Difference Analysis Of Water Soluble And Volatile Components Of Different Strains Of Hibiscus Syriacus L. Flowers

Hibiscus syriacus L.is a genus of the genus Hibiscus,which widely distributed and has a variety of colors and varieties.H.syriacus L.combines medicinal,edible,ornamental,greening and fiber raw materials.Yi Lin Zuan Yao introduced the white flowers of H.syriacus are helpful for people who cough and hematemesis,and Chinese medicine believes that has the effects of clearing heat,dampness and cooling blood.H.syriacus flowers have a long flowering period,large yield and unique flavor.At present,there is a lack of in-depth research on the edible use of different strains of H.syriacus flowers,which is not conducive to the rational use of resources.Therefore,in this paper,different strains of H.syriacus flowers were selected as research materials to analyze and compare the water-soluble and volatile components,so as to provide theoretical reference for the edible value and resource utilization of different varieties of hibiscus flowers.The research results are as follows:1.The optimal extraction conditions of H.syriacus flowers polysaccharides were explored by response surface methodology.The relative molecular mass and monosaccharide composition of four strains of flowers were analyzed by high performance gel chromatography and pre-column derivatization HPLC.The optimal extraction conditions for the polysaccharides of H.syriacus flowers by single factor experiment and response surface design were extraction temperature 96.8°C,liquid-to-liquid ratio 43.5:1(mL·g^-1),extraction time 3.1 h.Four kinds polysaccharides were composed of single peaks by high performance gel chromatography,the average relative molecular masses were 1.49×10⁵,1.25×10⁵,1.01×10⁵ and 1.37×10⁵.It is mainly composed of five monosaccharides such as glucose,mannose,galactose,rhamnose and arabinose.The proportion of galactose is the highest,and its ratio to glucose is1.656⁴.496.Through the determination of DPPH scavenging ability,Fe³⁺reduction capability and ABTS scavenging ability,the crude polysaccharides of different strains of flowers showed antioxidant activity.In general,the antioxidant capacity of the H.syriacus flower is stronger than that of the white flower.2.According to GB 5009.124-2016“Determination of Amino Acids in Foods”,the contents of 16kinds of amino acids in three strains of LSW,LSP and LSR were determined by amino acid analyzer,and the differences of amino acid contents among different strains were compared.The results showed that the total amino acid content of the three strains to 87.94 mg·g^-1 on average,and the amino acid content of the white flower of H.syriacus（LSW）to 101.34 mg·g^-1.The contribution of the two umami amino acids to the total taste amino acid was very large,and the content range was 25.2³0.5 mg·g^-1,and the average content was 26.2 mg·g^-1,the FAA/TAA average value is 29.8%.Compared with other three kinds of edible flowers,the flowers of H.syriacus have the highest amino acid content,and are suitable for eating due to the higher content of umami amino acid.3.The volatile composition of H.syriacus flowers were determined by HS-SPME-GC-MS.The composition and relative content of aroma components in different strains and storage time were compared.Total ion chromatogram and mass spectrum based on volatile components of different samples.Combined with the NIST mass spectrometry search and retention index（RI）,37 substances were identified from all samples.Total of 43 volatile substances were identified from the after 1 year later flowers,of which were 18 common.After storage,the volatile composition of hibiscus are different compared with fresh hibiscus flowers,the content of hydrocarbons is much lower than which of fresh hibiscus,and the types and relative contents of steroids and alcohols are increased.