Bran Layer Research Articles

Influence of Gradient Milling on Cooking and Sensory Attributes of Chinese Black Rice: Insights into Volatile Flavor Compounds.

This study investigated the impact of gradient milling on the cooking properties and sensory characteristics of Yangxian black rice. The results showed that as the degree of milling increased, the gelatinization time decreased (36.85-23.54 min) and the water uptake ratio of whole black rice (188.29%) was significantly lower compared to that of refined grains (194.05%). Low-field nuclear magnetic resonance (NMR) was further used to monitor the water concentration and distribution of black rice during soaking and cooking. It was found that the bran layers of black rice, as a physical barrier, impeded the water penetration into the kernels for a given soaking and cooking duration. The sensory evaluation conducted by a panel of trained volunteers demonstrated a high score for all sensory attributes in slightly milled black rice, corroborating findings from the taste analyzer. Through correlation analysis of volatile components determined by gas chromatography-mass spectrometry (GC-MS), smell scores in sensory evaluation, and electronic nose response values, 2-pentyl-furan (54.84-12.72 ng/g) and guaiacol (19.39-5.51 ng/g) were found to be the predominant volatile flavor contributors in cooked black rice. Overall, this study provides valuable insight into the intricate relationship between milling degrees and the cooking properties, sensory characteristics, and volatile flavor compounds of Yangxian black rice.

Physicochemical and Morphological Changes in Long-Grain Brown Rice Milling: A Study Using Image Visualization Technologies

This study evaluated the changes in physicochemical properties and appearance quality of long-grain rice during the grinding process using image technologies and aimed to provide reference for future research. The brown rice milling process was divided into three stages, and flatbed scanning, scanning electron microscopy (SEM), X-ray micro-computed tomography (micro-CT), low-field nuclear magic resonance (LF-NMR), and headspace–gas chromatography–ion mobility spectrometry (HS–GC–IMS) were employed to examine the physicochemical and volatile properties of the samples. Results revealed a continuous increase in the degree of milling, with a broken rice rate and a whiteness value increasing by 50.84% and 21.13%, respectively, compared with those during the initial stage; dietary fiber and vitamin B1 contents were reduced by 54.41% and 66.67%, respectively. The image results visualized showed that the cortex of brown rice was gradually peeled off with the increase in milling degree; the cortical thickness was gradually reduced, the endosperm was gradually exposed, and the surface was smoother and shinier. T2 populations exhibited a shift toward longer relaxation times, followed by a decrease in relaxation time during the milling process. Additionally, 31 target compounds impacting rice flavor, mainly ketones, alcohols, and esters, were identified, and the concentration of volatile substances in the B region decreased with the reduction in the bran layer; the concentration of volatile substances in the C region provided rice flavor, which increased with the milling process. This study showed changes in the physicochemical properties and appearance quality of long-grain brown rice during milling. Furthermore, the use of various image processing techniques offers significant insights for optimizing processing parameters and enhancing overall quality and taste.

Predictive modeling of rice milling degree for three typical Chinese rice varieties using interpretative machine learning methods.

Brown rice over-milling causes high economic and nutrient loss. The rice degree of milling (DOM) detection and prediction remain a challenge for moderate processing. In this study, a self-established grain image acquisition platform was built. Degree of bran layer remaining (DOR) datasets is established with image capturing and processing (grain color, texture, and shape features extraction). The mapping relationship between DOR and the DOM is in-depth analyzed. Rice grain DOR typical machine learning and deep learning prediction models are established. The results indicate that the optimized Catboost model can be established with cross-validation and grid search method, with the best accuracy improving from 84.28% to 91.24%, achieving precision 91.31%, recall 90.89%, and F1-score 91.07%. Shapley additive explanations analysis indicates that color, texture, and shape feature affect Catboost prediction accuracy, the feature importance: color>texture>shape. The YCbCr-Cb_ske and GLCM-Contrast features make the most significant contribution to rice milling quality prediction. The feature importance provides theoretical and practical guidancefor grain DOM prediction model. PRACTICAL APPLICATION: Rice milling degree prediction and detection are valuable for rice milling process in practical application. In this paper, image processing and machine learning methods provide an automated, nondestructive, and cost-effective way to predict the quality of rice. The study may serve as a valuable reference for improving rice milling methods, retaining rice nutrition, and reducing broken rice yield.

The structural-mechanical damage behavior of rice bran layer under tensile processing for moderate milling

Bran layer moderate removal during rice milling is a crucial process for reducing rice broken rate and nutrient loss. The bran layer structural-cracking behavior is analyzed using a self-developed in-situ observation tensile tester with high-speed image acquisition. The rice bran tissue microstructure, chemical composition, cracking morphology are in-depth investigated. The results show that rice bran pericarp cells are of reticulate network, cell shape with rectangular or elliptical.significant differences in cell distribution and density across rice varieties, with Japonica rice (NJ5055) with a denser and more uniform structure, exhibiting higher ductility and tensile strength. The rice bran exhibited linear elastic rheological behavior. The bran tensile property is different under tensing directions, the tensile strength shows longitudinal (Y) > radial (X). Cracking along the cell long axis is Y direction, showing orderly line cracking path. Cracking along cell short axis is X direction, showing zigzag cracking path. Pericarp cells geometrical structure determines the mechanical strength and cracking-removal resistance ability of rice bran. The pericarp layer significantly enhances the ductility of the bran layer, allowing it to stretch and deform under stress, thereby improving overall mechanical performance. Rice bran structural-mechanical properties are affected by micro-structure and components.

Effects of degree of milling on bran layer structure, physicochemical properties and cooking quality of brown rice

Effects of varying degree of milling (DOM) (0–22%) on the bran layer structure, physicochemical properties, and cooking quality of brown rice were explored. As the DOM increased, bran degree, protein, lipid, dietary fiber, amylose, mineral elements, and color parameters (a* and b* values) of milled rice decreased while starch and L* value increased. Microscopic fluorescence images showed that the pericarp, combined seed coat-nucellus layer, and aleurone layer were removed in rice processed at DOM of 6.6%, 9.2%, and 15.4%, respectively. The pasting properties, thermal properties, and palatability of rice increased as the DOM increased. Principal component and correlation analysis indicated that excessive milling lead to a decline in nutritional value of rice with limited impact on enhancing palatability. Notably, when parts of aleurone cell wall were retained, rice samples exhibited high cooking and sensory properties. It serves as a potential guide to the production of moderately milled rice.

Grains in a Modern Time: A Comprehensive Review of Compositions and Understanding Their Role in Type 2 Diabetes and Cancer.

Globally, type 2 diabetes (T2D) and Cancer are the major causes of morbidity and mortality worldwide and are considered to be two of the most significant public health concerns of the 21st century. Over the next two decades, the global burden is expected to increase by approximately 60%. Several observational studies as well as clinical trials have demonstrated the health benefits of consuming whole grains to lower the risk of several chronic non-communicable diseases including T2D and cancer. Cereals grains are the primary source of energy in the human diet. The most widely consumed pseudo cereals include (quinoa, amaranth, and buckwheat) and cereals (wheat, rice, and corn). From a nutritional perspective, both pseudo cereals and cereals are recognized for their complete protein, essential amino acids, dietary fibers, and phenolic acids. The bran layer of the seed contains the majority of these components. Greater intake of whole grains rather than refined grains has been consistently linked to a lower risk of T2D and cancer. Due to their superior nutritional compositions, whole grains make them a preferred choice over refined grains. The modulatory effects of whole grains on T2D and cancer are also likely to be influenced by several mechanisms; some of these effects may be direct while others involve altering the composition of gut microbiota, increasing the abundance of beneficial bacteria, and lowering harmful bacteria, increasing insulin sensitivity, lowering solubility of free bile acids, breaking protein down into peptides and amino acids, producing short-chain fatty acids (SCFAs), and other beneficial metabolites that promote the proliferation in the colon which modulate the antidiabetic and anticancer pathway. Thus, the present review had two aims. First, it summarized the recent knowledge about the nutritional composition and bioactive acids in pseudo cereals (quinoa, amaranth, and buckwheat) and cereals (wheat, rice, and corn); the second section summarized and discussed the progress in recent human studies, such as observational (cross-sectional studies, case-control studies, and cohort studies) and intervention studies to understand their role in T2D and cancer including the potential mechanism. Overall, according to the scientific data, whole grain consumption may reduce the incidence of T2D and cancer. Future studies should carry out randomized controlled trials to validate observational results and establish causality. In addition, the current manuscript encourages researchers to investigate the specific mechanisms by which whole grains exert their beneficial effects on health by examining the effects of different types of specific protein, dietary fibers, and phenolic acids that might help to prevent or treat T2D and cancer.

Composition of Whole Grain Dietary Fiber and Phenolics and Their Impact on Markers of Inflammation.

Inflammation is an important biological response to any tissue injury. The immune system responds to any stimulus, such as irritation, damage, or infection, by releasing pro-inflammatory cytokines. The overproduction of pro-inflammatory cytokines can lead to several diseases, e.g., cardiovascular diseases, joint disorders, cancer, and allergies. Emerging science suggests that whole grains may lower the markers of inflammation. Whole grains are a significant source of dietary fiber and phenolic acids, which have an inverse association with the risk of inflammation. Both cereals and pseudo-cereals are rich in dietary fiber, e.g., arabinoxylan and β-glucan, and phenolic acids, e.g., hydroxycinnamic acids and hydroxybenzoic acids, which are predominantly present in the bran layer. However, the biological mechanisms underlying the widely reported association between whole grain consumption and a lower risk of disease are not fully understood. The modulatory effects of whole grains on inflammation are likely to be influenced by several mechanisms including the effect of dietary fiber and phenolic acids. While some of these effects are direct, others involve the gut microbiota, which transforms important bioactive substances into more beneficial metabolites that modulate the inflammatory signaling pathways. Therefore, the purpose of this review is twofold: first, it discusses whole grain dietary fiber and phenolic acids and highlights their potential; second, it examines the health benefits of these components and their impacts on subclinical inflammation markers, including the role of the gut microbiota. Overall, while there is promising evidence for the anti-inflammatory properties of whole grains, further research is needed to understand their effects fully.

Exploring the potential of objective metabolite measures in dietary assessment: randomised cross over feeding study

Reliable dietary assessment is key to our understanding of diet-health interactions(1). Most current dietary assessment methods are self-reported, making them prone to a range of biases(2). Objective markers, such as certain metabolite concentrations in human tissue, may prove a more reliable method of dietary assessment in the future while reducing participant burden(2,3). An example of these metabolite markers are alkylresorcinols, a family of compounds found in the bran layer of common grains. High concentrations of alkylresorcinols reflect high wholegrain intakes, very low levels indicate only refined grain intake, while no alkylresorcinols would indicate a gluten-free diet. We conducted a randomised crossover feeding study of three interventions (one standardisation day followed by a feeding day where known amounts were consumed under observation). Each feeding day differed by which food groups were provided (e.g., chicken, legumes, and fruit) or entirely absent (e.g., grains, fish, and dairy). Participants provided 24-hour urine samples on all six days (standardisation days and feeding days), as well as a 24-recalls and fasted blood samples the morning after each day. Known metabolite markers of dietary intake (approximately 70) were identified in blood and urine with LC-MSqToF, and semi-quantified with a known standard. Twenty-four hour urine sodium content was also measured as the current best known objective marker of dietary intake(4). Twenty-four participants (74% female, age (SD) 24.8 (6.1), BMI 24.1 (4.0)) commenced the study, with 21 (88%) completing all three interventions. Mean energy intake on feeding days (11720 kJ (2943.01)) was higher than self-reported energy intake on standardisation days (9243.57 kJ (3582.92)). Meals were well tolerated, with mean (range) intakes of 9.8 (6.3 – 16.1) serves whole grains, 2.4 (1.6 – 4.8) serves fish, 3.1 (1.9 – 5.5) serves dairy, 5.6 (4.5 – 9.1) serves chicken, 8.2 (7.0 – 14.1) serves legumes, 3.1 (1.3 – 4.6) serves fruit, 3.9 (2.6 – 6.4) serves red meat, 1.7 (1.35 – 2.6) serves nuts and seeds, or 13.4 (9.4 – 19.5) serves vegetables on their respective feeding days. The three feeding days provided clearly identifiable clusters when assessing the overall metabolic profile, both in terms of what was measured on the feeding days, and the difference in metabolite concentrations between standardisation day and feeding day. The relative correlations between self-reported intakes and individual metabolite concentrations reflecting specific foods or food groups with the known dietary intakes from feeding days will be presented first at the conference.

Combined Strategy Using High Hydrostatic Pressure, Temperature and Enzymatic Hydrolysis for Development of Fibre-Rich Ingredients from Oat and Wheat By-Products

Wheat bran (WB) and oat hull (OH) are two interesting undervalued cereal processing sources rich in total dietary fibre (TDF) and other associated bioactive compounds, such as β-glucans and polyphenols. The aim of this study was to optimise a combination chemical (enzymes) and physical (high hydrostatic pressure-temperature) strategies to increase the bioaccessibility of bioactive compounds naturally bound to the bran and hull outer layers. WB and OH were hydrolysed using food-grade enzymes (UltraFloXL and Viscoferm, for WB and OH, respectively) in combination with HPP at different temperatures (40, 50, 60 and 70 °C) and hydrolysis either before or after HPP. Proximal composition, phytic acid, β-glucans, total phenolics (TPs) and total antioxidant activity (TAC) were evaluated to select the processing conditions for optimal nutritional and bioactive properties of the final ingredients. The application of the hydrolysis step after the HPP treatment resulted in lower phytic acid levels in both matrices (WB and OH). On the other hand, the release of β-glucan was more effective at the highest temperature (70 °C) used during pressurisation. After the treatment, the TP content ranged from 756.47 to 1395.27 µmol GAE 100 g−1 in WB, and OH showed values from 566.91 to 930.45 µmol GAE 100 g−1. An interaction effect between the temperature and hydrolysis timing (applied before or after HPP) was observed in the case of OH. Hydrolysis applied before HPP was more efficient in releasing OH TPs at lower HPP temperatures (40–50 °C); meanwhile, at higher HPP temperatures (60–70 °C), hydrolysis yielded higher TP values when applied after HPP. This effect was not observed in WB, where the hydrolysis was more effective before HPP. The TP results were significantly correlated with the TAC values. The results showed that the application of optimal process conditions (hydrolysis before HPP at 60 or 70 °C for WB; hydrolysis after HPP at 70 °C for OH) can increase the biological value of the final ingredients obtained.

Absorption, accumulation, and distribution of atmospheric metals in rice (Oryza sativa L.)

Crop metal contamination caused by atmospheric metal pollution has been increasingly reported. To investigate the absorption, accumulation, and distribution of atmospheric metals in rice (Oryza sativa L.), a field experiment was conducted with rice grown at an atmospheric metal pollution site and a background site. The concentrations of Pb, Cd, Cu, Mn, and Zn in the atmospheric deposition at the pollution site were significantly higher than those at the background site. Consequently, the rice tillering number decreased by 56–64% and the yield decreased by 53–69% at the pollution site compared to the background site. Particularly, Pb isotope analysis found that 76% of the Pb in the rice grain at the pollution site was attributed to atmospheric Pb. Furthermore, observations by transmission electron microscopy found penetration through the leaf cuticle seems to be the primary pathway for the absorption of atmospheric metals. Using laser ablation inductively coupled plasma-mass spectrometry, it was found that the distribution of metals in rice grains at the two sites was similar, with Pb, Cr, Fe, Mn, Cu, and Ca mainly in the bran layer while Cd and Zn uniformly distributed throughout the entire grains. Possible solutions to address atmospheric metal pollution in crops are discussed.

Exploring the Impact of Fermentation on Brown Rice: Health Benefits and Value-Added Foods—A Comprehensive Meta-Analysis

The escalating global incidence of obesity and chronic diet-related disorders, such as type 2 diabetes, hypertension, cardiovascular disease, malignancies, and celiac disease, has intensified the focus on dietary factors and disease risks. Rice, a dietary staple for billions, is under scrutiny, particularly polished or white rice, which is high in starch and in the glycemic index and low in nutrition due to the removal of the outer bran layer during milling. This study critically analyzes the comparison between whole brown rice (BR) and milled white rice in terms of health benefits. A significant finding is the enhancement of food nutrition through fermentation, which improves protein digestibility and mineral availability and releases peptides and amino acids. The study also highlights the increased antibacterial and antioxidant activity of foods, including health benefits, through fermentation. A comprehensive review of existing data on the nutritional content and health advantages of whole fermented BR grains is presented, alongside experiments in developing fermented BR-based foods. The safety, preservation, and the economic and environmental advantages of consuming regularly fermented BR instead of white or unfermented BR are discussed. Finally, the paper addresses the commercialization challenges and future opportunities for promoting fermented BR as a healthier food alternative.

Rice bran is a key structure affecting high nutrition and low toxicity of indica hybrid rice (Oryza sativa L.)

Rice is a staple for over half of the world's population. However, it presents toxicity risks. In this study, 23 indica rice varieties were selected; the concentration and accumulation of 18 elements in husk, bran, and milled rice were measured. The correlations between elements differ, with specific correlation networks in each grain layer, with the bran layer being the most complex. Cd and As in the bran layer accounted for 16.6% and 39.7% of the total accumulation in brown rice, respectively. Removal of the bran layer significantly reduced Fe by 35.2% and Zn by 30.2%. With the goals of high nutrition and low toxicity, the CY6709 and LLY7810 brown rice varieties were suitable without modification, whereas JY781 is best milled to reduce the risk of heavy-metal poisoning. Overall, the bran layer was enriched with both toxic and nutrient elements. To ensure greater nutrient intake, we encourage more brown rice consumption. Moreover, rice varieties should be milled according to their distributions of toxic elements to reduce safety concerns.

Antioxidant Activity of Colored Rice Flour with Drying Temperature Variations

Rice is the main product obtained from grain produced by the rice plant (Oryza sativa) whose entire layer has been peeled off and the bran layer has been separated in the form of head rice, whole rice grains, broken rice, and groats. There are several types of pigmented rice such as brown rice, black rice and black glutinous rice. These kinds of rice have not been utilized optimally so that a processing process is needed to increase the economic value of the colored rice. One of the processing is made as flour so that it is durable and easy to distribute and flour can be used as a food processing material that is practical, easy and durable. One of the processed rice is rice flour. Colored rice flour is the result of processing brown rice, black rice and black glutinous rice by milling or flouring. This study aims to determine the optimal temperature in the manufacture of colored rice flour in order to obtain colored rice flour which has high antioxidant activity and high anthocyanins. The result of flouring is in the form of very fine grains. Flour has a low water content so it is more durable and long lasting. In order to reduce the moisture content, drying is carried out. The study used a completely randomized design (RAL) consisting of 2 factors. The first factor was the type of colored rice, while the second factor was the drying temperature of rice flour. The optimal treatment results were a combination of black glutinous rice flour treatment and a drying temperature of 45°C for 60 minutes, the following results were obtained: water content 7.44%, antioxidant activity by DPPH method 69.89%, antioxidant activity by FRAP method 81.35%, yield 25.29%, total phenol 175.85 mg/kg, and anthocyanin levels 327.10 ppm. Changes in temperature during the drying process of colored rice will affect the characteristics of the colored rice.

Effects of milling on texture and in vitro starch digestibility of oat rice.

Compared with other oat products, consumers in China prefer oat rice and porridge made from naked oat. However, this oat product usually has poor sensory acceptance, which is directly related to the texture properties. This study aimed to use the milling method to improve the oat rice texture. The nutrient component, microstructure, pasting, and thermal properties of oat treated with different degrees of milling (0s, 20s, 40s, 60s, and 80s) were researched. The results showed that milling would damage the bran layer of oat rice, increasing starch, β-glucan, total leached solids content, and the gelatinization enthalpy (ΔH). Meanwhile, oil, protein content, the pasting viscosity, and the pasting temperature were decreased. Milling made oat rice sticky and soft, and the bound water and non-flowing water migrated like flowing water. The cross-section of oat rice showed that milling damaged the surface of oat rice, which was beneficial to water entry and starch dissolution, and increased the viscosity of oat rice. When the milling time was 40s and 60s, the appearance, aroma, taste, texture, and overall acceptability of oat porridge were better. Moreover, rapid digestion fraction (k1) and slow digestion fraction (k2) are the lowest and have the effect of low blood glucose rise rate.

Characteristics of antioxidant capacity and metabolomics analysis of flavonoids in the bran layer of green glutinous rice (Oryza sativa L. var. Glutinosa Matsum)

Green glutinous rice is a unique genetic germplasm that has yet to be adequately studied. This study investigated antioxidant capacity and flavonoid metabolites in the bran layer of green glutinous rice (LvH) compared to purple (HeiH), red (HongH) and white (GJG) varieties. The results showed that LvH bran had significantly higher content of total flavonoids and anthocyanin than that of HongH (1.91-fold and 4.34-fold) and GJG (2.45-fold and 13.30-fold). LvH bran also showed significantly higher levels of vitamin B1 and vitamin E than that of HeiH (1.94-fold and 1.15-fold) and HongH (1.22-fold and 1.13-fold), indicating that green glutinous rice bran was rich in bioactive components. LvH bran showed significantly lower IC50 values for scavenging DPPH and ATBS radicals than GJG and even significantly lower IC50 value for scavenging DPPH radicals than HongH, highlighting its potential as an effective source of antioxidants. LvH bran had significantly different downstream metabolite synthesis in the flavonoid pathway compared to HeiH, HongH, and GJG, with 40, 26, and 22 different metabolites, 23, 20, and 33 up-regulated differentially expressed metabolites (DEMs), and 73, 50, and 13 down-regulated DEMs, respectively. Of the 139 flavonoid metabolites identified in colored rice bran, 26 metabolites showed significant positive correlation with both ABTS and DPPH radical scavenging capacity. Typically, quercetin derivatives showed potential for evaluating the antioxidant capacity of colored rice bran. These findings offer valuable insights into the antioxidant properties of green glutinous rice bran and provide references for better understanding of flavonoid metabolites in different colored rice bran.

Effect of milling degree on volatile profiles of cooked rice determined by electronic nose and HS‐SPME‐GC‐MS

AbstractBackground and ObjectivesVolatile components are mainly distributed in the rice bran layer; thus, rice with different milling levels exhibit different volatile profiles, which affects the aroma of rice and cooked rice. Seven diverse rice varieties were investigated to explore the effect of milling degree on volatile profiles of cooked rice, odor activity value (OAV) was applied to identify key aroma compounds, and partial least squares discriminant analysis (PLS‐DA) was applied to determine important marker compounds that may affect aroma.FindingsThe volatile profiles of cooked rice with different milling times were different according to the result of electronic nose. A total of 82 volatiles were identified by headspace solid‐phase microextraction‐gas chromatography‐mass spectrometry. The number and total content of volatile compounds in most samples decreased with increasing milling time. The number of key aroma compounds (OAV > 1) in most samples also showed a decreasing trend with increasing milling time. PLS‐DA model successfully discriminated the differential volatile compounds in cooked rice samples with different milling times. Tridecane, 6‐methyl‐5‐heptene‐2‐one, nonanal, decanal, 2‐butyl‐2‐octenal, pentadecanal, 2,4‐decadienal, anethole, geranylacetone, 1‐dodecanol, 2‐pentadecanone, 2‐methoxy‐4‐vinylphenol, and indole were identified as 13 marker aroma‐active compounds.ConclusionsThe effect of milling degree on the volatile profiles of cooked rice was closely related to the rice varieties. Longer milling time was not in favor of the aroma of cooked rice. Milling degree mainly affected the nutty, citrus, fruity, waxy, herbal, fatty, celery, smoky, and floral aromas of cooked rice.Significance and NoveltyThe study provided important information for understanding the impacts of milling degree on volatile compounds and aroma properties of cooked rice. This is of great significance for advocating moderate processing of rice and regulating the aroma quality of cooked rice.

Influence of bran layer on rice milling quality

AbstractBackground and ObjectivesRice milling involves applying forces to remove bran from brown rice to produce milled rice. The physical and chemical properties of a rice kernel may affect both the amount of bran removed during milling and the amount of head rice yield (HRY) produced, which is a determinant of crop value. This study investigated bran thickness and bran chemical composition as factors that influence bran removal and HRY as a result of milling.FindingsThe results showed that brown rice kernels with initial higher surface lipid contents (SLCs) required longer milling times to achieve 0.4% SLC, but the longer milling times did not translate into lower HRYs or higher bran yields. Bran chemical composition had a more significant impact on the milling characteristics than bran thickness. Arabinoxylans had the greatest impact on HRY, followed by lipids and proteins.ConclusionsBran thickness did not have a significant impact on the milling time, bran yield, or HRY. There was significant interaction between arabinoxylans and proteins on HRY and bran yield, which indicates the probability of crosslinking between proteins and arabinoxylans.Significance and NoveltyThis study demonstrates the importance of rice bran chemical components and their interactions in terms of rice milling quality, rather than their physical properties.

A Rapid and Accurate Quantitative Analysis of Cellulose in the Rice Bran Layer Based on Near-Infrared Spectroscopy.

Cultivating rice varieties with lower cellulose content in the bran layer has the potential to enhance both the nutritional value and texture of brown rice. This study aims to establish a rapid and accurate method to quantify cellulose content in the bran layer utilizing near-infrared spectroscopy (NIRS), thereby providing a technical foundation for the selection, screening, and breeding of rice germplasm cultivars characterized by a low cellulose content in the bran layer. To ensure the accuracy of the NIR spectroscopic analysis, the potassium dichromate oxidation (PDO) method was improved and then used as a reference method. Using 141 samples of rice bran layer (rice bran without germ), near-infrared diffuse reflectance (NIRdr) spectra, near-infrared diffuse transmittance (NIRdt) spectra, and fusion spectra of NIRdr and NIRdt were used to establish cellulose quantitative analysis models, followed by a comparative evaluation of these models' predictive performance. Results indicate that the optimized PDO method demonstrates superior precision compared to the original PDO method. Upon examining the established models, their predictive capabilities were ranked in the following order: the fusion model outperforms the NIRdt model, which in turn surpasses the NIRdr model. Of all the fusion models developed, the model exhibiting the highest predictive accuracy utilized fusion spectra (NIRdr-NIRdt (1st der)) derived from preprocessed (first derivative) diffuse reflectance and transmittance spectra. This model achieved an external predictive R2p of 0.903 and an RMSEP of 0.213%. Using this specific model, the rice mutant O2 was successfully identified, which displayed a cellulose content in the bran layer of 3.28%, representing a 0.86% decrease compared to the wild type (W7). The utilization of NIRS enables quantitative analysis of the cellulose content within the rice bran layer, thereby providing essential technical support for the selection of rice varieties characterized by lower cellulose content in the bran layer.

Comparison of Nutritional Composition and Antioxidant Properties of Pulverized and Unutilized Portions of Waxy Barley.

To promote the use of waxy barley bran, an underutilized resource, samples of waxy barley were divided into three parts: polished waxy barley powder (PWBP), inner bran layer powder (IBLP), and outer bran layer powder (OBLP). The color and appearance, general properties, minerals, vitamins, β-glucan, antioxidant properties, and aroma of each part were compared. In terms of appearance and color, IBLP and OBLP appeared more yellow than PWBP; general components that were more abundant in IBLP and OBLP compared with PWBP were protein, fat, and ash. IBLP and OBLP had characteristically high values of Mg and Zn, monounsaturated and polyunsaturated fatty acids, vitamin B1, total polyphenol content, H-ORAC, and DPPH. In particular, the vitamin B1 content of OBLP was approximately 10 times higher than that of PWBP, and Mg and Zn content was more than five times higher than in PWBP. The β-glucan content of IBLP and OBLP was lower than that of PWBP, but relatively high. GC-MS analysis revealed that hexanal was the aroma component common to all three samples, and the peak areas were in the order of PWBP > OBLP > IBLP.

Bioaccessibility of ferulic acid in hulless barley varieties at stages of simulated in vitro digestion

AbstractBackground and ObjectivesFerulic acid has antioxidant, anti‐inflammatory, and antimicrobial activity. Ferulic acid in barley is present in esterified form in the bran layer, however, only the free form is bioaccessible in the upper gastrointestinal tract. The objectives of this study were to investigate the bioaccessibility of ferulic acid at four stages of simulated gastrointestinal digestion of two barley varieties to determine when ferulic acid is released and investigate factors which may affect the release of ferulic acid including digestive enzymes and pH.FindingsThe release of ferulic acid was strongly influenced by digestive enzymes and minimally by pH. The presence of enzymes reduced free ferulic acid but increased the amount of esterified ferulic acid. The major release of esterified ferulic acid occurred during the final hour of small intestinal digestion. The amount of bioaccessible ferulic acid remained constant throughout digestion. The bran thickness, measured by microCT imaging, significantly differed between the varieties.ConclusionDuring digestion, ferulic acid changed structurally, as observed by the changes in the amount of free and esterified ferulic acid at four digestion timepoints. The release of ferulic acid was strongly influenced by exposure to digestive enzymes and minimally by pH, although the mechanism of the presence of enzymes on ferulic acid release is unclear. The bioaccessibility of ferulic acid may be determined by the bran layer thickness and further investigation is required.Significance and NoveltyThis is the first study to investigate the bioaccessibility of ferulic acid in barley at various stages of digestion and to measure the bran thickness of barley using microCT imaging with preliminary findings indicating enhanced ferulic acid bioaccessibility in grains with a thinner bran layer.