| China’s ginkgo has large yield and abundant resources.Ginkgo itself has high nutritional value and integrates consumption,medicinal,health care and beauty.It’s development and deep processing are receiving increasing attention.However,at present,the research on the preparation of ginkgo powder in the academic community often has a pre-cooking pretreatment process,which can’t truly reflect the functional properties of ginkgo itself.Therefore,it is necessary to compare the properties of not-heat-treated and pre-cooked heat-treated ginkgo.Most of the processing applications of ginkgo are still at the level of primary processing,and new products need to be developed.At the same time,the food safety of ginkgo is also a factor that cannot be ignored.In this paper,ginkgo powder and pre-cooked ginkgo powder were prepared by spray drying method using ginkgo as raw material,and the drying process was optimized.At the same time,the physical and chemical components,physical and chemical properties,functional properties and structural properties of different pretreated ginkgo powders were compared.The ginkgo powder is applied to the rice noodles to prepare a safe and edible ginkgo noodle.Through research,it is expected to provide a basis for the development and utilization of ginkgo,and contribute to the development of ginkgo industry.The main findings are as follows:1.Determine the optimum process conditions for spray-dried ginkgo powder.After the shelling,peeling and germ removal treatment of the ginkgo,the effects of feed flow rate,inlet temperature,solid-liquid ratio and air flow rate on moisture content and yield were studied by single factor experiments.Based on this research,the response surface analysis method was used to optimize the process conditions of spray-dried ginkgo powder.The optimum process conditions were as follows:feed flow rate 6 mL/min,inlet temperature 188℃,material-to-liquid ratio 8%(w/v),air flow 603 L/h.Under this condition,the yield of ginkgo powder is about 75%.Analysis of the basic physical and chemical components of not-heat treated and pre-cooked heat-treated ginkgo powder showed that the protein and starch content of ginkgo powder was higher than that of pre-cooked ginkgo powder,which may be lost to water during pre-cooking.Ginkgo powder has a lower moisture content than pre-cooked ginkgo powder and is more resistant to storage.2.Ginkgo powder and pre-cooked ginkgo powder were prepared by spray drying,and the physical and chemical properties,functional properties and structural properties were compared and analyzed.It is found that the ginkgo powder has lower L*value than the pre-cooked ginkgo powder,the a*value and b*value is higher,and the color is closer to the ginkgo itself;the solubility of ginkgo powder and pre-cooked ginkgo powder increases with the increase of temperature,then tends to be gentle.The expansion force is increasing.The fluidity,water holding capacity and oil holding capacity of pre-cooked ginkgo powder were significantly higher(p<0.05)than ginkgo powder;the foaming ability and emulsifying ability of ginkgo powder were significantly higher(p<0.05)than that of pre-cooked ginkgo powder.Both foam stability and emulsion stability are lower than pre-cooked ginkgo powder.3.The particle morphology,functional group structure,thermodynamic properties and crystal structure were analyzed by modern instrumental analysis techniques.Scanning electron microscopy(SEM)results showed that the particles of ginkgo powder were round or oval in shape,and the particles of pre-cooked ginkgo powder were folded and wrinkled,and the shape was irregular.The absorption peaks of Fourier transform infrared spectroscopy(FT-IR)at 1022 cm-1,1045 cm-1 and 1554 cm-1 indicate that heating affects the crystal structure of the starch and affects the secondary structure of the protein.The results of differential scanning calorimetry(DSC)showed that the initial gelatinization temperature,denaturation temperature and enthalpy value of ginkgo powder were significantly higher than that of pre-cooked ginkgo powder.X-ray diffraction(XRD)results showed that the crystal structure of the ginkgo powder was C type,and the pre-cooked ginkgo powder changed from a crystalline structure to an amorphous structure.It indicates that pre-cooking treatment will have an effect on the properties of ginkgo powder.4.Apply the ginkgo powder to the rice noodle processing,and mix it with the sticky rice powder to prepare the ginkgo rice noodles.The results showed that with the increasing proportion of ginkgo powder,the optimal cooking time,cooking loss and broken strip rate increased continuously,and the water absorption rate decreased.Compared with the rice noodles made of sticky rice,the texture qualities of the ginkgo noodles,such as hardness,chewiness,elasticity and cohesion,are low.According to the comprehensive consideration of texture quality,sensory evaluation and utilization of ginkgo,the ginkgo rice noodles are modified with a 6:4 ratio of blending powder.5.Using corn starch as starch adjuvant,sodium carboxymethyl cellulose(CMC-Na)as thickener and glycerin monoglyceride(MG)as emulsifier to improve the quality of ginkgo rice noodles.The ratio of the best compounded powder improver was 6 g/100 g corn starch,0.1 g/100 g CMC-Na and 0.3 g/100 g MG by single factor and orthogonal experiments.The results showed that the hardness and elasticity indexes of the texture quality of the ginkgo rice noodles were significantly improved,the chewiness and cohesiveness were also improved,and the overall quality of the ginkgo rice noodles was improved.The ginkgolic acid content of the ginkgo noodles was not detected,indicating that it was safe and edible.The research results provide theoretical and technical support for the development and utilization of ginkgo. |
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