Different Degrees Of Milling Research Articles

Optimization of milling degree for maximizing nutrient retention and yield in milled rice: A study on six common Bangladeshi rice cultivars

Awareness of the nutritional value and health benefits of milled rice is crucial for its role as a staple food. This study explores the impact of different degrees of milling (DOM)—5%, 7%, and 9%—on head rice yield, proximate composition (protein, fat, fiber, and carbohydrates), and mineral content (sodium, magnesium, potassium, iron, calcium) in six rice cultivars: BRRI Dhan 28, 29, 36, 90, 51, and Bogura Katari. Our findings reveal that head rice yield decreases significantly, by 3% to 8%, when DOM is increased from 5% to 7% or 9%. Increasing the DOM also led to pronounced losses of protein (15% to 25%), fat (40% to 70%), and fiber (15% to 40%), while carbohydrate content increased. Additionally, substantial reductions in mineral content were observed at 9% DOM. Notably, consuming rice milled at 5% DOM can meet significant portions of daily nutrient requirements: 50% of protein, 10% of fiber, 20% of fat, 10% of sodium, 80% of magnesium, 35% of potassium, 100% of iron, and 30% of calcium, based on a per capita consumption of 400 g per day. This research highlights the importance of optimizing DOM between 5% and 7% to enhance head rice yield and maximize nutrient retention.

The effects of milling on the chemical forms, bioavailability, and in vivo distribution of Vitamin B1 in rice

Milling not only reduces the content of Vitamin B1 (Vit B1) in rice but may even affect its bioaccessibility, further affecting its activity in vivo. Therefore, this study investigated the changes in Vit B1 content and its chemical forms in rice at different degrees of milling (DOM) before and after cooking, as well as their bioaccessibility in vitro and bioavailability in vivo. In raw unmilled rice, the proportion of bound Vit B1 was slightly lower than that of free Vit B1, and the proportion increased significantly after cooking. DOM< 8% hindered this change of bound Vit B1 after cooking, resulting in a decrease in Vit B1 thermal stability from 90% to 80% and bioaccessibility from 80% to 60%. Fortunately, the content of Vit B1 stabilized in the digestive fluid remained superior to that of the high DOM group. DOM<8% shortened the time for Vit B1 to peak in the blood concentration of mice, whereas the decrease in bioavailability of Vit B1 in blood and liver was insignificant, unlike bioaccessibility. Hence, DOM < 8% can be applied to the rice milling process to maintain nutritional value. Correlation analyses indicated that the bound form of Vit B1 in cooked rice was the main factor affecting its digestion and absorption. These findings provide further support for the development of moderate rice processing.

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

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

Effects of degree of milling on nutritional quality, functional characteristics and volatile compounds of brown rice tea.

This study investigated the effects of rice preparation using different degrees of milling (DOM) from 0% to 13% on the nutritional composition, functional properties, major volatile compounds and safety of brown rice tea (BRT). We found that 2% DOM reduced 52.33% of acrylamide and 31.88% of fluorescent AGEs. When DOM was increased from 0% to 13%, the total phenolic content (TPC) of brown rice tea decreased by 48.12%, and the total flavonoid content (TFC) and condensed tannin content (CTC) also decreased significantly, with the smallest decrease at 2% DOM. In addition, the inhibitory activities of α-amylase, α-glucosidase and pancreatic lipase as well as the antioxidant activity also decreased gradually. Analysis by electronic nose and gas chromatography-mass spectrometry (GC-MS) showed that alkanes, furans, aldehydes, pyrazines and alcohols were the major volatiles in BRT, with 2% DOM having the greatest retention of aroma compounds. An orthogonal partial least squares discriminant analysis (OPLS-DA) and VIP score (VIP > 1 and p < 0.05) analysis were used to screen 25 flavor substances that contributed to the differences in BRT aroma of different DOMs. These results suggest that 2% milled BRT can improve safety and palatability while maximizing the retention of flavor compounds and nutrients. The findings of this study contribute to an enhanced understanding of the dynamics of changes and preservation of aroma compounds and nutrients present during the processing of BRT.

Effect of the degree of milling on the physicochemical properties, pasting properties and in vitro digestibility of Simiao rice

Simiao rice is a variety of long-grain Indica rice popular in South China. However, researches on the milling technology of Simiao rice are limited. The effect of different degrees of milling (DOMs) of Simiao rice (0–12%) were evaluated in terms of the physicochemical properties and in vitro starch digestibility of the rice. The results showed that, as the DOM increased from 0 to 12%, the head rice yield (HRY) and the content of protein, lipid, dietary fiber, vitamin B1, vitamin E and niacin nonlinearly decreased, while the content of total starch and amylose and paste viscosity parameters nonlinearly increased. The differences in chemical constituents between the brown and milled Simiao rice with different DOMs lead to the variation in their pasting properties and in vitro digestibility. Because of lower content of slowly digestible starch (SDS) and resistant starch (RS), milled Simiao rice exhibited greater digestibility and a higher estimated glycaemic index (EGI). The EGI of Simiao rice ranged from 77.98 to 85.55, and remained almost constant (approximately 84) when the DOM was above 4%. Correlation analysis indicated that the EGI had strong negative correlations with lipid, protein, dietary fiber and RS, but a positive correlation with amylose. These results provide theoretical guidance for the production of Simiao rice with desired physicochemical properties and digestibility by adjusting the DOM.

In vitro digestibility and the characteristics of puffed products from different degrees of milling and moisture content of adlay grain (Coix lacryma – jobi L.)

Adlay (Coix lacryma–jobi L.) is one of the cereals that can be developed into slowdigesting instant food. The degree of milling and moisture content of cereals can affect the digestibility of the food products. The purpose of this study was to determine the proper degree of milling and moisture content of adlay seeds so that a puffing product with high slowly digestible starch (SDS) content and organoleptic characteristics acceptable to the panelists was produced. This study used an experimental method consisting of two main treatments: the degree of milling (whole grain and polished) and the moisture content of adlay seeds (10%, 13%, 16%, and 19%). In vitro digestibility was measured by used pancreatic porcine α-amylase. The results showed that puffed adlay with the highest SDS and organoleptic characteristics that were still acceptable to the panelists was puffed polished adlay with an initial moisture content of 13%. The adlay puffed had SDS of about 35.98%, hardness 2795.83 gf, degree of gelatinization 67.90%, the moisture content of 5.94%, and rehydration power of 59.40%. The preferences for color, taste, aroma, and after-taste of adlay puffed were in the normal category while the texture was in the preferred category.

Effect of degree of milling and defatting on proximate composition, functional and texture characteristics of gluten-free muffin of bran of long-grain indica rice cultivars

Effect of different degrees of milling (DoM: 2%, 4%, 6% and 8%) and defatting on the proximate composition, protein characteristics, functional properties of bran of long grain rice cultivars and texture characteristics of bran (RB) supplemented muffins were evaluated. Protein, ash content, redness and yellowness increased while fat content decreased for RB by extended DoM and defatting. A higher proportion of β sheets, random coils, α-helix and β-turns for all fractions of RB of both cultivars after defatting were also observed. Defatting and extended DoM both improved the essential amino acid content in RB. A higher level of prolamines (15–18 kDa) in RB and DF-RB of PUSA1121 than PR111 was observed. Muffins made from 2% DoM bran from PUSA1121 showed improved texture characteristics and achieved the highest score for sensory attributes. Therefore, DoM and defatting improved the proximate, protein profiling, and functionality of the different fraction of RB.

Quality changes of yakju prepared from rice with different degrees of milling (DOM) due to accelerated aging

Quality changes of yakju prepared from rice with different degrees of milling (DOM) due to accelerated aging

Bioactive Compounds and Sensory Properties of Organic Rice: The Impact of Degree of Milling

Consumers assume organic rice to be healthy. However, there are several concerns regarding the bioactive compounds and sensory properties found in organic rice. This study aims to examine the effect of the milling duration of organic rice (0s, 30s, 60s, 90s and 120s) on its bioactive compounds (total phenolic content, flavonoid content, and dietary fibre) and sensory properties (taste, aroma, colour and texture). This study reveals that the degree of milling and the degree of whiteness increase when the milling duration increases, while the total number of phenolic, flavonoid, and dietary fibres decrease significantly as the milling duration increases. Moreover, the moisture content remains constant as the milling duration increases. Panellists can divide the rice samples based on colour and taste into three distinct groups. The overall liking of organic rice at different degrees of milling revealed that as the milling duration increases, the overall degree of consumer’s preference for the product also increases.

Sensory Profile of Rice-Based Snack (Nuroongji) Prepared from Rice with Different Levels of Milling Degree.

Nuroongji is a traditional rice-based snack that is widely consumed in Korea, but there is no reported comprehensive sensory characterization of this popular snack. The objective of this study was to conduct a sensory analysis of Nuroongji made with rice with different degrees of milling. Four different types of Nuroongji samples according to the degree of milling were prepared in the lab and subjected to physiochemical analysis. Descriptive sensory analysis was conducted by a trained panel (n = 8), and a consumer acceptance test was conducted using college students (n = 70). A sensory lexicon describing the flavor and texture characteristics of Nuroongji was developed: it included roasted brown rice, burnt, buckwheat, rice powder, glutinous rice power, and floral. The following texture attributes were evaluated in triplicate: hardness of particles, irregularity of particles, degree of coagulation, number of chews, and residual mouthfeel. Significant differences in flavor and mouthfeel attributes were observed between the Nuroongji samples according to the degree of milling (p < 0.05). Nuroongji made with white rice (N1) had a higher hardness value and less sweetness compared to other samples (p < 0.05). Texture- and mouthfeel-related attributes such as cohesiveness of the mass, irregularity of the surface, and astringency were identified as important characteristics that drive consumer acceptance of Nuroongji products. Findings from this study can provide Nuroongji product developers a valuable insight to extend their market by reformulating the product to be appealing to young consumers.

Determination of Optimum Degrees of Milling for Raw and Parboiled Basmati (PB1121) Rice Using Principal Component Analysis

Pusa Basmati 1121 (PB1121) rice (longest milled grain in the world), raw and parboiled, was dehusked and milled at 6 different degrees of milling (DOM) varied from 5-10 per cent. Head rice yield decreased up to 10% with increased DOM in both raw and parboiled rice. However, parboiling increased the yield of marketable rice by 18.68 per cent. DOM significantly (α=0.05) affected cooking and textural qualities of raw and parboiled rice. Mineral composition of raw and parboiled rice indicated that P, K, Mg and S constituted the major portion, about 97% of the mineral composition of PB1121 rice. DOM adversely affected the mineral content of rice, but this effect was less severe in parboiled rice. Principal component analysis (PCA) performed for selected quality characteristics of PB1121 rice indicated that optimum DOM (%) for raw and parboiled PB1121 rice would be 7% and 8%, respectively.

Determination of Optimum Degrees of Milling for Raw and Parboiled Basmati (PB1121) Rice Using Principal Component Analysis

Pusa Basmati 1121 (PB1121) rice (longest milled grain in the world), raw and parboiled, was dehusked and milled at 6 different degrees of milling (DOM) varied from 5-10 per cent. Head rice yield decreased up to 10% with increased DOM in both raw and parboiled rice. However, parboiling increased the yield of marketable rice by 18.68 per cent. DOM significantly (α=0.05) affected cooking and textural qualities of raw and parboiled rice. Mineral composition of raw and parboiled rice indicated that P, K, Mg and S constituted the major portion, about 97% of the mineral composition of PB1121 rice. DOM adversely affected the mineral content of rice, but this effect was less severe in parboiled rice. Principal component analysis (PCA) performed for selected quality characteristics of PB1121 rice indicated that optimum DOM (%) for raw and parboiled PB1121 rice would be 7% and 8%, respectively.

Degree of Milling Effect on Cold Water Rice Quality

The aim of this study was to examine the effects of degree of milling on various rice parameters such as proximate composition, and cooking properties using mathematical model. The experiments were performed in the laboratory of Food Research Division, Nepal Agricultural Research Council. The three different medium type rice varieties of Nepal (Lumle-2, Chhomrong and Machhapuchre-3) were exposed to five different degrees of milling (0%, 6%, 8%, 10% and 12%). The degree of milling (DM) level significantly (P≤0.05) affected the milling recovery; head rice yield, nutrient content as well as cooking properties of the rice. Increase in DM resulted in further reduction of protein content, fat content, minerals, milled rice and head rice yield after bran layer was further removed. A positive correlation between DM used in present model, amylose content, kernel elongation and gruel solid loss was observed, however, with an increase in DM; amylose content, kernel elongation and gruel solid loss were found to be increased. Adopting 6 to 8% DM for commercial milling of rice might help to prevent quantitative, qualitative and nutritional loss along with retention of good cooking characteristics.

Influence of milling on the nutritional composition of bran from different rice varieties.

The nutritional composition of bran from four rice varieties namely, Jyothi/IR64, Basmati and Agonibora representing high amylose, intermediate amylose and waxy, respectively were evaluated with friction and abrasive mills at different degrees of milling (DOM). Fat and protein content of the bran inversely correlated to amylose content of rice variety. The fat and fibre contents reduced with increased DOM due to increasing starch influx from the endosperm. Abrasive milling produced bran with higher protein content and total dietary fibre, resulting in superior quality bran, while friction milling led to higher fat. Agonibora bran was found to be superior in terms of nutritional quality. Industrial milling resulted in higher protein content in bran, and Jyothi variety had a better amino acid profile.

Changes in the zinc content of selected bangladeshi rice varieties through modified parboiling and milling methods

Zinc deficiency is prevalent among women and children in Bangladesh, and methods to increase the zinc content of parboiled rice could contribute to its prevention. We quantified the effect of modified parboiling conditions on zinc content and of the degree of milling on zinc and phytate contents of Bangladeshi rice varieties. Parboiling studies varied the conditions used in the local commercial operations, including pre-steaming and soaking times, change of soaking water, and steaming pressure. Milling studies used 10 Bangladeshi varieties at 0% (brown), 2%, 4%, 6%, 8%, and 10% degree of milling. With ambient soaking water, shorter soaking time was observed with a higher zinc content in brown rice, but not in 10% milled rice, and changing soaking water did not modify zinc content in brown or 10% milled rice. Pre-steaming time and open- vs. closed-system steaming had no significant effect on brown or 10% milled rice zinc content. Reducing the degree of milling from 10% to 6% or 4% resulted in a mean increase in zinc content of 27% and 47%, respectively, and an increase in phytate content of 35% and 72%, respectively. Zinc content in milled rice did not appear to be significantly affected by the parboiling conditions tested. While lower degree of milling resulted in higher zinc content, it is uncertain whether the higher phytate content would fully negate this increase by decreasing the bioavailable fraction of zinc. Human studies of zinc bioavailability from Bangladeshi rice at different degrees of milling are warranted.SAARC J. Agri., 15(2): 31-43 (2017)

Effect of milling degrees on volatile profiles of raw and cooked black rice (Oryza sativa L. cv. Sintoheugmi)

Volatile compounds in raw and cooked black rice (cv. Sintoheugmi) samples with different degrees of milling (step 0, 0%; step 1, 4.2%; and step 2, 10.5%, w/w) were investigated by headspace solid-phase microextraction and gas chromatography–mass spectrometry. A total of 101 volatile compounds were found. Among them, 44 compounds found in raw black rice were absent in cooked black rice and 20 compounds were newly formed in cooked black rice. The 8 identified major odor-active volatile compounds in raw and cooked black rice included 3 phenols (guaiacol, 4-vinylphenol, and 2-methoxy-4-vinylphenol), 2 benzenes (benzaldehyde and p-xylene), 2 furans (2-butylfuran and 2-pentylfuran), and 1 terpene (calamenene). Additionally, fatty acid oxidation products such as hexanal, 2-nonenal, octanal, and 2-pentylfuran were found in raw and cooked black rice samples. The relative concentrations of these volatile compounds were significantly higher in step 0 than in step 2 of raw and cooked black rice (p < 0.05). Partially milled cooked black rice (i.e., step 1) contained ~ 80% guaiacol (a favorable unique black rice flavor) of unpolished rice (step 0), with similar levels of several lipid oxidation indicator volatile products (e.g., 2-nonenal and 2-pentyl furan) of fully milled rice (step 2). Thus, partially milled black rice should be consumed rather than fully milled black rice.

도정도에 따른 쌀가루 및 쌀국수의 품질 특성

The objective of this study was to investigate the physicochemical properties of rice flour at different degrees of milling (DOM) and their influence on cooking, color, textural, and sensory properties of rice noodles. Higher DOM flour resulted in higher value of lightness and lower value of yellowness. Transition temperatures of rice flour were not significant, whereas the enthalpy of gelatinization increased with an increase in milling degree. Rice noodles were prepared with rice flours of DOM, and their quality and sensory properties were investigated. Cooking properties of rice noodles were not affected by DOM; however, color values were affected by DOM. In textural properties, values of hardness and chewiness of rice noodles were significantly reduced with an increase in milling degree. The sensory scores for overall acceptability, appearance, and texture were highest in higher DOM noodles (DOM 10% and DOM 12%)

Effect of High Pressure Treatment and Degree of Milling on Gelatinization and Structural Properties of Brown Rice

Brown rice (BR), medium-milled rice (MR), and fully milled white rice (WR), with different degrees of milling (DOM), 0, 6.6, and 10.4 %, respectively, were high pressure (HP) treated at 200 to 500 MPa for 5 to 15 min. Water absorption, swelling, and gelatinization properties, and microstructural changes were investigated. HP treatment (≥200 MPa) or partial milling (DOM 6.6 %) resulted in water absorption comparable with that of white rice. Swelling behavior was affected by milling and processing temperature. Both HP treatment and milling promoted gelatinization properties. In addition, partial milling reduced the pressure resistance of rice grain, while differences in water absorption, swelling behavior, and gelatinization properties due to milling were reduced by HP treatment. Further, the degree of gelatinization (DG) increased with HP treatment with 400 MPa and 10 min defined as the threshold values for pressure and holding time, respectively. DG values, observed with 400 MPa-10 min treatments, were 41.2, 50.2, and 39.9 %, respectively for BR, MR, and WR. Results demonstrated that HP treatment, combined with milling, is technically feasible and produces rice and rice flour with enhanced DG and swelling behavior. These basic data can be used to improve the processing efficiency and quality of brown rice-based product.

Revealing the Spatial Distribution of Inorganic Elements in Rice Grains

Femtosecond laser ablation (fs LA) was used in this study to identify pollution by heavy metals and the distribution of elemental nutrients at different rice milling ratios. Polished rice (degrees of milling of 3, 5, 7, 9, and 11) was collected from major Korean supermarkets and one sample thereof was selected. An internal quality control experiment was conducted using a rice flour certified reference material from the Korea Research Institute of Standards and Science (KRISS CRM) for the evaluation of the efficacy. To assess the effectiveness of the analysis method, the reliability was validated using a food analysis performance assessment scheme (FAPAS), with chili powder serving as an external quality control. The results of the analysis of the inorganic elements Ti, Ca, Al, Fe and Mn in white and brown rice with degrees of milling of 3, 5, 7, 9 and 11 using ICP-MS, ICP-OES and AAS revealed contents of 0.40, 49.2, 2.43, 5.36 and 10.3 mg/kg in white rice and 0.59, 78.0, 7.52, 11.0 and 18.5 mg/kg in brown rice, respectively. Among the elements, there were remarkable differences in the measured contents. By comparing the contents of the elements at different degrees of milling, Ti, Co, As, Ca, Al, Cu, Fe, and Mn were determined to be distributed on the surface of the rice grains, whereas the contents of Cd and Pb increased toward the center of the rice grains, and Si was evenly distributed. After the quantitative analysis of rice samples polished to different degrees of milling, Ca and Al, which were contained in large amounts, and Si were analyzed with specificity by fs LA. The results show that Ca and Al were distributed in the rice husk (protective covering of rice) and Si was distributed in all parts of the rice.

Behaviour of Aspergillus flavus and Fusarium graminearum on rice as affected by degree of milling, temperature, and relative humidity during storage

We investigated the survival and growth patterns of Aspergillus flavus and Fusarium graminearum, as well as mycotoxin production, on Korean rice as affected by the degree of milling (rough, brown, and white rice) and storage conditions (21 °C/85% relative humidity [RH], 21 °C/97% RH, and 30 °C/85% RH). When rice was stored at 21 °C/85% RH, the population of A. flavus remained constant and aflatoxin was not produced, regardless of the degree of milling. At 21 °C/97% RH and 30 °C/85% RH, the populations of A. flavus increased significantly (P ≤ 0.05) and aflatoxins were produced. The highest population of A. flavus and highest amount of aflatoxin B1 were observed on brown rice stored at 21 °C/97% RH. For F. graminearum, when stored at 85% RH, the populations were reduced to less than a detectable level (5 CFU/g of rice) within 120 days and no deoxynivalenol (DON) was produced, regardless of the degree of milling and storage temperature. However, at 21 °C/97% RH, the population of F. graminearum increased significantly (P ≤ 0.05) and DON was produced on all types of rice. Findings from this study provide insights concerning storage conditions necessary to prevent growth and mycotoxin production by A. flavus and F. graminearum on Korean rice with different degrees of milling.