Metabolomics Reveal Optimal Grain Preprocessing (Milling) toward Rice Koji Fermentation

Removal Capacity and Mechanism of Modified Chitosan for Ochratoxin A Based on Rapid Magnetic Separation Technology

Ochratoxin A (OTA) exposure in food is very dangerous to human health. Therefore, the development of a fast and efficient technique for OTA removal has become an urgent research topic in the field of food safety. Nano Fe3O4 modified chitosan nanocomposite (nano-Fe3O4@CTS) was synthesized as a rapidly separable and safe adsorbent and was used to adsorb OTA in wine. FT-IR, XRD, and VSM characterization methods indicated that chitosan was successfully modified by Fe3O4 and exhibited good magnetism. The adsorption and kinetics isotherms between OTA and nano-Fe3O4@CTS were studied by the Langmuir equation and the pseudo-second order kinetics equation. The mechanism of OTA adsorption on nano-Fe3O4@CTS nanoparticles was the combined effect of physical adsorption and chemisorption. The negative ΔH°, ΔG° and ΔS° values proved that the adsorption was a spontaneous and exothermic process. Nano-Fe3O4@CTS with a high maximum adsorption capacity of 5018.07 ng/g at 25 °C can rapidly separate the matrix immobilized OTA from wine, and to a certain extent retains some of the wine quality after OTA removal.

Recent Advances in the Health Benefits of Phenolic Acids in Whole Grains and the Impact of Processing Techniques on Phenolic Acids: A Comprehensive Review

Phenolic acids, essential compounds in whole grains, are renowned for their health-enhancing antioxidant and anti-inflammatory properties. Variations in concentration, particularly of hydroxybenzoic and hydroxycinnamic acids, are observed among grain types. Their antiobesity and antidiabetes effects are linked to their modulation of key signaling pathways like AMPK and PI3K, crucial for metabolic regulation and the body's response to inflammation and oxidative stress. Processing methods significantly influence phenolic acid content and bioavailability in whole grains. Thermal techniques like boiling, baking, or roasting can degrade these compounds, with loss influenced by processing conditions. Nonthermal methods such as germination, fermentation, or their combination, can protect or enhance phenolic acid content under ideal conditions. Novel nonthermal approaches like ultrahigh pressure (UHP), irradiation, and pulsed electric fields (PEF) show promise in preserving these compounds. Further research is needed to fully comprehend the impact mechanisms of these innovative methods on the nutritional and sensory attributes of cereals.

Urine metabolomics unravel the effects of short-term dietary interventions on oxidative stress and inflammation: a randomized controlled crossover trial

Dietary biomarkers in urine remain elusive when evaluating diet-induced oxidative stress and inflammation. In our previous study, we conducted a randomized controlled crossover trial to compare the short-term (4-weeks) effects of the balanced Korean diet (BKD) with Western diets, including the 2010 dietary guidelines for Americans (2010 DGA) and typical American diet (TAD), on various metabolic indices in obese Korean adults. Building on this work, the current research focuses on the impact of these dietary interventions on oxidative stress (d-ROMs and BAP) and inflammation (CRP, TNF-α, IL-6, IL-1β, MCP-1) biomarkers in serum, and the concurrent urine metabolomes. Each dietary regimen was in silico and experimentally examined for their antioxidant levels using ABTS, DPPH, and FRAP assays, as well as total flavonoid (TFC) and total phenolic (TPC) contents. We assessed post-intervention variations in oxidative stress and inflammation biomarkers in serum, as well as the urine metabolite profiles for the participants (n = 48, average age: 41 years). Antioxidant contents and associated total antioxidant capacity (TAC) were significantly higher for the recommended diets (BKD and 2010 DGA) compared to TAD (p < 0.05). Butanol extracts from recommended diets (BKD and 2010 DGA) showed significantly higher antioxidant activity compared to TAD in ABTS (p < 0.01), DPPH, and FRAP (p < 0.05) assays. Consistent results were observed in total phenolic and flavonoid contents, mirroring their respective antioxidant activities. Following the intervention period, oxidative stress & inflammation markers in serum varied marginally, however, the urine metabolite profiles were clearly demarcated for the BKD and Western dietary groups (PC1 = 5.41%). For BKD group, the pre- and post-intervention urine metabolite profiles were clearly segregated (PLS2 = 2.93%). Compared to TAD, urine extracts from the recommended dietary group showed higher abundance of benzoic acid & phenolic derivatives (VIP > 0.7, p < 0.05). Metabolites associated with oxidative stress were observed higher in the urine samples from Western dietary groups compared to BKD. Urine metabolomics data delineated the post-intervention effects of three dietary interventions which corroborates the respective findings for their effects on metabolic indices.

An investigation into the effects of various processing methods on the characteristic compounds of highland barley using a widely targeted metabolomics approach

This study explored the influence of diverse processing methods (cooking (CO), extrusion puffing (EX), and steam explosion puffing (SE), stir-frying (SF) and fermentation (FE)) on highland barley (Qingke) chemical composition using UHPLC-MS/MS based widely targeted metabolomics. Overall, 827 metabolites were identified and categorized into 16 classes, encompassing secondary metabolites, amino acids, nucleotides, lipids, etc. There 43, 85, 131, 51 and 98 differential metabolites were respectively selected from five comparative groups (raw materials (RM) vs CO/EX/SE/SF/FE), mainly involved in amino acids, nucleotides, flavonoids, and alkaloids. Compared to other treated groups, FE group possessed the higher content of crude protein (15.12 g/100 g DW), and the relative levels of free amino acids (1.32 %), key polyphenols and arachidonic acid (0.01 %). EX group had the higher content of anthocyanins (4.22 mg/100 g DW), and the relative levels of free amino acids (2.02 %) and key polyphenols. SE group showed the higher relative levels of phenolic acids (0.14 %), flavonoids (0.20 %) and alkaloids (1.17 %), but the lowest free amino acids (0.75 %). Different processing methods all decreased Qingke's antioxidant capacity, with the iron reduction capacity (988.93 μmol/100 g DW) in SE group was the lowest. On the whole, FE and EX were alleged in improving Qingke's nutritional value. CO and SF were also suitable for Qingke processing since fewer differential metabolites were identified in CO vs RM and SF vs RM groups. Differential metabolites were connected to 14 metabolic pathways, with alanine, aspartate, and glutamate metabolism being central. This study contributed theoretical groundwork for the scientific processing and quality control of Qingke products.

Comprehensive Metabolite Profiling of Four Different Beans Fermented by Aspergillus oryzae

Fermented bean products are used worldwide; most of the products are made using only a few kinds of beans. However, the metabolite changes and contents in the beans generally used during fermentation are unrevealed. Therefore, we selected four different beans (soybean, Glycine max, GM; wild soybean, Glycine soja, GS; common bean, Phaseolus vulgaris, PV; and hyacinth bean, Lablab purpureus, LP) that are the most widely consumed and fermented with Aspergillus oryzae. Then, metabolome and multivariate statistical analysis were performed to figure out metabolite changes during fermentation. In the four beans, carbohydrates were decreased, but amino acids and fatty acids were increased in the four beans as they fermented. The relative amounts of amino acids were relatively abundant in fermented PV and LP as compared to other beans. In contrast, isoflavone aglycones (e.g., daidzein, glycitein, and genistein) and DDMP-conjugated soyasaponins (e.g., soyasaponins βa and γg) were increased in GM and GS during fermentation. Notably, these metabolite changes were more significant in GS than GM. In addition, the increase of antioxidant activity in fermented GS was significant compared to other beans. We expect our research provides a basis to extend choice for bean fermentation for consumers and food producers.

Integrated multi-omics approaches to understand microbiome assembly in Jiuqu, a mixed-culture starter

The use of Jiuqu as a saccharifying and fermenting starter in the production of fermented foods is a very old biotechnological process that can be traced back to ancient times. Jiuqu harbors a hub of microbial communities, in which prokaryotes and eukaryotes cohabit, interact, and communicate. However, the spontaneous fermentation based on empirical processing hardly guarantees the stable assembly of the microbiome and a standardized quality of Jiuqu. This review describes the state of the art, limitations, and challenges towards the application of traditional and omics-based technology to study the Jiuqu microbiome and highlights the need for integrating meta-omics data. In addition, we review the varieties of Jiuqu and their production processes, with particular attention to factors shaping the microbiota of Jiuqu. Then, the potentials of integrated omics approaches used in Jiuqu research are examined in order to understand the assembly of the microbiome and improve the quality of the products. A variety of different approaches, including molecular and mass spectrometry-based techniques, have led to scientific advances in the analysis of the complex ecosystem of Jiuqu. To date, the extensive research on Jiuqu has mainly focused on the microbial community diversity, flavor profiles, and biochemical characteristics. An integrative approach to large-scale omics datasets and cultivated microbiota has great potential for understanding the interrelation of the Jiuqu microbiome. Further research on the Jiuqu microbiome may explain the inherent property of compositional stability and stable performance of a complex microbiota coping with environmental perturbations and provide important insights to reconstruct synthetic microbiota and develop modern intelligent manufacturing procedures for Jiuqu.

Metabolite Profiling and Anti-Aging Activity of Rice Koji Fermented with Aspergillus oryzae and Aspergillus cristatus: A Comparative Study

Rice koji, used as a starter for maximizing fermentation benefits, produces versatile end products depending on the inoculum microbes used. Here, we performed metabolite profiling to compare rice koji fermented with two important filamentous fungus, Aspergillus oryzae and A. cristatus, during 8 days. The multivariate analyses showed distinct patterns of primary and secondary metabolites in the two kojis. The rice koji fermented with A. oryzae (RAO) showed increased α-glucosidase activity and higher contents of sugar derivatives than the one fermented with A. cristatus (RAC). RAC showed enhanced β-glucosidase activity and increased contents of flavonoids and lysophospholipids, compared to RAO. Overall, at the final fermentation stage (8 days), the antioxidant activities and anti-aging effects were higher in RAC than in RAO, corresponding to the increased metabolites such as flavonoids and auroglaucin derivatives in RAC. This comparative metabolomic approach can be applied in production optimization and quality control analyses of koji products.

Metabolic Visualization Reveals the Distinct Distribution of Sugars and Amino Acids in Rice Koji

The compounds inside rice koji have been thoroughly investigated as an essential material in making many food-related products, including sake. However, these studies focused only on quantitative aspects, leaving features that can still be uncovered if seen from a new perspective. Visualization of the metabolites inside rice koji may as well be the new angle needed to retrieve more information regarding rice koji making. Here we utilized mass spectrometry imaging (MSI) to visualize the distribution of sugars, sugar alcohols, and amino acids inside rice koji. Imaging results revealed that several sugars alcohols and amino acids were shown to have characteristic distribution near the edges or surface of rice koji. Furthermore, the distribution appears to be correlated with the different structure of rice koji. This study is the first report of using MSI to visualize sugars, sugar alcohols, and amino acids in rice koji.

The Effect of Degree of Milling on the Nutraceutical Content in Ecofriendly and Conventional Rice (Oryza sativa L.)

We investigated the effects of the type of rice and degree of milling (DOM) on the nutraceutical content and antioxidant activity of rice (Oryza sativa L.). The fatty acid (FA), vitamin E homolog, and phenolic contents in organic (OR), pesticide-free (PFR), and conventional rice (CR) decreased significantly with an increase in the DOM of rice grains, particularly for a DOM of 7 and 9 (p < 0.05). The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity also decreased with the DOM; particularly, this activity decreased significantly, by approximately 60%, in rice grains with a DOM between 7 and 11, as compared to that of brown rice (p < 0.05). α-Tocopherol (r = 0.854) and p-coumaric acid (r = 0.501) showed the strongest correlation with DPPH activity in each chemical group. Stepwise discriminant analysis enabled the correct original and cross-validated classification of 87.0% and 81.5% of rice types, respectively. Additionally, the original and cross-validated classification of rice DOM levels showed that, overall, 93.8% and 92.6% of rice samples were correctly classified. Our findings reveal variations in the nutraceutical levels and antioxidant activities in rice grains based on the rice type and DOM, which can help improve the nutritional evaluation of human-health-promoting rice grains.

Long-term responses to climate change of the carbon and oxygen stable isotopic compositions and gelatinization temperature of rice

The stable isotopic compositions of carbon (δ¹³C) and oxygen (δ¹⁸O) in rice are often used to confirm its authenticity. The gelatinization temperature is a crucial factor in alcoholic fermentation. However, little is known about the isotopic and thermal responses of rice to climate change. We show that in sake rice grown annually in the same paddy field from 1994 to 2013, the δ¹³C (-27.4‰ to -25.9‰) and δ¹⁸O values (20.4‰ to 27.0‰) correlated negatively with the mean daily minimum air temperature and precipitation, and positively with the hours of sunshine during grain-filling. In contrast, of the air temperatures tested, the gelatinization temperature of the rice grains (63.2°C to 70.0 °C) correlated positively and most strongly with the mean daily mean air temperature. Thus, we identified the mean daily minimum temperature during grain-filling, a nocturnal temperature, as a major factor affecting the isotopic and thermal variations in rice grains.

Comparative Evaluation of Six Traditional Fermented Soybean Products in East Asia: A Metabolomics Approach

Many ethnic fermented soybean products (FSPs) have long been consumed as seasoning and protein sources in East Asia. To evaluate the quality of various FSPs in East Asia, non-targeted metabolite profiling with multivariate analysis of six traditional FSPs (Natto; NT, Cheonggukjang; CG, Doenjang; DJ, Miso; MS, Doubanjiang; DB, Tianmianjiang; TM) was performed. Six FSPs could be clearly distinguished by principle component analysis (PCA) and partial least square-discriminant analysis (PLS-DA). Amino acid contents were relatively higher in NT and CG, sugar and sugar alcohol contents were relatively higher in MS and TM, isoflavone glycoside contents were relatively highest in CG, isoflavone aglycon contents were the highest in DJ, and soyasaponin contents were the highest in CG. Antioxidant activity and physicochemical properties were determined to examine the relationships between the FSPs and their antioxidant activities. We observed a negative correlation between isoflavone aglycon contents and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) activity. Furthermore, the order of ABTS activity of FSPs has a positive correlation with the order of soybean content in the six FSPs. Herein it was found that primary metabolites were affected by the main ingredients and secondary metabolites were most influenced by the fermentation time, and that soybean content contributed more to antioxidant activity than fermentation time.

High Nighttime Temperature Induces Antioxidant Molecule Perturbations in Heat-Sensitive and Heat-Tolerant Coisogenic Rice ( Oryza sativa) Strains

Global warming-associated increases in temperature, particularly at nighttime, are detrimental to rice yield and quality. Metabolomic profiling was used to examine and compare the short-term extreme high nighttime temperature-induced molecular perturbations in rice ( Oryza sativa) coisogenic strains with contrasting heat-tolerances at the first stage of seed ripening. Compared to the heat-sensitive strain, antioxidant molecules were higher in abundance in the heat-tolerant strain, whereas the abundances of molecules involved in photosynthesis, nucleotide catabolism, and the S-adenosylmethionine (SAM) cycle varied only slightly. Thus, we proposed that the high abundance of antioxidant molecules in the heat-tolerant strain alleviated cellular oxidative stress, which protected photosynthesis, nucleotide catabolism, and the SAM cycle, leading to good grain filling.