Characteristics and Discrimination of the Commercial Chinese Four Famous Vinegars Based on Flavor Compositions.

Shanxi aged vinegar (SAV), Zhenjiang aromatic vinegar (ZAV), Sichuan bran vinegar (SBV), and Fujian monascus vinegar (FMV) are the representative Chinese traditional vinegars. However, the basic differential compositions between the four vinegars are unknown. In this study, compositions of commercial vinegar were investigated to evaluate the influence of diverse technologies on their distinct flavor. Unlike amino acids and organic acids which were mostly shared, only five volatiles were detected in all vinegars, whereas a dozen volatiles were common to each type of vinegar. The four vinegars could only be classified well with all compositions, and difference analysis suggested the most significant difference between FMV and SBV. However, SAV, ZAV, and SBV possessed similar volatile characteristics due to their common heating treatments. Further, the correlation of identification markers with vinegars stressed the contributions of the smoking process, raw materials, and Monascus inoculum to SAV, SBV, and FMV clustering, respectively. Therefore, regardless of the technology modification, this basic process supported the uniqueness of the vinegars. This study contributes to improving the standards of defining the characteristics of types of vinegar.

Effect of changing the melanoidins by decoction on the release of volatiles in Zhenjiang aromatic vinegar.

Melanoidins, making general contribution to the food characteristics, are extensively generated in the production of Chinese traditional vinegar; however, their effect on flavor modification remains unknown. This study investigated the changes in the melanoidins of Zhenjiang aromatic vinegar (ZAV) during decoction, and the interactions of crude melanoidins (CM) and pure melanoidins (PM) from decocted and undecocted ZAV with mixed aroma compounds were compared. With the exception of CN, OH and CH, chemical bonds and groups varied among the four types of melanoidins. However, CM and PM, obtained from decocted or undecocted vinegar, displayed generally similar structures, which resulted in their consistent retention of volatiles owning to the overall structure characteristics. Compared to aqueous solution, CM and PM from undecocted vinegar exhibited release, non-influence, or adsorption of flavors. However, melanoidins from decocted vinegar appeared the adsorption for all flavors but 2,3,5,6-Tetramethylpyrazine with weakened release. Free low molecular weight (LMw) compounds would affect the volatiles retention. Total solids (TS) from undecocted vinegar adsorbed volatiles except diethyl succinate; however, TS from decocted vinegar released all flavors significantly. Therefore, the decocted melanoidins were beneficial for the persistence of aroma. This study provided a base for elucidating the formation of melanoidins in decoction procedure and their roles in flavor modification.

Effects of human cerebellar thalamus disruption on adaptive control of reaching.

Lesion or degeneration of the cerebellum can profoundly impair adaptive control of reaching in humans. Computational models have proposed that internal models that help control movements form in the cerebellum and influence planned motor output through the cerebello-thalamo-cortical pathway. However, lesion studies of the cerebellar thalamus have not consistently found impairment in reaching or adaptation of reaching. To elucidate the role of the cerebellar thalamus in humans, we studied a group of essential tremor (ET) patients with deep brain stimulation (DBS) electrodes placed in the cerebellar thalamus. The stimulation can be turned on or off remotely and is thought to reduce tremor by blocking the spread of the pathological output from the cerebellum. We studied the effect of thalamic DBS on the ability to adapt arm movements to novel force fields. Although thalamic DBS resulted in a dramatic and significant reduction of tremor in ET, it also impaired motor adaptation: the larger the stimulation voltage, the greater the reduction in rates of adaptation. We next examined ET patients that had undergone unilateral thalamotomy in the cerebellar thalamus and found that adaptation with the contralateral arm was impaired compared with the ipsilateral arm. Therefore, although both lesion and electrical stimulation of the cerebellar thalamus are highly effective in reducing tremor, they significantly impair the ability of the brain to form internal models of action. Adaptive control of reaching appears to depend on the integrity of the cerebello-thalamo-cortical pathway.

Effects of deep brain stimulation on adaptive control of reaching.

Lesion or degeneration of the cerebellum can profoundly impair adaptive control of reaching in humans. Computational models have proposed that internal models for motor action form in the cerebellum and influence planned motor output through the cerebello-thalamo-cortical pathway. However, lesions in the cerebellar thalamus have not been consistently shown to result in motor adaptation impairment. To elucidate the role of the cerebellar thalamus in humans, we studied a group of essential tremor (ET) patients with deep brain stimulation (DBS) electrodes placed in the cerebellar thalamus. The stimulation can be turned on or off remotely, and is thought to reduce tremor by blocking the spread of the pathological output from the cerebellum. We found that while thalamic DBS resulted in a dramatic reduction in ET, it also led to impaired motor adaptation in the patients. Thus, human adaptive reaching motor control depends on the integrity of the thalamic nucleus that relays cerebellar output to the cerebral cortex.