Raw Rice Samples Research Articles

Food-mediated exposure of Hofmeister ions in Oryza sativa (Rice) from selected CKDu endemic regions in Sri Lanka.

The objectives of this study were to determine selected Hofmeister anions and cations that are important for kidney health, in raw rice samples from selected Chronic Kidney Disease of unknown etiology (CKDu) endemic and non-endemic areas in Sri Lanka and their intake. The anions and cations were analyzed by Ion Chromatography and Microwave Plasma Atomic Emission Spectrometry (MP-AES), respectively, after alkaline and acid digestion in thirty raw rice samples each from CKDu endemic and non-endemic areas, and the dietary intake was estimated. The mean concentrations of fluoride (F-), chloride (Cl-), phosphate (PO43-), sulfate (SO42-), sodium (Na+), magnesium (Mg2+), potassium (K+), and calcium (Ca2+) in raw rice in CKDu endemic areas were 53.317, 1515.3, 2799.6, 2704.9, 30.603, 300.76, 1001.3, and 90.075mg/kg, respectively. The mean concentration of the anions and cations in raw rice from CKDu non-endemic areas were 22.850, 947.52, 4418.7, 6080.2, 23.862, 364.45, 955.78, and 96.780mg/kg, respectively. Significantly higher differences (p < 0.05) were reported in the mean concentration of F-, Cl-, and Na+ in raw rice from CKDu endemic areas in comparison with the samples from non-endemic areas. The aggregated estimated daily intake (EDI) and cumulative EDI of F- via consumption of cooked non-traditional samba rice from CKDu endemic areas for adults were the highest (0.155 and 0.172mg/kg bw/d, respectively), which were higher than the recommended tolerable upper intake value (0.15-0.2mg/kg bw/d). In contrast, the traditional rice from CKDu non-endemic areas for adolescents, reported the lowest values (0.0210 and 0.0470mg/kg bw/d, respectively). Adults who consume non-traditional samba rice from CKDu endemic areas were at health risk, while children were the most vulnerable group due to their low body weight. These results indicate that the consumption of rice rich in Hofmeister ions may contribute to the total intake and act as risk factors to negatively affect weak kidneys in CKDu endemic areas. Further research to analyze Hofmeister ions in cooked rice and rice from different countries is recommended.

Comparative studies on nutritional and functional properties of selected traditional rice varieties in Sri Lanka

Non-communicable diseases are chronic metabolic diseases increasing rapidly around the world. Evaluation of natural food sources in terms of controlling or preventing non-communicable diseases is an immerging research area in food science and nutrition schemes. Traditional rice varieties are one of the food commodities currently becoming popular among health-conscious consumers, as they provide health benefits through bioactive compounds or functional food ingredients other than a variety of nutrients. This study aimed to assess the nutritional and functional properties of selected 20 traditional rice varieties in Sri Lanka. Proximate composition was analyzed for raw rice samples. Methanolic extracts of rice were analyzed for total phenolic content (TPC), total flavonoid content (TFC), carotenoid content (TC), antioxidant, anti-inflammatory and anti-diabetic properties. In vitro gastrointestinal digestion was performed to evaluate the bioavailability of bioactive compounds. Rice samples with higher anti-diabetic properties were tested for a postprandial glycemic response using healthy individuals. The results indicated fresh methanolic extracts of Rath Kadha had the significantly (p&lt;0.05) highest TPC (9.94±0.01mgGAE/g FW) and TC (2.27±0.06 mg/g FW), Beheth Heenati have the highest DPPH% inhibition (84.93±0.81%), Sudu Heenati had the significantly (p&lt;0.05) highest TFC (16.77±0.01mg RE/g FW), anti-diabetic properties (59.54±0.02%) and anti-inflammatory properties (65.85±0.01%). Among the rice varieties subjected to in vitro digestion, Suwadel showed highest significant (p&lt;0.05) TPC (0.45±0.02 mg GAE/g FW) and TFC (2.01±0.02 mgRE/g FW), Ma Vee showed the highest TC (0.24±0.015 mg/g FW) and Pachchaperumal showed the highest DPPH% inhibition (61.77±0.02%) in the gastric phase. In the intestinal Phase Sudu Heenati showed the highest TPC (0.99±0.04 mgGAE/g FW), Ma Vee showed the highest TFC (0.8±0.01 mgRE/g FW) and TC (3.24±0.04 mg/g FW), Beheth Heenati showed the highest DPPH% inhibition (63.98±0.07%). Tested all cooked rice varieties exhibited a lower postprandial glycemic response than glucose. Among the cooked rice varieties Maa Vee showed the lowest peak (97mg/dl) concerning glucose. According to glycemic response, values were significantly (p&lt;0.05) changed with the rice variety. The results highlighted that traditional rice verities are rich with a wide range of functional properties and useful in the management of non-communicable diseases and their complications.

Public health risk due to aflatoxin and fumonisin contamination in rice in the Mekong Delta, Vietnam

Mycotoxin contamination in rice can lead to a health risk for consumers. In this study, the health risk among different age groups of Vietnamese population in the Mekong Delta, Vietnam was evaluated through rice consumption. Total aflatoxins (AFs) and fumonisins (FBs) in raw rice samples (n = 50) were analyzed using an ELISA method. A survey (n = 155) was used to collect data on rice consumption and consumer practices for the evaluation of mycotoxin exposure. Results showed that the frequency of AFs and FBs contamination was 60 and 74% with the average concentrations in raw rice ranging from 1.88–4.00 ng/g and 227–290 ng/g from the lower bound (LB) to the upper bound (UB), respectively. The average AFs exposure due to rice consumption was estimated from 0.81 to 2.44 ng/kg bw/day at scenarios LB – UB with the medium bound (MB) of 2.10, 1.60, 1.92 and 1.23 ng/kg bw/day for children, adolescents, adults and elderly, respectively. These values ranged from 343 to 724 ng/kg bw/day with respect to FBs (scenarios LB - UB), which are below the provisional maximum tolerable daily intakes (PMTDI) value (2000 ng/kg bw/day). The margin of exposure (MoE) to AFs ranged from 160 to 1585,179-2669,149–2175 and 206–3480 for children, adolescent, adults and elderly, respectively from UB - LB, indicating a high health risk for this carcinogenic hazard since the values are so lower than 10,000 (safe limit). However, for FBs, MoE value ranged from 105 to 575 (UB-LB) for all groups, which are higher compared to 100 (safe limit), indicating no risk for public health. The mean cancer risk due to estimated AFs exposure at LB - UB was 0.05–0.13 cases/year/100,000 individuals with MB of 0.08–0.13 cases/year/100,000 people for all four age groups. This study provides new insights into probabilistic risk assessment and potential health impact of mycotoxins in rice in the Mekong Delta, Vietnam.

Impact of soaking and cooking treatments on the physicochemical and antioxidant properties of parboiled and non-parboiled rice (Oryza sativa L.).

The effects of soaking and cooking on the physicochemical properties and bioactive compounds of two parboiled and non-parboiled rice cultivars (BRRI-28 and Katari bhog) were investigated in this study. Total phenolic content (TPC) increased significantly (p ≤ 0.5) after soaking, while total flavonoid content (TFC) and proanthocyanidin content (PC) decreased significantly (p ≤ 0.5) compared to untreated rice samples. TPC increased by around 23% and 20% in parboiled BRRI 28 and Katari bhog rice extracts, respectively, due to the cooking process, while TFC and PC decreased significantly. DPPH radical scavenging increased whereas reducing power activity decreased after soaking and cooking in parboiled BRRI 28. After processing, the protein, starch, and amylose content of all samples decreased in the majority of cases. After being soaked, all samples L * and b * values increased as compared to raw rice samples. As a result, it can be concluded that the treatment of soaking and cooking of parboiled rice (BRRI-28) was suitable to improve the antioxidant properties as compared to non-parboiled rice.

Evaluation of in vitro bioaccessibility of Cr, Ni and Pb in rice varieties. Effect of cooking, dietary components and risk assessment

Cr, Ni and Pb content and bioaccessibility of six rice varieties (Oryza sativa L.) were studied. Raw rice samples showed values ranged between 0.079 - 0.138 μg/g; 0.063–0.405 μg/g; 0.094–0.223 μg/g for Cr, Ni and Pb respectively. Cr and Ni contents in rice cooked in glass cookware did not vary significantly from that initially present in the raw samples. Conversely, cooking rice in stainless steel containers implied an increase in Cr and Ni concentration about 1.5–3 fold with respect to the raw samples. Nevertheless, Cr and Ni bioaccessible concentrations in the later were very similar to those found for the same rice varieties cooked in glass containers. Pb content in cooked rice showed a high bioaccessibility. A negative correlation was observed between dietary fibre content and bioaccessible Cr and Pb concentrations. From the health risk point of view, cooking rice in stainless steel containers could represent a certain hazard in the case of Cr but not in the case of Ni. Regarding Pb, rice consumption represents a certain hazard as a good natural source of this heavy metal.

Profiling of 2-Acetyl-1-Pyrroline and Other Volatile Compounds in Raw and Cooked Rice of Traditional and Improved Varieties of India.

Herein, optimized headspace solid phase microextraction with gas chromatography–tandem mass spectrometry (HS-SPME-GC-MS/MS) was used to estimate the 2-acetyl-1-pyrroline (2-AP) in raw and cooked rice samples of ten different traditional and improved varieties. Furthermore, HS-SPME-GC-MS-based volatile profiling was subjected to untargeted analyses to identify major odorants in raw and cooked rice samples, and to understand chemical proximities among volatile profiles. Results showed that 2-AP content was remarkably increased in cooked rice compared to raw. Among the varieties studied, Pusa-1652 (Improved Kala Namak) and Kala Namak-2 were superior in the 2-AP content than Basmati varieties. Additionally, Govind Bhog, Kala Jeera and Jeera-32 had 2-AP content equivalent to or superior to Basmati rice varieties. Altogether, 18 and 22 volatiles were identified in the raw and cooked rice samples studied, respectively. Of these, ethyl butyrate, ethyl 3-methylbutanoate, 2-undecanone, ethyl benzoate, ethyl benzeneacetate, 2-methylnaphthalene, and 1-methylnaphthalene were characteristically detected in the cooked rice. The high amount of 2-ethyl-1-hexanol was uniquely found in raw rice samples, which can be a marker compound for freshly milled rice. Along with 2-AP, butanoic acid and benzoic acid derivatives, phenylethyl alcohol, ethyl 3-hydroxybutyrate, and indole may be responsible for the overall perceived characteristic Basmati-like aroma in cooked rice.

Arsenic bioaccessibility in rice grains via modified physiologically-based extraction test (MPBET): Correlation with mineral elements and comparison with As relative bioavailability

Rice consumption is a major dietary source of human exposure to arsenic (As), with As bioavailability being an important factor influencing its health risk. In this study, the As bioaccessibility was measured in 11 rice grains (140–335 μg As kg−1), which were compared to As relative bioavailability previously measured based on a mouse bioassay (Li et al., 2017). Using modified physiologically-based extraction test for rice (MPBET), As bioaccessibility in raw rice samples (44–88% in the gastric phase and 47–102% in the intestinal phase) was similar to those in cooked rice (42–73% and 43–99%). Arsenic bioaccessibility in rice was generally higher in the intestinal phase than in the gastric phase, with Fe and Ca concentrations in rice being negatively correlated with As bioaccessibility in the gastric phase (R2 = 0.47–0.49). In addition, for cooked rice, strong positive correlation was observed between bioaccessible As and inorganic As (R2 = 0.63–0.72), suggesting inorganic As in rice was easier to dissolve than organic As in gastrointestinal digestive fluids. Due to limited variation in As bioaccessibility and As bioavailability among the 11 samples, a weak correlation was observed between them (R2 = 0.01–0.03); however, As bioaccessibility values measured by the gastric phase (GP) of the MPBET agreed with As bioavailability values based on a mouse bioassay, suggesting the potential of the MPBETGP to predict As bioavailability in rice. Future work is needed to ascertain the robustness of the MPBETGP in predicting As bioavailability in rice using additional samples.

Inorganic arsenic in rice and rice products in New Zealand and Australia

ABSTRACTA total of 200 rice and rice products from New Zealand and Australia were purchased from retail outlets during 2017 for inorganic arsenic analysis by ICP-MS. The survey of foods placed a particular emphasis on products marketed specifically for infants and young. A total of 159 samples (80%) gave positive results for inorganic arsenic, with a mean concentration of 0.06 mg/kg and a range of <0.01–0.14 mg/kg. Two products marketed for infants and young children age-cohort had the highest concentrations of inorganic arsenic. Both exceeded the EU maximum level for rice destined for the production of food for infants and young children of 0.1 mg/kg. The mean concentration of inorganic arsenic for only raw rice samples was 0.07 mg/kg, with a range of <0.02–0.12 mg/kg. In general, the concentration of inorganic arsenic in rice and rice products from New Zealand and Australia was low compared to concentrations reported from comparable studies overseas.

Comparative measurement of metal contents in raw and cooked rice samples prepared in different rice cookers using SR-XRF and health risk assessment

Rice is full of nutrients that are essential to humans, however, exposure to the high metal contents in rice could also pose potential health risks to consumers. This work aimed to investigate this safety concern using the synchrotron radiation X-ray fluorescence spectrometry (SR-XRF), which is considered one of the most advanced and accurate elemental analysis techniques, to quantify metal contents, namely Fe, Zn, Cu, Ca, and Mn, in raw and cooked rice samples in order to assess the potential health risks associated with rice consumption. The results indicated that cooked rice samples had lower Fe and Ca but higher Zn, Cu, and Mn contents than raw rice samples (p < 0.05). The highest changes in metal contents were the decrease in the Ca content, which was reduced up to 8.5 times in rice samples cooked with running water and was lower than the detection limit (< 2.0 mg kg−1) in rice samples cooked with de-ionized water. When comparing the average estimated weekly intake with the available provisional tolerable weekly intake (PTWI) issued by the World Health Organization (WHO), the results showed that Fe, Zn, and Cu had lower average estimated weekly intake values than the PTWI levels. In terms of chronic, non-carcinogenic health risk assessment, the individual hazard quotient (HQ) of each metal of interest was less than the limit (1.0). However, the hazard index (HI), which combined all HQ values, was 1.15, indicating possible chronic health risks from rice consumption. The results obtained from this work suggest that further investigation is needed to fully understand and to promote awareness of the health risks caused by rice consumption.

Determination of trace concentration of aluminium in raw rice samples using instrumental neutron activation analysis and particle induced gamma-ray emission methods

Determination of aluminium concentration in food samples is important for the food safety and quality control purpose owing to its toxicity. This work demonstrates determination of aluminum concentrations in raw rice samples, obtained from agricultural field, by instrumental neutron activation analysis (INAA) using reactor neutrons and high resolution gamma-ray spectrometry. Particle induced gamma-ray emission (PIGE) method was also standardized for the determination of aluminium content in some samples. The aluminium contents were found to be in the range of 5–80 mg kg−1. INAA and PIGE methods were validated by analyzing five reference materials obtained from NIST and IAEA.

Electrospray droplet impact/secondary ion mass spectrometry (EDI/SIMS) using NaF and AgF as cationization matrices

In our previous paper, it was suggested that metal fluorides may be useful as cationization matrices in Electrospray droplet impact/SIMS. In this work, NaF and AgF were used as the cationization matrices for cyclodextrin (CD), polyethylene glycol (PEG), polystyrene (PS), garlic juice, and sliced raw rice. EDI mass spectra were measured without and with the use of matrices. Enhancement of ion abundances of [M + Na]+ for CD and PEG with NaF matrix and that of [M + Ag]+ for PS with AgF matrix were observed. However, the addition of matrices was not effective for the cationization of garlic juice and sliced raw rice samples. This may be due to the Coulombic repulsion of the reagent ions of Na+ or Ag+ with the preformed K+ adducts of oligosaccharides already present in the samples. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Effect of puffing on physical and antioxidant properties of brown rice

The objective of this study was to investigate the effect of puffing process on the physical, antioxidant properties and mineral composition of brown rice. Bulk density significantly varied (P<0.05) among the puffing stages and was lowest in expanded rice. From Hunter colour analysis, the lowest L∗ value and highest a∗ and b∗ values were observed for parboiled rice (P<0.05). A-type of diffraction pattern, observed in raw rice was altered by puffing process and led to the formation of B- and V-type patterns. Raman spectrum showed the intense peaks in raw rice and the intensity of those peaks was decreased during the puffing process. Scanning electron microscopy revealed a highly porous structure of expanded rice kernel. Significant decrease in the antioxidant properties was observed upon puffing process as compared to raw rice samples. Hence the present study demonstrates that the puffing process leads to the significant changes in the properties of brown rice.

A combined intervention using fermented ethanol and supercritical carbon dioxide to control Bacillus cereus and Bacillus subtilis in rice

Although the contamination of rice by Bacillus spp. is a great concern to the rice industry, very few studies to date have been performed on the control of Bacillus spp. in rice. The elimination of microorganisms in rice is quite difficult due to its solid phase. In this study, a new method of intervention for the inactivation of Bacillus cereus and Bacillus subtilis in rice was developed using fermented ethanol (FE) and supercritical carbon dioxide (SC–CO2). Raw rice samples inoculated with Bacillus spp. were treated with 1. FE only (concentrations: 0, 10, 30, 50, and 70%; treatment duration: 5, 10, 20, 30, and 60 min), 2. SC–CO2 only (temperatures: 36, 40, and 44 °C; pressure: 100, 150, and 200 bar; treatment duration: 10, 20, and 30 min) or 3. with both FE (30% for 30 and 60 min) and SC–CO2 (36 °C, 100 bar, 10 min and 44 °C, 200 bar, 30 min). The survival of Bacillus spp. populations was assayed, as were any changes in the hardness and color of the treated rice. When rice samples were treated with the combined treatment of FE (30%, 60 min) and SC–CO2 (200 bar, 44 °C, 30 min), Bacillus spp. were maximally reduced by approximately 5 log CFU/g. Sufficient log reduction of B. cereus (4.76 log CFU/g) and B. subtilis (4.66 log CFU/g) were also obtained with mild treatment (FE: 30%, 30 min and SC–CO2: 100 bar, 36 °C, 10 min). The combined treatment led to beneficial changes including decrease in the hardness of cooked rice and whitening of rice (increase of lightness and decrease of yellowness) compared to that of untreated rice, resulting in an increase in perceived quality. The changes of hardness and lightness were mainly affected by FE and SC–CO2, respectively. Our results indicate that a combined treatment with FE and SC–CO2 can be successfully used for the inactivation of Bacillus spp. in rice, with simultaneous improvements in rice.

Effects of storage conditions and cooking on colour and antioxidant activities of organic pigmented rice

SummaryInfluences of the conditions of raw rice storage and cooking on parameters related to colour and antioxidant activities of organic hulled red fragrant rice were investigated. Raw rice samples were vacuum‐packed in oriented polypropylene/aluminium/linear low‐density polyethylene or nylon/linear low‐density polyethylene pouches and stored at ambient temperature or 15 °C up to 12 months. Cooked samples were prepared from aged raw samples. Kernel colour, total anthocyanin content (TAC) of acidic methanolic extracts as well as total phenolic content (TPC), reducing power (RP) and radical scavenging activity (RSA) of methanolic extracts and enzymatically digested samples were maintained during 12‐month storage, regardless of packaging materials and storage temperatures. Cooked kernels had larger L value, lower a and b values, and greater TAC (dry basis), comparing with the raw rice. Cooking caused drastic decrease in TPC, RP and RSA of methanolic extracts. Nevertheless, less negative impacts of cooking were found for enzymatically digested samples.

RHEOLOGICAL CHARACTERIZATION AND MODELING OF RICE FLOUR DOUGH: EFFECT OF PARBOILING TIME, MOISTURE CONTENT AND GUM ARABIC

ABSTRACTSmall‐deformation compression and stress relaxation studies in addition to nonoral sensory assessments were performed on rice flour doughs, obtained by parboiling at different times (0–60 min), moisture (48–60%) and gum Arabic contents (0–0.5%). The response functions were the rheological (firmness and compression energy, initial and equilibrium moduli and relaxation time) and nonoral sensory attributes (ease of extrusion, cohesiveness and stickiness) of dough. Compression energy increased with parboiling time but decreased with moisture content. Relaxation time varied from 0.15 to 20.2 s, meaning a wide variation in the behavior of dough is possible to achieve. The viscoamylographic studies indicated that parboiled rice pastes exhibited more stable status toward retrogradation and showed lesser shear‐thinning phenomenon compared with their counterpart raw rice samples. The stress decay curves could be modeled by three‐element spring‐dashpot Maxwell–Voigt model (r ≥ 0.81, P ≤ 0.01). The optimum condition for obtaining a dough with minimum stickiness and maximum ease of extrusion was computed.PRACTICAL APPLICATIONSRice is extensively used in various forms of food as whole grain as much as flour. Because of nonglutinous properties, rice dough from raw flour cannot be easily flattened or shaped, whereas thermal treatment like parboiling and the use of gum Arabic can make the dough suitable for formulating different products. The addition of gum during dough preparation can retain more water and modify its rheological properties, improving the dough handling characteristics and textural attributes of the finished products. The specific applications of reported findings lie in the development of rice‐based products such as ready‐to‐eat and ready‐to‐fry/bake snacks, baby foods and breakfast cereals.

Development and application of a centrifugation-plating method to study the biodiversity of Bacillus species in rice products

A centrifugation-plating method was developed, using amylase and Tween 80 pre-treatment, for detection and enumeration of Bacillus spp. in rice products. The high sensitivity of this method improved detection of a variety of Bacillus species in rice products compared to the spread-plate method. Bacillus spp. were detected in 33 out of 35 raw rice samples with the centrifugation-plating method, but only 13 samples using the spread-plating method, even though 1 mL of a 10 −1 sample dilution was used, to increase sensitivity of the method. Known toxigenic or potentially toxigenic species ( Bacillus cereus/ Bacillus thuringiensis, Bacillus subtilis, Bacillus licheniformis, and Bacillus pumilus) were those most frequently found in both raw and cooked rice.

Arsenic removal from rice by washing and cooking with water

Two Hungarian and one Chinese rice samples were selected in order to establish the extractable arsenic content by washing and cooking in water in a ratio of 6:1, water:rice (cm 3:g) by inductively coupled plasma sector field mass spectrometry (ICP-SF-MS). Total arsenic concentration of the Zhenshan 97, Risabell and Ko˝röstáj-333 samples were 171.3 ± 7.1 ng g −1, 116.0 ± 3.7 ng g −1 and 139.0 ± 6.1 ng g −1, respectively, which did not exceed the toxic limits established for As in Hungary (0.3 μg g −1) or in China (0.7 μg g −1). The predominant chemical form of As in the raw rice samples determined by on-line high performance liquid chromatography and ICP-MS was arsenite. Moreover, enzymatic hydrolysis with α-amylase + protease and microprobe focused sonication proved that arsenite could be removed in the highest extent by washing and cooking, meanwhile the main As form remaining in the cooked rice was As(V). Thus, it is recommended to prepare rice-containing dishes in abundant water, which should be discarded after washing and cooking. The results were validated with a NIST SRM 1568a.