Native Rice Flour Research Articles

Enzymatic hydrolysis method for development of low glycemic index rice flour from temperate grown rice (var. Jehlum): Numerical optimization, rheological and spectroscopic characteristics

This study aimed at optimizing process protocols for development of low glycemic index (GI) rice flour (LGIRF) by employing enzymatic hydrolysis method using central composite rotatable design (CCRD). LGIRF was evaluated for pasting, farinographic, spectroscopic and microbiological attributes. Independent variables for optimization included concentrations of α-amylase (0.02–0.12 %), glucoamylase (0.02–0.24 %), as well as the incubation temperature (55–80°C). Resistant starch (RS), glycemic index (GI) and glycemic load (GL) were investigated as response variables. The optimum conditions for development of LGIRF with better quality were- α-amylase concentration of 0.040 %, glucoamylase concentration of 0.070 % and an incubation temperature of 60 °C. The results of mineral analysis revealed significantly (p < 0.05) lower levels of boron, potassium, zinc, phosphorus, magnesium, and manganese in LGIRF, while iron and copper were significantly higher. The viscosity profile as evident from pasting profile and farinographic characteristics of LGIRF were significantly (p < 0.05) lower than native rice flour. 1H NMR and 13C NMR spectroscopic studies showed an increase in flexible starch segments and a decrease in amorphous portion of starch LGIRF, along with chemical shift alterations in carbons 1 and 4. Free fatty acids and total plate count were significantly (p < 0.05) higher in LGIRF although was within limits.

Microwave-treated rice flour halves the need of hydroxypropyl methylcellulose in the formulation of gluten-free bread

Hydrocolloids such as hydroxypropyl methylcellulose (HPMC) are commonly used in gluten-free (GF) products to mimic the viscoelastic properties of gluten. However, GF products must meet current consumer expectations by not only being tasty and nutritious, but also adhering to ‘clean label’ principles, which involve minimizing ingredients and additives and favoring natural over chemical components. Modifying GF flours via hydrothermal treatments offers an alternative approach to reduce the use of additives in GF products. This work applied response surface methodology to study the potential reduction in HPMC dose in the formulation of GF-breads by the addition of microwave-treated rice flour (MWF) (treatment conditions: 8 min, 9 W/g, 30% moisture), without impairing their appearance, volume, and texture. The optimization study also included Water level and HPMC dose, and evaluated the dough's rheological properties at constant hydration. GF breads were made by varying the amount of native flour substituted with MWF, water level, and HPMC dose. Replacing 50% or 80% of native rice flour by MWF allowed to reduce the usual HPMC dose by more than half. This resulted in higher loaf volume and a softer crumb than their counterparts made with untreated flour and baked with the usual dose of additive (2%). Doses of HPMC as low as 0.7% with 80% MWF still resulted in breads with good texture and acceptable volume. Therefore, the structuring effect of MWF and its good performance in GF baking have been concluded, allowing to reduce the dose of additives required in formulating GF bread.

Study on physicochemical characteristics of local colored rice varieties (black, red, brown, and white) fermented with lactic acid bacteria (SBM.4A).

In this study, the physicochemical properties of local colored rice flour were studied after modification through fermentation with lactic acid bacteria (LAB) SBM.4A. SBM.4A was LAB isolated from the rice washing water and was in the cladogram of the Pediococcus pentosaceus strain SRCM102739 CP028266.1 and Pediococcus pentosaceus strain SRCM102738 CP028264.1. The studied rice varieties were wakacinda (white rice), wakawondu (red rice), warumbia (brown rice), and wakaombe (black rice). Characterizations of both fermented and native rice flour included chemical composition, FTIR profile, crystallinity, morphology, and pasting properties. Fermentation did not introduce new chemical functional groups to the flour and only slightly increased crystallinity from approximately 22.5% to 25.05%. In contrast, fermentation greatly affected the chemical composition and pasting properties of rice flour. Protein content of the fermented flour increased up to 214% relative to the native rice flour. Effect of fermentation on pasting properties varied between rice varieties. Increase in peak and final viscosities was observed in red, brown, and black rice. The opposite effect was found in white rice. However, fermentation improved the stability of flour to retrogradation for all rice varieties. These showed that the fermentation improved the properties of the local-colored rice flour and may widen their application as food ingredients.

Investigation of process and product parameters on physical attributes, resistant starch, and in vitro starch digestibility of modified rice flour‐based extruded snacks

Modified rice flour (MRF) with higher resistant starch content was explored to produce resistant starch, enriched extruded snacks. Effects of feed moisture (10%–35%), temperature (130–180°C), and screw speed (150–200 rpm) on specific mechanical energy input (SME), expansion ratio (ER), breaking strength (BS), L*, a*, and b* values, resistant starch (RS), predicted glycemic index (pGI), glycemic load (GL), and sensory evaluation of extrudates were investigated. Moreover, independent variables influenced both machine and product responses significantly (p < .05). Design expert predicted feed moisture of 26.90%, temperature of 130°C, and screw speed of 193 rpm as desirable conditions for the development of MRF extrudates. pGI decreased from 75.83 in control to 68.41 in the developed MRF extrudates. Novelty statement Resistant starch content increased from 4.12% in native rice flour (NRF) extrudates to 7.16% in MRF extrudates. Predicted glycemic response decreased from 75.83 in NRF extrudates to 68.41 in MRF extrudates. Moisture content of 26.90%, screw speed of 193 rpm, and temperature of 130°C were predicted as optimum extrusion cooking conditions. Using pregelatinized rice flour in the preparation of extrudates proved to be a novel way to decrease the glycemic index and glycemic load of rice-based snacks.

Enhancement of resistant starch content in modified rice flour using extrusion technology

AbstractBackground and objectivesThe present study was conducted with an aim to modify rice flour for enhancement of resistant starch content using extrusion technology. The effects of feed moisture, barrel temperature, and screw speed on resistant starch (RS), predicted glycemic index (pGI), glycemic load (GL), and instrumental color (L*, a*, and b* values) were investigated using response surface methodology.FindingsRS, pGI, GL, L*, a*, and b* varied between 4.91%–6.83%, 73.20–76.90, 48.0–53.04, 70.43–85.95, 6.92–10.32, and 15.09–30.81, respectively. Models obtained for these parameters were highly significant (p ≤ .0028). Significantly (p &lt; .05) higher RS content (6.20%) and lower pGI and GL values (75.10 and 50, respectively) were recorded in modified rice flour (MRF) as compared to native rice flour (NRF). Lower values of pasting properties and higher thermal properties were recorded in MRF than NRF. Scanning electron micrographs showed continuous and dense network structures in MRF, whereas ungelatinized granules were evident in NRF.ConclusionExtrusion processing caused significant changes in the digestibility of rice flour which increased the RS content and decreased the pGI in MRF. 30% moisture content, 140°C barrel temperature, and 70 rpm screw speed were found most feasible conditions to enhance RS content in MRF.NoveltyThe extrusion of rice flour without a die proved to be a unique way to produce pregelatinized rice flour with higher RS and lower pGI. MRF can be explored for development of functional foods especially for diabetic and celiac disease patients.

Influence of addition of extruded rice flour on preparation and quality of fresh gluten-free yellow alkaline noodles

Extrusion cooking was employed to physically modify structure and physicochemical properties of native rice flour (RF). In this study, blends of extruded rice flour (ERF) and RF were utilized to prepare gluten-free yellow alkaline noodles (GF-YAN). Exhibiting a cold-water swelling and a cold-peak viscosity, ERF acted as a binder paste for RF particles, thus allowing to prepare a smooth and cohesive GF dough at room temperature. Moreover, the dough could pass through a series of sheeting rollers to form a thin sheet prior to slitting into GF-YAN strands which is the traditional production process of YAN from wheat. Results showed that ERF exhibiting high peak viscosity improved tensile strength and elongation of cooked GF-YAN which implied that starch matrix developed strong binder paste. GF-YAN showed low cooking time and cooking loss. To improve texture and color, egg powder was incorporated in GF-YAN formulations. Results showed that adding egg powders improved yellow color (b* value), but decreased the noodle elongation. Confocal laser scanning micrograph revealed the swollen egg granules embedded in the starch matrix, which could disrupt the formation of continuous starch matrix and weaken the elongation property of the cooked GF-YAN. Results proved that pregelatinized ERF can be a promising alternative ingredient to prepare GF-YAN manufacturing by the traditional YAN sheeting process.

Rice flour physically modified by microwave radiation improves viscoelastic behavior of doughs and its bread-making performance

The physical modification of rice flour by heat-moisture treatment assisted by microwave radiation and its effect on the rheological and pasting properties of gluten-free doughs and the physical quality of their resulting bread was investigated. Two levels of flour initial moisture content, 20% (MW-20%) and 30% (MW-30%) and two levels of its addition (30% and 50%) to the dough were evaluated to assess the potential of the physical treatment to modify dough viscoelasticity and bread-making ability. MW-30% treated rice flour showed the most notable results. It provided enhanced dough viscoelasticity vs the control (100% native rice flour), increasing the dough G1′ modulus up to 69% and 135% for the treated flour additions of 30% and 50% of MW-30% respectively. The treated flour increased the resistance of doughs to deformation and enhanced their elastic behavior and recovery capacity up to 170% when compared to the control dough. The major effects on pasting parameters were also obtained for the doughs formulated with MW-30% flour at the maximum substitution level (50%). It delayed the pasting temperature, decreased the peak, trough and final viscosities with respect to the control dough. Both MW-treated rice flours (MW-20% and MW-30%) led to bread with higher-specific volume, softer crumb and delayed staling. The MW assisted heat moisture treatment of rice flour seems to be a valuable procedure to improve the viscoelastic behavior and bread-making performance of gluten-free doughs.

Effect of endogenous proteins and lipids on starch digestibility in rice flour

The composition and structure of the food matrix can have a major impact on the digestion. The aim of this work was to investigate the effects of endogenous proteins and lipids on starch digestibility in rice flour, with an emphasis on establishing the underlying physicochemical mechanisms involved. Native long-grain indica rice flour and rice flour with the lipids and/or proteins removed were subjected to a simulated digestion in vitro. A significant increase in starch digestibility was observed after removal of proteins, lipids, or both. The starch digestibility of the rice flour without lipids was slightly lower than that without proteins, even though the proteins content was about 10-fold higher than the lipids content. Microstructural analysis suggested that the proteins and lipids were normally attached to the surfaces of the starch granules in the native rice flour, thus inhibiting their contact with digestive enzymes. Moreover, the proteins and lipids restricted the swelling of the starch granules, which may have decreased their digestion by reducing their surface areas. In addition, amylose-lipid complex was detected in the rice flour, which is also known to slow down starch digestion. These results have important implications for the design of foods with improved nutritional profiles.

Influence of phosphorylated rice flour on the quality of gluten‐free bread

AbstractThe chemical modification of rice flour by phosphorylation is an alternative to improve the technological quality of bakery products. The aim of this study was to investigate the effect of phosphorylation process of rice flour on technological properties (specific volume, crumb and crust colour) of gluten‐free breads and the hardening of these breads during two storage temperatures (21 °C and −24 °C). Breads were made with native rice flour, with phosphorylated rice flour and with wheat flour, used as control. The phosphorylation causes significant reduction in the synaeresis of pastes and in retrogradation tendency of rice flours, varying from 258.7 cP (native rice flour) to 122 cP (phosphorylated rice flour). The breads prepared with phosphorylated rice flour showed reduction in the hardness in both storage temperatures studied and effect on rice bread volume, crumb appearance and colour, demonstrating the possibility of use of the phosphorylated rice flour in gluten‐free breads.

KARAKTERISTIK TEPUNG BERAS HASIL PERLAKUAN KOMBINASI GELOMBANG MIKRO, ULTRASONIKASI DAN PEMANASAN LEMBAB

Broken and brewer rice as by product of rice milling can be developed into a functional product with higher economic value, i.e. higher resistant starch (RS) rice flour. This research was aimed to study the modification of broken and brewer rice flour by the combination of microwave and ultrasonication with heat moisture treatment (HMT) to enhance RS contents and its associated microstructural and pasting characteristics changes. The r esults showed that five modified rice flours that had the highest RS contents were ultrasonicated with 20% of moisture content-HMT 10 and 12 hours rice flours, microwaved with 20% of moisture content-HMT 10 hours rice flour, microwaved with 50% of moisture content-HMT 8 and 10 hours rice flours. Their RS content ranged from 6.50–9.25% which were higher than the RS content of native rice flour (1.89%). Those five modified flours showed noticeable structural changes from the disappearance of non starch particulates, becoming more porous and larger size matrices. The pasting temperature of those modified flour increased (0.11–9.16% from native flour’s pasting temperature) and their peak viscosity decreased (47.15–71.15% from native flour’s peak viscosity). The modified flour had improved heat stability with the decrease in breakdown (88.07–100.00% from native flour’s breakdown value) and less retrogradation tendency during cooling (44.38–66.62% from native flour’s setback value). The combined treatment caused reduction of crystalinity ratio from 0.94 (native) to 0.91-0.86 (modified flour).

Physical properties of biodegradable films from heat‐moisture‐treated rice flour and rice starch

Native starch and flour are not successful in biodegradable film production. Heat moisture treatment (HMT) is a physical modification to improve functional properties of starch and flour, however, it is not fully understood if this method can enhance their film properties. This research, compares physical properties of biodegradable films produced from native rice flour (RF), rice starch (RS), and their heat‐moisture‐treated counterparts (HMTRF and HMTRS, respectively). Water solubility of the films reduced in the following order: RS film (23.91%) &gt; RF film (19.77%) &gt; HMTRS (19.50%) &gt; HMTRF (16.22%). Water vapor permeability values of RF and RS films were 0.032 and 0.017 g mm m−2 h−1 KPa−1 which were increased to 0.043 and 0.027 g mm m−2 h−1 KPa−1, respectively, after HMT. RF film was darker, more reddish, and yellowish but less transparent than RS film. HMT increased all the color parameters and further reduced the transparency of the films particularly for RF film. RS films had less flexibility, higher elongation at break, and tensile strength than RF films. HMT reduced films firmness, tensile strength, and resistance to stretch of both films. Overall, biodegradable films from HMTRF and HMTRS showed lower transparency, water solubility, rigidity, and extensibility while higher permeability to water vapor compared to their native counterparts.

EFFECTS OF PHOSPHATES ON THE PASTING PROPERTIES OF RICE FLOUR FROM WAXY AND NON‐WAXY VARIETIES

ABSTRACTThe objective of this study was to investigate the effects of phosphates on the pasting properties of rice flour. Taisen 2 and Taisen waxy 2 (TSW2) were selected as rice material. Different phosphates including sodium phosphate dibasic, sodium tripolyphosphate and sodium trimetaphosphate were added to the rice flour at 0.1, 0.2 and 0.5% (w/w, dry basis) levels and cooked in Rapid Visco Analyser at 95C for 12.5 min. Results showed that the addition of the phosphates significantly (P &lt; 0.05) changed pasting properties that relate to the native rice flour. Addition of phosphates significantly (P &lt; 0.05) decreased overall viscosities (except for breakdown) of the non‐waxy rice flour compared with those of the control. Hardness and adhesiveness of the non‐waxy rice flour gel was also significantly (P &lt; 0.05) reduced with addition of the phosphates. For waxy rice flour, TSW2 showed a significant (P &lt; 0.05) decrease in overall viscosity parameters compared with the control due to addition of phosphates. The texture of waxy and non‐waxy rice flour gel was different with the addition of phosphates.PRACTICAL APPLICATIONSRice flour is widely used in the rice food industry. Phosphates are widely used in traditional rice products, i.e., rice noodle, rice vermicelli and bamboo‐leaves‐wrapped alkaline waxy rice dumpling (alkaline tsong‐tsu) to improve pasting properties and texture of these products. The use of phosphates in tsong‐tsu has replaced the illegal uses of borax for the improvement of pasting properties and texture of the product. Rice flour is usually used along with other ingredients such as salts, sugar, lipids, emulsifiers and phosphates. The presence of phosphates may cause interactions with other food ingredients and influence the rice flour pasting properties and rice product texture differently. Because very little information on this area is available, the effects of phosphates on the pasting behaviors and texture of rice flour need to be examined. Such investigations are of importance to rice food industries and especially to the rice consuming peoples.

EFFECT OF HYDROTHERMAL TREATMENT ON THE PHYSICOCHEMICAL, RHEOLOGICAL AND OIL‐RESISTANT PROPERTIES OF RICE FLOUR*

ABSTRACT Rice flour was thermomechanically modified by steam‐jet cooking and the physicochemical, rheological and oil‐resistant properties of the resulting product were characterized. Compared with native rice flour, the steam jet‐cooked rice flour exhibited significantly increased hydration properties. Its pasting properties were also characterized by cold initial viscosity, decreased setback and the lack of peak viscosity. The shear‐thinning behaviors of the steam jet‐cooked rice flour were satisfactorily fitted into the Carreau equation. In addition, dynamic viscoelastic measurements showed that the liquid‐like nature was more dominant over the solid‐like properties. When incorporated into frying batter formulations, the steam jet‐cooked rice flour increased the batter viscosity and pickup. The use of steam jet‐cooked rice flour also enabled fried batters to control the moisture loss effectively. Furthermore, the wheat flour replacement with 20% steam jet‐cooked rice flour in batters led to dramatic reduction of oil uptake by around 40%. PRACTICAL APPLICATIONSThis study introduces a hydrothermal treatment (steam‐jet cooking) as a new technique to impart better functional properties to rice flour. Specially, the steam jet‐cooked rice flour exhibited oil‐resisting properties when incorporated into frying batters, consequently producing fried foods with reduced content of oil and calorie.

Rheological properties of black gram (Phaseolus mungo) batter: characterisation of flour from native and modified rice and their effect on batter viscosity

SummaryRheological properties of black gram batter as a function of soaking time, and effect of flour from native and thermally modified rice on black gram batter have been studied. Greater increase in hydration capacity of black gram dhal was observed during 5–15 min of soaking, a gradual increase up to 90 min and a marginal increase beyond this period. Apparent viscosity of batter showed 100% increase up to 90 min and less than 20% increase beyond 120 min, and shear‐thinning nature of batter indicated that they were pseudo‐plastic in nature. Yield stress and consistency index showed greater changes after 90 min, while flow behaviour index did not show significant change beyond 90 min of soaking. Compared with the addition of native rice flour, incorporation of flaked rice flour and expanded rice flour into black gram batter significantly increased the cold paste viscosity of the batter, probably because of their greater water‐holding capacity, compared with that from native rice. Differences in physicochemical characteristics and pasting behaviour of these flour slurries, as studied by Rapid Visco Analyser, corroborated these results by the typical profile of pregelatinised products for flaked rice and expanded rice in comparison to native rice.