Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Food Science and Nutrition | en_US |
| dc.contributor.advisor | Wu, Jian-yong (FSN) | en_US |
| dc.contributor.advisor | Dong, Xiaoli (FSN) | en_US |
| dc.contributor.advisor | Wen, Chunyi (BME) | en_US |
| dc.creator | Zhao, Zichen | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/14159 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Extraction, purification and characterization of bioactive polysaccharides and proteins from Lentinula edodes mushroom | en_US |
| dcterms.abstract | Edible fungi, commonly known as mushrooms, are widely recognized for their nutritional and health benefits. Polysaccharides (PS) and proteins are two of the most abundant components in edible mushrooms, contributing significantly to their medicinal and nutritional value. While numerous studies have explored the diverse biological activities of polysaccharides extracted from edible mushrooms, research on their proteins remains limited. Lentinula edodes, known as Shiitake in Japanese and Xianggu in Chinese, is one of the most popular edible mushrooms and is widely consumed as a health food. This project aims to develop and implement effective methods for extracting and purifying proteins from L. edodes, as well as to investigate their molecular properties, nutritional composition, and immunostimulatory activity. | en_US |
| dcterms.abstract | The first part of this project focused on evaluating the effectiveness of the three-phase partitioning (TPP) method for isolating PS and proteins from L. edodes mushrooms. By analyzing molecular properties and biological activities, the study optimized TPP conditions using response surface methodology (RSM), determining that 48.0% (w/v) ammonium sulfate ((NH4)2SO4), a 1.2 volume ratio of t-butanol to crude extract, and a temperature of 52 °C yielded the best results. Under these conditions, maximum yields of 11.64% for PS and 2.06% for protein were achieved. The PS fraction was primarily composed of glucose, galactose, and mannose, with a molecular weight of 7.35 kDa. Both fractions exhibited significant immunostimulatory effects, including increased nitric oxide (NO) production and enhanced phagocytic activity in RAW 264.7 cells. The protein-rich fraction demonstrated particularly strong efficacy, with a low EC50 value of 0.28 μg/mL. In summary, TPP proved to be a simple and efficient method for isolating bioactive polysaccharides and proteins from mushrooms. | en_US |
| dcterms.abstract | In the second part, protein extracted from L. edodes mushrooms using the TPP method, which has previously demonstrated significant immunostimulatory activity, was further investigated in this study. The research focused on fractionating and characterizing proteins to evaluate their nutritional and immunostimulatory properties. Crude protein was obtained from the mushroom aqueous extract and purified using anion exchange chromatography, resulting in two fractions: F1 and F2, with protein contents of 66.1% and 74.0%, respectively. Both fractions primarily exhibited protein structures consisting of β-sheets and random coils, while the crude protein also displayed an α-helix structure. SDS-PAGE analysis showed that F1 contained two molecular weight bands, one below 10 kDa and another at 34 kDa, whereas F2 exhibited multiple bands, including one below 10 kDa and others ranging from 34 to 95 kDa. In terms of nutritional value, as determined by essential and non-essential amino acid profiles, the ranking was F2 > F1 > crude protein. The amino acid ratio coefficient values were 63% for crude protein, 67% for F1, and 72% for F2. The combination of PS and protein fractions exhibited greater immunoactivity than either F1 or F2 alone. F2 demonstrated superior immunostimulatory activity in RAW264.7 cell cultures and contained a higher concentration of easily absorbed high-quality proteins compared to F1. These findings provide important insights into the dietary and medicinal applications of protein fractions derived from L. edodes and other edible mushrooms. | en_US |
| dcterms.abstract | The third part aimed to identify the most effective method for extracting proteins from L. edodes mushrooms by comparing water extraction (WE), enzyme-assisted extraction (EAE), ultrasound-assisted extraction (UAE), and various combinations of EAE and UAE, including EAE followed by UAE (EUE), UAE followed by EAE (UEE), and simultaneous EAE and UAE (SEUE). Among these methods, the two-step sequential process of EAE followed by UAE (EUE) yielded the highest protein content compared to UEE and SEUE. The soluble protein yield obtained by EUE (9.4%) was nearly three times higher than that of UEE (3.6%) and about twice as high as EAE (4.9%). Additionally, the protein fraction extracted by EUE had the highest protein content (56.0%) and β-sheet content (55.8%), and exhibited the strongest in vitro immunostimulatory activity. Using statistically designed experiments and response surface methodology, the optimal EUE conditions were determined to be 0.28% (w/v) enzyme concentration, 62% ultrasound amplitude, and 69% ((NH4)2SO4) saturation, resulting in a protein yield of 9.7% and a protein content of 58.4%. The extracted proteins had molecular weights below 10 kDa and between 25-75 kDa. The protein fraction contained essential amino acids and demonstrated significant immunostimulatory activity in vitro. Overall, EUE shows great promise as an efficient method for protein extraction from mushrooms for use in the food industry. | en_US |
| dcterms.abstract | The studies above have shown that protein fractions from L. edodes exhibit even stronger immunostimulatory activity than its PSs, closely linked to their composition and structural characteristics. More efficient extraction methods and optimized conditions have been developed to improve both protein yield and bioactivity. This research is expected to make a significant contribution to advancing knowledge and understanding of the processes required for the efficient extraction, isolation, and purification of protein from edible and medicinal L. edodes. Additionally, the project aims to deepen our understanding of the relationship between the molecular properties of these proteins and their immunomodulatory activity. With these findings, this thesis can provide valuable foundational insights for utilizing L. edodes protein as a targeted dietary supplement to enhance immune health. | en_US |
| dcterms.extent | 1 volume (various pagings) : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2025 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.accessRights | open access | en_US |
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