| Fumaric acid(trans-but-2-enediodic) is one of the criterias for the evaluation of quality of apple juice concentrate, which indicates indirectly of producing technics and managing level. The level of fumaric acid in well-prepared apple juice usually does not exceed 3.0 mg/L. Fumaric acid formed in apple juice did not exceed 1.0 mg/L during excessive heat treatment, the primary source of fumaric acid in apple juice concentrate is the use of apples decayed by certain microorganisms capable of producing fumaric acid. R. stolonifer appeared to be the most responsible microorganism for the formation of fumaric acid in apple juice concentrate.In this paper, based on the AJC production line, we isloted several strains from the AJC raw materials,then further investigated the fermentation kinetics in the basic culture medium and apple juice culture medium,in order to find the mechanism for the formation of fumaric acid in AJC,And so established the fumaric acid control technology frame in AJC processing.Main results as follows:1.Isolates successfully 3 fumaric acid-producing strains from raw material.The conclusion was Rhizopus stolonifer ATCC 14037 by identificated in morphology, microstructure and 18SrDNA.2. The effect of different carbon sources on fumaric acid production by Rhizopus stolonifer was studied using glucose, fructose,sucrose, lactose,solubility starch as substrate. The higher fumaric acid concentration was obtained when glucose and fructose was present in the medium as the sole carbon source. Rhizopus stolonifer can not grow without carbon sources. The effect of different nitrogen sources on fumaric acid production by Rhizopus stolonifer was studied using amino sulfate, peptone, carbamide, sodium nitrate. as substrate. The higher fumaric acid concentration was obtained when amino sulfate and peptone was present in the medium as the sole nitrogen source. Rhizopus stolonifer can grow a little and produce some fumaric acid...
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