Iron-fortified parboiled rice – A novel solution to high iron density in rice-based diets

The present study pioneered an investigation of a novel and cost-effective approach to fortify Fe in rice and to greatly improve Fe nutrition in rice-based diets through parboiling, though it remains at its preliminary phase. Rice grains of seven cultivars were parboiled in deionised water containing different levels of Fe chelate made by mixing different proportions of Fe sulfate (FeSO₄) with ethylenediaminetetra-acetic acid disodium salt (Na₂EDTA). Adding Fe to the parboiling water resulted in an increased Fe concentration in the most grain, effectively where FeSO₄ and Na₂EDTA were mixed at 2:1 molar ratio (11.16 g Fe per 100 g raw paddy grain). This treatment resulted in Fe concentrations in white rice milled for 60 s and 120 s, which were 20–50 times higher than those in the unfortified milled raw rice grains. The Fe concentrations in milled rice grains were 50–150 mg Fe kg⁻¹ in 60 s milled grains with a slight reduction in 120 s milled grains. Perls Prussian blue staining of the cross section of Fe-fortified parboiled rice grains suggested inward movement of added Fe into the endosperm through the apoplastic pathway in the dorsal region of the rice grain. The retention rates of fortified Fe varied among the different cultivars, possibly due to different physical–chemical properties of the grains. The percentages of soluble fraction of the total Fe were higher than 50% in all cultivars tested, indicating its high bioavailability potential, though it remains to be evaluated. The present findings provided a preliminary basis for further investigation of this innovative technique, before its adoption by parboiled rice industry, such as optimising the levels of Fe addition and industrial process and Fe bioavailability in Fe-fortified-parboiled rice.     

Effect of Physical Processing of Commercial De-oiled Rice Bran on Particle Size Distribution, and Content of Chemical and Bio-functional Components

Rice bran is a rich source of nutrients and nutraceuticals, which has bio-functional properties. De-oiled rice bran, a major byproduct of rice bran oil industry, is not yet efficiently utilized for human consumption due to its poor edible quality. Various physical processing methods like sieving, pin milling and air classification were applied to upgrade the quality of bran and also to investigate its effect on particle size distribution, content of ash, protein, total dietary fiber, insoluble fiber, soluble fiber and oryzanol as well as total antioxidant activity in bran fractions. Sieve separation resulted in an increase in the content of protein and bio-functional components like soluble fiber and oryzanol as well as total antioxidant activity. Pin milling and sieving resulted in smaller particle size fraction without loss in the content of protein and other bio-functional components and antioxidant activity. Air classification of this material resulted in significant decrease in ash content with moderate increase in protein content and significant increase in the contents of oryzanol and soluble fiber and the total antioxidant activity. This resulted in quality improvement of commercial de-oiled bran viz., reduction in coarse bran fraction (>250μ_m size particles) from 65% to 0%, content of ash from 14.3 to 13.1 g/100 g, and insoluble fiber from 49.3 to 46.1 g/100 g, and increase in the content of protein from 13.7 to 17 g/100 g, soluble fiber from 2.75 to 4.35 g/100 g, oryzanol from 13.6 to 18.1 mg/100 g, and total antioxidant activity from 61 to 96 mM α-tocopherol equivalent/g. About 30% edible and nutrient rich rice bran, which can be used as an ingredient in the bakery products and health food formulations, was obtained from unutilized commercial de-oiled bran by this process.     

Rice degree of milling effects on hydration,texture, sensory and energy characteristics. Part 1. Cooking using excess water

The purpose was to assess the effect of degree of milling (DOM) on cooking kinetics, sensory attributes, and energy requirements when cooking rice in excess water. Commercial milling equipment was adjusted to produce parboiled and non-parboiled rice samples that were milled to varying DOMs, including brown rice lots having no milling. Surface lipid content (SLC) ranged from 0.15% to 0.55% for non-parboiled rice and from 0.40% to 0.95% for parboiled rice. The percentage gelatinized kernels, moisture content, peak force and sensory attributes were determined as a function of cooking duration for all samples. The cooking duration required to attain ‘well-cooked’ rice was determined, after which the energy required for cooking was measured. Within the SLC range tested, DOM did not affect cooking kinetics, texture and flavor of rice. Non-parboiled brown rice required the most energy, expressed as energy per unit mass of uncooked rice, to be cooked, followed by parboiled brown, parboiled milled and non-parboiled milled rice.     

RETENTION OF IODINE IN FORTIFIED PARBOILED RICE AND ITS PASTING CHARACTERISTICS DURING STORAGE

Iodine fortification, as potassium iodide (KI) or potassium iodate (KIO₃), in parboiled milled rice was investigated. The fortified parboiled milled rice (9–10% moisture content) contained 11.6 × 10^?2 mol KI per 100‐g salt or 9 × 10^?2 mol KIO₃ per 100‐g salt. The iodine‐fortified parboiled milled rice after dialysis retained 80.50–84.87% iodine, while the milled rice retained 97–100% iodine in the samples. Test on in vitro starch digestion showed that most iodine was released within 15 min of starch digestion. The iodine‐fortified and nonfortified parboiled milled rice showed significant higher pasting temperature, peak time and setback viscosity than normal milled rice. After storage for 5 months, iodine content in fortified parboiled milled rice decreased significantly (P ≤ 0.01), while iodine content in milled rice did not change during storage. For the rice stored at ambient temperature, the rapid visco‐analyzer amylograph viscosity (peak viscosity, trough viscosity and final viscosity) increased during the first 2 months and decreased during storage. Iodine did not affect these attributes of parboiled milled rice.     

Physicochemical and antioxidative properties of red and black rice varieties from Thailand,China and Sri Lanka

Nine red and three black rice varieties from Thailand, China and Sri Lanka were analysed to determine their proximate composition and their physicochemical and antioxidant properties. Four groups of rice varieties with different amylose contents were identified. Cyanidin 3-glucoside and peonoidin 3-glucoside were confirmed as the dominant anthocyanins in black rice varieties with contents ranging from 19.4 to 140.8 mg/100 g DM and 11.1–12.8 mg/100 g DM, respectively. Total phenolic content (TPC) differed significantly between the varieties, but not between the colours. Highest TPC was found in the red Thai rice Bahng Gawk (BG) with 691 FA equivalent mg/100 g DM, which showed as well the highest antioxidant properties. In red varieties, the major phenolic acids in the free form were ferulic, protocatechuic and vanillic acid, whereas in black varieties protocatechuic acid was dominant followed by vanillic and ferulic acid. In the bound form, ferulic acid was predominant in both colours, where contents differed significantly, followed by p-coumaric and vanillic acid. The antioxidative capacity did not differ significantly between both colours but amongst genotypes. Antioxidant capacity of rice varieties ranged within 0.9–8.1 mmol Fe(II)/100 g DM for FRAP and 2.1–12.3 mmol TEAC/100 g DM. DPPH scavenging ability ranged from 13.0% to 76.4% remaining DPPH.     

Effect of processing on thiamin and riboflavin contents of some high-yielding rice varieties of punjab

Six high-yielding varieties of rice (Oryza sativa L) were taken and subjected to 6 and 8% degree of milling. The raw rice and the parboiled rice were analysed microbiologically for thiamin and riboflavin contents. Milled parboiled rice contained more thiamin and riboflavin that milled raw rice at both the levels of milling because parboiling of paddy results in inward diffusion of water-soluble vitamins to the endosperm. The thiamin content of brown rice is reduced after parboiling. The loss may be due to the partial decomposition of thiamin during the stages of parboiling, but the riboflavin content of brown rice is found to be increased after parboiling.     

Studies on Expanded Rice. Physicochemical Basis of Varietal -Differences

Extent of expansion of milled parboiled rice when heated varied widely among 35 varieties. Expansion correlated strongly with the amylose content, being maximum at 27% total amylose and/or 13.5% hot-water-insoluble amylose. In general rice quality type II gave the highest expansion. Protein content had a small negative correlation. Mineral content of the milled grain had no effect, The influence of grain gelatinization temperature is uncertain. Overall shape of the rice grain remained largely unchanged after expansion.     

Zinc fortification of whole rice grain through parboiling process

The present study evaluated the effectiveness of zinc (Zn) fortification in a parboiling process for improving Zn density in parboiled-polished rice and its potential bioavailability in the human diet. Fortification of Zn in whole paddy rice grain with 50–400 mg Zn/kg paddy rice, during parboiling, increased Zn concentrations in polished-parboiled rice from 1.3 to 4.5 times those in unfortified parboiled rice. The added Zn rapidly penetrated into parboiled rice grains in the initial soaking process before saturation. There was an exponential correlation between Zn concentrations in unpolished (r = 0.63) (p < 0.01) and polished rice (r = 0.30) (p < 0.05) and soaking time. Zinc concentrations in unpolished rice were linearly correlated with Zn concentration in the polished rice (r = 0.60) (p < 0.01). Moreover, more than half of the added Zn is retained after a simulated washing process before cooking, ranging from 64–100%. In the Zn-fortified parboiled rice, 57–100% of Zn in polished rice grain was soluble in dilute acid, which was indicative of a high potential Zn bioavailability for human intake. The results suggest that parboiled rice has great potential for Zn fortification.     

不同加工精度籼米的感官品质和营养品质

为保证大米良好的食用品质的条件下尽可能保留营养成分,寻找籼米的适度加工范围,以6种不同品种的籼糙米为研究对象,将其分别碾磨成不同加工精度的籼米,通过感官评价和喜好度评价对不同加工精度的籼米米饭进行实验,并对比适碾米和精碾米的部分营养成分含量的差异,进而评价不同加工精度籼米的感官品质和营养品质.结果表明:随着加工精度的逐...     

Some physical properties of paddy and rice and their interrelations

Grain dimensions, density, bulk density, porosity and angle of repose of paddy and rice were studied with respect to (a) varietal difference, (b) effect of moisture content, and (c) effect of degree of milling.

• (a) Grain breadth and thickness were mutually correlated; all dimensions of milled rice were closely related to those of the corresponding paddy. Density was nearly constant at 1.452 g/ml in all rice varieties; in paddy, the value was around 1.182 g/ml for round varieties and around 1.224 g/ml for others. Bulk density varied appreciably in both rice (0.777–0.847) and paddy (0.563–0.642 g/ml), and so did porosity (41–46% in rice, 46–54% in paddy). These were related to the grain shape (l/b ratio); the more round the grain, the greater was the bulk density and the lower the porosity and vice versa. Angle of repose was relatively constant in different varieties of rice (average 37.5°) and paddy (average 36.5°).
• (b) With increasing moisture content, in rice, density decreased linearly; but the bulk density decreased twice as fast and the porosity increased owing to a concurrent progressive increase in the frictional property which decreased the degree of grain packing. In paddy, with increasing moisture content, density and bulk density increased, showing the presence of void space between the husk and the kernel; the angle of repose also increased moderately, but the porosity remained nearly constant.
• (c) Density of rice increased slightly with milling; but bulk density, porosity and angle of repose were markedly affected by the degree of milling. In general, with progressive milling, bulk density decreased at first and then increased, while porosity and angle of repose changed in reverse fashion—the changes being more pronounced in parboiled rice than in raw rice. Thus brown rice packed well and flowed freely; rice of intermediate polish, particularly parboiled rice, had poor packing and flow properties; and fully milled rice again packed and flowed well. The primary change in these was in frictional property, which affected the porosity and hence the bulk density. The frictional property in turn was related primarily to the surface fat content of the rice. The surface fat increased sharply on initial milling, more in parboiled rice, and then gradually disappeared on full milling.

     

A study on the acceptability and consumer attitude towards parboiled rice

Despite nutritional claims and other advantages that parboiled rice possesses, its consumption is still low in Brazil mainly because of the local preference for milled rice. In the first part of this study, the acceptability of five commercial brands of parboiled and milled rice was assessed by 100 consumers and similar acceptance levels were observed, evidencing that consumers might not reject parboiled rice for its sensory properties. In the second part, 286 consumers were surveyed about their eating habits and attitude towards rice, focusing especially the nutritional value, sensory and convenience aspects of parboiled rice. In the survey 35% of the respondents were unaware of parboiled rice. Cluster analysis performed on data grouped consumers in one segment with positive attitude and in two other segments with negative attitude towards parboiled rice. Segmentation was mainly because of negative beliefs about the sensory characteristics of the product, although its nutritional claims were unknown to most respondents, revealing the need of marketing efforts focused on informing consumers the health benefits and convenience of eating parboiled rice.     

The bioavailability of iron fortified in whole grain parboiled rice

The present study was to evaluate the bioavailability of iron (Fe) fortified in parboiled rice grain, expressed as Fe uptake by Caco-2 cells after in vitro digestion. The bioavailability of Fe-fortified in the rice grain was closely and positively correlated with increasing concentrations of Fe in the grains of the three cultivars (r = 0.96∗∗). The uptakes of the Fe-fortified in parboiled rice milled for 120 s (34.2, 47.7 and 107 ng ferritin mg protein⁻¹ in three cultivars, respectively) were well above those of the unfortified raw (6.1, 4.9 and 5.7 ng ferritin mg protein⁻¹) or parboiled rice (4.7, 3.6 and 4.4 ng ferritin mg protein⁻¹), the high Fe rice line IR68144-2B-3-2-2 (4.0 ng ferritin mg protein⁻¹) and popular Jasmine rice cultivar KDML 105 (3.9 ng ferritin mg protein⁻¹). Increasing milling time and rinsing the Fe-fortified parboiled rice decreased Fe bioavailability, due to their negative effects on total Fe concentrations in the parboiled rice grains, but uptakes were still well above that of their unfortified raw or parboiled rice grains. Rinsing or washing the Fe-fortified and milled rice grains decreased the bioavailability to 85 ng ferritin mg protein⁻¹ in the YRF cultivar, compared to about 100 ng ferritin mg protein⁻¹ in its non-rinsed grains. Dilute acid-extractable (DAE) Fe was linearly, positively correlated with the uptake of Fe assessed by the in vitro digestion/Caco-2 cell technique (r = 0.90∗∗), which can be used as a rapid method for optimizing levels of bioavailable Fe to be fortified in the parboiled rice by parboiled-rice mills if this Fe-fortification technique should be adopted in south and southeast Asia.     

Nutrient composition and physicochemical properties of Indian medicinal rice – Njavara

Njavara, a medicinal rice, was assessed for its nutrient composition and physicochemical properties, in order to understand its therapeutic properties. Dehusked Njavara rice consisted of 73% carbohydrates, 9.5% protein, 2.5% fat, 1.4% ash and 1628 kJ per 100 g of energy. Physicochemical properties and nutritive components of dehusked rice of Njavara were evaluated and compared with two commonly consumed non-medicinal rice varieties – Jyothi (red coloured) and IR 64 (brown coloured). The carbohydrates, fats, apparent amylose equivalent, fatty acid profile and triglycerides of Njavara were comparable to Jyothi and IR 64. However, Njavara rice had 16.5% higher protein, and contained higher amounts of thiamine (27–32%), riboflavin (4–25%) and niacin (2–36%) compared to the other two rice varieties. The total dietary fibre content in Njavara was found to be 34–44% higher than that of Jyothi and IR 64. Significantly higher phosphorus, potassium, magnesium, sodium and calcium levels were found in Njavara rice, compared to the other two varieties. The cooking time of dehusked Jyothi and IR 64 varieties were found to be 30 min, while Njavara needed longer time to cook, (38 min). The cooked rice of Njavara was slimy in nature, probably due to the presence of non-starch polysaccharides.     

Characteristics of functional brown rice prepared by parboiling and microwave drying

Brown rice (BR) is well known for its functional properties; however, it is considered unsuitable for consumption in modern diet owing to its hard texture, low digestibility, and high lipid peroxidation. In this study, we investigated the physicochemical properties, and cooking and storage characteristics of functional BR prepared by parboiling (100°C, 15 min) and microwave drying (100 kW, 8 rpm, 91°C, 40 min) processes. These processes significantly increased resistant starch (RS) content by 1.5-fold and total dietary fiber (TDF) content by 1.8-fold; Parboiling and microwave drying processes increased the umami taste by 10% using electronic tongue and decreased the hardness by 10% using texture analyzer, respectively. Additionally, irrespective of the storage duration, these processes remarkably decreased acidity and bacterial counts in the parboiled BR group compared to that in the BR group. Presumably, higher RS and TDF contents, enhanced umami taste, and longer shelf-life of BR would help patients with obesity and diabetes, and industries developing relevant high-value food products.     

Effect of parboiling on thiamin, protein and fat of rice

Parboiling decreased the thiamin content of rice. Nevertheless, milled parboiled rice contained more thiamin than milled raw rice at the same degree of milling because parboiling caused thiamin to diffuse inwardly. Both the degree of loss and the degree of diffusion depended on the severity of the heat treatment. Bran-polish of parboiled rice had a higher fat and protein content than bran-polish of raw rice at the same degree of milling because the starchy endosperm of parboiled rice had a greater resistance to milling and so the bran and the germ were more effectively removed. Milled parboiled rice tended to have lower protein content than milled raw rice. Starch content was lower in bran-polish from parboiled rice.     

Key factors affecting Fe density in Fe-fortified-parboiled rice: Parboiling conditions,storage duration,external Fe-loading rate and genotypic differences

The present study evaluated the key factors affecting the efficiency of iron (Fe) penetration into the endosperm in parboiled rice of different varieties. It also investigated effects of storage time on Fe bio-accessibility, rice colour and Fe retention after rinsing. Rice grains of three varieties were fortified with an increasing range of Fe-fortification rates during the parboiling process, under two typical parboiling conditions, which are ambient soaking temperature for 24 h and 60 °C soaking temperature for 6 h at neutral (6.0–6.5) and acidic pH (3.0–3.5). Soaking of paddy rice, at 60 °C in acidic water for 6 h before steaming, was found to be better for maximising the Fe concentration in white-parboiled rice than the former ambient soaking. Under this parboiling condition, adding 250 mg Fe kg⁻¹ of paddy rice, at soaking, produced the most desirable Fe concentration in white rice, ranging from 17.5 to 25.4 mg kg⁻¹ among the rice varieties tested. The concentrations of Fe in parboiled white rice exhibited an exponential increase with increasing concentrations of Fe in the soaking water in all varieties, which were linearly related to Fe concentration of brown rice (r = 0.96∗∗, p < 0.01). The colour of the parboiled rice fortified with Fe was initially light yellow, with variation among rice varieties, but it did become slightly darker after 16 weeks of storage, probably because of Fe oxidisation. This may be related to decreasing bio-accessibility after 20 weeks of storage. Storage, however, did not affect the total Fe retention after rinsing, though the retention rate was variety-dependent. Information about parboiling will provide the basis for formulating an optimal industry protocol for producing Fe-fortified-parboiled rice, which can be further refined in pilot studies on the industrial scale.     

挤压处理番茄皮膳食纤维的化学组成与结构

以番茄酱加工废弃物番茄皮为原料,以制备得到的番茄皮膳食纤维为研究对象,采用普通挤压和二氧化碳爆破挤压对其进行处理,并考察挤压处理前后番茄皮膳食纤维的化学组成、表面形貌、一级结构及晶体结构的变化。结果表明：两种挤压处理不改变番茄皮总膳食纤维的含量,但能显著增加其水溶性膳食纤维的含量,并使其组成和结构发生显著改变。番茄皮膳食纤维经普通挤压或二氧化碳爆破挤压处理,其水溶性膳食纤维含量从初始的（3.40±0.23）g/100 g分别上升到（5.86±0.29）g/100 g和（12.13±0.37）g/100 g,可见二氧化碳爆破挤压的效果更好。增加的水溶性膳食纤维来自水不溶性膳食纤维的降解转化。二氧化碳爆破挤压处理的番茄皮膳食纤维表面粗糙,尺寸显著减小,结晶度下降。     

Functional Properties as Affected by Laboratory‐Scale Parboiling of Rough Rice and Brown Rice

ABSTRACT: Rough rice (RR) is the conventional feedstock for parboiling. The use of brown rice (BR) instead of RR is gaining interest because it results in shorter processing time and lower energy requirement. This study compared the functional properties of milled parboiled rice under different parboiling conditions from RR and BR. Presoaked RR and BR from cultivars Bolivar, Cheniere, Dixiebelle, and Wells were parboiled under mild (20 min, 100 °C, 0 kPa) and severe (20 min, 120 °C, 98 kPa) laboratory‐scale conditions. Head rice yield improved on the RR and BR samples subjected to severe parboiling and was comparable to that of a commercially parboiled sample. Mild parboiling of BR resulted in lower head rice yields. Parboiling generally resulted in decreased head rice whiteness, decreased apparent amylose, increased total lipid, and sparingly changed protein content. Under the same parboiling conditions, the extent of starch gelatinization was higher for BR compared to RR as manifested by some distinct differences in pasting and thermal properties. The cooking characteristics (water uptake ratio, leached materials, and volumetric expansion) and cooked rice texture (hardness and stickiness) of RR and BR subjected to severe parboiling were fairly comparable. Differences in parboiled rice functional properties due to cultivar effect were evident.     

The most important bioactive components of cold pressed oil from different pumpkin (Cucurbita pepo L.) seeds

The composition and content of certain bioactive components of the cold pressed oil obtained from six samples of pumpkin seeds (Cucurbita pepo L.) cultivated in Serbia were analyzed by GC and GC/MS. The composition and content of fatty acids, tocopherols and phytosterols, and the total content of squalene were determined. The results indicate oil's excellent quality, with high contents of monounsaturated fatty acids (37.1 ± 0.70–43.6 ± 0.69 g/100 g of total fatty acids), total tocopherols (38.03 ± 0.25–64.11 ± 0.07 mg/100 g of oil), sterols (718.1 ± 6.1–897.8 ± 6.8 mg/100 g of oil) and especially squalene (583.2 ± 23.6–747 ± 16 mg/100 g of oil). High content of squalene, phytosterols and monounsaturated fatty acids recommend the use of this type of the oil in the nutritional and medical purposes.     

Physicochemical characterisation of dietary fibre components and their ability to bind some process-induced mutagenic heterocyclic amines,Trp-P-1, Trp-P-2, AαC and MeAαC

The physicochemical properties of potato fibre, wheat bran and oat samples were investigated, along with their binding capability to heterocyclic amines (HCAs). Potato fibre displayed highest total dietary fibre content (71.8/100 g dry weight basis, dwb), followed by wheat bran (57.2/100 g dwb) and oat sample 2 (53.0/100 g dwb). Oat samples 1, 3 and 4 displayed considerably lower dietary fibre content (20.5–28.8/100 g, dwb). Oat samples 3 and 4 displayed highest soluble fibre content (70–83%), and oat sample 3 also displayed highest swelling and water retention capacity (WRC). Dietary fibre samples, except samples 3 and 4, displayed improved binding to HCAs as sample weight increased. The behaviour of wheat bran and potato fibre was similar to oat samples 1 and 2. Binding of MeAαC was comparatively greater than that of other HCAs. Dietary fibre fractions with high insoluble fibre and functional groups of HCAs may significantly contribute to the binding capacity.