Core Viewpoint - The study investigates the impact of removing endogenous proteins from distiller's grains on the physicochemical structure of starch molecules and brewing characteristics, highlighting the potential for improved starch utilization and reduced resource waste in liquor production [1]. Group 1: Research Methodology - Distiller's grains were sourced from Yibin Nanxi Distillery, and various enzymes and reagents were used for protein extraction and analysis [2][3]. - The study involved multiple methods for protein extraction, including the use of distilled water, NaCl, ethanol, and NaOH to obtain different soluble protein fractions [4][5]. Group 2: Protein Composition Analysis - The relative content of different soluble proteins in distiller's grains was analyzed, revealing that alkaline soluble proteins had the highest content at 37.47%, followed by alcohol soluble proteins at 15.97% [24][25]. - Raman spectroscopy indicated that the secondary structure of proteins was predominantly β-folded, with water-soluble proteins showing the highest β-folded content at 65.11% [24][27]. Group 3: Physicochemical Properties - The solubility and swelling degree of starch increased with temperature, while the removal of proteins led to significant changes in these properties, with the highest swelling degree observed at 85°C for the sample without alcohol-soluble proteins [27][29]. - Water retention and transparency were also affected by protein removal, with the highest water retention rate of 126.64% for the sample without water-soluble proteins [30][31]. Group 4: Freezing and Thawing Stability - The study found that the freezing and thawing stability of starch improved with the removal of different soluble proteins, with alcohol-soluble proteins having the most significant impact [32]. - The results indicated that the removal of proteins enhanced the starch's ability to withstand freezing and thawing cycles, which is crucial for its application in brewing [32]. Group 5: Brewing Characteristics - The study assessed the liquefaction, saccharification, and fermentation performance of starch, noting that the removal of alcohol-soluble proteins significantly improved the liquefaction and saccharification rates [20][22]. - The fermentation performance was evaluated by measuring weight loss during fermentation, indicating that the removal of certain proteins facilitated better fermentation outcomes [22].

Core Viewpoint - The study investigates the impact of endogenous proteins on the physicochemical properties and brewing characteristics of starch in distiller's grains, revealing that the removal of these proteins enhances starch utilization and reduces resource waste [2][46]. Group 1: Materials and Methods - Distiller's grains were sourced from Yibin Nanxi Distillery, Sichuan, China, and various reagents were used for protein extraction and analysis [3][5]. - The study involved multiple extraction methods to isolate different soluble proteins, including water-soluble, salt-soluble, alcohol-soluble, and alkaline-soluble proteins [5][7]. Group 2: Results and Discussion - The relative content of different soluble proteins was analyzed, with alkaline proteins being the most abundant at 37.47%, followed by alcohol-soluble proteins at 15.97% [24][26]. - The removal of endogenous proteins significantly improved the swelling degree, freeze-thaw stability, and in vitro digestibility of starch, indicating enhanced brewing performance [28][32]. - Scanning Electron Microscopy (SEM) showed that the removal of proteins increased the porosity of starch granules, facilitating enzyme access and improving digestibility [35]. - Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Diffraction (XRD) analyses indicated that the removal of proteins altered the crystalline structure of starch, enhancing its digestibility [38][40]. Group 3: Brewing Characteristics - The study found that the removal of alcohol-soluble and alkaline proteins significantly improved the liquefaction and saccharification performance of starch, leading to higher fermentation efficiency [41][44]. - The total weight loss during fermentation was highest in samples with removed proteins, indicating better utilization of starch by yeast [44]. Group 4: Conclusion - The findings suggest that optimizing the removal of endogenous proteins from distiller's grains can enhance starch utilization, reduce waste, and contribute to sustainable practices in the liquor industry [46].