Research Of Sub-critical Extraction Technology And Quality Of Oil And Protein From Hibiscus Manihot L. Seed

Hibiscus manihot L. has edible, medicinal and health care functions, but the recent research and development applications mostly concentrated on high levels of bioflavonoids thereof, for the 15 to 29.3% seed oil, which had reasonable fatty acid composition ratio, were also only occasionally reported at the level of laboratory research. Therefore, work out the optimum extraction of Hibiscus manihot L. seed oil,can provide a reference for future oil production. Meanwhile, if depth development of industrial processes was realized for the residual meal, which was rich with high-quality vegetable protein, would increase actual value of Hibiscus manihot L..The study of Hibiscus manihot L. seed by using subcritical extraction technology,which not only enriched product variety, obtained oil and meal with high quality and quantity, expanded the application scope, enhanced the processing technology of functionality oil, but provide reference for the further development of Hibiscus manihot L. seed oil and meal.This research first study on extraction process of Hibiscus manihot L. seed oil by using subcritical technology, including the effect of temperature, time, solid-liquid ratio and extraction times on oil extraction yield, and the extraction process was optimized by response surface methodology to get best process conditions as:extraction time 45 min, liquid-solid ratio 10, temperature 55 oC, while yield can reach to 11.98%. Results of response surface optimization analysis showed that, of the three factors affected Hibiscus manihot L. seed oil extraction, liquid-solid ratio was the highest, while temperature was the lowest.Secondly, the research compared quality of the oil extracted by three kinds of different methods as subcritical extraction, solvent extraction and supercritical carbon dioxide extraction, respectively, including general physical and chemical indicators,fatty acid composition and oil oxidation stability. Finally, the following conclusions were made: 1, extracting ability of three methods was different; 2, components,physics and chemical properties of Hibiscus manihot L. seed oil obtained from three methods had little differences; 3, to oil oxidation stability, compared to organic solvent extraction, subcritical extraction was slightly worse, but significantly better than the supercritical extraction.Finally, protein, amino acids and flavonoids content of residual meal after the seed oil extracted by subcritical fluid were analyzed. It concluded as follows: 1,flavonoid content of residual meal was 1.03%; 2, four types of protein were isolated from residual meal, and main was glutelin; isoelectric point of protein was 4,water-holding capacity was 2.94 g/g, oily holding reached maximum 2.75 g/g at 30oC;emulsification and emulsion stability of the protein was similar to the pH change trend; change tendency of foaming was similar as emulsification solubility, which were positively correlated with meal protein; 3, through the analysis of meal protein amino acid, percentage of non-essential amino acids was 69.55%, essential amino acids were 30.45%, wherein the maximum content was Glutamic acid; the maximum ratio coefficients was Leucine, followed by were Phenylalanine + Tyrosine and Valine;score ratio coefficient of all essential amino acids were 30.