| Lardizabalaceae plants are often used in traditional Chinese medicine. There are four kinds of Lardizabalaceae plants in total, including A.quinata(Houtt.) Decne, A.trifoliata(Thunb.) Koidz and A.trifoliata var.australis Diels, and seeds of them are rich in extractable oils and proteins, they are potential to be exploited as a kind of wild plant seeds. A.trifoliata var.australis Diels are copious fruit in Jiangxi province, the maximum yield can reach to 3000 kg per acre. In order to improve the comprehensive utilization of A.trifoliata var.australis Diels, it is necessary to study the protein in it to broaden its application. Plant protein is a kind of great source of dietary protein, it can be used replace expensive animal protein in human diet. Developing proteins in A.trifoliata var.australis Diels seeds is just according with the requirement of this subject. In this paper, we investigated and compared the nutritional compositions of five kinds of Lardizabalaceae plants, A.quinata(Houtt.) Decne, A.trifoliata(Thunb.) Koidz and A.trifoliata var.australis Diels(red peel, yellow peel and gray peel), including the moisture content, ash content, crude protein and oil, composition of fatty acids, amino acids and trace elements. On the basis of previous study, the solubility, emulsifying properties and other properties of unmodified A.trifoliata var.australis Diels protein were not ideal, limiting its application. In this paper, effects of high pressure microfluidization and deamidation with edible acid on the Akebia trifoliata var. australis seed protein were studied. The main results are as follows:1. In this paper, we investigated and compared the nutritional compositions of five kinds of Lardizabalaceae plants, A.quinata(Houtt.) Decne, A.trifoliata(Thunb.) Koidz and A.trifoliata var.australis Diels(red peel, yellow peel and gray peel), including the moisture content, ash content, crude protein and oil, composition of fatty acids, amino acids and trace elements. Results showed that the moisture content were from 2.41% to 4.27% for the five samples, the ash content of A.quinata(Houtt.) Decne was the highest(4.28%), and ash contents of the four other seeds were similar but significantly lower than A.quinata(Houtt.) Decne. The five samples were all rich in crude protein(14.65%-16.57%) and crude oil(29.43%-45%). The fatty acid compositions of five lardizabalaceae plant seeds were similar that rich in oleic acid and linoleic acid. meanwhile, the content of unsaturated fatty acids was high. Amino acid analysis results showed that content of aspartic acid and glutamic acid were high in all the five samples, and for the essential amino acids, there are more leucine, serine, lysine and aromatic relatively. There were a wide range in content of trace elements of five samples, but contents of K(6.025-11.108 mg/g), Ca(3.205-4.067 mg/g), Mg(2.112-2.374 mg/g) and P(3.131-4.144 mg/g) were higher than other trace elements.2. In this study, we investigate the effects of high pressure microfluidization on the conformational and rheological properties of Akebia trifoliata var. australis seed protein isolate(API). The results showed that the particle size of API became smaller, subunits of API were unchanged and solubility increased significantly after HPM treatment. The contents of the total and exposed sulfydryl decreased with the pressure increased. Meanwhile, the composition of secondary structure in API changed, the maximum change was showed when the pressure at 130 MPa and the unstable group β-sheet and Random coil decreased. On the contrary, β-turn, the stable group increased. Dates of rheology measurement indicated that the API solution kept to be pseudoplastic liquid before and after HPM treatment, the apparent viscosity of all API solution samples showed a trend of decreasing when the shear rate ranged from 1 s-1 to 10 s-1, and with the increase of pressure treatment, apparent viscosity of API solution showed obviously Shear-thinning phenomenon.3. The characteristics of glutelin samples from Akebia trifoliata var. australis seeds(AG) that had been deamidated by malic acid(MDAG) and by citric acid(CDAG) were investigated. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis showed high-molecular-weight subunits that were degraded into smaller fragments, and FTIR indicated a decrease in the number of b-sheet groups and an increase in the amount of b-turns in the deamidated samples. These results could be caused by the cleaving of partial disulfide bonds to form new sulfhydryl groups during deamidation. Citric acid was found to be more effective at deamidation and hydrolysis, resulting in a higher solubility and emulsifying activity for CDAG, and MDAG also exhibited some improvement in terms of surface hydrophobicity and emulsion ability. Rheology showed that the gelation point for deamidated samples was increased, and the gel network was strengthened. The amounts of essential amino acids that were well-preserved and the improved solubility, emulsification, and rheology properties of AG after acid-heating deamidation show that this technique can be useful for treating other plant-based food ingredients in the future. |
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