Papers by Author: Dan Huang

Abstract: Using ultrasonic-extraction technology, the condition of extracting the active compounds-flavonoids and rosmarinic acid of Perilla was studied. The effects of four main factors include ultrasonic power, temperature, time and solid-liquid ratio on the extraction-rate of the flavonoids and the rosmarinic acid of Perilla were reviewed by single factor experiments,and the flavonoids and the rosmarinic acid was determined by NaNO₂-Al (NO₃)₃-NaOH method and FeSO₄ method. On the base of single factor experiments, the extraction technique was optimized in the orthogonal test. The result showed that temperature was the most important factor in the influencing factors on the extraction-rate. The subsequence of importance was temperature > time > solid-liquid ratio > ultrasonic. The optimal extraction conditions were: extraction solvent 3%borax, solid-liquid ratio 1:50(w/v), ultrasonic power 300W, time 90min , temperature 75°C. Under the optimum technological conditions, 34.64mg/g of flavonoids and rosmarinic acid from Perilla could be obtained.

Abstract: The salt-tolerance lactic acid bacteria strain was isolationed and identified from soy sauce mash. The ability producing lactic acid was studied in different culture conditions. The salt-tolerance lactic acid bacteria strain was isolationed and screened by MRS medium with CaCO₃ and NaCl gradient plate from soy sauce mash. They were identified according to morphorlogy characters and 16S ribosomal RNA (rRNA) gene sequencing methods. The ability producing lactic acid was studied at different fermentation temperature, NaCl concentration and pH value. The results showed: the strain with superior salt-tolerant was identified as Lactobacillus delbrueckii subsp. bulgaricus. Its optimum fermentation temperature was 38°C. When NaCl concentration was 18%, its lactic acid yield could reach 22.68 g/L. It had a better absorbing ability of lactic acid in neutral or slight alkaline condition.

Abstract: Six moulds were isolated from Luzhou-flavor Daqu through traditional microorganism isolation method. Among them, two strains njsys-3 and njsys-6 have shown higher glucoamylase activity, their enzyme activity were 1842 U/g and 2349U/g separately. Molecular biological identification results shown that strain njsys-3 was Aspergillus clavatus and strain njsys-6 was Aspergillus niger. Daqu-making test showed that once the inoculating amount of seeding broth of njsys-3 attached to 6 ‰, the glucoamylase activity of Daqu can increase 26.9%; when the inoculating amount of seeding broth of njsys-6 attached to 6 ‰, the activity of glucoamylase of Daqu can increase 34.1% and the fragrance of Daqu can increase.

Abstract: The conditions of glucoamylase production of the Rhizopus oryzae in Luzhou-flavor DaQu by solid state fermentation were studied. According to the Box-Benhnken design, the conditiones of glucoamylase production of the Rhizopus oryzae were optimized by solid state fermentation. The results showed the optimum conditions of glucoamylase production of the Rhizopus oryzae in Luzhou-flavor DaQu by solid state fermentation were culture temperature 29°C, the water content in culture medium 53%, culture time 164h, glucoamylase activity was 2194.44U/g.

Abstract: A Rhizopus strain producing esterifying enzyme was isolated from Luzhou-flavor DaQu. It was preliminary identified as Rhizopus arrhizus. Through the research of the culture conditions of the strain producing esterifying enzyme, it was found that the enzyme activity could reach 7.91U/mL as 2% corn meal used as C source, 6% peptone used as N source, initial pH value was 6.0, and 72h culture with 150 r/min agitation at 30°C.

Abstract: The metabolies characterization of mold producing esterifying synthetase of different culture conditions were studied. A mold strain producing esterifying enzyme was isolated from Luzhou-flavor DaQu and it was identified by Biolog Microbes automated identification System. Culture conditions such as culture temperature, fermentation time and carbon source were changed. The fermentatiom broth was extracted by ethanol and analyzed by GC-MS. The results showed that the strain was Aspergillus flavus. When the culture temperature increased, the molecular weight of its metabolites increased, the synthesis of high alcohol increased too, and their carbon chain lengthened gradually. When incubation time was prolonged, the varying law of the synthesis of its metabolites was alcohols-acid-ester, the metabolites with longer carbon chain produced earlier than the metabolites with shorter carbon chain. When the carbon source were starch, sucrose and bran, n-butyl alcohol and isoamyl alcohol were the common metabolites. When the carbon source was sucrose, most of the metabolites were alcohol and acid with shorter carbon chain. When the carbon source was starch, diethyl succinate was produced. When the carbon source was bran, the metabolites were less.