Studied On Preparation And Properties Of Dietary Fiber From Fujian Porphyra Haitanensis

Porphyra haitanensis is an important economic aquaculture algae in Fujian province, which has medicine and food function. The quality of dried porphyra haitanens is decreased with harvesting time. The porphyra haitanens after the fourth time harvesting is rich in dietary fiber, which has not been utilized. In this paper, the porphyra haitanens which harvested in the fifth time was used as raw materials to extract dietary fiber, and the extracted dietary fiber’s physical characteristics was studied too. The aim of this study was to find a way to comprehensively utilize the porphyra haitanens and to increase products’additional value, to reduce waste and environmental pollution. The results were as follows:(1)Porphyra haitanens were treated with hot air drying, vacuum drying and microwave vacuum drying, respectively, and dietary fiber contents and the organizational structure of different products were compared. The results showed that the product of microwave vacuum drying had high dietary fiber contents and sensory qualities. The optimum parameters of drying technology of microwave vacuum drying for Porphyra haitanens were:microwave power1000W, vacuum degree0.09MPa, on/off ratio30s-on/30s-off, drying time22min.(2) We compared the hot water method, microwave method and ultrasonic method effect on extraction yield of SDF. The result showed that ultrasonic method was the best way. According to single factor and orthogonal test, the optimum conditions of extract process were:ratio of liquid to material1:25g/mL, ultrasonic power400W, temperature70℃, time45min, times2. Under that technology conditions, the extraction rate of SDF reached22.74%. The results of experiment in the rheological properties of the aqueous solution showed that SDF was pseudoplastic fluid, which had weak gel properties.(3)In this study we used enzymatic methods to extract IDF from Porphyra haitanens residue. According to single factor and orthogonal test, the optimal condition for the extraction of IDF were as follow:ratio of liquid to material1:20g/mL, enzymes dosage4000U/g, temperature50℃, time5h, times2, pH7.0, and through verification, the content of IDF was87.16g/100g.(4)In this paper we compared different solvents and methods effect on the processing of bleaching the product to increase the product’s whiteness. By single factor and orthogonal test, the optimal conditions of IDF bleaching were:ratio of liquid to material1:20g/mL, ultrasonic power 240W, ultrasound frequency45KHz, temperature70℃, concentration of ClO23%, time30min, The whiteness of the product was54.10. Its water holding capacity, oil holding capacity and swelling force were higher than before. The result of structure observation showed that the processing of bleaching had changed its physical structure.