Middle infrared stabilization of individual rice bran milling fractions

The impact of milling degree on physicochemical, nutritional, rheological, textural properties, and in vitro digestibility of rice: From brown rice to white rice

The objective of this study was to characterize the rice milling fractions acquired at each stage of a commercial milling system. This characterization included an analysis of color, ash content, dietary fiber, mineral composition, as well as antinutritional compounds like phytic acid, trypsin inhibitor activity, and saponin. Additionally, we investigated in vitro starch and in vitro protein digestibility, along with pasting, cooking, and textural properties. Our findings revealed that milling improved the visual appeal of rice (e.g., volume expansion, weight gain, whiteness) and notably enhanced its starch digestibility. However, milling reduced dietary fiber, mineral content, antinutrients, cooking time, and texture characteristics such as hardness, chewiness, gumminess, springiness, and cohesiveness to varying degrees. Certain parameters, such as dietary fiber, exhibited a gradual change with the duration of milling, while others, such as mineral content and texture, showed significant variation at the initial stage of milling, particularly at the first mill.

Production of fermented milk analogs using subcritical water extraction of rice by-products and investigation of its physicochemical, microbial, rheological, and sensory properties

Rice milling by-products extract and Persian grape syrup (Persian grape molasses), as the proper alternatives for milk ingredients and sucrose, respectively, can be considered a promising way to produce functional milk analogs. In this study, we studied the production of rice milling by-product extracts via the subcritical water extraction method, as a green method. The optimum extract was then fermented by Lactobacillus casei and Lactobacillus plantarum, and the different physicochemical, sensory, and rheological properties and the viability of these lactic acid bacteria were assessed during fermentation and certain intervals of 28-day storage. Considering rheological properties, the optimum rice milling by-product extract was recognized based on DOE analysis and the rheological curves of fermented drinks and Persian grape molasses were fitted by Herschel-Bulkley and Bingham models, respectively. The extract and also milk analog had excellent fitness with Herschel-Bulkley model, and this fermented milk analog showed a drop in the consistency index, flow behavior, and yield stress during the 28-day storage. According to the results, the viable cell count of Lactobacillus plantarum and Lactobacillus casei remained at 106-108 colony forming unit/mL after 28-day storage, which showed a combination of rice milling by-product ingredients and inulin had a positive effect on the survival rate of lactic acid bacteria. An increase in values of total phenolic compounds, as well as antioxidant activity observed during fermentation; however, these compounds dropped considerably during storage as a result of degradation and interaction with other compounds. Moreover, in terms of sensory evaluation, Lactobacillus plantarum drinks provided the highest overall acceptability among other samples on the 28th day.

Effect of various phosphorus levels on the extraction of Cd, the transformation of P, and phosphorus-related gene during the phytoremediation of Cd contaminated soil

Phytoremediation has emerged as a common technique for remediating Cd pollution in farmland soil. Moreover, phosphorus, an essential element for plants, can alter the pectin content of plant cell walls and facilitate the accumulation of Cd in plant tissues, thereby enhancing phytoremediation efficiency. Therefore, pot experiments were conducted in order to investigate the effect of phosphorus levels on Cd extraction, phosphorus transformation and phosphorus-related genes during phytoremediation. The results revealed that an optimal application of suitable phosphate fertilizers elevated the soil's pH and electrical conductivity (EC), facilitated the conversion of soil from insoluble phosphorus into available forms, augmented the release of pertinent enzyme activity, and induced the expression of phosphorus cycling-related genes. These enhancements in soil conditions significantly promoted the growth of ryegrass. When applying phosphorus at a rate of 600 mg/kg, ryegrass exhibited plant height, dry weight, and chlorophyll relative content that were 1.27, 1.26, and 1.18 times higher than those in the control group (P0), while the Cd content was 1.12 times greater than that of P0. The potentially toxic elements decline ratio and bioconcentration factor were 42.86% and 1.17 times higher than those of P0, respectively. Consequently, ryegrass demonstrated the highest Cd removal efficiency under these conditions. Results from redundancy analysis (RDA) revealed a significant correlation among pH, total phosphorus, heavy metal content, phosphorus forms, soil enzyme activity, and phosphorus-related genes. In conclusion, this study suggests applying an optimal amount of suitable phosphate fertilizers can enhance restoration efficiency, leading to a reduction in soil Cd content and ultimately improving the safety of crop production in farmlands.

Stabilization of Rice Bran by Infrared Radiation Heating for Increased Resilience and Quality of Rice Bran Oil Production

Rice bran, a by-product of rice milling, is a valuable source of rice bran oil (RBO). However, it is prone to rancidity and must be processed quickly after rice polishing. The researchers found that rice bran stabilization with infrared radiation (IR) at 125 V and 135 V for 5∼10 min. The most promising IR treatments were 125 V for 10 min and 135 V for 5 min, which resulted in the lowest lipase activity (93∼96% inhibition) and levels of γ-oryzanol and α-tocopherol comparable to those of the untreated control. However, the color of rice bran and RBO based on L*, a*, b*, and total color difference (ΔE) and Gardner-20 mm index darkened. Upon storage of rice bran at 38°C for 8 weeks, the use of these two IR treatments completely inhibited the rise in free fatty acid (FFA) content and peroxide values throughout the storage period. In contrast, the control had a pre-storage FFA more than double that of IR-stabilized rice bran, which further increased during storage and, in the 8th week, was more than 6-fold higher than the pre-storage level. γ-oryzanol and α-tocopherol slightly decreased with storage and their levels did not differ between stabilized and unstabilized rice bran. RBO color darkening was again observed, but the color lightened with storage, especially upon treatment at 135 V for 5 min. In contrast, the color of control RBO darkened with storage. Thus, IR at 135 V for 5 min was the most promising method for rice bran stabilization, based on which commercial IR treatment instruments can be developed.

Stabilization of Rice Bran: A Review

One of the major problems in food science is meeting the demand of the world's growing population, despite environmental limitations such as climate change, water scarcity, land degradation, marine pollution, and desertification. Preventing food from going to waste and utilizing nutritive by-products as food rather than feed are easy and powerful strategies for overcoming this problem. Rice is an important staple food crop for more than half of the world's population and substantial quantities of rice bran emerge as the main by-product of rice grain milling. Usually, rice bran is used as animal feed or discarded as waste. Although it is highly nutritious and comprises many bioactive compounds with considerable health benefits, the rapid deterioration of bran limits the exploitation of the full potential of rice bran. Hydrolytic rancidity is the main obstacle to using rice bran as food, and the enzyme inactivation process, which is termed stabilization, is the only way to prevent it. This study reviews the methods of stabilizing rice bran and other rice-milling by-products comprising rice bran in the context of the efficiency of the process upon storage. The effect of the process on the components of rice bran is also discussed.

The Effects of Thermal Treatment on Lipid Oxidation, Protein Changes, and Storage Stabilization of Rice Bran

Rice bran is a nutrient-rich and resource-dense byproduct of rice milling. The primary cause of rice bran utilization limitation is oxidative deterioration and inadequate storage facilities. Improving stability to extend the shelf-life of rice bran has thus become an utmost necessity. This study aimed to stabilize raw fresh rice bran (RB) by using dry heat methods at 120 °C (233, 143, and 88 min) and 130 °C (86, 66, and 50 min). The results indicated that after dry heat pretreatment, peroxidase levels were at 90%, and the storage stability of dry-heat-stabilized RB was better. However, with an increase in treatment temperature and time, the peroxidase activity improved while the lipase activity decreased to a certain extent without significant changes. The total saturated and unsaturated fatty acids were significantly unchanged during storage, while oleic/linoleic acid increased substantially by 1% at 120 °C for 88 min. The increase in treatment time and temperature was beneficial in controlling the fatty acid values. However, extended treatment time caused an increase in the peroxide value and MDA. The essential and non-essential amino acid ratios, which evaluate a protein's nutritional value, remained relatively stable. The essential subunit of rice bran protein was not affected by the temperature and time of dry heat treatment and storage time.

Effect of novel combination processing technologies on extraction and quality of rice bran oil

Rice bran, a primary by-product from the rice processing industries, containing 10-15% oil, attracts significant attention from consumers due to its many health-promoting effects. The extraction methodology used is one of the most critical factors affecting the quality and yield of oil from rice bran. Using solvents is the current commercial process for rice bran oil extraction, which has its setbacks. It is challenging and expensive, and there is a risk of traces of solvent residue in the oil. Emerging combination extraction technologies offer zero to minimal solvent residues or chemical deformation while considering increasing environmental and energy footprint. Emerging combination processing technologies include new-age methods like supercritical fluid extraction, sub-critical fluid extraction, ultrasound-assisted enzymatic extraction, ohmic heating, and microwave-assisted extraction. These techniques have been reported to extract oil from rice bran, improving extraction efficiency and quality. These techniques demonstrate solid prospects for future applications. The present review discusses and compares these emerging technologies for oil extraction from rice bran commercially.

Research advance in gas detection of volatile organic compounds released in rice quality deterioration process

Rice quality deterioration will cause grievous waste of stored grain and various food safety problems. Gas detection of volatile organic compounds (VOCs) produced by deterioration is a nondestructive detection method to judge rice quality and alleviate rice spoilage. This review discussed the research advance of VOCs detection in terms of nondestructive detection methods of rice quality deterioration, applications of VOCs in grain detection, inspection of characteristic gas produced during rice spoilage, rice deterioration prevention and control, and detection of VOCs released by rice mildew and insect attack. According to the main causes of rice quality deterioration and major sources of VOCs with off-odor generated during rice storage, deterioration can be divided into mold and insect infection. The results of literature manifested that researches mainly focused on the infection of Aspergillus in the mildew process and the attack of certain pests in recent years, thus the research scope was limited. In this paper, the gas detection methods combined with the chemometrics to qualitatively analyze the VOCs, as well as the correlation with the number of colonies and insects were further studied based on the common dominant strains during rice mildew, that is, Aspergillus and Penicillium fungi, and the common pests during storage, that is, Sitophilus oryzae and Rhyzopertha dominica. Furthermore, this paper pointed out that the quantitative determination of characteristic VOCs, the numeration relationship between VOCs and the degree of mildew and insect infestation, the further expansion of detection range, and the application of degraded rice should be the spotlight of future research.

Immobilization of cadmium by Burkholderia sp. QY14 through modified microbially induced phosphate precipitation

Microbially induced phosphate precipitation (MIPP) is an advanced bioremediation technology to immobilize heavy metals. An indigenous bacterium QY14 with the function of mineralization isolated from Cd contaminated farmland soil was identified as Burkholderia ambifaria. The minimum inhibitory concentration value for QY14 was 550 mg/L for soluble Cd concentration. This study found that the addition of 10 mM Ca²⁺ during MIPP process could significantly increase the removal ratio of Cd, and the maximum removal ratio of Cd with 10 mM Ca²⁺ and without Ca²⁺ in solution was 99.97% and 76.14%, respectively. The increase of acid phosphatase activity and the formation of precipitate containing calcium caused by 10 mM Ca²⁺ addition contributed the increase of Cd removal efficiency. The results of SEM-EDS, FTIR and XRD showed that Cd was removed by forming Cd containing hydroxyapatite (Cd-HAP). In addition, the dissolution experiment showed the Cd release ratio of Cd-HAP (0.01‰ at initial pH 3.0 of solution) was lower than Cd-absorbed HAP, indicating that Cd was more likely removed by the formation of Ca_10-xCd_x(PO₄)₆(OH)₂ solid solution. Our findings revealed MIPP-based bioremediation supplied with 10 mM Ca²⁺ could increase the Cd removal and could potentially be applied for Cd remediation.

Lipase - The fascinating dynamics of enzyme in seed storage and germination - A real challenge to pearl millet

Pearl millet is considered as 'nutri-cereal' because of high nutrient density of the seeds. The grain has limited use because of low keeping quality of the flour due to the activities of rancidity causing enzymes like lipase, lox, pox and PPO. Among all the enzymes, lipase is most notorious because of its robust nature and high activity under different conditions. we have identified 2180 putative transcripts showing homology with different variants of lipase precursor through transcriptome data mining (NCBI BioProject acc. no. PRJNA625418). Lipase plays dual role of facilitating the germination of seeds and deteriorating the quality of the pearl millet flour through hydrolytic rancidity. Different physiochemical methods like heat treatment, micro oven, hydrothermal, etc. have been developed to inhibit lipase activity in pearl millet flour. There is further need to develop improved processing technologies to inhibit the hydrolytic and oxidative rancidity in the floor with enhanced shelf-life.

Effects of Radio Frequency Heating on the Stability and Antioxidant Properties of Rice Bran

Radio frequency (RF) technology is considered as a rapid heating method. Lipase in rice bran could highly accelerate lipid oxidation. The objectives of this study were to establish the radio frequency heating conditions for lipase inactivation and to evaluate the stability and antioxidant capacity. The results showed that the suitable electrode gap for a 1 kg sample load was 6 cm, and it only took 2 min to heat rice bran from 25 °C to 100 °C. Besides, there were no significant differences in the total phenolic content, flavonoid content and color between the untreated and RF-treated group, and the DPPH free radical scavenging activity of the RF treatment reached 84.8%. The acid value, free fatty acid content and peroxide value of the RF-treated rice bran met the quality standard after 8 weeks of storage at 4, 25 and 37 °C. In summary, this study provides valuable information about the RF heating procedure, and shows the great potential of RF technology for stabilizing rice bran efficiently.

A clinical empirical study on the role of refined rice bran in the prevention and improvement of metabolic syndrome

Rice bran contains lipolytic enzymes with extremely high activity that facilitate the hydrolysis of triglycerides into glycerol and fatty acids. This also causes rice bran to easily deteriorate, limiting its use, and they are not popular in the market. Researchers look forward to seeing the refined rice brans work well for metabolic syndrome. This study used gas cooling by liquid nitrogen and an instant sterilization system operated at high temperature to stabilize and refine the rice bran. The refined rice bran was compared using in vitro tests with three other types of rice bran that had not been specially treated. The refined rice bran was discovered to have superior solubility, fast absorption, and excellent oxidation resistance compared with the other three rice bran samples. In a human subject test, significant improvements in waistline, systolic pressure, diastolic pressure, fasting plasma glucose, glycated hemoglobin, and triglyceride level were discovered after participants ingested refined rice bran for 8 weeks. This indicated that consuming refined rice bran can reduce the waistline, control blood pressure and blood glucose, and inhibit fate formation. The items for which significance was obtained are also the indicators of metabolic syndrome, as stipulated by the World Health Organization. Therefore, according to the results of the human subject test, ingesting refined rice bran can improve the metabolic syndrome. PRACTICAL APPLICATIONS: This refinement improved the in vivo absorption and stabilized the properties of the rice bran for better preservation. In this study, excellent results were obtained using the refined rice bran in both in vitro tests and a human subject test. Refined rice bran thus has potential for mass production and used as a health supplement. It can alleviate the symptoms of metabolic syndrome and reduce the incidence of cardiovascular diseases.

Storage characteristics of infrared radiation stabilized rice bran and its shelf-life evaluation by prediction modeling

BACKGROUND

Rice bran is a nutrient-dense and resource-rich byproduct produced from the rice milling. The limitation of rice bran utilization is mainly caused by oxidative deterioration. Improvement of stability to prolong rice bran shelf-life has thus become an urgent requirement.

RESULTS

The present study aimed to determine the characteristics of infrared radiation heat treatment of rice bran (IRRB) and raw rice bran stored under different temperatures. The effects of heating and storage time on physicochemical, microbial, storage stability and structural properties were investigated. Additionally, the prediction model for the shelf-life of rice bran was established based on free fatty acids and the peroxide value by fitting the curve of bran lipid oxidation. The results obtained demonstrated that infrared radiation heating at 300 °C for 210 s resulted in decreased lipase activity and peroxidase activity of 73.05% and 81.50%, respectively. The free fatty acids and peroxide value of IRRB stored at 4 and 25 °C for 8 weeks were only reached at 2.35% and 3.17% and 2.53 and 3.64 meq kg^-1 , respectively. The shelf-life prediction model showed the the shelf-life of infrared radiation-treated samples increased to 71.6 and 25.8 weeks under storage at 4 and 25 °C, respectively.

CONCLUSION

The stabilizing process could effectively suppress microbial growth and had no prominent effect on the physicochemical and microstructure properties of rice bran and, simultaneously, storage life was greatly extended. © 2020 Society of Chemical Industry.

Effect of citric acid and vermi-wash on growth and metal accumulation of Sorghum bicolor cultivated in lead and nickel contaminated soil

The aim of the present study is to assess the influence of vermi-wash (VW) and citric acid (CA) on Sorghum bicolor growth and phytoaccumulation of lead (Pb) and nickel (Ni) contaminated soil. The biomass of the S. bicolor has been enhanced by the addition of VW (24 and 26%) and CA (11 and 9%) in Pb and Ni contaminated soil, respectively. The VW treatment showed enhanced shoot and root lengths and chlorophyll concentrations compared to CA. The shoot anatomic structure showed an accumulation of Pb and Ni were positively impacted by the amendment of VW and CA. In addition, VW treatment showed enhanced antioxidant enzymes activity (140, 125 and 152 U/mg of CAT, SOD and POD). Further, the plants grown in Pb contaminated soil treated with VW showed enhanced Rubisco activity of 1.49 U/ml, whereas, CA treatment showed 1.23 U/ml of Rubisco. It has been observed that the VW showed as a potential chelator as well as plant beneficial formulation for the enhanced phyto-remediation of Pb and Ni.

Stabilization of rice bran milling fractions using microwave heating and its effect on storage

Rice bran tends to become rancid during storage if it is not stabilized. In commercial rice mills, bran is removed in phases using battery of polishers and different fractions of rice bran are produced. The stabilization reduces peroxidase, lipases, lipoxygenase and auto-oxidation enzymatic activities. The bran fractions were stabilized by continuous microwave heating at different treatment combinations (850, 925 and 1000 W; 3, 4.5 and 6 min) and stability of bran fractions were analysed in terms of Free Fatty Acid (FFA), Acid value (AV) and Peroxide value (PV) for 90 days at the interval of 15 days. As power and exposure time increases the FFA, AV and PV are found to be low during storage period. The rancidity level was high in last milling bran fraction and as milling progressed, the rancidity level also increased and it was similar throughout the storage. The bran fractions processed at 925 W to 3 min found to be the suitable condition for stabilization of rice bran milling fractions.

Impact on the nutritional attributes of rice bran following various stabilization procedures

Rice bran, a valuable byproduct of the rice milling process, has limitations in food industrial applications due to its instability during storage. This review summaries the methodology for stabilization and its impact on the nutritional properties of rice bran. A variety of treatments have been used and these include heat treatment, low-temperature storage, biological and chemical approaches and these will be discussed in terms of their ability to destroy/inhibit enzyme activity and improve storage performance of rice bran. More importantly, changes in the nutritional value of rice bran in terms of vitamins, polyphenols, tocopherols, flavonoids, free fatty acids caused by stabilization of rice bran will also be discussed. This review highlights the importance of appropriate design of processes for stabilization and controlling storage conditions to ensure quality of the rice bran and enhancing levels of phytochemicals in the bran for novel applications in functional foods.

Inactivation of Lipase and Lipoxygenase of Wheat Germ with Temperature-Controlled Short Wave Infrared Radiation and Its Effect on Storage Stability and Quality of Wheat Germ Oil

Wheat germ (WG) is quite susceptible to deterioration due to the presence of lipase (LA) and lipoxygenase (LOX). Therefore it is indispensable to adopt a stabilization step to decrease the activity of LA and LOX while retaining a maximum level of nutrients. But over-drying can make foodstuffs more susceptible to autoxidation. So a stabilization protocol for inactivating LA and LOX of WG with a temperature- controlled short wave infrared (SIR) radiation system was adopted to retard its rancidity and retain a maximum level of fat-soluble nutrients. Meanwhile, the critical storage water activity (Aw) of WG for inhibiting both hydrolytic and oxidative rancidity was appraised. Results indicate that WG irradiated at 90°C for 20 min acquired the optimal stabilization effect, and its residual LA and LOX activity were 18.02% and 19.21%, respectively. At this condition, the free fatty acids (FFA) content and peroxide value (PV) increment of WG oil at 40°C remained below 5% and 2.24 meq O2/kg for 60 days, respectively. The residual Aw of this WG sample was 0.13, and it is near the Aw corresponding to its monolayer. No significant decrease of fatty acids was observed during SIR processing, while about 96.42% of its original tocopherols still retained in WG treated at 90°C for 20 min.