Time-Course Comparative Metabolome Analysis of Different Barley Varieties during Malting

Deletion of the DEAD-box helicase CshA in Lacticaseibacillus paracasei elicits heightened low-temperature sensitivity and reduced post-acidification capacity

While cold chain logistics remains the primary strategy to mitigate post acidification in fermented dairy products, maintaining reliable refrigeration systems presents substantial challenges, especially in resource-limited settings. Biological approaches targeting strain low-temperature sensitivity modulation for post-acidification control are increasingly recognized as promising alternatives. This study utilized CRISPR/Cas9-mediated knockout of DEAD-box helicase genes in Lacticaseibacillus paracasei, successfully identifying a low-temperature-sensitive strain, ∆AF91_12,710. Under optimal conditions, ∆AF91_12,710 showed comparable growth patterns and pH profiles to the wild-type strain. However, under low-temperature conditions, ∆AF91_12,710 demonstrated significantly impaired growth capacity and distinct pH regulation patterns. Metabolomic analysis of post-acidification revealed 39 unique differential metabolites in ∆AF91_12,710 fermented milk over 21 days, featuring decreased ATP, γ-linolenic acid, and dGMP concentrations, alongside elevated glucose-6-phosphate, cAMP, and D-galactose levels. These metabolic alterations indicate impaired glycolysis, likely resulting from DEAD-box helicase gene deletion-induced RNA instability and reduced metabolic activity in ∆AF91_12,710 under cold stress. The AF91_12,710 deletion significantly enhanced low-temperature sensitivity while reducing post-acidification capability in fermented milk. This research provides valuable insights into post-acidification attenuation in low-temperature-sensitive strains and demonstrates the potential for developing robust starter cultures in dairy applications.

Sensory quality and Metabolomic fingerprinting of Lacticaseibacillus paracasei-derived fermented soymilk beverages: Impact of starter strain and storage

Few previous studies have concurrently evaluated the effects of different fermentation bacterial strains and storage durations on the characteristics of fermented soymilk beverages (FSBs). This study used Lacticaseibacillus paracasei to conduct systematic assessments and demonstrated that soy protein is the optimal ingredient for sensory evaluation. Both investigated strains (PC-01 and PC646) significantly enhanced the nutritional and flavor profiles of FSBs, introducing a range of bioactive metabolites absent in non-fermented soymilk. Throughout the storage period, a decline in pH and viable bacterial counts was observed, along with an increase in titratable acidity and stability. Moreover, the metabolomic structure and metabolite abundance varied considerably between the FSBs produced by the two strains, with the non-volatile components showing greater variation, whereas the storage duration predominantly influenced the volatile metabolite components. These insights highlight the critical roles of strain selection and storage duration in shaping the nutritional and sensory qualities of FSBs.

Integrative LC-MS and GC-MS metabolic profiling unveils dynamic changes during barley malting

Malting involves complex biochemical transformations affecting sensory and quality attributes. Despite extensive research on storage carbohydrates and proteins in malting, the lack of a detailed metabolic understanding of this process limits our ability to assess and enhance malt quality. This study employed untargeted GC-MS and LC-MS metabolite profiling across six malting timepoints to identify 4980 known metabolites, 82 % of which exhibited significant changes during the malting process. Here we identified stage-dependent metabolic shifts and dynamic chemical classes and pathways between each studied stage. These results can guide the fine-tuning of malting conditions to improve malt quality for beer production and other malt-based applications. Additionally, metabolites with antimicrobial properties were identified, underscoring the interplay between barley and microbial metabolic processes during malting. Further research into these microbial metabolites and cognate microbes may lead to novel malting assessment traits for high-quality and safe malted barley.

Gas chromatography-mass spectrometry analysis of metabolites in finger millet and Bambara groundnut as affected by traditional and novel food processing

Metabolite profiling is an analytical technique used to assess metabolites in complex biological samples. This technique allows for the identification of both targeted and untargeted metabolites. In this study, the effect of traditional (fermentation and malting) and novel processing (ultrasonication) on the metabolites of finger millet (FM) and Bambara groundnut (BGN) flour was investigated using gas chromatography-mass spectrometry. Various metabolite classes, including amino acids, alcohol, aldehyde, organic acid, ester, fatty acids, glycoside, and sugar, were identified in FM and BGN flours. The adopted processing techniques impacted metabolite composition, as evidenced by substantial variations in volatile compound levels and metabolite composition among the FM and BGN samples before and after traditional and novel processing. Important health-promoting compounds, such as oleic acid, linoelaidic acid, and linoleic acid, were identified at their highest levels in fermented FM and BGN flours. The results obtained from this study offer an important context for monitoring and regulating the metabolite composition of FM and BGN flours under traditional and novel processing. PRACTICAL APPLICATION: Fermentation, malting, and ultrasonication induced desirable changes in some health-promoting compounds of finger millet and Bambara groundnut flours. The food and pharmaceutical industries could benefit from these traditional- and novel-modified flours as they could be used as improved food sources with health benefits.

Barley-derived beer brewing by-products contain a high diversity of hydroxycinnamoylagmatines and their dimers

To aid valorisation of beer brewing by-products, more insight into their composition is essential. We have analysed the phenolic compound composition of four brewing by-products, namely barley rootlets, spent grain, hot trub, and cold trub. The main phenolics detected were hydroxycinnamoylagmatines and dimers thereof. Barley rootlets contained the highest hydroxycinnamoylagmatine content and cold trub the highest dimer content. Additionally, variations in (dimeric) hydroxycinnamoylagmatine composition and content were observed in fourteen barley rootlet samples. The most abundant compound in all rootlets was the glycosylated 4-O-7'/3-8'-linked heterodimer of coumaroylagmatine and feruloylagmatine, i.e. CouAgm-4-O-7'/3-8'-(4'Hex)-DFerAgm. Structures of glycosylated and hydroxylated derivatives of coumaroylagmatine were elucidated by NMR spectroscopy after their purification from a rootlet extract. An MS-based decision tree was developed, which aids in identifying hydroxycinnamoylagmatine dimers in complex mixtures. In conclusion, this study shows that the diversity of phenolamides and (neo)lignanamides in barley-derived by-products is larger than previously reported.

Metabolite Changes in Soybean (Glycine max) Leaves during the Entire Growth Period

Although soybean (Glycine max) leaves generate building blocks to produce seeds, a comprehensive understanding of the metabolic changes in soybean leaves during the entire growth stages is limited. Here, we investigated the metabolite changes in soybean leaves from five cultivars among four vegetative (V) and eight reproductive (R) stages using metabolite profiling coupled with chemometrics. Principal component analysis (PCA) of all samples showed a clear separation by growth stage. The total amount of monosaccharides and organic acids for energy production were highly detected in the V stage samples, accumulating in concentrations 2.5 and 1.7 times higher than in the R stage samples, respectively. The results of partial least-squares-discriminant analysis (PLS-DA) revealed a clear separation from R1 to R5 by the first PLS, suggesting significant alterations in the metabolic networks up to R5. After flowering, the stage of seed formation, R5, was associated with lower levels of most amino acids and an accumulation of phytosterols. The negative correlation observed between amino acids and phytosterol levels suggests a sophisticated coordination between carbon and nitrogen metabolism in plant, ensuring and supporting optimal growth (r = -0.50085, P = 0.0001). In addition, R-stage samples had decreased monosaccharide levels, indicating redistribution to seeds and senescence-related metabolite changes. Thus, metabolite profiling coupled with chemometrics could be a useful tool for investigating alterations in metabolic networks during various plant growth and development stages. Furthermore, we observed variations in flavonoid contents among the different cultivars. The results could be a basis of further studies on the source-sink interactions in the plant system.

Understanding the influence of genotype and temperature on proteolytic activity in distinct barley genotypes

This study aimed at investigating the effects of genotype and temperatures on the proteolytic activity in green malt of 48 barley genotypes, including 19 mutants, 15 hulled, 4 hulless, and 10 wild using enzyme assays based on casein, as substrate. During malting, insoluble barley protein must be hydrolyzed into soluble peptides and free amino acids to supply the brewing yeast with sufficient nutrients to grow rapidly and metabolize glucose and other sugars into alcohol through fermentation. However, the relatively hot temperatures employed during kilning usually denature the proteolytic enzymes due to their thermolabile nature. Even though the hydrolytic activity of most of the proteases is destroyed during the kilning process, the malt includes a small fraction of thermostable proteases that can further degrade protein in the subsequent mashing process. Considering the higher temperature range employed in industrial kilning and mashing, three temperatures (37, 50, and 70°C) were selected to identify the genotypes possessing high activity at the higher range of temperatures as well as thermostable variant of the enzyme. The proteolytic activity in all the genotypes declined after 50°C depicting its optimum temperature. Overall proteolytic activity was observed to be positively correlated with the amino acids and negatively correlated with protein content. Three mutant (BL2086, BL2091, and BL2079) and one wild (WS 237) genotypes possessing proteolytic activity in a higher range at all the studied temperatures have the potential to be exploited in the breeding programs for incorporating trait of thermostable proteolytic activity into low malting efficiency cultivars. PRACTICAL APPLICATION: The optimal hydrolytic activities of carbohydrases and proteases during mashing are essential for producing high-quality wort from malted barley to ensure that hydrolyzed molecules are available to brewers' yeast to support fermentative metabolism. In this study, several barley cultivars were grown under identical environmental conditions but assayed at different temperatures. As result, four genotypes had been obtained that possessed optimal proteolytic activities at a higher temperature range and can be of great interest to breeders and maltsters for altering wort amino acid profiles and better exposure of starch to mashing enzymes, thereby increasing the fermentable sugar yield from the malt.