| Chinese jujube(Zizyphus jujube Mill.) is a traditional and distinctive fruit in China. It has various nutritions and health functions. The jujube production in our country occupies above 98% of the world output. However, the development of Chinese jujube processing industry is slow for lack of key technology and systemic research. Recent studies showed that polysaccharides possessed many bioactivities, i.e., anti-tumor, antioxidant, anticomplement, anti-ulcer, etc. They had a very high research and application value. Therefore, polysaccharides product is one of the desirable direction of jujube further processing. The extraction, separation, purification, antioxidant activities, structural characterizations and drying of polysaccharides from Ziziphus jujube Mill. cv. Hupingzao was studied in this paper. The main contents and results were as follows:The oven drying(OD), vacuum oven drying(VOD), vacuum freeze drying(FD), two-fluid spray drying(TFSD) and ultrasonic spray drying(USD) technologies were used to dry Ziziphus Jujube Mill. cv. Hupingzao in this paper. The product by TFSD and USD was more granular, those moisture contents were lower(2.39% and 2.58%), those particle size appeared normal distribution within 30- 200 ?m, and those average particle size was about 75 ?m. However, the products by OD, VOD and FD are shown in block shape. The OD, VOD, TFSD and USD demonstrated significant impact on the color difference(?E) and the water-soluble component of the product. Considering all these factors, FD is the suitable drying methods for jujube drying. Extraction of polysaccharides from Ziziphus jujube Mill. cv. Hupingzao by reduced pressure boiling method was studied in this paper.According to protein and polysaccharide yield, the optimum technological conditions were system temperature of 60 ?, water/solid ratio of 20 : 1(m L : g), time of 30 min, vacuum degree of 80 kPa, and external temperature of 70 ?. Under these conditions, the protein and polysaccharides yields were 0.13% and 2.60%. Compared with traditional water extraction, the protein and polysaccharides yields were improved by 18.18% and 23.22%.According to the decolorization rate, deproteinization rate and surplus rate of polysaccharides, the macroporous adsorption resin D900 which was selected among 10 kinds of decolorization materials was a better one. The optimum decolorization conditions were additive amount of D900 of 3.5%, time of 20 h, pH value of 11.7 and temperature of 40 ?, respectively. Under these conditions, the decolorization rate, deproteinization rate and surplus rate of polysaccharides were 81.94%, 38.19% and 87.42%, respectively. The deproteinization technology was studied in this paper. The optimum deproteinization conditions were additive amount of NaCl of 10%, time of 30 min and temperature of 20 ?, respectively. Under these conditions, the deproteinization ratio and surplus ratio of polysaccharides were 90.59% and 81.85%, respectively.The crude polysaccharides were purified by macroporous adsorption resin D900, DEAEcellulose-52 and Sepharose CL-6B column chromatography. The active polysaccharides were selected from the different fractions by comparison of the strength of antioxidant activities. Its molecular weight, monosaccharide composition and functional group were also studied in this paper. The active polysaccharides(ZJP-2b and ZJP-5a) obtained from the purification were homogeneous, and the molecular weights were 89.21 kDa and 61.60 kDa. IR showed that ZJP-2b and ZJP-5a had the characteristic absorption peaks of polysaccharide. The polysaccharide of ZJP-2b was composed by rhamnose, arabinose, mannose, glucose and galactose with the molar ratio of 32.4 : 9.5 : 9.4 : 14.7 : 9.7, and the polysaccharide of ZJP-5a was composed by rhamnose, arabinose, xylose, mannose and galactose with the molar ratio of 20.2 : 42.9 : 2.2 : 7.5 : 14.5. At the polysaccharides concentration of 3.5 mg/m L, scavenging DPPH radical activities of ZJP-2b and ZJP-5a were 17.30% and 22.59%, scavenging hydroxyl radical activities were 30.51% and 57.22%, scavenging superoxide anion radical activities were 50.88% and 37.11%, respectively.According to the hydroxyl radical scavenging capacity, moisture content and particle size distribution of product, the optimum technological conditions of ultrasonic spray drying of polysaccharides were studied in this paper. The optimum technological conditions were inlet air temperature of 135 ?, feed rate of 16 m L/min, intake pressure of 0.10 MPa and outlet air temperature of 89 ?. Three drying methods had no effects on functional group and monosaccharide composition of the product, and these scavenging capacities were about 50%. Compared with two-fluid spray drying and vacuum freeze drying, the product of ultrasonic spray drying was more granular, the particle size that appeared normal distribution within 2-20 ?m, and the average particle size was about 9.14 ?m. It is concluded that ultrasonic spray drying has no effect on the activity and structure of polysaccharides, and its quality is better. |
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