雪茄烟叶的风味物质对雪茄风格特征起到决定性的作用。从雪茄烟叶发酵研究进展、雪茄烟叶风味物质研究和不同发酵条件下风味物质研究三个方面开展了综述，发酵是改善雪茄烟叶品质的重要过程，能够影响雪茄烟叶的风味物质种类、含量和组成比例，从而决定雪茄烟叶质量和雪茄烟品质，本研究对雪茄烟叶的发酵机理和方法进行了分析，风味物质是决定雪茄产品风格特征的关键因素，总结了风味感知机理、分析方法、风味物质分类的研究进展，对雪茄烟叶在不同温湿度、发酵时间和发酵介质条件下的风味物质开展了研究。同时对未来雪茄风味研究进行展望，为相关的研究提供理论支撑。

Variations in industrial fermentation techniques have a significant impact on the fermentation of cigar tobacco leaves (CTLs), consequently influencing the aromatic attributes of the resulting cigars. The entire fermentation process of CTLs can be categorized into three distinct phases: phase 1 (CTLs prior to moisture regain), phase 2 (CTLs post-moisture regain and pile fermentation), and phase 3 (CTLs after fermentation and drying). These phases were determined based on the dynamic changes in microbial community diversity. During phase 2, there was a rapid increase in moisture and total acid content, which facilitated the proliferation of Aerococcus, a bacterial genus capable of utilizing reducing sugars, malic acid, and citric acid present in tobacco leaves. In contrast, fungal microorganisms exhibited a relatively stable response to changes in moisture and total acid, with Aspergillus, Alternaria, and Cladosporium being the dominant fungal groups throughout the fermentation stages. Bacterial genera were found to be more closely associated with variations in volatile compounds during fermentation compared to fungal microorganisms. This association ultimately resulted in higher levels of aroma components in CTLs, thereby improving the overall quality of the cigars. These findings reinforce the significance of industrial fermentation in shaping CTL quality and provide valuable insights for future efforts in the artificial regulation of secondary fermentation in CTLs. KEY POINTS: • Industrial fermentation processes impact CTLs microbial communities. • Moisture and total acid content influence microbial community succession in fermentation. • Bacterial microorganisms strongly influence CTLs' aldehyde and ketone flavors over fungi.© 2024. The Author(s).

The pool of free, genetically encoded AA in plasma plays an essential role not only as substrate for every protein synthesized in the body but also as signaling molecules that regulate a wide range of physiological processes. Here we present a method for the analysis of 19 of the 20 encoded AA (except Cys) in dairy cow plasma. Isolated plasma or standards for the 19 AA were gravimetrically mixed with an internal standard mix consisting of C isotopes of each AA. Plasma proteins were precipitated on acetonitrile and supernatants transferred to glass vials. For precolumn derivatization, plasma supernatants were buffered with sodium borate (pH 9.5-10), and AA were derivatized with 9-fluorenylmethoxycarbonyl (Fmoc) chloride. Analytes were isolated by solid-phase extraction using a strong-anionic ion exchange column and dry eluates were reconstituted in mobile phase consisting of 70% water solution of ammonium formate and 30% acetonitrile. Amino acid derivatives were separated by reverse-phase liquid chromatography over 17.5 min with a C18 column in which acetonitrile increased to 80% over the first 11 min of the method, before returning to initial levels. Electrospray ionization on negative mode was used for most AA, except Arg and Pro, for which positive mode yielded superior results. Single or double (only Lys) derivatives were measured by single quadrupole-mass spectrometry. We hypothesized that precolumn Fmoc derivatization would yield optimal resolution for quantitative analysis of the 19 targeted AA and their respective C internal standards, with limits of quantitation beyond physiological ranges. All 19 AA were detected with minimal background noise. An 11-point standard curve was developed for each AA. Limits of quantitation were beyond concentrations observed in plasma samples of lactating dairy cows, except for Gly where upper curve points had to be removed to maintain linearity, limiting quantitation to the upper range of physiological concentration. After removing the 4 highest concentrations from the Gly standard curve, coefficients of determination were greater than 0.999 for all of the AA. Recovery of spiked AA from plasma samples ranged from 89.9% for Phe to 100.3% for Trp. Instrument repeatability averaged 0.91 and ranged from 0.33 for Val to 2.29 for Arg. Meanwhile, sample preparation method repeatability averaged 2.02 and ranged from 1.14 for Tyr to 3.34 for Arg. Although robust methods have been developed, they depend on either availability of sophisticated instruments, mostly limited to core facilities (i.e., tandem MS methods), long and expensive chromatography without specific internal standards for each AA (i.e., HPLC-ultraviolet and HPLC-fluorescence detector), or unstable derivatization (GC-MS). Here we describe a method with high throughput, stable derivatization, high precision and recovery, and potentially more affordable than most existing methods. This method could help dairy nutritionists to consider plasma AA information for diet formulation strategies, potentially reducing feeding costs and N emissions.© 2024.