title: Microbiological and physicochemical analysis of pumpkin juice fermentation by the basidiomycetous fungus Ganoderma lucidum.
abstract: A new protocol for processing of pumpkin juice was set up which included fermentation by the basidiomycete Ganoderma lucidum at 28 °C for 7 d. The growth curve of G. lucidum in pumpkin juice was successfully (R(2)  = 0.99) fitted by a 4-parameter logistic model and the ideal highest biomass was estimated to be 4.79 g/L. G. lucidum was found to have a significant acidification effect on pumpkin juice. The lowest pH (4.05 ± 0.05) and highest total titratable acidity (14.31 ± 0.16 mL 0.1 M NaOH/100 mL) were found on the 4th day during fermentation. Sugars in pumpkin juice fermented with G. lucidum showed a significant decrease, especially glucose and fructose. On the contrary, the release of exo-polysaccharides and free amino acids greatly enriched the pumpkin juice. The variation of color index and viscosity also mirrored the above behavior. Based on headspace solid phase microextraction and gas chromatography-mass spectrometry, 68 volatile compounds were identified, including 17 esters, 14 alcohols, 13 phenyl compounds, 11 aldehydes, 8 ketones, 3 acids, 1 furan, and 1 benzothiazole. The pumpkin juices fermented for different days were markedly differentiated with principal component analysis and the fermentation process was tentatively divided into 3 periods: the booming (from the 1st to 4th day), steady (from the 5th to 6th day), and decline (the 7th day) period.
authors.affiliation: College of Food Science and Nutritional Engineering, China Agricultural Univ, Beijing 100083, China; National Engineering Research Center for Fruit and Vegetable Processing, Beijing, 100083, China; Key Laboratory of Fruit and Vegetable Processing, Ministry of Agriculture, Beijing, 100083, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Dong
authors.initials: D
authors.lastname: Chen
authors.forename: Chunli
authors.initials: C
authors.lastname: Zhou
authors.forename: Yi
authors.initials: Y
authors.lastname: Song
authors.forename: Yuyu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yuanying
authors.initials: Y
authors.lastname: Ni
authors.forename: Quanhong
authors.initials: Q
authors.lastname: Li
mesh_terms: D000596:Amino Acids / Q000032:analysis; D018533:Biomass; D019149:Bioreactors; D002241:Carbohydrates / Q000032:analysis; D003116:Color; D028464:Cucurbita / Q000737:chemistry* / Q000382:microbiology*; D005285:Fermentation; D005502:Food; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D025282:Mycelium / Q000254:growth & development*; D011134:Polysaccharides / Q000378:metabolism; D020940:Reishi / Q000254:growth & development* / Q000378:metabolism*; D052617:Solid Phase Microextraction; D013997:Time Factors; D014783:Viscosity; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D011134:Polysaccharides; D055549:Volatile Organic Compounds
keywords: Ganoderma lucidum; carbohydrates; free amino acid; growth curve; pumpkin juice; volatile compounds