Glucoamylase

Proso millet (Panicum miliaceum L.), cornmeal, cake flour, and white sugar were purchased from Fugu County Tianmo Agricultural Products Co., Ltd. (Yulin, China). α-amylase (4000 u/g), papain (800,000 u/g), glucoamylase (100,000 u/g), pepsin (800,000 u/g), trypsin (400 U/L), glycolytic enzyme (10,000 U/L), and gallic acid were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) were purchased from Shanghai Taitan Technology Co., Ltd. (Shanghai, China). Other reagents were of analytical grade.

Broken rice was supported by Jinhe Group Co., Ltd. (Herbin, China). Alkaline protease from Bacillus licheniformis, Neutral proteinase, Trypsin, α-amylase, and Glucoamylase were purchased from Yuanye Bio-Technology Co., Ltd (Shanghai, China). Pepsin and ChymoTrypsin were obtained from SUMMUS biological technology co., Ltd. (Harbin, China). DPPH, 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and ferrozine were donated by Sigma Chemical Co. (St. Louis, MO, USA). The Caco-2 cells, derived from human colon adenocarcinoma, were purchased from the American Type Culture Collection (ATCC). Dulbecco′s modified Eagle medium (DMEM, high glucose), fetal bovine serum (FBS), penicillin-streptomycin, and 2′, 7′-dichlorofluorescin diacetate (DCFH-DA) were obtained from Solarbio Science & Technology Co., Ltd. (Beijing, China). A Cell Counting Kit-8 (CCK-8) was obtained from Beyotime Biotechnology (Shanghai, China). All the other chemicals used in this study were analytical grade.

Auricularia cornea var. Li. (AU) was supplied by Anhui Qin’er Fungi Co., Ltd. (Suzhou, China). The preparation for the material (dried AU) involved drying the fresh AU with an electric thermostatic blast drying oven (DHG-9053A, Shanghai Shenxian thermostatic equipment factory), where the drying parameters were as follows (temperature: 55 °C, time: 6 h). Subsequently, the material underwent high-speed crushing, and the resulting powder was sifted through 120 mesh sieves before being stored at room temperature for later use (Figure 1). Sweet potato starch (83% carbohydrate) was obtained from Sichuan Youjia Food Co., Ltd. (Chengdu, China), while mung bean starch (86.4% carbohydrate) was acquired from Shandong Jincheng Co., Ltd. (Zhaoyuan, China). The sodium carboxymethyl cellulose (food-grade) originated from Zhejiang Yinuo Biotechnology Co., Ltd. (Lanxi, China), and the sodium alginate (food-grade) was obtained from Henan Qiaoshou Food Additives Co., Ltd. (Zhengzhou, China). Salt (food-grade) was supplied by China Salt Dongxing Salt Co., Ltd. (Chuzhou, China). α-amylase (CAS: 9001-19-8, 100 U/mg) and gluco-amylase (CAS: 9032-08-0, 100 U/mg) were purchased from Yuanye Biotechnology Co., Ltd. (Shanghai, China). All other reagents were analytical grade.

Initial fermentation conditions were as follows: the solid medium containing 30 g of dry yellow wine lees (dispensedin 360 mL jar) was inoculated with yeast 1 × 10⁸ CFU/g, with a water-to-material ratio of 1:1, and a natural pH value. All of the jars were incubated at 30 °C for 72 h. Then the samples were used for the assay of the yeast count. Single-factor experiments were carried out in terms of glucoamylase (Yuanye Biotechnology Company, Shanghai, China), the ratio of water to material, inoculum size, temperature, carbon sources and nitrogen sources. After that an orthogonal design in three levels of three factors (glucoamylase, soluble starch and (NH₄)₂SO₄) was used for the experiments in order to obtain an optimum medium.

The purple sweet potato (Jinshu No.17) variety was grown in an experimental field in Fuzhou city (Fujian, China) and harvested in October 2020. α-amylase (50,000 U/g) and glucoamylase (100,000 U/g) were acquired from Yuanye Bio-Technology Co., Ltd. (Shanghai, China), while pullulanase (≥1000 npun/g) was obtained from Shanghai Aladdin Biotechnology (Shanghai, China). All other chemicals and reagents used in this experiment were analytical grades.

Glutinous rice starch (starch content 87.16%, water content 12.28%, amylopectin content 98.23%, crude protein content 0.36%, and fat content 0.04%) and tea (tea kind: Tieguanyin) was purchased from Anxi Sijin Co., Ltd. (Quanzhou, China). Pig pancreas α-amylase (20,000 U/mL) and glucoamylase (100,000 U/g) used for in vitro digestibility were purchased from Shanghai Yuan ye Biotechnology Co., Ltd., Shanghai, China. All of the solvents used for sample preparation and extraction were purchased from Tianjin Kaitong Chemical Reagent Co., Ltd., Tianjin, China. Other reagents were obtained from Tianjin Guangfu Technology Development Co., Ltd., Tianjin, China. All reagents used were of analytical grade.

Porcine pancreatic α‐amylase and glucoamylase (amyloglucosidase from aspergillus niger, CAS number 9032‐08‐0, enzyme activity 100,000 U/g) were purchased from Shanghai Yuanye Biotechnology. 3,5‐Dinitrosalicylic acid, sodium potassium tartrate, and sodium sulfite were purchased from the Damao Chemical Reagent Factory. Crystalline phenol, sodium hydroxide, and anhydrous sodium acetate were purchased from Tianjin Fuchen Chemical Reagent Factory. Glacial acetic acid was purchased from Tianjin Kermel Chemical Reagent, and glucose was purchased from Guangzhou Chemical Reagent Factory. The reagents used were all of analytical grade.
The constant temperature oscillator was purchased from Changzhou Aohua Instrument, the QUINTIX224‐1CN electronic balance was obtained from Sartorius Scientific Instruments, and the UV‐1800 UV–Visible Spectrophotometer was purchased from Shimadzu Corp.