Abstract：
The production of natural flavors by means of microorganisms is of great interest for the food and flavor industry, and by-products of the agro-industry are particularly suitable as substrates. In the present study, Citrus side streams were fermented using monokaryotic strains of the fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbaceous notes. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryon were prepared, and the volatiles were isolated via solvent-assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweetish, anisic- and woodruff-like) with a flavor dilution factor of 218 as a character impact compound. The coconut-like, herbaceous, and sweetish smelling acyloin identified as (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone also contributed to the overall aroma and was described as an aroma-active substance with an odor threshold in air of 0.2 ng L-1 to 2.4 ng L-1 for the first time. Supplementation of the culture medium with isotopically substituted l-tyrosine elucidated this phenolic amino acid as precursor of p-anisaldehyde as well as of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone. Chiral analysis via HPLC revealed an enantiomeric excess of 97% for the isolated product produced by P. sapidus.
摘要：
通过微生物生产天然香料对食品和香料工业非常感兴趣，和农业工业的副产物特别适合作为底物。在本研究中,柑橘侧流是使用真菌白灵菇的单核菌株发酵的。一些文化表现出令人愉快的气味，让人想起伍德拉夫和茴香，以及草本笔记。为了评估整体香气的组成，制备了选定单核体的浸没培养物的液/液提取物，并通过溶剂辅助的风味蒸发分离挥发物。香气提取物稀释分析显示对茴香醛(甜味，anisic和woodruff-like），风味稀释因子为218，作为特征影响化合物。像椰子一样，草本,被鉴定为（2S）-羟基-1-（4-甲氧基苯基）-1-丙酮的甜味酸碱也有助于整体香气，并被描述为一种香气活性物质，其在空气中的气味阈值为0.2ngL-1首次至2.4ngL-1。用同位素取代的1-酪氨酸补充培养基阐明了这种酚类氨基酸作为对茴香醛以及（2S）-羟基-1-（4-甲氧基苯基）-1-丙酮的前体。通过HPLC的手性分析显示,由P.sapidus产生的分离产物的对映体过量为97%。
