The potential improvements of naked barley pretreatments on GABA, β-glucan, and antioxidant properties

Effects of synergistic modification using alkalis and guar gum on the pasting, rheological, and microstructural properties of germinated highland barley starch gels

Germination treatment of highland barley enhances its nutritional value while weakening the starch gel properties. This study aims to enhance the characteristics of germinated highland barley starch (GBS) by exploring the synergistic effects of two alkalis (Na2CO3 and NaHCO3) and guar gum (GG) on GBS gel properties. The combined action of alkalis and GG significantly improved the peak viscosity, setback viscosity, and hardness compared with GG alone. The highest G' and G" reached 998 and 204 Pa at 0.4% Na2CO3 addition, which were increased by nearly 44% and 50%, respectively. Fourier-transform infrared spectral analysis revealed that the alkalis strengthened interaction forces, particularly with intensified absorption peaks at 3200-3700 cm-1 and 1550-1750 cm-1. The Na2CO3 and NaHCO3 reduced the spin-spin relaxation time (T2), resulting in a dense starch gel network. This study contributes to enhancing the market application of GBS and offers innovative insights for modifying other starches.

Change of physiochemical characteristics, nutritional quality, and volatile compounds of Chenopodium quinoa Willd. during germination

The impacts of varying germination periods (0-72 h) on morphological properties, proximate composition, amino acid profile, GABA levels, antioxidant attributes, polyphenol content (both free and bound), and volatile compounds of quinoa were evaluated. Germination significantly increased the content of fiber, amino acids, GABA, polyphenols, and in-vitro antioxidant activities in quinoa. The optimal nutritional quality and antioxidant capacity of quinoa were observed during the 36-72 h germination period. We examined the dynamics of 47 phenolic compounds in quinoa during germination and noted a substantial rise in free phenolic acids and bound flavonoids post-germination. A total of 53 and 84 volatile compounds were respectively identified in ungerminated quinoa and germinated quinoa. It was found that the germination period of 24-48 h contributed to reducing the presence of undesirable flavors. TEM analysis revealed significant structural damage to the ultrastructure and relaxation of the cell wall in germinated quinoa grains.

Recent advances in the biosynthesis and industrial biotechnology of Gamma-amino butyric acid

GABA (Gamma-aminobutyric acid), a crucial neurotransmitter in the central nervous system, has gained significant attention in recent years due to its extensive benefits for human health. The review focused on recent advances in the biosynthesis and production of GABA. To begin with, the investigation evaluates GABA-producing strains and metabolic pathways, focusing on microbial sources such as Lactic Acid Bacteria, Escherichia coli, and Corynebacterium glutamicum. The metabolic pathways of GABA are elaborated upon, including the GABA shunt and critical enzymes involved in its synthesis. Next, strategies to enhance microbial GABA production are discussed, including optimization of fermentation factors, different fermentation methods such as co-culture strategy and two-step fermentation, and modification of the GABA metabolic pathway. The review also explores methods for determining glutamate (Glu) and GABA levels, emphasizing the importance of accurate quantification. Furthermore, a comprehensive market analysis and prospects are provided, highlighting current trends, potential applications, and challenges in the GABA industry. Overall, this review serves as a valuable resource for researchers and industrialists working on GABA advancements, focusing on its efficient synthesis processes and various applications, and providing novel ideas and approaches to improve GABA yield and quality.

The contribution of cell wall integrity to gastric emptying and in vitro starch digestibility and fermentation performance of highland barley foods

Studies have shown that the structure, composition, and bioavailability of compounds in whole grains are affected by processing and the role of cells walls. In this study, the effects of different processing methods on highland barley, one of the mostly widely produced whole grains worldwide, were investigated. The processing methods applied were flaking-boiling (HB flake), sand-roasting (Puffed HB), and sand-roasting-milling (Tsamba). Results showed Puffed HB and Tsamba had higher levels of damaged starch content, starch short-range molecular order, and relative crystallinity than HB flake. The half-time of gastric emptying (t_1/2) was the slowest for Tsamba (132.3 min) compared to HB flake (122.5 min) and Puffed HB (84.0 min), indicating the slowest gastric emptying rate, which could be attributed to its high viscosity of gastric digesta. After in vitro gastroduodenal digestion, Puffed HB exhibited the lowest starch digestibility and the least amount of β-glucan due to its less damaged cellular structure. Furthermore, Puffed HB resulted in a 21% and 18% higher in vitro production of total short-chain fatty acids than Tsamba and HB flake, respectively. Besides, undigested starch of Puffed HB after in vitro gastroduodenal digestion delayed in vitro fecal fermentation of β-glucan. Our study provided insight into the potential mechanisms of how cell wall integrity affected the gastric emptying, in vitro starch digestibility, and in vitro fecal fermentation of highland barley foods.

The role of guar gum in improving the gel and structural characteristics of germinated highland barley starch

Germinated highland barley has been shown to have many health benefits, but the weakening of the starch gel properties during the germination limits its further application. In this study, germinated highland barley starch (GBS) was obtained after germination treatment. Guar gum (GG) was added to explore the effects of gelatinization on the rheology, gel and structural characteristics of GBS, and the potential of preparing gel-based products was also evaluated. The results showed that the addition of GG significantly increased the viscosity, gel strength and viscoelasticity of GBS, which was beneficial to the formation of gel, and promoted its formation of an ordered and compact gel network structure. The study provides a theoretical reference for the preparation of gel-based food with highland barley starch, and increases the application range of highland barley.

Effect of Extrusion or Fermentation on Physicochemical and Digestive Properties of Barley Powder

In this work, the effect of extrusion and fermentation on the physicochemical and digestive properties of barley powder was studied. The results showed that the contents of phenolics, β-glucan, protein, and lipid decreased after extrusion. The contents of nutrients (except lipid) increased after fermentation. Both extrusion and fermentation of barley can lead to the darkening of the color and effectively optimize the palatability by reducing the viscosity. In vitro digestion of starch showed that the content of as rapidly digestible starch increased after extrusion and fermentation. The contents of ferulic acid, 2-hydroxybenzoic acid, and caffeic acid decreased after extrusion, while the contents of chlorogenic acid, p-coumaric acid, and ferulic acid increased after fermentation. Basically, the content of all the phenolic showed an increasing trend after digestion. The antioxidant activity decreased after extrusion and increased after fermentation. Therefore, the nutritional composition and properties of barley powder were changed under the two processing methods.

The effect of β-glucan and inulin on the reduction of aflatoxin B1 level and assessment of textural and sensory properties in chicken sausages

In recent years, people have a tendency to consume ready-made foods such as sausages. Therefore, the use of quality raw materials in these products is very important because these compounds may be contaminated with aflatoxin B₁ (AFB₁). Various biological and natural methods have been introduced to reduce aflatoxins in food products. The aim of the present study was to reduce AFB₁ levels. So, β-glucan (βG) and Inulin (IN) were used in different ratios (1: 2%, 2: 1%, 1.5: 1.5%, 0: 3, 3: 0%) in chicken sausages. AFB₁ levels were measured by High Performance Liquid Chromatography (HPLC) in a period of 1–45 days. Then, texture and sensory properties were examined. After 45 days, AFB₁ levels were decreased in all samples, and the highest level of reduction (73.7%) was observed in samples with 5 μg/kg AFB₁ and 3% βG. Texture analysis showed that all the evaluated features complied with the standard. The hardness of chicken sausage with addition of IN (3%) (3.162N) was close to that of the control (2.99N). None of the products were significantly different from the control sample in terms of sensory properties. Therefore, βG and IN are effective in reducing AFB1, and the produced sausages can be acceptable for marketing and be offered for consumption.

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Aflatoxin B₁ levels were assessed by adding β-glucan and inulin.

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Texture and sensory characteristics were investigated.

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Aflatoxin B₁ levels were reduced in all samples.

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The impact of β-glucan on the reduction of aflatoxin B₁ was more than that of inulin.

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The textural and sensory characteristics of the sausage samples were acceptable.

Transcriptome Analysis Reveals the Molecular Mechanism of GABA Accumulation during Quinoa (Chenopodium quinoa Willd.) Germination

Quinoa (Chenopodium quinoa Willd.) with a history of 5000 years as food is extremely rich in nutrients and bioactive compounds, including γ-aminobutyric acid (GABA), a natural four-carbon non-protein amino acid with great benefits to human health. In quinoa, GABA generally increases with the germination time, but the underlying molecular mechanism is unclear. Here, we found that the GABA content in quinoa varied significantly among 25 varieties using an automatic amino acid analyzer. Next, six varieties (three low-GABA and three high-GABA varieties) were used for further analyses. The content of GABA in six varieties all showed an increasing trend after germination. In addition, Pearson's correlation analysis showed that the changes in GABA content were closely related to the transcript level or enzyme activity of three key enzymes including glutamate decarboxylase (GAD), GABA transaminase (GABA-T), and succinate-semialdehyde dehydrogenase (SSADH) in the GABA shunt, especially GAD. Based on RNA-sequencing analysis, eight GAD genes, two GABA-T genes, one SSADH gene, nine polyamine oxidase (PAO) genes, five diamine oxidase (DAO) genes, four 4-aminobutyraldehyde dehydrogenase (BADH) genes, and three thermospermine synthase ACAULIS5 (ACL5) genes were identified. Among these, CqGAD8 and CqGABA-T2 may make a greater contribution to GABA accumulation during quinoa germination.

Molecular structure, morphological, and physicochemical properties of highlands barley starch as affected by natural fermentation

The influence of natural fermentation on the highlands barley starch chemical structure, morphological, physicochemical, and thermal properties was studied. The findings showed that fermentation had no impact on starch fine structure but it decreased the molecular-weight from 2.26 to 1.04 × 10⁸ g/mol in native highlands barley and after 72 h fermentation (FHB72) respectively. Also, it decreased amylopectin long-chains (B1 and B2) while increased short-chains. The intensity ratio of FT-IR at 995/1022 and 1047/1022 bands were found to be higher as the time of fermentation progressed, and the highest absorption-intensity at 3000-3600 cm^-1 and higher swelling capacity were noticed in the starch of FHB72. During fermentation, pasting peak, final and setback viscosities were decreased. Microscopically, granules with more pores, damaged, cracked, and no growth rings were found in starches isolated after 48 h and 72 h of fermentation. This study indicated that fermentation up to 72 h is an effective method to modify highlands barley starch.

Physicochemical and bioactive properties of a high β-glucan barley variety 'Betaone' affected by germination processing

This study was conducted to investigate the effects of germination on the bioactive phytochemicals in the barley variety 'Betaone', which has high β-glucan content. Betaone barley seeds were germinated for 24, 48, 72, and 96 h at 25 °C in a growth chamber. As the germination period progressed, crude protein, crude fat, and crude ash levels increased, while starch content decreased. β-Glucan content significantly decreased during the germination period. However, after 96 h of germination, it was still 4.31%, which is similar to the amount found in ordinary barley varieties. The α- and β-amylase activities in Betaone barley increased, thereby significantly decreasing pasting viscosities (p ≤ 0.05), as germination progressed. The water absorption index increased in the early germination stage, subsequently decreasing as germination progressed. While the water solubility index fell in the first stage of germination, it subsequently increased as germination progressed. Oil absorption decreased as germination progressed. Bioactive compounds, in particular the total phenolic (122.84-322.67 μg/g), total flavonoid (32.20-124.09 μg/g), and GABA content (176.94-212.64 μg/g), increased as germination progressed. The antioxidative properties mainly DPPH and ABTS radical scavenging activity also increased during the germination period. Therefore, these findings could be a useful method for improving new products with enhanced bioactive phytochemicals.