Study On Drying Characteristics And Extraction Of Flavor Nucleotides From Agaricus Bisporus Waste Stipe

Agaricus bisporus is not only the largest production of edible fungi in the world, but also the largest cultivated and exported edible fungi in China. It is well known for its delicacy, flavor, nutritional value. Just like pileus, stipe of Agaricus bisporus is also riched in bioactive compounds such as protein, amino acid, nucleic acid, polysaccharides and others, but in the course of trimming process, a large number of waste stipe and inferior mushroom were produced. According to statistics, the waste stipe in trimming process account for at least 10% of Agaricus bisporus yield annually. And these waste stipe often discard as waste, which caused not only resource-wasting, but also environmental pollution. If the waste stipe of Agaricus bisporus can be comprehensively utilized, it could not only improve the additional value of Agaricus bisporus, but also reduce environmental pollution. In this study, using Agaricus bisporus waste stipe as raw material, firstly studied its drying property, then studied the ultrasonic extraction technology of nucleic acid, the technology of nucleic acid hydrolysis and stability of 5’-nucleotides. The main results were exhibited as follows:Agaricus bisporus waste stipe hot-air drying time was shortened with the increase of hot-air temperature and the decrease of slices thickness. The hot-air drying procedure of Agaricus bisporus waste stipe slices was mostly in decelerate drying rate, and had a short accelerate and constant drying rate. The hot-air drying kinetics model of Agaricus bisporus waste stipe was agreed with Page equation (P <0.0001), the predicted values of the model were nearly consistent with the experimental values.50℃ and 60℃ in waste stipe effective composition there were no significant differences on the retention, but 60℃ drying can save more time, so the comprehensive consideration, drying with hot air temperature 60℃, section 5 mm as a condition of Agaricus bisporus waste stipe effectively preserved.At 60℃ hot-air drying of Agaricus bisporus waste stipe as raw material, extracted nucleic acid from Agaricus bisporus waste stipe by ultrasonic method. Is obtained by single factor experiment, the ultrasonic power 600w, liquid-solid ratio 30:1 mL/g, ultrasonic work-pause time of 5s, 10min ultrasonic time when nucleic acid yield the most significant, and then using the response surface analysis to optimize the main technological parameters, get the optimal process parameters for:ultrasonic power 580w, liquid-solid ratio 34:1 mL/g,15min ultrasonic time, the theoretical yield for nucleic acid was 3.49g/100g. Furthermore, the actual yield was 3.43g/100g, The fitted regression model had excellent goodness of fit and showed lower prediction error. Compared with the traditional process, the ultrasonic extraction of nucleic acid was not only fast and efficient, and no material loss and no side effects reaction process, was a kind of security, economic and simple extraction method.For 5’-nucleotides, Agaricus bisporus waste stipe of nucleic acid was hydrolyzed by 5’-phos-phodiesterase, the main factors influencing the nucleic acid digestion followed by enzyme/substrate^ enzymolysis temperature% enzymolysis time、pH. Optimized by the orthogonal experiment analysis in pH5.0, enzyme/substrate of 3000U/g, enzymolysis temperature 50℃, enzymolysis time 3h. Agaricus bisporus waste stipe of nucleic acid digestion rate is maximum, the 5’-nucleotides mass concentration of 1.60g/100g.To study 5’-nucleotides in the cooked food processing, the application of the 5’-nucleotides under different temperature、pH、water bath time respectively the single factor experiment, the result was: Agaricus bisporus waste stipe in the 5’-nucleotides in the pH value of neutral partial acid (pH5～7) under the condition of relatively stable; the higher the heating temperature 5’-nucleotides is unstable; in the test scope to retain more of the 5’-nucleotides, heat treatment time with no more than 1.5 h is advisable.