《食品工业科技》F5000论文展播：HS-SPME-GC-MS结合HPLC分析5种食用菌鲜品中的风味成分

Objectives:The volatile and non-volatile flavor components are important indicators to evaluate the quality of mushroom. This study explored the differences in volatile and non-volatile components of five common edible fungi including Pleurotus ostreatus, Lentinula edodes, Agaricus bisporus, Flammulina velutipes and Pleurotus eryngii. The study will lay a foundation for further understanding the flavor characteristics and guiding the varieties improvement, directional cultivation and processing of edible fungi.

Methods: Headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to identify and analyze the flavor substances in five fresh edible fungi. Mass spectra data were tandem retrieved using the NIST11.L standard spectral library. The matching degree greater than 80% was identified as the correct material. The relative content of each volatile component was determined by peak area normalization method. The relative odor activity value (ROAV) was used to evaluate the contribution of each volatile component to the total flavor of the sample. The components with ROAV value ≧ 1 are considered as the key flavor compounds in the sample, and the components with the value of 0.1 ≦ ROAV < 1 have important modification effect on the total flavor of sample. The larger of the ROAV value, the greater contribution was considered to the total flavor of sample. The total free amino acid content was determined by ninhydrin colorimetry method. TCA (trichloroacetic acid) -ultrasonic method was used to extract 5' -taste nucleotides from samples and the content of 5 ' -taste nucleotides was determined by high performance liquid chromatography (HPLC).

Results:A total of 35 volatile compounds were identified in 5 fresh edible fungi, including 5 aldehydes, 5 ketones, 9 alcohols, 8 alkanes, 6 heterocyclic and sulfides, 1 ester and 1 nitrogenous compound. Among the obtained compounds, 8 volatile ingredients including benzaldehyde, 3-octanone, 1-octen-3-one, 3-octanol, 2-ethylhexanol, 5-methyl-2-acetylfuran, 2-pentylfuran and methoxybenzoxime were detected in all the species, but the relative contents were different. The unique volatile components in L. edodes include sulfur-containing compounds such as methyl mercaptan (0.37%), carbon disulfide (0.57%), dimethyl disulfide (21.30%) and dimethyl trisulfide (0.38%). The specific volatile components in A. bisporus were octadecane (2.68%), tetracosane (15.70%), octacosane (2.37%) and other alkanes. The specific volatile component in F. velutipes was 6-methyl-5-hepten-2-one (0.30%). The specific volatile components in P. eryngii were 2-octenal (0.20%) and decane (0.09%). No specific volatile components were detected in P. ostreatus, but the key volatile flavor components (ROAV ≥ 1) were 1-octen-3-one, 1-octen-3-ol and 3-octanone. The key volatile flavor components in L. edodes were dimethyl disulfide, dimethyl trisulfide, 1-octen-3-one and methyl mercaptan. In A. bisporus and F. velutipes, the key volatile flavor components were 1-octen-3-one, 3-octanone and 3-octanol. Similarly, 1-octen-3-one and 1-octen-3-ol were the key volatile flavor components in P. eryngii. The total free amino acid content of P. ostreatus (3.65 mg/g), L. edodes (3.49 mg/g) and F. velutipes (3.05 mg/g) were higher than P. eryngii (2.75 mg/g) and A. bisporus (2.72 mg/g). The total flavor nucleotides content in five fresh edible fungi were ranged from 154.40 to 1013.60 μg/g. The content of 5'-CMP in P. ostreatus (646.20 μg/g) and P. eryngii (836.40 μg/g) were significantly higher than that in the other three edible fungi. The content of 5'-IMP in P. ostreatus (50.10 μg/g) was significantly higher than that in L. edodes, A. bisporus and P. eryngii. The content of 5'-UMP in F. velutipes (117.90 μg/g) and P. eryngii (112.70 μg/g) were higher than the other three edible fungi. 5'-GMP was only detected in P. ostreatus, but 5'-AMP and 5'-IMP was not detected in P. eryngii and F. velutipes, respectively. 

Conclusion: HS-SPME-GC-MS and HPLC were used to analyze the volatile flavor components and non-volatile taste components in five common edible fungi. It was found that the contents of flavor components and taste components in different varieties of edible fungi were quite different. The unique volatile components in L. edodes and A. bisporus were sulfur-containing compounds and alkanes, respectively. P. ostreatus showed relatively higher total free amino acid content and had five kinds of 5'-nucleotide, while F. velutipes showed the highest content of 5'-nucleotide.