Razvoj proteolitičkih komponenata okusa tradicionalnoga kineskog predjela dobivenog fermentacijom soje (douchiba)

Douchiba, a traditional Chinese soy-fermented appetizer, has been abundantly produced and widely consumed in Guizhou province of Southwest China. In this study, analysis of low-molecular mass peptide fractions, hydrophobic bitter peptide fractions, and free amino acid (FAA) profiles was conducted to understand the changes in tasty components of douchiba during five consecutive stages of its manufacture: steamed soybean (SS), 5-day incubated douchi qu (DQ), 6-month fermented douchi (DC), semi-finished douchiba (sm-DCB), and 6-month ripened douchiba as a finished product (DCB). Results indicated that the ratio of potentially taste-active oligopeptides (500–1000 Da) accounted for 13.98 and 2.54 % of low-molecular mass peptide fractions and hydrophobic bitter peptide fractions at DCB stage, respectively. The evolution patterns of total free amino acids (TFAA) increased significantly (p<0.05) from SS to DCB by about 11 times and amounted to 20.14 % of crude protein. At the end of the ripening period (6 months), Arg, Glu, Phe, Leu, and Lys were the most abundant FAA, adding up to 64.37 % of TFAA. The most abundant tasty FAA class was bitter FAA, about 8-and 3-fold higher than the content of sweet and monosodium glutamate (MSG)-like FAA, respectively. The final values of all bitter and MSG-like FAA at DCB stage were significantly higher than their respective thresholds. However, the final characteristic taste of douchiba was predominated by saltiness, followed by moderate umami taste and slight bitterness, possibly as a result of the balance and interaction among different tasty components.Douchiba, tradicionalno kinesko predjelo dobiveno fermentacijom soje, u velikim se količinama proizvodi i koristi u provinciji Guizhou u jugozapadnom dijelu Kine. U ovom radu istražene su peptidne frakcije male molekularne mase, hidrofobne frakcije peptida koje pridonose gorčini proizvoda i profili slobodnih aminokiselina (free amino acid – FAA) za bolje razumijevanje uzroka promjene okusa tijekom 5 uzastopnih faza proizvodnje: parenog zrna soje (steamed soybean – SS), proizvoda dobivenog nakon 5 dana inkubacije (douchi qu – DQ), proizvoda dobivenog fermentacijom tijekom 6 mjeseci (DC), poluproizvedene douchibe (sm-DCB) i gotovog proizvoda dobivenog nakon 6 mjeseci zrenja (DCB). Rezultati pokazuju da je omjer potencijalno aktivnih oligopeptida (500-1000 Da) i frakcije peptida male molekularne mase te hidrofobnih peptida koji daju gorčinu proizvodu DCB iznosio 13,98 i 2,54 %. Razvojni uzorak ukupnih slobodnih aminokiselina (total free amino acids – TFAA) značajno se povećao (p<0,05) proizvodnjom DCB iz SS (otprilike 11 puta) i iznosio je 20,14 % sirovih proteina. Pri kraju zrenja (nakon 6 mjeseci) bilo je najviše slobodnih aminokiselina Arg, Glu, Phe, Leu i Lys, i to od 64,37 % TFAA. Od komponenata okusa najviše je bilo FAA koje daju gorčinu proizvodu, 8 puta više nego slatkastih te 3 puta više od FAA sličnih mononatrijevu glutamatu (monosodium glutamate – MSG). Konačne vrijednosti svih gorkastih FAA i onih sličnima MSG u proizvodu DCB bile su kudikamo veće od njihovih minimuma. Međutim, gotovi proizvod imao je karakterističan slankast, zatim blago pikantan te naposljetku gorkast okus, vjerojatno zbog interakcije različitih komponenata okusa

Characteristics of traditional Chinese acidic rice soup (rice-acid) prepared with different fermentation methods

peer-reviewedRice-acid, a Chinese traditional acidic rice soup (rice-acid), is widely accepted by consumers due to its unique flavor and anti-oxidation, anti-aging and immunity enhancement functions. This study confirmed that L-lactic acid and malic acid were the main organic acids in rice-acid. Low-temperature rice-acid samples produced by enterprises had the highest signal intensity of sour taste. The total content of free amino acids in different fermented rice-acid samples were in the range of 0.003–0.468 mg/g. 42 key volatile flavor compounds were identified in rice-acid. 8 volatile compounds with a higher contribution to the aroma of rice-acid were respectively acetic acid, 1-octen-3-ol, 2-heptanol, ethyl acetate, propyl propionate, hexanal, nonanal, and 2,3-butanedione. The interaction between lactic acid bacteria (3.00 × 103–7.02 × 106 CFU/mL) and yeasts (5.04 × 104–2.25 × 108 CFU/mL) affected the formation of taste and aroma components in rice-acid. The physicochemical characteristics including titratable acidity, pH, reducing sugars, amino acid nitrogen, gamma-aminobutyric acid showed significant differences between low-temperature fermentation samples and high-temperature fermentation samples. In addition, relationships linking all data through Pearson coefficient correlation were also reported. In summary, the study can be used to improve the quality of rice-acid products

Formation mechanisms of ethyl acetate and organic acids in Kluyveromyces marxianus L1-1 in Chinese acid rice soup

peer-reviewedThis study aims to explore the formation mechanism of ethyl acetate and organic acids in acid rice soup (rice-acid soup) inoculated with Kluyveromyces marxianus L1-1 through the complementary analysis of transcriptome and proteome. The quantity of K. marxianus L1-1 varied significantly in the fermentation process of rice-acid soup and the first and third days were the two key turning points in the growth phase of K. marxianus L1-1. Importantly, the concentrations of ethyl acetate, ethanol, acetic acid, and L-lactic acid increased from day 1 to day 3. At least 4231 genes and 2937 proteins were identified and 610 differentially expressed proteins were annotated to 30 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways based on the analysis results of transcriptome and proteome. The key genes and proteins including up-regulated alcohol dehydrogenase family, alcohol O-acetyltransferase, acetyl-CoA C-acetyltransferase, acyl-coenzyme A thioester hydrolase, and down-regulated aldehyde dehydrogenase family were involved in glycolysis/gluconeogenesis pathways, starch and sucrose metabolism pathways, amino sugar and nucleotide sugar metabolism pathways, tricarboxylic acid (TCA) cycle, and pyruvate metabolism pathways, thus promoting the formation of ethyl acetate, organic acids, alcohols, and other esters. Our results revealed the formation mechanisms of ethyl acetate and organic acids in rice-acid soup inoculated with K. marxianus L1-1

Fortified Fermented Rice-Acid Can Regulate the Gut Microbiota in Mice and Improve the Antioxidant Capacity

peer-reviewedThe study aimed to explore the effects of fortified fermented rice-acid on the antioxidant capacity of mouse serum and the gut microbiota. Hair characteristics, body mass index, intestinal villus height, intestinal crypt depth, serum antioxidant capacity, and gut microbiota of mice were first measured and the correlation between the antioxidant capacity of mouse serum and the gut microbiota was then explored. The mice in the lactic acid bacteria group (L-group), the mixed bacteria group (LY-group), and the rice soup group (R-group) kept their weight well and had better digestion. The mice in the L-group had the better hair quality (dense), but the hair quality in the R-group and the yeast group (Y-group) was relatively poor (sparse). In addition, the inoculation of Lactobacillus paracasei H4-11 (L. paracasei H4-11) and Kluyveromyces marxianus L1-1 (K. marxianus L1-1) increased the villus height/crypt depth of the mice (3.043 ± 0.406) compared to the noninoculation group (R-group) (2.258 ± 0.248). The inoculation of L. paracasei H4-11 and K. marxianus L1-1 in fermented rice-acid enhanced the blood antioxidant capacity of mouse serum (glutathione 29.503 ± 6.604 umol/L, malonaldehyde 0.687 ± 0.125 mmol/L, catalase 15.644 ± 4.618 U/mL, superoxide dismutase 2.292 ± 0.201 U/mL). In the gut microbiota of L-group and LY-group, beneficial microorganisms (Lactobacillus and Blautia) increased, but harmful microorganisms (Candidatus Arthromitus and Erysipelotrichales) decreased. L. paracasei H4-11 and K. marxianus L1-1 might have a certain synergistic effect on the improvement in antibacterial function since they reduced harmful microorganisms in the gut microbiota of mice. The study provides the basis for the development of fortified fermented rice-acid products for regulating the gut microbiota and improving the antioxidant capacity

A Survey on Large Language Models for Recommendation

Large Language Models (LLMs) have emerged as powerful tools in the field of Natural Language Processing (NLP) and have recently gained significant attention in the domain of Recommendation Systems (RS). These models, trained on massive amounts of data using self-supervised learning, have demonstrated remarkable success in learning universal representations and have the potential to enhance various aspects of recommendation systems by some effective transfer techniques such as fine-tuning and prompt tuning, and so on. The crucial aspect of harnessing the power of language models in enhancing recommendation quality is the utilization of their high-quality representations of textual features and their extensive coverage of external knowledge to establish correlations between items and users. To provide a comprehensive understanding of the existing LLM-based recommendation systems, this survey presents a taxonomy that categorizes these models into two major paradigms, respectively Discriminative LLM for Recommendation (DLLM4Rec) and Generative LLM for Recommendation (GLLM4Rec), with the latter being systematically sorted out for the first time. Furthermore, we systematically review and analyze existing LLM-based recommendation systems within each paradigm, providing insights into their methodologies, techniques, and performance. Additionally, we identify key challenges and several valuable findings to provide researchers and practitioners with inspiration. We have also created a GitHub repository to index relevant papers on LLMs for recommendation, https://github.com/WLiK/LLM4Rec.Comment: 10 pages, 3 figure

Evolution of Proteolytic Tasty Components During Preparation of Douchiba, a Traditional Chinese Soy-Fermented Appetizer

Douchiba, a traditional Chinese soy-fermented appetizer, has been abundantly produced and widely consumed in Guizhou province of Southwest China. In this study, analysis of low-molecular mass peptide fractions, hydrophobic bitter peptide fractions, and free amino acid (FAA) profiles was conducted to understand the changes in tasty components of douchiba during five consecutive stages of its manufacture: steamed soybean (SS), 5-day incubated douchi qu (DQ), 6-month fermented douchi (DC), semi-finished douchiba (sm-DCB), and 6-month ripened douchiba as a finished product (DCB). Results indicated that the ratio of potentially taste-active oligopeptides (500–1000 Da) accounted for 13.98 and 2.54 % of low-molecular mass peptide fractions and hydrophobic bitter peptide fractions at DCB stage, respectively. The evolution patterns of total free amino acids (TFAA) increased significantly (p<0.05) from SS to DCB by about 11 times and amounted to 20.14 % of crude protein. At the end of the ripening period (6 months), Arg, Glu, Phe, Leu, and Lys were the most abundant FAA, adding up to 64.37 % of TFAA. The most abundant tasty FAA class was bitter FAA, about 8-and 3-fold higher than the content of sweet and monosodium glutamate (MSG)-like FAA, respectively. The final values of all bitter and MSG-like FAA at DCB stage were significantly higher than their respective thresholds. However, the final characteristic taste of douchiba was predominated by saltiness, followed by moderate umami taste and slight bitterness, possibly as a result of the balance and interaction among different tasty components

Physicochemical, taste, and functional changes during the enhanced fermentation of low-salt Sufu paste, a Chinese fermented soybean food

In this study, the physicochemical, taste, and functional changes in low-salt Sufu paste were investigated during fermentation as enhanced by a mixed starter (Pichia fermentans, Kodamaea ohmeri, and Lactococcus lactis subsp. lactis) and α-ketoglutarate. The total free amino acids increased from 0.02 mg/g dry matter to 12.63 mg/g dry matter, and monosodium glutamate-like was the major free amino acid group (3.89 mg/g dry matter), followed by bitter according to the taste characteristics. Functional components such as γ-aminobutyric acid, riboflavin (VB2), and puerarin significantly increased to 30.96, 4.97, and 12.03 mg/g dry matter, respectively, at the end of post-ripening (p < 0.05). Protease, lipase, peptidase, α-amylase, aromatic amino acid aminotransferase, and branched-chain amino acid aminotransferase activities increased and were significantly correlated (p < 0.05) with most physicochemical and functional components, indicating that enzymes may play an important role in the fermentation process of Sufu paste. Additionally, the color of the Sufu paste changed from pale yellow to yellowish brown, whereas the Sufu paste fermented without the mixed starter and α-ketoglutarate changed to gray, the unique color of gray Sufu. The preliminary results indicated that the mixed starter and α-ketoglutarate are beneficial for taste quality and color and that fermentation may be an effective method to enhance the functional components in Sufu paste. This information would be useful for future improvements in the manufacturing process and quality of Sufu paste

Increases of Lipophilic Antioxidants and Anticancer Activity of Coix Seed Fermented by Monascus purpureus

peer-reviewedLipophilic tocols, γ-oryzanol, and coixenolide in coix seed before and after fermentation by Monascus purpureus were determined. Antioxidant and anticancer activities of raw and fermented coix seed were evaluated using free-radical-scavenging assays and polyunsaturated fatty acid oxidation model, and human laryngeal carcinoma cell HEp2, respectively. Compared to the raw seed, the tocols, γ-oryzanol, and coixenolide contents increased approximately 4, 25, and 2 times, respectively, in the fermented coix seed. Especially, γ-tocotrienol and γ-oryzanol reached 72.5 and 655.0 μg/g in the fermented coix seed. The lipophilic extract from fermented coix seed exhibited higher antioxidant activity in scavenging free radicals and inhibiting lipid oxidation. The inhibitory concentrations for 50% cell survival (IC50) of lipophilic extract from fermented coix seed in inhibiting HEp2 cells decreased by 42%. This study showed that coix seed fermented by M. purpureus increased free and readily bioavailable lipophilic antioxidants and anticancer activity. Therefore, fermentation could enhance the efficacy of the health promoting function of coix seeds.the Agriculture Committee of Guizhou Provinc

Effect of Coix Seed Extracts on Growth and Metabolism of Limosilactobacillus reuteri

Coix seed (Coix lachryma-jobi L.) is an important nourishing food and traditional Chinese medicine. The role of their bioactive constituents in physiology and pharmacology has received considerable scientific attention. However, very little is known about the role of coix seed bioactive components in the growth of Limosilactobacillus reuteri (L. reuteri). This study aimed to evaluate the effects of coix seed extract (CSE) on the growth, acidifying activity, and metabolism of L. reuteri. The results showed that CSE can increase the growth and acidifying activity of L. reuteri compared with the control group. During the stationary phase, the viable bacteria in the medium supplemented with coix seed oil (CSO, 13.72 Log10 CFU/mL), coix polysaccharide (CPO, 12.24 Log10 CFU/mL), and coix protein (CPR, 11.91 Log10 CFU/mL) were significantly higher (p &lt; 0.05) than the control group (MRS, 9.16 Log10 CFU/mL). CSE also enhanced the biosynthesis of lactic acid and acetic acid of L. reuteri. Untargeted metabolomics results indicated that the carbohydrate metabolism, amino acid metabolism, and nucleotide metabolism activities of L. reuteri were increased after adding CSE. Furthermore, CSE increased the accumulation of bioactive metabolites, such as phenyl lactic acid, vitamins, and biotin. Overall, CSE may have prebiotic potential and can be used to culture L. reuteri with high viable bacteria