Preparation And Characteirstics Of Ginkgo Starch Noodles

Ginkgo biloba. L is the precious plant resource used as food and medicine. In China, theannual yield of ginkgo seeds were beyond ten thousands of tons, but the consumption waslimited. Recently some companies have developed industrial process for making ginkgobeverage on the base of the centrifugal separation of ginkgo slurry. Then a suitable way to utilizethe solid part shoud be defined. The present work deals with a process of starch noodles makingfrom the ginkgo starch (GBS) for the first time together with the alternative additives to improveits qualities, as well as the digestibility characteristics and structure of starch noodles.The content of ginkgo acids in GBS was0.50ppm determined by high performance liquidchromatography (HPLC), which was lower than the limited content of Germany standard. Theprotein and lipid content of GBS were low, and the amylose content was33.90%. GBS granuleswere spherical or elliptic in shape with smooth surfaces, and particle size was between5and18μm. GBS belonged to CAcrystal structure. The average molecular weight (Mw), z-average radiusgyration (Rz) of GBS was3.45×107g/mol and125.75nm respectively, which molecular structurewas denser than mung bean starch (MBS). The gelatinization temperatures of GBS was73.1~77.9~85.0oC (To~Tp~Tc), which were higher than those of MBS.The key process parameters of producing ginkgo starch noodles (GBSN) were as following:(1) starch paste:70oC preheated water temperature,5:1weight ratio of preheated water to GBS,and80s gelatinization time in boiling water bath;(2) starch dough:6%starch paste content,43%water content, and30oC holding temperature;(3) retrogradation:4oC for4h and-7oC for4h;(4) drying:45oC dry temperature for3h. The cooking qualities, broken percentage and texturalproperties of GBSN were better under the above conditions.The effects of isolated soybean protein, chitosan, sodium alginate, sodium chloride andalum on the quality of GBSN were investigated. Results showed that sodium alginate and alumhad larger influence on the quality of GBSN, and the quality of GBSN added with0.50%sodiumalginate or0.75%alum was best. Compared with commercial mung bean starch noodles (MBSN)and MBSN self-made, the quality of GBSN added with sodium alginate or alum was close to thatof commercial MBSN. GBSN added with sodium alginate or alum had similar quality,suggesting that sodium alginate could replace alum as an additive of GBSN.The digestion characteristics of GBSN and MBSN conducted with-amylase and-amylase+pullulanase system were discussed, and the structure of the hydrolyzed residues ofstarch noodles were analyzed by high performance size exclusion chromatography (HPSEC),X-ray diffraction and differential scanning calorimetry (DSC). The results indicated that thehydrolysis degree of GBSN was a little lower than that of MBSN, and the structure of GBSN hydrolyzed residues was more compact, which displayed weak B-type crystal structure. The Mwvalues, melting temperatures and enthalpy values of GBSN hydrolyzed residues were higher thanthose of MBSN, suggesting that GBSN was more resistant to the enzyme hydrolysis. The starchin noodles might be composed of two parts: one part with relatively loose structure could beeasily degraded, and the other with compact structure would be degraded more slowly.