Rice Bran Protein Concentrate Research Articles

Rice bran protein increases the retention of anthocyanins by acting as an encapsulating agent in the spray drying of grape juice

Rice bran protein concentrate (RPC), an industrial by-product, may emerge as a green alternative for substituting animal proteins in microencapsulating compounds of interest. This study applied RPC, combined with maltodextrin (MD) as carrier agents, in the spray drying of grape juice, a product rich in these bioactive compounds, seeking to protect anthocyanins from degradation. The effects of carrier agent concentration [C: 0.75, 1.00, and 1.25 g of carrier agents (CA)/g of soluble solids of the juice (SS)] and RPC:CA ratio (P: 0%, as a control sample, 5%, 10%, 15%, and 20%) on anthocyanin retention and powder properties were evaluated. At 1.00 g CA/g SS, the internal and total retentions of anthocyanins improved by 2.4 and 3.2 times, respectively, when the RPC:CA ratio increased from 0% to 20%. The protein also exhibited excellent surface activity on the grape juice and positively influenced the physicochemical properties of the microparticles. There was a reduction in stickiness, degree of caking, and hygroscopicity, in addition to an increased antioxidant capacity when protein was used in combination with MD, especially at 1.00 and 1.25 g CA/g SS. Therefore, this study demonstrated that RPC could enhance the protection of anthocyanins during the spray drying of grape juice.

Ultrasonic modulated rice bran protein concentrate: Induced effects on morphological, functional, rheological, and thermal characteristics

The effect of low frequency (20 kHz) ultrasonication at varying amplitude (20%, 30%, 40% for 30 min) on the morphological, functional, rheological, and thermal characteristics of rice bran protein concentrate (RBPC) from three different rice varieties: Pusa Basmati- 1509, 1121 and Sugandha were undertaken for the study. Scanning Electron Microscopy images showed that sonication treatment changed the microstructure of RBPC as some pores appeared on the smooth particles surface and more disordered structures compared to the untreated sample. Sonication treatment decreased mean particle size, D[4,3] from 89.77 μm (untreated) to 64.34 μm (20% amplitude), and increased surface hydrophobicity significantly (p < 0.05), from 1.34 ± 0.0080 (untreated) to 1.65 ± 0.0081 (20% amplitude) of 1121 RBPC variety. The FTIR analysis showed that sonication treatment altered RPBC secondary structure as β sheets, and random coils increased while reducing α-helix and β-turns. Sonication treatment at a lower amplitude of 20% made RBPCs brighter in color as lightness, redness, and yellowness values increased. The results showed that sonication treatment has improved the foaming capacity (FC), foaming stability (FS), and oil binding capacity (OBC) of all RBPC varieties. The FC increased significantly from 34.10 ± 0.27 (untreated) to 50.13 ± 0.98 (30% amplitude), FS (60 min) from 21.19 ± 0.63 (untreated) to 44.20 ± 0.26 (30% amplitude), and OBC from 1.42 ± 0.05 (untreated) to 1.61 ± 0.01 (30% amplitude) of 1509 RBPC variety, respectively (p < 0.05). Furthermore, water binding capacity and emulsion activity were reduced for all RBPC varieties after sonication, while solubility and digestibility improved for the 1121 variety, whereas reduced for the 1509 and Sugandha RBPC varieties. Frequency sweep analysis showed that sonication treatment reduced both the storage modulus and loss modulus of RBPC dispersions. Moreover, protein gel linkages transformed from non-covalent to covalently cross-link with increasing % amplitude for the 1121 RBPC variety. Ultrasonication at a lower 20% amplitude, first decreased the denaturation temperature (Tp) of 1121 RBPC variety from 72.5 °C to 63 °C, then increased it to 77.3 °C at higher 40% amplitude. In conclusion, under the conditions investigated in this study, sonication treatment has the potential to modify the foaming and oil-binding properties of RBPCs.

Enzymatic modification of rice bran protein: Impact on structural, antioxidant and functional properties

Rice bran protein concentrate (RBPC) was hydrolysed by a commercial food grade enzyme-papain to get ~15%, 25% and 32% degree of hydrolysis (DH) to investigate its effect on structural, antioxidant and functional properties as well as in-vitro digestibility. Bulk density and structural flexibility (α-helix and random coils) of rice bran protein hydrolysates (RBPHs) increased with an increase in DH. However, surface hydrophobicity (SHO), total β-sheets, β-turns, and thermal properties decreased with increasing DH. RBPHs possessed improved antioxidant activity as compared to native protein, except metal chelating power. RBPHs had higher solubility and digestibility. Thermal properties were positively correlated with β-sheets content while inversely related to α-helix content. An inverse correlation was observed in protein solubility and SHO. Emulsion activity index and foaming stability were positively related to SHO. Protein digestibility was negatively correlated to the β-sheets, β-turns, and SHO. The results indicated that secondary structure and SHO are the primary factors in affecting the thermal and functional properties as well as digestibility. It is thus concluded that the enzymatic hydrolysis might be applicable for RBPC to increase its potential bioactivity but reserve partial interfacial properties.

Optimization of Extraction Process Parameter for Rice Bran Protein Concentrate and its Utilization in High Protein Biscuit Formulation

In the present study rice bran protein concentrate (RBPC) was extracted from defatted rice bran by alkali extraction method and the extracted protein concentrate was characterized and utilized in biscuit production. Protein concentrate was extracted from rice bran at different rice bran water ratio (25.86-54.14) and solution pH (8.09-10.91). The extraction parameters were optimized by response surface methodology. Optimum conditions for protein concentrate extraction ratio were 1:40.77 bran/water and 9.55 pH of solution. At the optimum conditions the extraction yield of protein concentrate was 11.76% and protein content was 36.29% where native rice bran contained 20.78% protein. RBPC contained most of essential amino acids except tryptophan and phenylalanine, among them arginine was the highest 2.27 mg/100g and the lowest was histidine 0.59 mg/100g. RBPC also contained non-essential amino acid like aspartic acid, serine, glutamic acid, alanine, glycine and tyrosine. The emulsifying capacity, emulsion stability, water absorption capacity, bulk density and oil absorption capacity of RBPC were 56 percent, 36 min, 3.02 g/g, 0.49 g/ml and 1.72 g/g respectively. A 5% rice bran protein concentrate supplemented biscuits upgrade the total protein content in biscuits from 7.54 to 9.13. Therefore, utilization of RBPC can be beneficially achieved through formulation of protein enriched biscuits with enhanced nutritional value especially for malnourished or undernourished people.

Feasibility of ultrasound-assisted optimized process of high purity rice bran protein extraction

ABSTRACT: Rice bran is a by-product of the rice milling process, found worldwide in abundance and highlighted due its protein content. This study optimized the conditions for ultrasonic-assisted extraction of protein from defatted rice bran (DRB) and characterized the rice bran protein concentrate (RBPC). A sequential strategy of experimental design was employed; the effect of pH, temperature, ultrasound exposure time, and amplitude were evaluated regarding the percentage of protein extraction by a Full factorial design (FFD) with a fixed frequencies (FFD-A: 37 kHz; FFD-B: 80 kHz). Subsequently, the percentage of protein extracted was optimized employing a Central composite rotatable design (variables: pH and ultrasound exposure time) and RBPC obtained was characterized regarding chemical and functional properties. The pH and ultrasound exposure time had positive effect (P ≤ 0.05) on percentage of protein extraction; moreover, 37 kHz frequency was more effective in protein extraction. The optimized condition (frequency: 37 kHz; temperature: 30 °C; pH: 10; ultrasound exposure time: 30 min; and amplitude: 100%) allowed 15.07% of protein recovery and the RBPC presented 84.76 g 100 g-1 of protein. Magnesium and copper were the main mineral in RBPC (34.4 and 25.5 µg g-1, respectively), while leucine was the limiting amino acid (0.42) and threonine presented the highest chemical score (1.0). The RBPC solubility was minimal at pH 4 and higher at pHs 6-10; the water and oil absorption capacity were higher than bovine serum albumin (BSA) and the emulsifying capacity was comparable to BSA, with a suitable stability. It was possible to obtain a higher purity RBPC than described in the literature, due to the optimization in the extraction process steps, with functional properties suitable for application in food products, especially emulsified ones.

QUALITY CHARACTERISTICS OF CORN TORTILLA PREPARED WITH DIFFERENT LEVELS OF RICE BRAN PROTEIN CONCENTRATE

This study was conducted to evaluate the possibility of partial replacement of yellow corn flour with rice bran protein concentrate (RBPC) to prepare highly nutritive and acceptable tortilla.The crude protein and total ash contents of tortilla were increased (p ≤ 0.05) by increasing the level of RBPC in a tortilla. However, total carbohydrates, crude fat and crude fiber had an opposite trend. The caloric values of tortilla were not affected (p > 0.05) byRBPC. Alkaline water retention capacity of the tortilla was increased (p ≤ 0.05) by increasing RBPC levels in the tortilla.However, it was decreased (p ≤ 0.05) by increasing the storage period from 24 to 72 hours.Tortillaprepared with RBPC had darker color than control tortilla. Tortilla prepared with 7.5% RBPC had higher lysine (27.31%) and tryptophan (33.33%) than control tortilla. In-vitro protein digestibility of tortilla was increased (p ≤ 0.05) by increasing the RBPC up to 7.5%.Control tortilla had sensory rating scores ranged from 4.35 (neither like nor dislike) to 6.75 (like very much) for all sensory properties. However, tortilla prepared with 7.5% RBPC had rating scores ranged from 5.35 (like moderately) to 6.95 (like very much) for all sensory properties.The results showed that partial replacement of corn flour with 7.5% of RBPC resulted in an improvement in the nutritive value and overall acceptability of the tortilla.

Preparation and assessment of bioactive extracts having antioxidant activity from rice bran protein hydrolysates

Rice bran protein concentrate (RBPC) was digested using four commercial enzymes, Alcalase, Trypsin, Protamex, and Flavourzyme at a various digestion time (2, 4, and 6 h), in order to produce antioxidant active peptides. The degree of hydrolysis (DH), total phenolic content (TPC), and antioxidant activity, including DPPH, ABTS, and metal chelating assays were examined. The obtained results indicated that DH varied with the type of enzyme used, Protamex > Trypsin > Alcalase > Flavourzyme, respectively. The optimum conditions of hydrolysis was 2 h using Flavourzyme, which gives protein content of 62.90 ± 0.77 mg/100 g, TPC of 893.75 ± 0.57 mg GAE/100 g, DPPH of 83.68 ± 0.97%, ABTS of 35.11 ± 0.66%, and a metal chelating activity of 53.90 ± 0.13%. These results indicate that the hydrolysate produced by digesting RBPC using Flavourzyme may contain bioactive components useful as natural food antioxidants. That can increase their potentials as natural food additives which could be useful in the food industry sector.

Effects of rice bran protein concentrate on the growth performance and digestive enzyme activities of jundiá ( Rhamdia quelen ) (Quoy and Gaimard, 1824)

The aim of this study was to assess the effect of increasing inclusion levels (100, 150, 200 and 300 g/kg) of rice bran protein concentrate (RBPC) in jundia (Rhamdia quelen) diets using growth, body composition, somatic indices and digestive enzyme activity as parameters. Five isoproteic (370.08 ± 0.04 g/kg) and isocaloric (13.38 ± 0.04 MJ/kg) diets were formulated with four replicates per treatment. After acclimation, 500 jundia juveniles (initial mean weight of 6.28 ± 0.12 g) were distributed into 20 round polyethylene tanks (280 L) (25 fish per tank) coupled to a thermoregulated water recirculating system. The fish were fed experimental diets three times daily (at 9:00, 13:00 and 17:00 hr) to apparent satiation. At the end of the trial (45 days), no significant differences were found in the body chemical composition, somatic indices, and trypsin and chymotrypsin enzymes of the fish fed experimental diets. A lower final weight and a lower condition factor were found in fish fed diets RBPC10 (100 g/kg of RBPC) and RBPC15 (150 g/kg of RBPC). Based on the results of this study, it is clear that the use of RBPC (at high dietary inclusion levels of 200 and 300 g kg⁻¹) is an effective alternative protein source to fishmeal.

Effects of protein enrichment on the properties of rice flour based gluten-free pasta

Manufacturers have long complained about gluten-free pasta for its apparent low cooking properties and reduced nutritional value. Proteins are not only bio-polymer that can improve the quality of a product, but they are also an essential nutrient for human health. Therefore, it was proposed to develop a multi-sourced protein enriched gluten-free pasta. The whey protein concentrate (WP) enriched pasta demonstrated the shortest optimal cooking time at 4.3 min. The enrichment of 9% (w/w) egg albumen (EB) displayed the greatest capacity for preventing structure disintegration with the lowest cooking loss of 4.38–4.63% (P < 0.05), whereas rice bran protein concentrate (RBPC) induced the highest cooking loss (P < 0.05). Enrichment with 6% soy protein concentrate (SP) provided similar L* values with a commercial. Moreover, the 9% EB enrichment clearly affected to pasta structure as the pasta firmness improved up to 72.25%. The protein networks around the starch granules were observed to be enriched with EB and WP, whereas the pasta enriched with RBPC produced a cracked and non-continuous surface. Among the four sources of protein tested, EB had the highest potential for improving cooking properties of rice flour based gluten-free pasta.

Comparative study of rice bran protein concentrate and egg albumin on gluten-free bread properties

Gluten-free (GF) based products have been studying for several years especially for quality improvement by enriching with proteins. A common protein source is egg albumin, but it has limitation for using causes of allergenic character. So, aim of this study was to replace egg albumin by rice bran protein concentrates which is a non-allergy protein in order to improve the quality of GF bread. Rice bran, a by-product, was used as starting material for rice bran protein concentrate (RBPC) preparation under alkaline-acid extraction technique. The obtained RBPC was composed of 68.07 ± 0.54% protein (dry basis). For baking trials, the addition of RBPC had strongly influenced the rheological properties, especially elastic modulus (G′) of GF batters during oscillation, and the relative elasticity of final GF breads. Breads enriched with 2% RBPC, and a combination of 1% egg albumin and 1% RBPC had the highest specific volume (P < 0.05). Additionally, crumb porosity and sensory attributes were improved. RBPC also showed higher efficacy to inhibit bread staling than egg albumin. This study suggested that RBPC could be used as a protein source for GF bread.

Effect Adding Of Rice Bran Or Tomato Seed Protein Concentrate On Wheat Dough Performance And Pan Bread Quality Properties

This study was carried out to investigate the effect of partial supplementation of wheat flour with different ratio of rice bran or tomato seed protein concentrate on quality parameters of pan bread. It was used to supplement wheat flour under levels 5, 10 and 15% for rice bran protein concentrate (RBPC) and 3, 5 and 8% for tomato seed protein concentrate (TSPC) for production of pan bread. The results showed that the significant highest protein content was achieved by TSPC followed by RBPC. Lysine content, as a limited amino acid in wheat flour, increased in all supplemented samples. Samples supplemented with RBPC gained the highest chemical score than those of TSPC supplemented samples. Water absorption of wheat flour and stability of dough increase gradually by increasing of RBPC or TSPC. The addition of TSPC at all tested levels to wheat flour decreased the C3 values (pasting ability). All tested samples showed lower values of (C4, C3 –C4, and γ) compared to the control sample (increasing the activity of amylase), also, retrogradition ability decreased (C5 and C5 – C4). Extensibility of wheat flour dough was decreased as a result to adding RBPC, but it increases by adding TSPC. Energy of the dough was decreased gradually by increasing of RBPC. Moisture, crude protein, ash and crude fiber contents of pan bread had gradually increased with increasing the supplementation levels of PBPC or TSPC. As the supplementation ratio of either RBPC or TSPC increased, volume and specific volume of bread decreased. Pan bread produced by supplementation with 5%RBPC or 3%TSPC had more sensory acceptable rather the control bread. On the other hand, pan bread prepared by added 10% RBPC or 5% TSPC had the best freshness percentages during storage.

Comparison the effect of three commercial enzymes for enzymatic hydrolysis of two substrates (rice bran protein concentrate and soy-been protein) with SDS-PAGE.

In this research enzymatic hydrolysis of rice bran protein concentrate (RBPC) and soybean Protein (SBP) as control were studied with 3 commercial enzymes (Alcalase®, Papain and acommercial 3-enzyme cocktail containing of 1.6mgml(-1) Trypsin, 3.1mgml(-1) Chymotrypsin, 1.3mgml(-1)Aminopeptidase (SIGMA P7500) and 7.95mgml(-1)pronase type XIV (SIGMA P5147) by the pH stat method. The hydrolysis was carried out at temperature of 28 C, 60min and pH8.00. Results were showed that RBPC, and SBP had higher Degree hydrolysis (DH %) with Alcalase® enzyme. Alcalase®had stronger capability for hydrolysis compared to the other tested enzymes. After 60minute of hydrolysis time, the DH% of Alcalase® for RBPC and SBP was 12.69 and 12.50%, respectively. In contrast, papain enzyme was showed lowest DH% in three substrates that 1.56 and 1.24% were for SBP and RBPC, respectively.The hydrolysis of the protein fraction performed the three enzymes on the two substrates was followed in SDS-PAGE. RBPC and SBP showed almost complete digestion with Alcalase® enzyme after 60minutes. 3-enzyme cocktail enzyme hydrolyzed better the RBPC than the SBP. Papain enzyme had less effect on the two substrates than other 2 enzymes. It was found that Alcalase® has highest capability for hydrolysis compared to other enzyme preparations. The high value protein hydrolysates prepared by Alcalase® can be used as value added ingredients in many food formulations. They are also suitable for a broad range of industrial food applications and also for cosmetic and personal care products.

Sensory aroma characteristics of alcalase hydrolyzed rice bran protein concentrate as affected by spray drying and sugar addition.

The sensory aroma characteristics of alcalase hydrolyzed rice bran protein concentrate as affected by spray drying and sugar addition were investigated. Rice bran protein concentrate (RBPC) was hydrolyzed by alcalase. Sucrose, glucose or fructose was added to the liquid rice bran protein hydrolysate (LRBPH) and subsequently spray dried. The sensory aroma intensities of the hydrolysates were evaluated. Results showed that after spray drying, the rice bran protein concentrate powder (RBPC-P) had higher sweet and cocoa-like aroma intensities than RBPC (p ≤ 0.05) and hydrolyzed rice bran protein powder (HRBPP) had higher milk powder-like aroma intensities than LRBPH (p ≤ 0.05). The sweet, cocoa-like and milk powder-like aroma intensities in hydrolyzed rice bran protein powder with fructose addition (HRBPP-F) were significantly higher (p ≤ 0.05) than those of hydrolyzed rice bran protein powder with sucrose or glucose addition (HRBPP-S or HRBPP-G). HRBPP-F had the highest overall aroma liking score. These results also indicate that spray drying and sugar addition could improve the sensory aroma characteristics of alcalase hydrolyzed RBPC.

Studies on the preparation of Rice Bran Protein Concentrate by Ultrafiltration

In this study, ultrafiltration with a membrane of molecular weight cut off (MWCO) 50 kDa or 100 kDa was applied to produce rice bran protein concentrate and influence process variables such as operation pressure, time, and volume concentration ratio (VCR) on the composition of rice bran protein concentrate and changes in permeation flux were investigated. An increase in permeation flux was observed in accordance with increasing operation pressure, while it decreased with operation time, possibly due to concentration polarization. In addition, the permeation flux was observed to be higher when a membrane with larger MWCO was used and a maximum permeation flux (32 L/m·h) was observed with an operation pressure of 2 kgf/cm 2 and a 100 kDa membrane. Protein content in the concentrate rose with increasing VCR, and also with membranes of smaller MWCO (i.e, 50 kDa). It was found at VCR 8 and with an operation pressure of 2 kgf/cm 2 that total processing time decreased by 40% and average permeation flux increased by about 2 times, when a membrane with 2 times larger MWCO (i.e., 50 kDa→100 kDa) was used.

Extraction, characterization and utilization of rice bran protein concentrate for biscuit making

PurposeThe purpose of this paper is to study the utilization of the rice bran protein concentrate (RBPC) in biscuits to upgrade the nutritional quality.Design/methodology/approachExtraction of rice bran protein concentrate (RBPC) from defatted rice bran was standardized using alkali extraction method. Defatted rice bran and RBPC were analyzed for their proximate composition. RBPC was analyzed for its bulk density, foaming capacity (FC), emulsion activity (EA), and water and oil absorption capacity. RBPC was incorporated in biscuits at 5, 10 and 15 per cent levels. The biscuits were analyzed for their physicochemical, fracture strength (texture analyzer) and sensory attributes (nine‐point hedonic scale) to assess their acceptability.FindingsThe maximum yield of 13.2 per cent for RBPC was obtained at alkaline pH of 11, temperature of 60°C and extraction time of 60 minutes. The bulk density, foaming capacity, emulsifying ability, water and oil absorption capacity of RBPC were 0.4 g/ml, 11 per cent, 40 per cent, 2.9 ml/g and 2.3 ml/g respectively. The protein content of biscuits increased significantly from 7.3 per cent in control biscuits to 15.4 per cent in the 15 per cent RBPC supplemented biscuits with their fracture strength also significantly higher than the control biscuits (p&lt;0.05). Replacement of refined wheat flour up to 10 per cent RBPC produced protein‐enriched biscuits with desirable overall acceptability.Originality/valueRice bran protein concentrate can be beneficially utilized to formulate protein enriched biscuits with enhanced nutritional value especially for malnourished or undernourished people.

A study on the development of high functional food protein ingredient from rice bran

ABSTRACT Rice bran proteins from different cultivars(Youngan, Sindongj in, Suwon 511) were extracted with Xylanase using orthogonal analysis method and their functional properties were investigated. The optimum extraction conditions, based on protein content in the extract found to be at 1 wt% xylanase, pH 7 and 50:1, solvent to rice bran ratio(v/w %). Nitrogen solubility indices(NSI) of rice bran protein concentrates were shown a minimum value at pH 4 ranged 2～23%, varied with different cultivars and a maximum (NSI≥90% for all cultivars) at pH 10. As for water adso rption and fat adsorption capacity, rice bran protein concentrates were shown to be better than Na-caseinate and isol ated soy protein, respectively. Emulsifying activities were observed high in order of Na-caseinate>Youngan rice bran protein>Shindongjin rice bran protein>Suwon 511 rice bran protein>isolated soy protein. In general, the surface tension o f rice bran protein solution(10 -3 wt%, 5 mM bis-tris, pH 7) was increased with increasing concentrations and found a minimum va lue near pI. On heating, it was decreased slightly with increasing temperatures up to 70 ℃ and then increased above 80 ℃. Addition of sodium chloride was made the surface tension decrease. In conclusion, with Xylanase, rice bran prote in concentrate can be successfully extracted from the rice bran of different cultivars and the Youngan rice bran protein was thought to have best functionality among rice cultivars tested. I t might be used as a milk protein substitute. Key words: rice bran protein concentrate, extraction, emulsifying activit y, surface tension

Effect of preparation conditions on composition and sensory aroma characteristics of acid hydrolyzed rice bran protein concentrate

Hydrolysates were prepared from rice bran protein concentrate (RBPc) in paste form (P-RBPc), or as spray-dried (S-RBPc) or freeze-dried (F-RBPc) powder by acid hydrolysis with aqueous 0.5N HCl at 95 °C for 12 or 36 h. The forms of the protein raw material had only a slight influence over the sensory aroma characteristics of the liquid hydrolysates. The liquid hydrolysate (S-H-RBPc-12) prepared from S-RBPc with hydrolysis time of only 12 h could produce the desirable aromas as to a similar extent as that of 36 h. In order to demonstrate the effect of drying method on the composition and aroma characteristics, a representative S-H-RBPc-12 was converted into a powder by freeze- and spray-drying techniques. Sensory analysis indicated that the spray-dried powder had higher cracker-like and salty aroma intensities and received a higher overall liking score compared to the freeze-dried hydrolysate powder.

EFFECT EXTRACTION METHODS OF RICE BRAN PROTEIN ON THEIR FUNCTIONAL PROPERTIES

This investigation was carried out to study the functional properties and amino acids compositions of rice bran protein isolate (RBPI) and rice bran protein concentrate (RBPC). The results indicate that (RBPI) had better water binding capacity, protein content and yield as compared to (RBPC), while oil binding capacity lower in (RBPI) than (RBPC). Nitrogen solubilities of (RBPI) were 52.3, 8.4, 63.5, 79.1, 83.7 and 81.5% at pH 2, 4, 6, 8, 10 and 12, respectively. RBPI had better foaming and emulsifying properties than (RBPC). While, RBPI had similar foaming properties in comparison to egg white, but emulsifying properties of RBPI were lower than those of bovine serum albumin. The results of amino acid analysis showed that the relative content of cystine and methionine in RBPC were lower than that of RBPI and RBP, while leucine and phenylalanine were higher in RBPC .The computed protein efficiency ratio(C-PER) and biological value (B V) of RPBI were higher than those of RBPC and value of all samples were lower than that of standard casein protein. Obtained results indicate that the RBPC and RBPI have high qualities of both nutritional and functional properties and could be competitive proteins ingredients in food products.

Preparation and Some Functional Properties of Rice Bran Protein Concentrate at Different Degree of Hydrolysis using Bromelain and Alkaline Extraction

Rice bran protein was extracted by using defatted rice bran and water at 1:6 (w/w) and 6% of bromelain at pH 9.0, 50°C, 500 rpm for 15 and 30 mins. The degree of hydrolysis (DH) of rice bran protein extract (RBPE) was 19 and 36.5%, respectively, and their nitrogen solubility was higher than the controls. Rice bran protein concentrate (RBPC) was prepared by spray drying. Emulsion activity of RBPC produced from 19% DH RBPE was increased while emulsion stability index was not significantly different from the control. Foam capacity and rehydration ability of RBPC were greater than the control.

Aroma Components of Acid-Hydrolyzed Vegetable Protein Made by Partial Hydrolysis of Rice Bran Protein

Hydrolyzed vegetable protein (HVP) was prepared from rice bran protein concentrate (RBPc) by partial hydrolysis with aqueous 0.5 N HCl at 95 degrees C for 12 or 36 h (H-RBPc-12 and H-RBPc-36, respectively). Aroma components of the RBPc and the HVPs were characterized by gas chromatography-olfactometry, gas chromatography-mass spectrometry, aroma extract dilution analysis, and calculation of odor activity values (OAVs). The predominant odorants in RBPc were 3-methylbutanal, hexanal, 2-aminoacetophenone, (E)-2-nonenal, phenylacetaldehyde, and beta-damascenone. Among these, the odor of 2-aminoacetophenone, present at 59 ng/g in RBPc, was reminiscent of the typical odor of RBPc. Most of the predominant odorants had higher log3FD factors in the H-RBPc-36 as compared to H-RBPc-12. Aroma impact compounds of H-RBPc-12 and H-RBPc-36 were 2-methoxyphenol (guaiacol), 4-hydroxy-2,5-dimethyl-3(2H)furanone, 3-hydroxy-4,5-dimethyl-2(5H)furanone (sotolon), vanillin, 3-methylbutanal, (E)-2-nonenal, 4-vinyl-2-methoxyphenol (p-vinylguaiacol), and beta-damascenone. Guaiacol had the highest OAV values of 2770 and 17650 in H-RBPc-12 and H-RBPc-36, respectively.