Effects of milling on proximate composition, folic acid, fatty acids and technological properties of rice

Application of sourdough in gluten-free bakery products

ABSTRACTSIn recent years, the demand for gluten-free (GF) bakery products has grown rapidly due to the remarkable rising number of celiac patients and the increasing health awareness of GF products. However, GF products generally suffer from defects such as poor sensorial level, low nutritional value, high prices and short shelf life. Sourdough is the important starter culture applied in bakery field, and it has been proven to be ideal for enhancing the overall quality of bakery products. This review aims to systematically reviewed the application of sourdough in GF bakery products and its improvement to GF bakery products in terms of texture, shelf life, nutrition and flavor. Its positive effects derive from the complex metabolic activities of sourdough microorganisms, such as acidification, proteolysis, production of exopolysaccharides (EPS), activation of endogenous enzymes, and production of antibacterial substances. Finally, researchers are encouraged to expand the use of sourdough in GF bakery products to increase the variety of GF products. And the technical and nutritional potential of sourdough should be developed more widely.

Variations in the Major Nutrient Composition of Dominant High-Yield Varieties (HYVs) in Parboiled and Polished Rice of Bangladesh

Rice (Oryza sativa L.) is the principal staple food, a fundamental component of food security, a significant source of energy and major nutrients, and a key player in the overall nutritional status in Bangladesh. Parboiling is a common rice-processing treatment in Bangladesh. Recently, polishing has also become a common practice among millers seeking to attract consumers. Polishing may influence the nutrient composition of rice. The present study aimed to investigate the impact of parboiling and polishing on the nutritional content of the five High Yield Varieties (HYVs) of rice (BR11, BRRI dhan28, BRRI dhan29, BRRI dhan49, and BRRI dhan84) and their percent contributions to the Recommended Dietary Allowances (RDA) of vitamins and minerals. All of the rice samples were analyzed for proximate parameters, vitamins (B1, B2, B3, B6, and folate), and minerals (Ca, Mg, Fe, Zn, Na, K, P). Moisture, ash, fat, and total dietary fiber (TDF) were determined gravimetrically, according to the AOAC Official Methods; protein was measured by the Kjeldahl method; B-group vitamins were measured using Ultra Pressure Liquid Chromatography; and mineral content was determined by ICP-OES. The energy, protein, fat, and total dietary fiber (TDF) content of the samples ranged between 342-357 kcal/100 g, 6.79-10.74 g/100 g, 0.31-1.69 g/100 g, and 2.59-3.92 g/100 g respectively. Thiamin, riboflavin, niacin, pyridoxin, and folate content ranged from 0.11-0.25 mg/100 g, 0.01-0.05 mg/100 g, 2.82-6.42 mg/100 g, 0.12-0.30 g/100 g, and 5.40-23.95 g/100 g respectively. In a comparison of parboiling and polishing, macronutrients and vitamin retention were higher in parboiled unpolished rice than in polished unparboiled rice. The minerals (mg/100 g) Ca, Mg, Fe, Zn, Na, K, and P were in the ranges 32.82-44.72, 30.69-58.34, 0.51-0.70,1.83-2.79, 5.00-5.36, 106.49-112.73, and 162.23-298.03. Minerals of BRRI dhan84 were unaffected by polishing and parboiling. BRRI dhan84 contributed a higher percentage of RDA of all B vitamins and minerals. Therefore, to reduce nutrient loss in rice, industries and consumers should be encouraged to avoid polishing or limit polishing to 10% DOM and to consume unpolished rice, either parboiled or unparboiled.

Drying and intermittence processes on the polished and brown rice physicochemical and morphological quality by near-infrared spectroscopy, X-ray diffraction, and scanning electron microscopy

In this study was correlate the effects of drying time and intermittence of paddy rice on the physical, physicochemical, and morphological quality of polished and brown rice using near-infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Rice grain batches from mechanized harvesting with moisture contents between 24 and 20% (w.b.) were immediately subjected to drying and intermittence (average temperature of the grain mass of 40 °C) for a time of 14 h (number of times that the product underwent the drying and intermittence processes). For each drying time, grain sampling was performed to evaluate the physical quality of paddy rice and the physicochemical and morphological quality of polished and brown rice. The accumulated drying time provided an increase in the temperature of the grain mass, altering the physicochemical and morphological quality of polished and brown rice. The intermittence process did not contribute for the quality of the polished rice.

Physicochemical properties, phenolic content and in vitro digestion profile of Chinese black rice (Oryza sativa L.)

Yangxian black rice, as one of the ancient Chinese black rice varieties, is widely planted in the Yangxian area of China. This study investigated the physicochemical properties, phenolic content and in vitro digestion profile of Chinese black rice under gradient milling treatment. The chemical composition, color, pasting and thermal properties of black rice with different milling degrees were comprehensively compared. In vitro digestion analysis indicated that cooked rice flour had higher rapidly digestible starch (RDS) and lower resistant starch (RS) contents compared with the uncooked one. Besides, all cooked black rice samples exhibited high predicted glycemic index (pGI) value and whole black rice showed a lower pGI than refined rice. The microstructure and the abundance of phenolic compounds in the solid matrix during different treatments or digestion stages were observed by CLSM. Furthermore, a total of 102 phenolic constituents were absolutely quantified by targeted metabolomics techniques. Methanol extraction and moderate cooking treatment contributed to the release of phenolic compounds from the solid matrix of whole black rice. Besides, compared to the gastric digestion stage, the transition in the intestinal environment caused a decrease in the majority of the analyzed polyphenols. Identifying the phenolic constituents was favorable for a better elucidation of the chemical basis of the function and nutritional value of Chinese black rice.

Effect of processing methods and storage on the bioactive compounds of black rice (Oryza sativa L.): a review

Compared to brown and white rice, black rice contains more nutrients and numerous unique bioactive substances, such as essential amino acids, dietary fiber, γ-oryzanols, γ-aminobutyric acid, phenolic compounds, and anthocyanins, which makes it highly valuable for development and use. Whole-grain black rice typically requires a certain amount of processing prior to consumption, with the primary goal of enhancing the taste and texture of whole grains and their products. However, various new processing technologies have been effectively applied to the processing of black rice and the enhancement of its qualitative characteristics, but they also have both positive and negative effects on its nutritional quality. Therefore, evaluation of changes in concentrations of the bioactive substances as natural antioxidants due to processing and storage conditions is critical for establishing dietary guidelines for rice. This review highlights the primary bioactive components of black rice and provides a discussion of the impact of processing methods and storage on the bioactive components of black rice. Furthermore, we summarized the issues that currently exist in the processing and storage of black rice.

B-vitamins and heat processed fermented starchy and vegetable foods in sub-Saharan Africa: A review

Micronutrient deficiency still occurs in sub-Saharan Africa (SSA) despite the availability of several food resources, particularly fermented foods and vegetables, with high nutritional potential. Fermentation enhances the quality of food in several aspects. Organoleptically, certain taste, aroma, and textures are developed. Health and safety are improved by inhibiting the growth of several foodborne pathogens and removing harmful toxic compounds. Furthermore, nutrition is enhanced by improving micronutrient contents and bioavailability from the food, especially vitamin B content. However, during processing and before final consumption, many fermented foods are heat treated (drying, pasteurization, cooking, etc.) to make the food digestible and safe for consumption. Heat treatment improves the bioavailability of B-vitamins in some foods. In other foods, heating decreases the nutritional value because some B-vitamins are degraded. In SSA, cooked starchy foods are often associated with vegetables in household meals. This paper reviews studies that have focused fermented starchy foods and vegetable foods in SSA with the potential to provide B-vitamins to consumers. The review also describes the process of the preparation of these foods for final consumption, and techniques that can prevent or lessen B-vitamin loss, or enrich B-vitamins prior to consumption.

Thick layer drying and storage of rice grain cultivars in silo-dryer-aerator: Quality evaluation at low drying temperature

Drying rice in a single layer in a silo-dryer-aerator allows uniform drying. The objective of this study was to evaluate the physical, physicochemical, and morphological quality of rice grain cultivars (IRGA 424, BRS Pampeira, and Guri INTA) in the lower (initial time) and upper (final time) layers in a silo-dryer-aerator, employing single-layer loading at low temperatures, using the methods of near-infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, and multivariate statistical analysis. Drying rice in silo-dryer-aerator attenuated the moisture diffusivity in the grains, minimizing its effects on the physical, physicochemical, and morphological properties of the grains. However, the physicochemical constituents and morphology of starch were preserved by the low drying temperatures, mainly in the lower layers throughout the 2-month drying. The rice grains of the Guri INTA and BRS Pampeira cultivars were the most resistant to drying and showed greater uniformity on the final quality.

Influence of γ-irradiation on physicochemical, functional, proximate, and antioxidant characteristics of pigmented rice flours

In recent years, food irradiation using γ-rays is one of the most valuable practices for insect disinfestation in rice grains for extended shelf life. In this study, flours from four pigmented rice cultivars were exposed to γ-irradiation using 60Co at different doses (0, 5, 10, and 15 kGy). The impact of γ-irradiation on the physico-chemical, functional, and morphological characteristics of pigmented rice flours were analyzed. Results revealed that reduction in amylose content, pH, bulk density, tapped density, and syneresis, while solubility, water absorption capacity, and swelling power values increased significantly (p < 0.05). Pasting characteristics of pigmented rice flours also reduced after exposure to γ-irradiation. Morphological features of pigmented rice flour granules revealed no evidence of physical destruction after irradiation except for black kavuni flour. The structural analysis by FTIR confirms no effect of γ-irradiation on pigmented rice flours. Overall, the study revealed that irradiated pigmented rice flours with enhanced functional properties of less than 10 kGy can be effectively used in the development of value-added rice-based food products considering all the beneficial and safety aspects.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05709-z.

Breakpoint Planning Method for Rice Multibreak Milling

Excessive milling of rice kernels will result in nutrient loss and grain waste. To avoid grain waste, multibreak milling systems have been widely used in large-scale commercial rice mills. However, there is still no reasonable breakpoint planning method to guide the multibreak milling process. To construct a reasonable multibreak milling system, in this research, taking rice milling, a typical heterogeneous cereal-kernel milling process, as an example, the multivariate analysis method was used to comprehensively analyze the characteristic changes of milled rice during the whole milling process. A breakpoint planning method was established, including planning the number of breakpoints, determining the degree of milling or milling time corresponding to each breakpoint, and estimating the actual breakpoint to which the milled rice belongs. The verification results showed the rationality and high accuracy of the planning method. The presented work will help operators to plan the multibreak milling system of rice efficiently and objectively so as to significantly improve the commercial value of milled rice.

Eating Quality and In Vitro Digestibility of Brown Rice Improved by Ascorbic Acid Treatments

The effects of ascorbic acid treatment alone and in combination with degreasing or hydrothermal treatment on eating quality and in vitro digestibility of brown rice were explored for improving poor mouthfeel and low digestibility, and the improvement mechanism was investigated. The results indicated that the texture of cooked brown rice was significantly improved by degreasing combined with ascorbic acid hydrothermal treatment; the hardness and chewiness decreased to the level of polished rice; the stickiness increased three times of the cooked untreated brown rice; and the sensory score and in vitro digestibility were significantly enhanced from 68.20 and 61.37% to 83.70 and 79.53%, respectively. In addition, the relative crystallinity and water contact angle of treated brown rice were respectively reduced from 32.74% and 113.39° to 22.55% and 64.93°, and normal temperature water uptake significantly increased. Scanning electron microscope showed that the separation of starch granules occurred inside cooked brown rice grain obviously. The improvement of eating quality and in vitro digestibility of brown rice is conducive to enhancing the consumers acceptance and human health.

Photochemistry, Functional Properties, Food Applications, and Health Prospective of Black Rice

This review investigates black rice’s photochemistry, functional properties, food applications, and health prospects. There are different varieties of black rice available in the world. The origins of this product can be traced back to Asian countries. This rice is also known as prohibited rice, emperor’s rice, and royal’s rice. Black rice is composed of different nutrients including fiber, protein, carbohydrates, potassium, and vitamin B complex. It contains an antioxidant called anthocyanin and tocopherols. Antioxidants are found mostly in foods that are black or dark purple. Due to its nutritious density, high fiber level, and high antioxidant content, black rice is a good alternative to white and brown rice. Utilizing black rice in various foods can enhance the nutritional value of food and be transformed into functional food items. Many noncommunicable diseases (NCDs) can be prevented by eating black rice daily, including cancer cells, atherosclerosis, hypertension, diabetes, osteoporosis, asthma, digestive health, and stroke risk. This review aim was to discuss the role of nutritional and functional properties of black rice in the formation of functional food against different noncommunicable diseases.

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.

Modeling and Optimization of Process Parameters for Nutritional Enhancement in Enzymatic Milled Rice by Multiple Linear Regression (MLR) and Artificial Neural Network (ANN)

This study involves information about the concentrations of nutrients (proteins, phenolic compounds, free amino acids, minerals (Ca, P, and Iron), hardness) in milled rice processed with enzymes; xylanase and cellulase produced by Aspergillus awamori, MTCC 9166 and Trichoderma reese, MTCC164. Brown rice was processed with 60-100% enzyme (40 mL buffer -undiluted) for 30 to 150 min at 30 °C to 50 °C followed by polishing for 20-100 s at a safe moisture level. Multiple linear regression (MLR) and artificial neural network (ANN) models were used for process optimization of enzymes. The MLR correlation coefficient (R2) varied between 0.87-0.90, and the sum of square (SSE) was placed within 0.008-8.25. While the ANN R2 (correlation coefficient) varied between 0.97 and 0.9999(1), MSE changed from 0.005 to 6.13 representing that the ANN method has better execution across MLR. The optimized cellulase process parameters (87.2% concentration, 80.1 min process time, 33.95 °C temperature and 21.8 s milling time) and xylanase process parameters (85.7% enzyme crude, 77.1 min process time, 35 °C temperature and 20 s) facilitated the increase of Ca (70%), P (64%), Iron (17%), free amino acids (34%), phenolic compounds (78%) and protein (84%) and decreased hardness (20%) in milled rice. Scanning electron micrographs showed an increased rupture attributing to enzymes action on milled rice.

Effects of cultivars and fertilization levels on the quality of rice milling: A diagnosis using near-infrared spectroscopy, X-ray diffraction, and scanning electron microscopy

Cultivars and fertilization levels influence rice productivity and can be associated with grain quality. Thus, it is possible to make decisions regarding the choice of cultivars and application of fertilizer levels based on the type of milling, a necessary post-harvest process that may minimize the nutrient load in the grains and result in loss in quality. This study relates the physicochemical composition and morphological quality of brown and polished milled rice grains, cultivar types, and different levels of soil fertilization using near-infrared spectroscopy analysis, X-ray diffraction and scanning electron microscopy. Statistical tools were used to test the various treatments and identify the relationship between factors and variables. A high fertilization level is related to increasing crude protein composition and starch for cultivar IRGA 431 CL associated with polished rice. However, the combination of cultivar IRGA 424 RI and brown rice demonstrated a higher grain resistance, and different percentages of whole, chalky, and damaged rice. The correlation between ash × crude protein and starch × crude fiber was found to be positive for brown rice and negative for the polished rice. Further, an increase in starch content was inversely proportional to the ash content, whereas an increase in crude protein was inversely proportional to the low-fat content in milled rice. The crystalline characteristics of rice starch were preserved at high fertilization levels associated with polished grains that demonstrated high starch content. Polished grains, however, showed more pores and cavities, and consequently greater permeabilities in the surface. It is recommended that batches of grains produced from cultivar IRGA 431 CL with high levels of fertilization be subjected to polished rice milling to achieve high protein and starch quality. However, grains from cultivar IRGA 424 RI with high levels of fertilization are recommended for brown rice milling owing to the high percentage of physical defects observed.

Metabolic engineering of rice endosperm towards higher vitamin B1 accumulation

Rice is a major food crop to approximately half of the human population. Unfortunately, the starchy endosperm, which is the remaining portion of the seed after polishing, contains limited amounts of micronutrients. Here, it is shown that this is particularly the case for thiamin (vitamin B1). Therefore, a tissue-specific metabolic engineering approach was conducted, aimed at enhancing the level of thiamin specifically in the endosperm. To achieve this, three major thiamin biosynthesis genes, THIC, THI1 and TH1, controlled by strong endosperm-specific promoters, were employed to obtain engineered rice lines. The metabolic engineering approaches included ectopic expression of THIC alone, in combination with THI1 (bigenic) or combined with both THI1 and TH1 (trigenic). Determination of thiamin and thiamin biosynthesis intermediates reveals the impact of the engineering approaches on endosperm thiamin biosynthesis. The results show an increase of thiamin in polished rice up to threefold compared to WT, and stable upon cooking. These findings confirm the potential of metabolic engineering to enhance de novo thiamin biosynthesis in rice endosperm tissue and aid in steering future biofortification endeavours.

Enhancing health benefits of milled rice: current status and future perspectives

Milled rice is an essential part of the regular diet for approximately half of the world's population. Its remarkable commercial value and consumer acceptance are mostly due to its promising cooking qualities, appealing sensory properties, and longer shelf life. However, the significant loss of the nutrient-rich bran layer during milling makes it less nutritious than the whole grain. Thus, enhancing the nutritive value of milled rice is vital in improving the health and wellbeing of rice consumers, particularly for those residing in the low-economic zones where rice is the primary source of calories and nutrition. This article provides a critical review on multiple frontiers of recent interventions, such as (1) infusing the genetic diversity to enrich amylose and resistant starch to reduce glycaemic index, (2) enhancing the minerals and vitamins through complementary fortification and biofortification as short and long-term interventions, and (3) developing transgenic solutions to improve the nutrient levels of milled rice. Additionally, the review highlights the benefits of functional ingredients of milled rice to human health and the potential of enhancing them in rice to address the triple burden of malnutrition. The potential merit of milled rice concerning food safety is also reviewed in this article.

Interactive effects and modeling of some processing parameters on milling, cooking, and sensory properties for Nigerian rice using a one-step rice milling machine

This study investigates the interactive effects of processing parameters on the quality of milled rice using a one-step milling machine. Also, predictive models were generated using response surface methodology. The processing parameters were moisture content (10–14 % dry basis), shaft speed of rotation (600–900 rpm), and polishing time (1–3 min). The quality parameters evaluated were milling (head rice yield, percentage broken rice, fine broken rice, and milled rice yield), cooking (optimum cooking time, kernel elongation ratio, and width expansion ratio), and sensory (flavor, aroma, appearance, texture, and overall acceptability) properties. The results showed that the interactive effects of moisture content, shaft speed, and polishing time were significant (P < 0.05) on percentage broken rice, milled rice yield, fine broken rice, optimum cooking time, kernel elongation ratio, width expansion ratio, aroma, and appearance but was not significant on head rice yield, flavor, texture, and overall acceptability. These results were similar to the regression models generated. In conclusion, the interactive effects of these processing parameters affect all the cooking properties but not all milling and sensory properties while using a one-step milling machine.

In Vitro Protein Digestibility and Fatty Acid Profile of Commercial Plant-Based Milk Alternatives

Plant-based milk alternatives (PBMA) are a new popular food trend among consumers in Europe and North America. The forecast shows that PBMA will double their value by 2023. The objective of this study was to analyze the nutritional value of commercial products in terms of their fatty acid profile and protein digestibility from commercial PBMA. Eight commercially available PBMA were selected for fatty acid analysis, performed with gas chromatography of methylated fatty acids (GC-FAME), and, from these, four commercial products (almond drink, hemp drink, oat drink, and soy drink) were selected for a short-term in vitro protein digestibility (IVPD) analysis. The fatty acid analysis results showed that most of the products predominantly contained oleic acid (C18:1 ω-9) and linoleic acid (C18:2 ω-6). Hemp drink contained the highest omega-6/omega-3 (ω6/ω3) ratio among all tested products (3.43). Oat drink and almond drink were the PBMA with the highest short-term protein digestibility, non-significantly different from cow’s milk, while soy drink showed the lowest value of protein digestibility. In conclusion, PBMA showed a significant variability depending on the plant source, both in terms of fatty acid composition and protein digestibility. These results provide more in-depth nutritional information, for future product development, and for consumer’s choice.

Properties of South-Indian rice cultivars: physicochemical, functional, thermal and cooking characterisation

Physicochemical, functional, thermal, pasting and cooking properties of five Indian rice cultivars, ADT 36, 43, 39, IW PONNI and CR1009 were investigated. The starch, protein and fat contents varied from 1.321 to 2.489 mg/ml, 11.16-13.32% and 1.19-1.77% respectively, showing significant difference amongst the cultivars. ADT46 showed the highest amylose-amylopectin ratio. Water (103.55-132.48%) and oil (112.89-137.30%) absorption capacities also varied significantly. CR1009 showed highest swelling power at 60 °C, whereas IW PONNI exhibited the highest solubility (10.165%). The gel consistency of rice flours extended from 1.32 to 4.12 cm. The thermal properties of rice cultivars were found to be profoundly affected by amylopectin and showed correlation with amylose-amylopectin ratio. The pasting properties of rice flours also varied significantly, with peak viscosity and breakdown viscosity ranging between 2068.5-839 Cp and 1609.5-764.15 Cp respectively. The cooking time of the rice grains was found to be consistent with their shape and size. ADT43 and ADT46 showed the highest and least water uptake % on cooking. ADT46 showed the least cooking loss %, owing to the highest pasting viscosity. This study delivers the knowledge of the Indian rice cultivars, to be used for utilization of rice varieties for different products with relevance to the properties and enhance the post-harvest value chain improvement.

Efficient fortification of folic acid in rice through ultrasonic treatment and absorption

Folate deficiencies are prevalent in countries with insufficient food diversity. Rice fortification is seen as a viable way to improve the daily intake of folates. This work reports an efficient process of rice fortification involving ultrasonic treatment and absorption of the folic acid fortificant. Increased porosity due to sonication allowed the efficient absorption of folic acid into the brown rice kernel up to 5.195 × 10⁴ μg/100 g, a 1,982-fold increase from its inherent content. The absorbed folic acid in brown rice has 93.53% retention after washing and cooking. Fortification of ultrasound-treated milled rice with folic acid was also efficient affording 6.559 × 10⁴ μg/100 g, a 4,054-fold increase from its basal content. The effect of fortification caused a decrease in the thermal and pasting temperatures. The fortification also caused yellow coloration, decrease in hardness, and increase in the adhesiveness of the rice. The resulting fortified brown rice showed improved textural properties favorable for consumers.

Effect of Rice Flour Fermentation with Lactobacillus spicheri DSM 15429 on the Nutritional Features of Gluten-Free Muffins

Lactobacillus Spicheri DSM 15429 strain was used to ferment rice flour, aiming at exploiting its influence on the amino-acids, minerals, lactic acid, total phenols, and antioxidant activity of the rice sourdough and gluten-free muffins. Gluten-free muffins were prepared by using 15% rice sourdough fermented with the above strain of lactic acid bacteria and compared with rice spontaneous fermentation. Methods like LC-MS (Liquid chromatography–mass spectrometry), AA (atomic absorption), HPLC (High-performance liquid chromatography), Folin–Ciocalteu, and 1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity (DPPH) were used to fulfill the aim of the study. The addition of rice sourdough fermented with LAB was reflected in the chemical composition of the final baked good, improving its amount on bioactive compounds such as amino acids, mineral bioavailability, total phenols, and antioxidant activity. Total phenols and antioxidant activity increased their amount by 70.53% and 73.70%, respectively, meanwhile, lactic acid, minerals, and amino-acids increased their values at least twice. Thus, rice fermented with Lactobacilus spicheri DSM 15429 strain could be a tool to further increase the nutritional value of gluten-free baked products.

Nutritional variability and milling losses of rice landraces from Arunachal Pradesh, Northeast India

Rice landraces of North-East India have wide bio-diversity but remained nutritionally uncharacterized. Nutritional profiling of 33 indigenous rice landraces from the state of Arunachal Pradesh, Northeast India, and effect milling was evaluated. Total dietary fiber (5.22 g/100 g) was significantly higher than high yielding or hybrid cultivars. Principal nutrient variability of brown rice were: ash (13% c. v.) > insoluble dietary fibre, IDF (12% c. v.) > protein (11.% c.v.) fat (11% c. v.). Compositional diversity exists among rice landraces. Average iron was lesser but zinc content was higher than popular high yielding cultivars. Nutrient changes due to milling were most profound for thiamin (-69%), IDF (-66%) followed by phytate (-66%). Nutritionally Arunachal rice landraces are comparable to high yielding cultivars with added advantage of significantly higher total dietary fiber and lower phytate content. Thus, Arunachal rice landraces represents an agronomically and nutritionally important pool for rice improvement/breeding.

Influence of parboiling of red paddy varieties by simple hot soaking on physical, nutrient, phytochemical, antioxidant properties of their dehusked rice and their mineral, starch, and antioxidant's bioaccessibility studies

The objective of this study was to know about the effect of simple parboiling on physical properties, proximate composition, phenolic compounds, and antioxidant activity.  These were  studied in raw and parboiled paddy varieties as well as bioaccessibility of specific nutrients (minerals, starch, and antioxidants). The pigmented rice paddy varieties such as Jyothi, Meter & Athikaraya were parboiled by hot soaking treatment after soaking for 2, 2½, and 3 hr. Athikaraya rice showed high protein, low ash in raw and parboiled than other varieties. Amylose equivalents of all three varieties exhibited in the range of 24%-27% (d.b). Whereas, the soluble amylose content showed 12.7, 8.7, and 7.7% (d.b) in Athikaraya, Meter and Jyothi rice varieties, respectively. Jyothi rice showed less cooking time and more cooking volume. Athikaraya showed high phenolic content and antioxidant properties compared to other two varieties. The dialysability of minerals, starch, and antioxidants were increased due to simple hot soaking parboiling. PRACTICAL APPLICATIONS: The present study has the significance in assessing the variation among different pigmented rice varieties after parboiling by simple hot soaking with various soaking periods. The industrial advantage of this method is, there is no usage of boiler for cooking the paddy by steam, which was economically better. The information gained by this study might be beneficial for consumers and suppliers regarding the quality of the selected pigmented rice varieties with respect to nutrient composition, antioxidant activities, and bioaccessibility of minerals, starch, and antioxidants. Ultimately, the present study can lead to better appreciation of pigmented rice and assist food processors in selecting rice variety with unique characteristics for specialty food preparations.

Modification of nutritional properties of whole rice flours (Oryza sativa L.) by soaking, germination, and extrusion

Modifications of nutritional properties (amino acids, available lysine, protein digestibility, fatty acids, fiber, inositol phosphate (IPs), free and bound phenolics, and antioxidant properties) of whole rice ingredients processed by soaking, germination, and/or extrusion cooking were evaluated. Soaking and germination reduced proteins by lixiviation and hydrolysis, respectively. Lysine was the limiting amino acid. Polyunsaturated fatty acids increased after germination. Protein digestibility was 100% for germinated rice, decreased to 75% after the extrusion process. Fiber content decreased around 73% after the extrusion of soaked and germinated flours. Soaking-extrusion combined processes produces >50% IPs reduction. Germination-extrusion produced flours with the highest antioxidant capacity (54 µmol trolox g^-1 ), which was in accordance with the highest content of free and bound phenolics (66 and 69 mg GA 100 g^-1 , respectively). Grain treatments changed nutritional properties of flours resulting in low antinutrient whole grain ingredients, which could be used to develop whole grain-based foods. PRACTICAL APPLICATIONS: Phytic acid (PA) is an antinutrient having negative effects on mineral bioavailability and protein digestibility. There are processes such as soaking, germination, and extrusion, which alone or combined can decrease PA. However, nutritional composition and functionality of flours can change. We observed PA was highly reduced by soaking or germination combined with extrusion and antioxidant capacity and phenolic content increased in germinated and germinated-extruded flours compared to the other treatments. These modified whole grain rice flours low in anti-nutrients could be used in the production of expanded products or pre-cooked ingredients to develop whole grain based foods nutritionally improved.

Effect of operating parameters on milling quality and energy consumption of brown rice

The objective of this study was to evaluate the effect of operating parameters including milling weight (MW; 10, 95, 220, 345, 430 g), filling ratio (FR; 1, 1.4, 2, 2.6, 3) and milling duration (MD; 6, 30, 65, 100, 124 s) on head rice yield (HRY), whiteness index (WI) and specific energy consumption (Es). The experiments were conducted based on a vertical circulation mill employing a 5 level, 3 parameters CCD design and operating parameters were optimized using response surface methodology. During the processing, MW and MD had significant negative effects on HRY. On the contrary, they both had significant positive effects on WI. All the three parameters had a significant effect on Es Taking HRY, WI, Es as the evaluative index and degree of milling, temperature rise of milled rice as the restrictive index, the best combination of operating parameters was obtained, namely MW of 345 g, FR of 2.6 and MD of 30 s. The Pearson correlation coefficients between all the milling qualities were analyzed. Results showed that the temperature rise as an easy measurement index was highly correlated with the other qualities. The regression models between temperature rise and the other milling quality indices can assist in evaluating the quality of milled rice quickly and quantifiably.

Milling and thermal treatment induced changes on phenolic components and antioxidant activities of pigmented rice flours

Processing methods involved in value addition to pigmented broken rice, a milling by-product may affect the nutraceutical qualities. Hence the effect of pulverisation and toasting on nutraceutical content in brown rice flours of red and black rice varieties were studied. Plate milling reduced soluble, bound and total polyphenols in red, but increased in black; increased insoluble polyphenols and oryzanol, and reduced anthocyanin in both varieties; antioxidant activity is reduced in red, but increased in black. Toasting caused reduction of soluble, insoluble and total polyphenol, anthocyanin and antioxidant activity in both varieties with an increase in bound polyphenols, and retention of flavonoids and oryzanol. HPLC characterization of phenolics showed changes on processing in content of catechin, caffeic, vanillic, protocatechuic and ferulic acid. It can be concluded that processing impacts the phenolic components of pigmented broken brown rice flour and this information is useful for functional food industry.

Effects of milling on aromatics, lipophilic phytonutrients, and fatty acids in unprocessed white rice of scented rice 'Cheonjihyang-1-se

To understand effects of milling, scented rice 'Cheonjihyang-1-se' was milled from 10 to 140 s and changes in volatiles, phytonutrients, and fatty acids were evaluated. Among 43 identified odor-active compounds, four volatiles, including hexan-3-one, exhibited decreases of up to 78%, while four others including (E)-non-2-enal, increased following milling. Levels of 2-acetyl-1-pyrroline, the most distinctive popcorn-flavoring compound in scented rice, were not affected by the degree of milling (DM). Partial least squares discriminant analyses of volatiles were able to differentiate white rice according to the DM. Benzene and 2-pentylfuran showed the highest variable importance in projection scores, which could be applied in estimating the DM of rice. Milling significantly decreased tocopherols, tocotrienols, squalene, phytosterols contents and oleic acid composition, while palmitic acid composition was increased. These results suggest milling-dependent variations in phytonutrient levels and lipid composition, as well as changes in aroma and subsequent market quality, in 'Cheonjihyang-1-se' rice.

Effect of degree of milling on physicochemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars

The effects of degree of milling (DOM) between 0 and 8% on physico-chemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars were studied. Ash, protein, lipids and minerals decreased while blue value and crystallinity increased with increase in DOM. The colour parameters (a∗, b∗) and cooking time (CT) decreased while L∗(lightness) increased with increase in DOM. Elongation ratio (ER), gruel solid loss (GSL), length/breadth (L/B) and paste viscosities during cooking increased with increase in DOM. Short grain rice contained lower ash, protein, lipids, Mn, K, Ca, CT and GSL than long grain while the later showed higher crystallinity, Mn, P, K, Ca and ER. Paste and dough characteristics measured using Rheometer and Mixolab, respectively correlated well and differed with cultivar and DOM. Short and long grain cultivars showed variation in loss of different chemical constituents during varied DOM causing variation in cooking characteristics.