The effect of yeast growth stages on the absorption of polyphenols

Colloidal stability of beer is one of the most critical challenges facing the brewing industry. In brewing, stabilization agents are widely used to remove colloids such as proteins and polyphenols. However, the removal efficiency of polyphenols depends on the yeast, which adsorbs these compounds on its surface. The adsorption of polyphenols on the yeast surface is associated with the zeta potential of the cell wall, which correlates with the mannan content in them. The purpose of the study was to investigate the role of yeast strains in adsorption of polyphenols (increasing colloidal stability of beer) and the correlation of this property with the mannan content in the cell wall during the fermentation. Two S. cerevisiae strains were used in this study, and the specific growth rate of yeast, the specific rate of change in the polyphenol content and the mannan content were determined. The results of this study showed that the highest mannan content in yeast was after 9 hours (the end of exponential growth phase). Its content was 10.97% by weight of dry matter in the yeast S. cerevisiae Californian Lager (M54), and 13.69% in the yeast S. cerevisiae Belgian Wit (M21). The desorption of polyphenols was observed during the period from 9 to 24 hours of fermentation, where an increase in the content of polyphenols in the medium was observed. Based on these results, it is necessary to remove the yeast at the end of the exponential growth phase to increase the colloidal stability of the beer

PENGENALAN BUDAYA SUMATERA UTARA (ULOS BATAK TOBA) MELALUI PERMAINAN ULAR TANGGA EDUKATIF SEBAGAI BAHAN AJAR BIPA

Penelitian ini bertujuan sebagai bahan ajar BIPA tentang Ulos Budaya Batak Toba Provinsi Sumatera Utara melalui permainan ular tangga edukatif. Jenis penelitian ini menggunakan kualitatif deskriptif. Teknik pengumpulan data yang digunakan dalam penelitian ini adalah studi pustaka yaitu Internet searching dengan mengkaji beberapa artikel pada jurnal. Berdasarkan hasil penelitian dan pembahasan diperoleh simpulan bahwa kain ulos merupakan kerajinan tenun khas Batak Toba Sumatera Utara, kain ulos yang mempunyai ragam jenis, makna dan fungsi yang berbeda dalam setiap pengunaannya. yang dimana didalam nya permainan ular tangga edukatif sebagai media belajar yang digunakan pemelajar BIPA. Ular Tangga Edukatif merupakan permainan yang dikembangkan dari permainan ular tangga biasa menjadi jenis permainan yang memiliki nilai edukasi. Dalam belajar bahasa Indonesia , pemelajar BIPA Sekaligus belajar Budaya masyarakat Batak Toba . Dengan demikian proses belajar mengajar dapat lebih efektif sesuai dengan tujuan pemelajar BIPA dan tujuan pembelajaran

Comparison of the yeast Saccharomyces cerevisiae var. boulardii and top-fermenting brewing yeast strains during the fermentation of model nutrient media and beer wort

Received: June 27th, 2022 ; Accepted: September 18th, 2022 ; Published: October 17th, 2022 ; Correspondence: [email protected], the yeast Saccharomyces cerevisiae var. boulardii have attracted the attention of Food Science researchers due to their unique properties, the main among which are probiotics. Thus, research is conducted on the use of this yeast as a starter culture in the technology of yogurt, fermented vegetables, fruit, vegetable juices, as well as beer. This paper is aimed at studying Saccharomyces cerevisiae var. boulardii 's fermentation performance compared to top-fermenting brewing yeast strains during fermentation of model nutrient media and beer wort. Fermentation activity of the studied strains was assessed based on the character of fermentation curves, as well as the values of the maximum substrate assimilation rate and apparent degree of fermentation. Moreover, during the study, beer was produced using the yeast Saccharomyces cerevisiae var. boulardii as a starter culture. According to the obtained results, it can be concluded that Saccharomyces cerevisiae var. boulardii have less fermentation activity compared to brewing strains. In turn, beer produced with Saccharomyces cerevisiae var. boulardiisignificantly differed in physicochemical, microbiological, and organoleptic parameters from the control sample obtained using the 047A brewing strain. Thus, it contained less ethanol and secondary metabolites; however, the concentration of living cells was significantly higher, which indicates a relatively high viability of the yeast Saccharomyces cerevisiae var. boulardii. From an organoleptic point of view, final beer has a positive sensory profile. The aroma of the product had a complex character: it included caramel, spicy, fruity and phenolic notes, as well as smoked and wine elements; while honey was the dominant note of the taste

Recycling of yeast multifunctional autolysates and extracts in the food industry

Recycling of industrial waste is one of the most crucial problems for the food industry. The forces of modern researchers are focused on solving this problem and using the biopotential of spent resources. Residual yeast from fermentation industries, in particular brewing, is of particular interest among the variety of food production waste. This is due to the extremely rich chemical composition of the yeast cell, and the possibility of obtaining a wide range of ingredients that exhibit both biological activity and technologically significant properties. Spent brewer's yeast is rich in proteins and carbohydrates, as well as vitamins B and minerals. The protein fraction, which accounts for 45–60% by dry weight (dw), contains all essential amino acids in sufficient quantities, which allows considering this secondary material resource an excellent source of protein with high biological value and a well-balanced AA profile. The carbohydrate fraction, comprising approximately 40% by dw, consists of intracellular carbohydrates (such as simple sugars and glycogen) as well as cell wall polysaccharides (such as β-glucan and α-mannan). Special emphasis is placed on the cell wall components due to their significant multidirectional biological activity and technologically important properties. Thus, β-glucan and α-mannan, along with emulsifying, sorbing and stabilizing properties, exhibit antioxidant and antimicrobial activity, immunomodulatory and prebiotic properties. This review presents an analysis of yeast autolysates and extracts sources as well as the influence of cultivation conditions and production methods on their chemical composition

Three dimensional mapping of Fe dopants in ceria nanocrystals using direct spectroscopic electron tomography

Electron tomography is a powerful technique for the 3D characterization of the morphology of nanostructures. Nevertheless, resolving the chemical composition of complex nanostructures in 3D remains challenging and the number of studies in which electron energy loss spectroscopy (EELS) is combined with tomography is limited. During the last decade, dedicated reconstruction algorithms have been developed for HAADF-STEM tomography using prior knowledge about the investigated sample. Here, we will use the prior knowledge that the experimental spectrum of each reconstructed voxel is a linear combination of a well-known set of references spectra in a so-called direct spectroscopic tomography technique. Based on a simulation experiment, it is shown that this technique provides superior results in comparison to conventional reconstruction methods for spectroscopic data, especially for spectrum images containing a relatively low signal to noise ratio. Next, this technique is used to investigate the spatial distribution of Fe dopants in Fe:Ceria nanoparticles in 3D. It is shown that the presence of the Fe2+ dopants is correlated with a reduction of the Ce atoms from Ce4+ towards Ce3+. In addition, it is demonstrated that most of the Fe dopants are located near the voids inside the nanoparticle

Sol-gel coatings for photolithography on nanoporous anodic alumina and aluminum

The results of the patterned microstructures fabrication through electrochemical anodizing, sol-gel synthesis, photolithography and chemical etching are presented. The continuous xerogel films were used as a protective mask. They are good alternative to metal in photolithography. Perspectives of application of these structures in planar optoelectronics are discussed