 25 and 37℃,respectively, and was evaluated by indexes such as, appearance, water solubility and variation of protein patterns analyzed by SDS-PAGE and capillary zone electrophoresis(CZE). Obviously, the water solubility of protein was decreased, and brown color was increased as the time was increased. Conspicuous changes of SDS-PAGE patterns of water soluble protein in royal jelly was not observed until it was stored at 25℃for six weeks, whereas, the change of pattern was noted at the second week when it was stored at 37℃. Based on the SDS-PAGE patterns, the concentrations of the bands corresponding to molecular weight of 65000 and 54000 were decreased, while that corresponding to 34000 was decreased, as the storage time was increased.In the presence of phosphate buffer at pH 2.5, water soluble fraction of royal jelly was resolved by capillary zone electrophoresis( CZE) into four major peaks as denoted by N1, N2, N3 and N4. Peak height ratio of N1/N2 was decreased , while that of N3/N4 was increased as the storage time was increased. The change of both peak height ratios was obviously observed in seven days, when the royal jelly was stored at 37℃. In the presence of Cit/MES buffer at pH 6.0, two distinct peaks (as denoted by R1and R2) were well resolved by CZE. R2 peak diminished as storage time increased and vanished completely when it was stored at 37℃for one week. Apparently, the peak height ratio of N1/N2, N3/N4 and R1/R2 obtained by CZE at pH 2.5 and pH 6.0 respectively, can be used as an index to evaluate the freshness of royal jelly. －iv－