Characteristics and Functions of Dominant Yeasts Together with Their Applications during Strong-Flavor Baijiu Brewing.

Yeasts are pivotal brewing microbes that are associated with the flavor and quality of Chinese baijiu, yet research on dominant yeasts in strong-flavor baijiu brewing remains limited. In this study, Saccharomyces cerevisiae, Pichia kudriavzevii, and Kazachstania bulderi were identified as predominated yeasts in strong-flavor baijiu. Each strain showed distinct characteristics in ethanol resistance, thermal tolerance, and lactic acid tolerance, severally. S. cerevisiae FJ1-2 excelled in ethanol and ethyl ester production, P. kudriavzevii FJ1-1 in ethyl acetate, and K. bulderi FJ1-3 in lactic acid generation. Subsequently, the reinforced Fuqu of each yeast were severally prepared for application in baijiu brewing to verify their functions. Results revealed that the relative abundance of fortified yeast in each group rose. Pichia, Kazachstania, and Saccharomyces emerged as the core microbe for each group, respectively, by co-occurrence network analysis, influencing the microbiota to regulate flavor substances. In short, P. kudriavzevii FJ1-1 enhanced ethyl acetate. K. bulderi FJ1-3 improved ethyl caproate production and decreased levels of ethyl acetate and higher alcohols by modulating yeast community between Pichia and Saccharomyces. This is a systematic endeavor to study the functions of yeasts of strong-flavor baijiu, providing a solid basis for improving baijiu quality.

Highly efficient field-free switching of perpendicular yttrium iron garnet with collinear spin current.

Yttrium iron garnet, a material possessing ultralow magnetic damping and extraordinarily long magnon diffusion length, is the most widely studied magnetic insulator in spintronics and magnonics. Field-free electrical control of perpendicular yttrium iron garnet magnetization with considerable efficiency is highly desired for excellent device performance. Here, we demonstrate such an accomplishment with a collinear spin current, whose spin polarization and propagation direction are both perpendicular to the interface. Remarkably, the field-free magnetization switching is achieved not only with a heavy-metal-free material, Permalloy, but also with a higher efficiency as compared with a typical heavy metal, Pt. Combined with the direct and inverse effect measurements, we ascribe the collinear spin current to the anomalous spin Hall effect in Permalloy. Our findings provide a new insight into spin current generation in Permalloy and open an avenue in spintronic devices.

Fingerprints of volatile flavor compounds from southern stinky tofu brine with headspace solid-phase microextraction/gas chromatography-mass spectrometry and chemometric methods.

It is difficult to produce southern stinky tofu, a famous traditional Chinese snack, at industry scale due to the complex composition of its brine. In this study, the fingerprints of organic volatile flavor compounds in the southern stinky tofu brine samples from five manufacturers were studied using headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) with the aid of chemometric methods. The fingerprints were obtained by HS-SPME/GC-MS and analyzed with the time shift alignment method, Shannon entropy, correlation coefficient, and principal component analysis. The results show that the time shifts in the samples can be accurately corrected by the time shift alignment method despite unexpected interferences. The fingerprint information was evaluated by Shannon entropy, while the similarities and differences in the fingerprints were investigated by correlation coefficient. Moreover, the identification of stinky tofu manufacturers can be achieved by principal component analysis. The predominant volatile compounds in southern stinky tofu brines were indole, 3-methylindole, phenol, and 4-methylphenol. Therefore, the established fingerprinting of volatile compounds for the brines by combining HS-SPME/GC-MS with chemometric methods was a simple and reliable method.