Research On The Preparation And Application Of Ginkgo Starch Based Fat Substitute

In the current research, ginkgo seeds were selected as the raw material and the extraction method of ginkgo starch was investigated by solvent extraction. Ultrasonic was used to assist the extraction of ginkgo starch. The ginkgo starch based fat substitutes with different DE value were obtained by thermostable α-amylase and their physical and chemical properties were detected. Finally, the ginkgo starch based fat substitute was used in the processing of cake. The mainly results are as follows:(1) Starch was extracted with the use of alkali extraction, single factor experiment showed that the ginkgo starch extraction rate using NaOH solution is higher than the Ca(OH)2 and NH3H2 O. Based on this, the response surface method obtained that in condition of extraction temperature 45℃, NaOH concentration 0.08mol·L-1, time5 h, liquid ratio 3.5∶1(V/w), starch extraction rate yield up to 74.88%.(2) On the basis of ginkgo starch extraction using alkali-extraction, ultrasonic assisted extraction was applied to extract ginkgo starch, and the response surface method is used to optimize the extraction conditions, the result indicate that when the optimal technological conditions was 40℃, time 29 min, power 170 W under which the extraction rate yield 75.65%. Starch extraction rate were not significantly improved using ultrasonic assisted extraction, but the extraction time were shortened, so we adopt the ultrasonic assisted extraction to extract starch.(3) Using high temperature α-hydrolyze ginkgo starch, the results of single factor experiment showed that in the range of selected DE value, DE value of the sample showed a positive correlation with hydrolysis temperature, hydrolysis time and dosage of enzyme but showed a negative correlation with starch milk concentration, the response surface method obtained that the enzymatic hydrolysis conditions under the enzyme dosage 2.3 U·g-1; hydrolysis time 2.6 min; hydrolysis temperature 88℃, starch milk concentrations 14.9% can be prepared the ginkgo starch based fat substitute of DE 1 value; the enzyme dosage 2.1 U·g-1; hydrolysis time 6.0 min; hydrolysis temperature 91℃, starch milk concentrations 15.2% can be prepared the sample of DE 2 value; the enzyme dosage 5.0 U·g-1; hydrolysis time 2.5 min; hydrolysis temperature 89℃, starch milk concentrations 14.9% can be prepared the sample of DE 3 value; the enzyme dosage 4.3 U·g-1; hydrolysis time 5.2 min; hydrolysis temperature 90℃, starch milk concentrations 14.7% can be prepared the sample of DE 4 value; the enzyme dosage 6.0 U·g-1; hydrolysis time 5.1 min; hydrolysis temperature 90℃, starch milk concentrations 17.4% can be prepared the sample of DE 5 value; the enzyme dosage 4.9 U·g-1; hydrolysis time 6.0 min; hydrolysis temperature 90℃, starch milk concentrations 13.3% can be prepared the sample of DE 6 value.(4) Through the study on the properties of the samples with different DE value, we considered samples with DE value of 4 to 6 was unfit for fat substitutes in terms of poorer emulsification, emulsifying stability, freeze-thaw stability, water holding capacity and holding oiliness, while samples with DE value of 1 to 2 samples was unfit for fat substitutes because the gelling temperature was too high to form a gel or form a harder gel, analysis gel properties of different concentration showed sample concentration 15% was suitable for fat substitutes as the soft, smooth texture. So the fat substitutes was selected as the enzymatic starch extracted when sample concentration was 15% and DE value was 3.(5) The ginkgo starch based fat substitute was used in the processing of cake, as the fat substitutes rate increases gradually, the moisture content and mass loss rate of cake increased gradually, texture analysis results show that hardness and elasticity of cake adding fat substitutes was lower than the original formula, but restorative slightly higher than cake made according to the original formula; Fuzzy sensory evaluation results showed that the fat replacement rate within 40% of the cake score good and close to the original cake, so it can replace the fat in the cake perfectly.