lAccepted 10 October 2014

Keywords:Rice cultivarsPhysicochemical propertiesColourFlours and starchesThermal properties

g ad 5

in the d

amount of Oryza glaberrima, a perennial species is grown in Africa(Falade, Semon, Fadairo, Oladunjoye, & Orou, 2014; Yadav & Jindal,2008; ). Rice is grown in paddies or on upland elds, depending onthe requirements of the particular variety; there is limitedmangrove cultivation. Different varieties are grown, some of which

Kadan, Robinson,, and Miller, 2008;re rice ours androperties (Kadan,ich could indicateces of rice cultivarsrded as the most

important constituent of rice which affects the pasting behaviourand functionality (Zhou, Robards, Helliwell, & Blanchard, 2002).The main variation in the composition of rice starch caused by therelative proportions of the two fractions in the starch granules andthis, together with the chain length distribution and the frequencyand spacing of branch points within the amylopectin molecule (Lu,Chen,& Lii, 1997), has a profound inuence on the physicochemicalproperties of starch (Jane, Chen,& Lee,1999). The pasting behaviourof starch-water pastes is inuenced by the chemical and physical* Corresponding author. Tel.: 234 807 318 7227.

Contents lists available at ScienceDirect

Food Hydr

ls

Food Hydrocolloids 44 (2015) 478e490E-mail address: kolawolefalade@yahoo.com (K.O. Falade).2008). In sub-Saharan Africa, over 20 million farmers grow andproduce about 4.8 million tonnes of rice (FAOSTAT, 2014). The de-mand for rice in sub-Saharan Africa is expected to grow substan-tially as the population is currently growing at the rate of 3e4% perannum and rice consumption is growing faster than other foods(Akinwale et al., 2011). About 20 species of the genus Oryza arerecognized, but nearly all cultivated rice is Oryza sativa L. A small

gluten-free breads (Kadan & Ziegler, 1989;Thibodeux, & Pepperman, 2001; Kadan, BryantMcCue, 1997). These novel foods usually requistarches having known physicochemical pChampagne, Ziegler, & Richard, 1997, 2008), whmarket value, utilization and consumer preferen(Falade et al., 2014). Starch is generally regaa staple food of over three billion people, constituting over half theworld's population (Cantral & Reeves, 2002; Ebuehi & Oyewole,

functional properties, is used in a number of novel foods such astortillas, beverages, processed meats, puddings, salad dressings and1. Introduction

Rice is the most important cerealhttp://dx.doi.org/10.1016/j.foodhyd.2014.10.0050268-005X/ 2014 Elsevier Ltd. All rights reserved.higher yield. Starch granules were small and polyhedral shaped, with average length and width of 5.37e9.25 and 3.94e6.94 mm, respectively. The Faro 40 (5.49) and Faro 55 (2.80) exhibited highest and lowestswelling power, respectively at 60 C. The Faro 52 (2376.0 cP) and Faro 44 (3988.5 cP) ours showedhighest and lowest peak viscosities, respectively. Amylose content of the rice starches varied from 20.68(Faro 40) to 25.95 (Faro 55). Peak viscosity of starches (4893e6080 cP) was higher than ours, andincreased in the order: Faro 52 < Faro 21 < Faro 40 < Faro 55 < Faro 44 < Faro 46. The FTIR spectroscopyof starches identied most of the a-1/4 glucosidic linkages within spectral absorption bands of 1149.55e1023.00 cm1. Thermal properties of the rice starches ranged: gelatinization onset To (50.8e68.8 C),gelatinization peak, Tp, (78.7e93.7 C), glass transition temperature Tg (35.2e50.2 C), gelatinizationconclusion Tc, (116.4e127.6 C), gelatinization enthalpy, DHG (7.58e17.35 J/g) and peak height index, DHG/(Tp To) (0.26e1.64). This study provides knowledge for the utilization of ours and starches isolatedfrom Nigerian rice cultivars that would be relevant for the postharvest value addition chain.

2014 Elsevier Ltd. All rights reserved.

eveloping world and is

are considered traditional while new cultivars have been intro-duced within the last twenty years (Falade et al., 2014).

In recent years, rice, especially rice our, because of its uniqueAvailable online 1 November 2014than ours (81.09e90.03). Water (122.64e143.35%) and oil (59.97e72.98%) absorption capacities variedsignicantly among the cultivars. Starch yield varied between 41.21 and 52.57%, with Faro 52 showingPhysical, functional, pasting and thermastarches of six Nigerian rice cultivars

Kolawole O. Falade*, Akinpelu S. ChristopherDepartment of Food Technology, University of Ibadan, Ibadan, Nigeria

a r t i c l e i n f o

Article history:Received 6 May 2014

a b s t r a c t

Physical, functional, pastin(Faro 21, 40, 44, 46, 52, an

journal homepage: www.eproperties of ours and

nd thermal properties of ours and starches of six Nigerian rice cultivars5) were investigated. Starches showed higher CIE L (96.37e99.81) value

ocolloids

evier .com/locate/ foodhyd

od Hproperties of the samples, including the amounts and types ofstarch, and the presence of lipids, proteins and low molecularweight solutes (Dang & Copeland, 2004).

A small proportion of rice crop is used as raw material for pro-cessed foods but the bulk is consumed as cooked rice. Processedrice products may be derived from rough rice, brown rice, milledrice, cooked rice, brokens, dry-milled our, wet-milled our andrice starch among others. Rice our is an important ingredient inthe manufacture of puffed grains and breakfast cereals. In order tocontrol better production process, it is necessary to understand theproperties of rice our as well as their starches. Most Nigerian ricecultivars are consumed as whole milled grains or as tuwo shinkafa,which the our is mixed with boiling water and stirred to producedough with smooth consistency, and then eaten with accompani-ment. Therefore, the developments of value added products such asrice ours and starches would increase their utilization, andimprove the rice industry. There exists little or no available infor-mation on functional, pasting and thermal properties of ours andstarches of the selected Nigerian rice cultivars. Consequently, theobjective of this research was to investigate the functional, pastingand thermal properties of ours and starches of six Nigerian ricecultivars.

2. Materials and methods

Paddy rice of Faro (Federal agricultural research oryza) 40, 46and 55 (Upland cultivars) were obtained from National CerealsResearch Institute, Ibadan, while Faro 21, 44 and 52 (Lowland cul-tivars) were obtained from the from the Africa Rice Center Sub-station based at the International Institute of Tropical Agriculture,Ibadan. Nigeria and National Seed Centre, Ibadan.

2.1. Parboiling and milling of the rice cultivars

The parboiling of rice paddywas carried out using the proceduredescribed by Biswas and Juliano (1988) with slight modication.After cleaning and manual de-stoning, batches of rough rice weresoaked for 24 h at 60 C, drained and pressure-parboiled for15 min at 120 C (1.0 kg/cm2) in an autoclave (LDZX-50 KB,Shanghai Shen). The parboiled rice was sun dried to a moisturecontent of 14% (w/b) prior to dehulling. The parboiled rice wasmilled (single pass) with a friction-type laboratory milling machine(Yanmar HS 1000 EH, Japan). The outlet pressure and ow rate inthe milling machine were also xed by trial and error before eachmilling to obtain the desired degree of milling. The milled rice waskept in sealed polyethylene bags and stored at 25 C.

The % milling yield was calculated.

% Milling Yield Mass of rough rice grainMass of brown rice

100

The degree of milling (DOM) is the amount of bran that has beenremoved from kernels during the milling process (Bello, Baeza, &Tolaba, 2006).

Degree of Milling Mass of rice branMass of rice

100

2.2. Isolation of the rice starches using the alkaline extractionmethod

The starch was extracted from dehulled rice by alkali extractionof the protein described by Lawal et al. (2011) with slight modi-

K.O. Falade, A.S. Christopher / Focations. Milled rice (1 kg) was steeped in NaOH solution (0.2%, 1 L)at 25 C for 24 h to soften the endosperms. The steep liquor wasdrained off, then the endosperms were washed and ground with acommercial blender (Philips HR2001, Holland), low speed at rst,then at full speed for 1min. The slurry was again dispersed in NaOHsolution (0.2%, 1 L), agitated with a magnetic stirrer (Stuart CB161,Barloworld Scientic, Staffordshire, UK) for 20 min and allowed tosettle for 6 h and the supernatant was drained off. The process wasrepeated for another 10 hwith the yellow tailings skimmed off eachtime until the supernatant gave a negative response to the Biuretprotein test (Cardoso, Putaux, Samios, and da Silveira, 2007). Theslurry was suspended in distilled water, the pH was adjusted to 7.0with HCl (0.5 M) and passed through nylon screen (75 mm). After-ward, it was allowed to settle for another 6 h and the clear super-natant was discarded. The starch obtained as sediment was dried inan air convection oven (Uniscope SM9053, Surgifriend medicals,England) at 40 C for 48 h. The dried starch was pulverized into asmooth owing powder using the dry mill of the commercialblender (Philips HR2001, Holland). Samples were sealed in Ziploc

double zipper high density (26.8 27.3 cm, 100 mm) packages(Ziploc Brand Products, WI, USA) and kept for analysis.

2.3. Determination of moisture, protein and fat contents of the ricecultivars

Milled rice samples were ground into our with a commercialblender (Philips HR2001, Holland). Moisture content was deter-mined by gravimetric method using a cross ow Gallenkamp Sizetwo BS model OV-160 hot air oven (Gallenkamp, England, UK) at102 C until constant weight (AOAC, 1990). Protein and fat contentswere determined using a standard Kjeldahl distillation and solventextraction methods, respectively (AOAC, 2011.11).

2.4. Physical properties

2.4.1. Physical characteristics of rice kernelsLength (L) and width (W) of randomly selected 150 paddy and

unbroken milled rice grains were measured using a digital veneercalliper (1200 Digital Caliper Carrera Precision, China) with accuracyof 0.01 mm. Also, the average length/width (L/W) ratio wascalculated. Aspect ratio (AR) and total volume (Vt) of the rice ker-nels were calculated: ARW/L (Mohsenin, 1986), Vtp d2(hd) /44/3p(d/2)3 (Oikonomopoulou, Krokida, & Karathanos, 2011),respectively, where Vt (m3) is the total volume of each rice kernel,d (m) the diameter and h (m) the height of the cylindrical part of therice kernel.

2.4.2. Determination of one thousand grain weightA thousand grain weight of randomly selected rice kernels was

determined using an analytical balance (OHAUS Discovery DV 241C,Pine Brook, NJ, USA).

2.4.3. Determination of the colour parameters of rice ours andstarches

The Commission Internationale de lEclairage (CIE) L, a and bparameters of rice ours and starches were determined using aChroma Meter (CR-410, Konica Minolta, Japan) having opticalsensor lens at 2 observer. The following colour traits were assessedby the equipment: L (lightness) axise 0 is black, while 100 is white;a (red e green) axis e positive values are red while negative valuesare green and 0 is neutral; b (yellow-blue) axise positive values areyellow while negative values are blue. The instrument was cali-brated with a standard white tile (L* 93.75, a*5.36, b* 8.50).Multiplemeasurements of L*, a* and b* parameterswas determined

ydrocolloids 44 (2015) 478e490 479using the colourimeter on the samples. From the data obtained,

d HChroma (DC Da2 Db2

q), colour intensity

(DE DL2 Da2 Db2

q) and hue angle (Hue angle Tan1b/

a) were calculated (Hunt, 1991).

2.5. Functional properties of rice ours and starches

2.5.1. Determination of loose and packed bulk densitiesAmeasuring cylinder (100 mL) was lled with the sample to the

100 mL mark and the weight was obtained with a digital weighingbalance (OHAUS Discovery DV 241C, Pine Brook, NJ, USA). Loose andpacked bulk densities of the paddy, brown, our and starch of ricewere determined using similar procedure, but packed density waswith additional tapping (50) of the edge of the work bench priorto re-weighing. The densities were calculated as the ratio of thebulk weight to the volume (g/mL).

2.5.2. Determination of water (WAC) and oil (OAC) absorptioncapacities

Water and oil absorption capacities of rice ours and starcheswere determined according to the procedure of Sosulski (1962).One gram of sample was suspended in 10 mL distilled water (orrened soybean oil) in a weighed centrifuge tube. The suspensionwas vortexed three times and 10 min rest periods were allowedbetween each mixing. This suspension was centrifuged at 2000 gfor 30 min and the supernatant was decanted, and the tubes wereair-dried. The bound water was calculated from the increase in theweight of the samples. Water (or oil) absorption capacity wasexpressed as percentage of water (or oil) adsorbed by 100 g ofsample.

2.5.3. Determination of swelling power and solubilitySwelling power and solubility of isolated rice starches were

determined using the method described by Osundahunsi, Fagbemi,Kesselman, and Shimoni (2003). A starch-water slurry (0.35 g in12.5 mL distilled water) was heated in a water bath at 60 C for30 min with constant agitation. The slurries were then centrifugedat 3500 g for 20 min. The supernatant was decanted in pre-weighed evaporating dish and dried at 100 C for 20 min. Thedifference in weight of the evaporating dish was used to calculatethe solubility. Swelling power was calculated by weighing theresidue after centrifugation and dividing by the original weight ofthe starch on a dry weight basis.

2.5.4. Determination of gel consistencyGel consistency was determined using the method described by

Cagampang, Perez, and Juliano (1973). Rice our/starch (0.1 g) ofdifferent samples was taken in test tubes of 18 150 mm di-mensions. Ethanol (0.2 mL; 95%) containing thymol blue (0.025%)and 2mL of potassium hydroxide (0.2 N) was added to samples. Thesamples were heated in boiling water bath for 10 min and thencooled in ice water bath for 20 min. Gel consistency was measuredby the length of cold gel in test tubes held horizontally on graphpaper after 30 min.

2.5.5. Determination of the alkaline spreading valueAlkali spreading value of the rice kernels was determined using

the method of Bhattacharya and Sowbhagya (1972). The test wasconducted in Petri plates containing 4e6 rawmilled rice grains andpotassium hydroxide (1.7%) solution. The plates were incubatedovernight at 28 1 C, and the score (based on a 7-point scale) wasgiven on the basis of degradation of rice grains, which included theamount of residual chalky substance in the degraded grain, the

K.O. Falade, A.S. Christopher / Foo480diameter of the collar and the consistency of the collar. The highestscore was given for complete degradation of kernels in potassiumhydroxide solution and vice versa.

2.5.6. Determination of amylose contentAmylose content (%) was determined using a spectrophotom-

eter (Spec UNICO 1100 RS, United products and Instruments Inc.)at 620 nm using the iodine binding method of Juliano (1971) andHoover and Ratnayake (2002). Amylopectin was determined fromdeduction of amylose from 100%.

2.6. Pasting properties of rice ours and isolated starches

A rapid visco analyser (RVA super 4, Newport Scientic Pty. Ltd.,Narrabeen, Australia) was used for the determination of the pastingproperties of the ours and starches of rice. The mixture of 3.5 gsample and 3.5mL distilledwater was stirred in the sample canisterat 960 rpm for 10 s to prevent sedimentation and then at 160 rpmfor the remainder of the test. The temperature prole was startedfrom 50 C for 1min followed by raising the temperature linearly to95 C in 3 min 42 s, holding for 2 min 30 s, then cooling the systemto 50 C in 3 min 48 s, and ending the process in about 13 min. Theviscosity breakdown ratio was dened as the ratio of trough to peakviscosity (Waramboi, Dennien, Gidley, & Sopade, 2011).

2.7. Fourier transform infrared spectrocopy (FTIR)

The Fourier Transform Infrared Spectroscopy was used toidentify the functional groups present in rice starch samples usingthe compressed alkali metal halide pellet method described byWidjanarko et al. (2011). A mixture of 0.1 g starch sample wasground with 0.1 g anhydrous KBr in a crucible to obtain a homog-enous mixture. The mixturewas compressed in a hydraulic press toform a transparent pellet. The pellet was scanned at infra-red ab-sorption area of 450e4000 cm1 in an Infra-red Spectrum (BXPerkin Elmer, USA).

2.8. Differential scanning calorimetry

Thermal properties of rice starches were determined usingdifferential scanning calorimeter (DSC-204 (Netzsch, Germany)according to the method of Mweta (2009). About 1.0 mg starchsamplewasweighed into pierced DSC aluminium pans and distilledwater added to make a starch:water ratio of 1:3. The pans werehermetically sealed and samples left to stand for 1 h at 25 2 C formoisture equilibration. The sealed pans were heated from 20 C to130 C under nitrogen gas at a heating rate of 10 C min1 togelatinise the starch samples. An empty aluminum panwas used asreference and the calorimeter was calibratedwith indium. From theDSC thermograms, the onset temperature (To), peak temperature(Tp), conclusion temperature (Tc) and enthalpy of gelatinisation(DHG). Temperature range and peak height index (PHI) were alsocalculated as Tc To and as the ratio DHG/(Tp To), respectively.

2.9. Starch granule morphology

Light microscopymethod described by Falade and Okafor (2013)was used in assessing the morphology of rice starch samples. About0.1 mg of starch sample was dispersed in 2 mL double-distilledwater containing one drop of Safranin red stain. One drop of thesuspension was placed on a clean slide and covered. The slide wasviewed under 40 and 100 magnications (Olympus BX 51,Tokyo, Japan). Imaging of the starchmorphology was obtained witha Viewnder Studiolite Version 1.0 software connected to the mi-croscope. The granule size was obtained by measuring the di-

ydrocolloids 44 (2015) 478e490ameters of 20 random granules and taking the average. Size

distributions of the starch granules were estimated by classifyingthe size of starch granules into four groups: large (>25 mm), me-dium (10e25 mm), small (5e10 mm) and very small ( 0.05). Meansresult of lower water activity amongst other factors. Fat and proteincontents of the rice starches varied from 0.04 to 0.35 and0.35e0.48%, respectively. Protein content of rice starch depends onthe method of isolation (Singh et al., 2000) but should not exceed0.5%.

3.4. Physical characteristics of rice paddy and milled rice

Average length of rice paddy ranged from 8.98 mm (Faro 40) to9.76 mm (Faro 52) while the average width ranged from 2.53 mm(Faro 40) to 2.73 mm (Faro 55). The Faro 21, Faro 44 and Faro 52were signicantly longer (p 0.05) than other cultivars (Table 1).Packed bulk density, a very useful parameter for the design of silosand storage bins for grains, was higher in Faro 55 (0.65 g/mL) andlower in Faro 44 (0.53 g/mL). Similar result (0.56e0.64 g/mL) wasreported by Bhattacharya et al. (2006). The Faro 55 showedsignicantly higher paddy packed bulk density than other cultivars.The high paddy packed bulk density of Faro 55 could be due to itslow L/W ratio (3.31); the more round the grain, the less the porosityand the higher the compactness represented by the bulk packeddensity. Consequently, Faro 44 with the lower packed bulk densitywould require larger storage space and invariably more storagecosts per weight than Faro 55. The 1000-kernel weight of Faro 55(28.99 g/1000 kernel) paddy was signicantly higher than others.This could be attributed to the high bulk density of the paddy.However, Faro 40 (25.37 g) had the lowest 1000 kernel weight.

Average length, width and length/width ratio of the milled ricecultivars were in the range 6.33e6.80 mm, 2.21e2.34 mm and2.81e3.04, respectively (Table 1). Length of the milled grain variedbetween 6.33 mm (Faro 40) and 6.80 mm (Faro 52). Ebuehi andOyewole (2008) reported relatively similar values for Ofada ricewith average length and width of 6.95 mm and 2.04 mm

vars.

Total volume(mm3)

Loose bulkdensity (kgm3)

Packed bulkdensity (kgm3)

1000-kernelWeight (g)

Graintype

63.42ab 0.01 0.51cd 0.01 0.56c 0.01 27.54 0.40 Long58.44b 0.02 0.52bc 0.03 0.56c 0.01 25.37 0.23 Medium71.60a 0.29 0.47d 0.01 0.53d 0.00 25.99 0.31 Long69.48ab 0.01 0.56ab 0.02 0.62b 0.01 27.58 0.12 Medium66.35ab 0.01 0.53bc 0.01 0.57c 0.01 27.66 0.20 Medium69.60ab 0.01 0.59a 0.01 0.65a 0.01 28.99 0.31 Medium

34.34a 0.06 0.84a 0.02 0.88a 0.01 21.37b 1.19 Long33.35a 0.65 0.82a 0.02 0.89a 0.01 20.97b 0.20 Medium33.87a 0.09 0.82a 0.02 0.89a 0.00 21.27b 0.46 Long38.41a 0.01 0.83a 0.01 0.88a 0.01 21.83b 0.45 Medium38.15a 0.11 0.81a 0.02 0.85a 0.03 21.17b 0.30 Medium38.50a 0.01 0.81a 0.02 0.88a 0.02 23.13a 0.25 Mediumof 150 replicates for physical dimensions.

b1

1

d HTable 2Colour parameters of ours and starches of Nigerian rice cultivars.

Cultivar Commodity L a

Faro 21 Flour 87.43b 0.02 0.05d 0.01Faro 40 Flour 81.09e 0.29 2.39a 0.02Faro 44 Flour 90.03a 0.63 0.01d 0.01Faro 46 Flour 85.21d 0.11 0.17c 0.05Faro 52 Flour 86.54c 0.21 0.27c 0.02Faro 55 Flour 86.85c 0.09 0.70b 0.13

Faro 21 Starch 97.11bc 1.06 0.14b 0.07Faro 40 Starch 96.37c 0.57 0.24a 0.66Faro 44 Starch 97.61b 0.06 0.13b 0.00

K.O. Falade, A.S. Christopher / Foo482respectively. All the grains were longer than the Ofada rice cultivarlength (5.48e6.31 mm) and width (2.02e2.37 mm) reported byAdekoyemi et al. (2012). Using the characterization principle ofCodex Alimentarius Commission (1990) for milled rice, Faro 21 andFaro 44 fell within the long grain category, having length to widthratio 3 while the other cultivars fell within the medium graincategory. Consequently, with enhanced processing facilities, Faro 21and Faro 44 stand a good chance of competing in the world ricemarket which favours long grain cultivars.

The 1000-kernel weight of milled rice kernels ranged between20.97 (Faro 40) and 23.13 g/1000kernels (Faro 55). Our resultsagreed with the value of 21.64 g/1000 kernel reported by

Faro 46 Starch 99.24a 0.35 0.15b 0.00Faro 52 Starch 99.81a 0.37 0.13b 0.01Faro 55 Starch 98.91a 0.12 0.16b 0.00

Means in a column with the same letter are not signicantly different (p > 0.05). Means

Table 3Functional properties of rice our and starches the Nigerian rice cultivars.

Cultivar Moisturecontent (%)

Loose bulkdensity (g/mL)

Packed bulkdensity (g/mL)

Water absorptioncapacity (%)

Faro 21 Flour 10.32bc 0.22 0.54ab 0.04 0.70b 0.05 126.56b 2.37Faro 40 Flour 10.99a 0.15 0.51bc 0.02 0.69b 0.01 126.95b 1.58Faro 44 Flour 10.36bc 0.20 0.46c 0.03 0.65b 0.04 143.35a 2.37Faro 46 Flour 10.70ab 0.04 0.60a 0.01 0.79a 0.02 129.90b 1.58Faro 52 Flour 10.34bc 0.01 0.57ab 0.03 0.78a 0.01 122.69b 6.31Faro 55 Flour 10.05c 0.01 0.46c 0.02 0.71b 0.04 126.74b 1.57

Faro 21 Starch 9.45a 0.08 0.36a 0.00 0.43a 0.01 97.19bc 1.56Faro 40 Starch 9.56a 0.13 0.34a 0.04 0.40a 0.00 106.15a 1.56Faro 44 Starch 8.79ab 0.21 0.31a 0.02 0.41a 0.01 106.34a 6.20Faro 46 Starch 8.29b 0.70 0.30a 0.01 0.43a 0.01 96.50bc 5.40Faro 52 Starch 8.93ab 0.04 0.33a 0.00 0.43a 0.01 103.77ab 0.77Faro 55 Starch 8.78ab 0.01 0.30a 0.01 0.42a 0.00 93.73c 0.77

Means in a column with the same letter are not signicantly different (p > 0.05).

Table 4Pasting properties of ours and starches of Nigeria rice cultivars.

Cultivar Commodity Peak viscosity(cP)

Trough viscosity(cP)

Breakdown visco(cP)

Faro 21 Flour 3201.53b 32.53 2565b 26.87 636c 5.66Faro 40 Flour 2399.50d 62.93 1618.50e 10.61 781b 52.32Faro 44 Flour 3982.50a 30.41 3062.50a 50.20 920a 80.61Faro 46 Flour 2962.50c 50.20 1992c 32.53 970.50a 17.68Faro 52 Flour 2376d 59.40 1712.50d 19.09 663.50c 40.31Faro 55 Flour 2880.50c 2.12 2003.50c 13.44 877.00ab 11.31

Faro 21 Starch 5176c 118.79 2176.5e 26.16 2999.5b 92.63Faro 40 Starch 5331.5bc 24.75 3658.5c 38.89 1673f 14.14Faro 44 Starch 5918a 57.98 4036.50a 8.48 1882e 49.49Faro 46 Starch 6080.50a 48.79 3788.5b 44.54 2292d 93.33Faro 52 Starch 4893d 114.55 2304.50d 74.95 2589c 39.60Faro 55 Starch 5490.50b 21.92 2335d 4.24 3155.5a 26.16

Means in a column with the same letter are not signicantly different (p > 0.05). MeansDE DC Hue angle

8.96c 0.05 4.57d 0.00 2.03c 0.05 89.69a 0.080.20bc 0.02 10.78a 0.27 2.70b 0.00 76.82e 0.088.77d 0.04 3.47e 0.26 3.10a 0.04 89.89a 0.030.24bc 0.35 6.53b 0.16 1.62d 0.35 89.05b 0.2510.37b 0.13 5.20c 0.23 1.49d 0.13 88.50c 0.1311.44a 0.47 4.73d 0.07 0.71e 0.19 86.50d 0.52

1.64e 0.02 1.69c 0.36 1.45a 0.01 85.26a 2.582.64b 0.25 0.77d 0.24 0.44e 0.16 84.82a 1.181.87d 0.05 1.47c 0.02 1.24b 0.04 86.03a 0.10

ydrocolloids 44 (2015) 478e490Varnamkhasti et al. (2008) on Iranian rice varieties. The bulk den-sity of the rice cultivars increased after milling, owing to theremoval of less dense fractions (Table 1). This property increasedwhen the volumewas reduced by dehulling: volume reductionwashigher than the mass reduction, assuming that the materialremoved in each unity operation was of lower specic gravity.Similar views were expressed by Bhattacharya and Sowbhagya(2006) and Correa, Silva, Jaren, Junior, and Arana (2007). Bulkdensity did not vary signicantly among the varieties after milling.The total volume occupied by each rice kernel is an importantdesign variable in the postharvest storage and transportation. Totalvolume occupied by each rice kernel varied from 33.35 mm3 (Faro

2.30c 0.10 2.60b 0.30 0.93c 0.06 86.17a 0.292.55b 0.03 3.09a 0.36 0.77d 0.01 87.01a 0.282.89a 0.11 2.21b 0.07 0.71d 0.19 86.76a 0.23

of 3 replicates.

Oil absorptioncapacity (%)

Gel consistency(mm)

Alkalinespread value

Swellingpower (%)

Solubility(%)

60.74b 1.56 39.00b 1.41 3.57ab 1.81 ND ND72.98a 1.56 27. 00c 1.41 4.43a 0.78 ND ND65.24b 0.77 16.00d 0.00 3.43ab 1.61 ND ND59.97b 1.54 64.00a 0.00 1.86c 0.89 ND ND66.98b 6.20 39.00b 1.41 2.29bc 1.38 ND ND62.48b 1.55 16.00d 0.00 3.86a 1.06 ND ND

150.19a 0.00 16.00d 0.00 ND 3.70b 0.76 7.89a 2.23151.48a 6.25 96.00a 11.31 ND 5.49a 0.04 4.73ab 2.23133.76ab 1.54 17.00d 1.41 ND 4.80a 0.06 4.70ab 2.21119.39bc 13.11 76.50b 0.70 ND 3.17bc 0.10 3.11b 0.00112.55c 8.54 56.00c 11.31 ND 2.85bc 0.27 3.14b 0.00117.85bc 8.52 55.00c 1.41 ND 2.80c 0.04 4.70ab 2.21

sity Final viscosity(cP)

Setback viscosity(cP)

Peak time(min)

Pasting Temp.(C)

5210c 93.34 2645d 66.47 6.53a 0.00 86.40a 0.004542d 188.09 2923.50c 177.48 6.10b 0.14 84.00c 0.006456a 31.82 3394b 82.02 6.37ab 0.14 82.35e 0.145972b 29.70 3980a 2.83 6.20b 0.00 83.08d 0.254086e 45.25 2373.50e 21.17 6.23ab 0.24 84.7 3b 0.04

5303c.50 72.83 3200b 59.39 6.23ab 0.05 82.73de 0.60

5783d 101.82 3606.5a 75.66 4.67c 0.00 75.98b 0.046570b 35.35 2911.5d 3.54 5.33a 0.00 79.10a 0.007581a 32.52 3545ab 41.01 5.17b 0.05 73.88c 0.536068c 18.38 2279.5e 26.16 5.10b 0.05 80.00a 0.07

5458.5e 212.84 3154.50c 137.89 4.47d 0.09 79.53a 0.605697de 95.46 3362.5b 91.22 4.53d 0.00 79.53a 0.67

of 3 replicates.

Fig. 1. Pasting viscosities of Nigerian rice ours.

Fig. 2. Pasting viscosities of Nigerian rice starches.

K.O. Falade, A.S. Christopher / Food Hydrocolloids 44 (2015) 478e490 483

nul

ericyheyheericyheyheericyheyhe

the

d HTable 5Granule morphology and DSC thermal properties of Nigerian rice starches.

Cultivar Length Width Gra

Mean(mm)

Min(mm)

Max(mm)

Mean(mm)

Min(mm)

Max(mm)

Faro 21 6.81bc 3.15 1.30 12.50 5.69ab 2.38 1.00 10.00 Sphpol

Faro 40 7.75ab 2.85 2.50 12.50 5.31bc 2.39 3.00 11.00 PolFaro 44 6.61bc 2.70 2.50 12.50 5.13bc 1.98 1.00 9.00 Sph

polFaro 46 9.25a 3.98 1.30 15.00 6.94a 3.28 1.00 13.00 PolFaro 52 5.00c 1.72 1.30 8.80 3.94c 1.53 1.00 6.00 Sph

polFaro 55 5.37c 3.09 1.30 12.50 4.38 bc 2.61 1.00 10.00 Pol

Means of 20 replicates for the starch granule morphology. Means in a column with

K.O. Falade, A.S. Christopher / Foo48440) to 38.50 mm3 (Faro 55). Similar low total volume was observedfrom the dimensions of its paddy which had a total volume58.44 mm3 compared with Faro 55 which had 69.60 mm3.

3.5. CIE L, a and b, and other colour parameters of rice ours andstarches

The CIE L parameter of the rice ours, which indicates white-ness/lightness, ranged from 81.09 (Faro 40) to 90.03 (Faro 44). TheFaro 44 (90.03) our showed signicantly higher lightness thanother cultivars. The Faro 40 our was darker probably due to thepresence of colour pigments on the kernels (Table 2). Calculatedchroma (DC) values of rice our varied from 0.71 (Faro 55) to 3.10(Faro 44), with no signicant difference among the ours. Also,colour intensity (DE) varied from 3.47 (Faro 44) e 10.78 (Faro 40).Hue angle was in the range 76.82 (Faro 40) e 89.89 (Faro 44).Generally, the objective colour evaluation showed that Faro 44showed signicantly higher (p 0.05) lightness, chroma, colourintensity and hue angle than other rice ours.

Fig. 3. Starch granule morphology of Nigerie shape To(C)

Tp(C)

Tc(C)

Tg(C)

DHG(J/g)

DTG(Tc- To)

PHI(DHG/(Tp To)

al anddral

60.90 88.10 126.70 35.20 7.58 65.8 0.41

dral 68.80 87.90 124.80 39.40 8.66 56.0 0.38al anddral

66.20 78.70 122.80 45.00 19.29 56.6 0.29

dral 50.80 88.50 122.50 43.00 12.94 71.70 1.64al anddral

61.20 86.90 116.40 45.50 14.47 55.20 0.68

dral 66.70 93.70 127.60 50.10 17.35 60.90 0.26

same letter are not signicantly different (p > 0.05).

ydrocolloids 44 (2015) 478e490The CIE L value of the isolated rice starches (96.37e99.81) washigher than the ours (81.09e90.03). Boudries et al. (2009) statedthat L values higher than 90 indicated satisfactory whiteness for thestarch purity. The Faro 40 and Faro 52 starches showed lower andhigher L values respectively. Similar trend of low L value wasobserved in Faro 40 our, an occurrence possibly due to theleaching of colour pigments into the starch during the extractionprocess. Generally, the isolated starches could be utilized in productformulations without adverse colour impartation. Calculatedchroma (DC) of the starches varied from 0.44 (Faro 40) to 1.43 (Faro21). Also, calculated colour intensity (DE) varied from 0.77 (Faro 40)to 3.09 (Faro 52), while the hue angle varied 84.82 (Faro 40) to 87.01(Faro 52). There was no signicant difference (p 0.05) betweenthe hue angles of the isolated starches. Differences in L, a, b colourparameters of the rice ours and their corresponding starchescould be due to the discolouration of parboiled rice as a result ofMaillard browning and the diffusion of hull and bran pigments intothe endosperm during soaking (Bhattacharya, 2004; Lambertset al., 2006).

an rice cultivars stained with Safranin.

mog

K.O. Falade, A.S. Christopher / Food Hydrocolloids 44 (2015) 478e490 4853.6. Functional properties of rice our and starches

Fig. 4. DSC glass transition ther3.6.1. Water (WAC) and Oil (OAC) absorption capacity of rice oursand starches

The WACs of the rice ours determined at 25 C ranged from122.64 to 143.35% (db) (Table 3). Williams et al. (2009) reported anaverage of 1.0 g H2O/g our for the WAC of Australian rice ours.However, higher values (2.5 g H2O/g our) were recorded at highertemperatures (70 C) as a result of the swelling of starch granulesby same authors. Mweta (2009) reported that the WAC of starchesis temperature dependent. The major chemical compositions thatenhance the water absorption capacity of ours are proteins andcarbohydrates, since these constituents contain hydrophilic parts,such as polar or charged side chains (Lawal & Adebowale, 2004).

The WAC of rice starches varied from 93.73% (Faro 55) to106.64% (Faro 44). Kim et al. (2010) reported higher water binding

Table 6FTIR functional group identication in isolated starches.

Sample Group frequency (cm1) Functional group assignment

Faro 21 3368.13e2928.57 Presence of -CeH stretch, eOH group1152.30e1023.00 Presence ofeC]O group, mostly aldehy853.27e578.93 Presence of -CeOH bending vibrations

Faro 40 3763.73e2923.07 Presence of -CeH stretch, eOH group1152.30e1020.61 Presence ofeC]O group, mostly aldehy

Faro 44 3406.59e2923.07 Presence of -CeH stretch, eOH group1152.30e1023.36 Presence ofeC]O group, Octyl b- D glu

Faro 46 3417.58e2906.59 Presence of -CeH stretch, eOH group1155.04e1026.10 Presence ofeC]O group, Heptyl b- D g

anhydrous, cyclodextrinsFaro 52 3752.74e2934.06 Presence of -CeH stretch, eOH group

1157.78e1028.84 Presence of eC]O group, Heptyl b- D gFaro 55 3703.29e2939.56 Presence of -CeH stretch, eOH group

1149.55e1023.36 Presence of eC]O group, Heptyl b- D gcapacity of 112.7% and 115.6% for high amylose Thailand and Goamyrice starches, respectively. Difference in WAC between the cultivars

rams of Nigerian rice starches.could be due to differences in starch structure giving rise to varyinginternal associative forces maintaining granule structure and, de-gree of engagement to form hydrogen and covalent bonds betweenstarch chains and hence the degree of availability of water bindingsites. Higher densities have been reported for larger granules ofpotato starch over those of yam and maize starches (Zuluaga,Baena, Mora, & PonceDleon, 2007).

The OAC of the rice ours, a reection of their emulsifying ca-pabilities in product formulations, ranged from 59.97% (Faro 46) to72.98% (Faro 40). However, OAC of Faro 40 was not signicantlyhigher than other cultivars (Table 3). The OAC is important since oilacts as avour retainer and increases the mouth feel of foods(Aremu et al., 2007). Variations in the presence of non-polar sidechains, which might bind the hydrocarbon side chains of oil among

de group, L-glucose, cyclodextrins

de group, L-glucose, cyclodextrins

copyranoside, Dodecyl- b- D glucopyranoside, L-glucose, cyclodextrins

lucopyranoside, Octyl- b- D glucopyranoside, L-glucose, D-glucose

lucopyranoside, Octyl- b- D -glucopyranoside, L-glucose, cyclodextrins

lucopyranoside, Octyl- b- D glucopyranoside, L-glucose, amygdalin, cyclodextrins

Table

7PearsonCorrelation

matrixbetw

eenthefunctional

andpastingproperties

ofNigerianrice

ou

r.

Peak

Trou

ghBreakdow

nFinal

viscositySetbackPeak

timePastingtemp.Moisture

contentPacked

bulk

den

sity

WAC

OAC

Gel

consisten

cyL

ab

DE

DC

Huean

gle

Peak

1.00

Trou

gh0.97

**1.00

Breakdow

n0.41

0.19

1.00

Final

viscosity

0.88

*0.76

0.75

1.00

Setback

0.42

0.21

0.94

*0.79

1.00

Peak

time

0.64

0.78

0.36

0.34

0.22

1.00

PastingTemp.

0.32

0.11

0.90

**0

.55

0.71

0.48

1.00

Moisture

content

0.33

0.39

0.12

0.14

0.21

0.53

0.02

1.00

Packed

bulk

den

sity

0.58

0.61

0.04

0.35

0.07

0.34

0.15

0.08

1.00

WAC

0.89

*0.80

0.60

0.84

*0.53

0.26

0.58

0.02

0.60

1.00

OAC

0.43

0.41

0.22

0.53

0.40

0.56

0.04

0.55

0.29

0.08

1.00

Gel

consisten

cy0

.27

0.30

0.02

0.03

0.28

0.06

0.29

0.38

0.80

0.330

.41

1.00

L0.78

0.81

*0.09

0.55

0.05

0.72

0.14

0.78

0.24

0.54

0.57

0.25

1.00

a0

.57

0.61

0.03

0.46

0.12

0.70

0.08

0.65

0.20

0.27

0.81

*0

.26

0.86

*1.00

b0

.66

0.76

0.18

0.41

0.06

0.69

0.30

0.12

0.47

0.58

0.07

0.01

0.42

0.37

1.00

DE

0.65

0.69

0.03

0.45

0.00

0.71

0.06

0.87

*0.09

0.36

0.67

0.17

0.98

**0.91

*0.28

1.00

DC

0.44

0.47

0.04

0.29

0.04

0.15

0.03

0.53

0.61

0.65

0.47

0.20

0.00

0.19

0.79

0.21

1.00

Huean

gle

0.57

0.60

0.06

0.47

0.14

0.67

0.04

0.67

0.21

0.28

0.81

0.24

0.87

*0.99

**0

.33

0.91

*0

.22

1.00

*nSign

icantcorrelationsat

10%;**nSign

icantcorrelationsat

5%.

K.O. Falade, A.S. Christopher / Food H486the ours, explain differences in the oil binding (Adebowale &Lawal, 2004), an occurrence suspected to be due to the presenceof oil soluble purple phyto-chemicals present in the endosperm.The major chemical component affecting oil absorption capacity isprotein, which is composed of both hydrophilic and hydrophobicparts. Non-polar amino acid side chains can form hydrophobic in-teractions with hydrocarbon chains of lipid (Jitngarmkusol,Hongsuwankul, & Tananuwong, 2008). The low OAC of the riceours could be important in the development of low oil uptakefrying batters and other fried products in which low oil uptake is adesirable attribute. Rice based batters showed outstanding fryingproperties and substantially reduced oil uptake when comparedwith the wheat our based batter (Shih, Daigle, & Clawson, 2001)

3.6.2. Loose and packed bulk density of rice ours and starchesPacked bulk density represents the highest attainable density

with compression. Loose and packed bulk densities of rice oursvaried from 0.46 to 0.60 g/mL and 0.65e0.79 g/mL, respectively.The Faro 46 and Faro 52 ours showed signicantly higher looseand packed bulk densities (p 0.05) than other cultivars (Table 3).Also, loose and packed bulk densities of the cultivars showedsimilar trends. Loose and packed bulk densities of the isolatedstarches varied from 0.30 to 0.36 and 0.40e0.43 g/mL, respectively.Loose and packed bulk densities of the isolated starches did notvary signicantly among the rice cultivars.

3.6.3. Swelling power, solubility and amylose content of ricestarches

Swelling power of the starches ranged 2.80 (Faro 55) and 5.49%(Faro 40). The low swelling power of Faro 55 could be due to itslow WAC (Table 3). When starch dispersions are heated, granules'swelling and starch polymers solubilization occur, which inuencethe properties of both continuous and dispersed phases. Our re-sults were similar to the swelling power (2.5e7.0%) reported forthe Mexican rice cultivars (Chavez-Murillo et al., 2012). Li and Yeh(2001) observed that granules' swelling increased with increasedtemperature. Same authors posited that rice starch granules reachpeak swelling values at 75 C, above which granule disruptionoccurs. Mandala and Bayas (2004) have positively related swellingpower and granule size to the amount of soluble solids leachedoutside the granules during heating. Rheological behaviour ofstarch systems is also inuenced by granules swelling andconsequently by their volume fraction and their rigidity. Whenstarch granules are swollen enough and can be deformed underapplying shear force, pseudoplastic behaviour will be observed. Onthe contrary, when granules are rigid and they are not so readilydeformed, dilatancy will be observed (Bagley & Christianson,1982).

Solubility of the rice starch, which indicated the ability of thestarch solids to disperse in aqueous solution, varied from 3.11 (Faro46) to 7.89% (Faro 21). The Faro 21 starch showed signicantlyhigher solubility than the other ve cultivars (Table 3). Similarresult was reported by Yu et al. (2012) who reported a range of6.28e7.06% for non-waxy rice cultivars.

Amylose content of Faro 21, 40, 44, 46, 52 and 55 were 21.86,20.68, 21.23, 22.25, 25.28 and 25.95% respectively. Rice weregrouped based on their amylose content into waxy (0e2%), verylow (3e9%), intermediate (20e25%) and high (>25%) (Cruz &Khush, 2000). Rice with high amylose content showed high vol-ume expansion during cooking and cook dry, less tender andbecome harder upon cooling (Juliano, 1985) while low amylosevarieties cook moist and sticky. Both Faro 52 and 55 cultivarsshowed high amylose content (>25%) while Faro 21, 40, 44 and 46showed intermediate (20e25) amylose content. Difference in

ydrocolloids 44 (2015) 478e490amylose content of the rice cultivars could be due to different

factors such as genotype, environmental conditions, and cultural & Voragen, 2003). After peak paste viscosity, the ours showed

Pasting behaviours that result from interactions between starch

recorded by the DSC was also consistent with the high pasting

K.O. Falade, A.S. Christopher / Food Hydrocolloids 44 (2015) 478e490 487practice (Kim and Wiesenborn, 1995), and is affected by the cli-matic conditions and soil type during growth (Asaoka, Okuno, &Fuwa, 1985; Morrison, Milligan, & Azudin, 1984). Amylose contentplays a key role in the digestion of starches, as starches with lowamylose content digests easily than that of high amylose content(Riley et al., 2004).

3.7. Pasting properties of rice ours and starches

Peak viscosity of the six Nigerian rice ours varied from 2376.0to 3988.5 cP (Table 4). Similar range of peak viscosity(2532e3104 cP) was reported for ours of long grain US rice (Kadanet al., 2008). However, the nal viscosity of the Nigerian rice ourswas higher (6456e4086 cP) than those reported by same authorsfor ours of long grain US rice (3616.8 cP e 3091.32 cP). The highernal viscosity of the rice cultivars in our study indicated that theyhave a higher tendency to retrograde after cooling due to the re-crystallization of leached amylose molecules. Similar assertionwas reiterated by (Wu, Chang, Pan, & Huang, 2011). Among thecultivars, pasting temperature of the rice ours under study did notvary signicantly from 82.4 (Faro 44) to 86.4 C (Faro 21). Thehigher pasting temperature of Faro 21 suggested higher energycosts would be required during cooking. Also, the peak time forFaro 21 our (6.53 min) was signicantly higher than other culti-vars. Peak viscosity of the rice starches varied from 4893 cP (Faro54) to 6080 cP (Faro 46). The Faro 44 and Faro 46 starches showedsignicantly higher while the Faro 52 (4893 cP) showed signi-cantly lower peak viscosity than other cultivars. At constant shearrate, the starches of Faro 46 and Faro 44 would demonstrate agreater resistance to shear stress and would be able to carry ahigher viscous load that could be encountered during mixingoperations.

Final viscosity (5458.5e7581.0 cP) of isolated starches from allthe rice cultivars increased upon cooling. In this study, Faro 44(7581.0 cP) starch displayed signicantly higher nal viscositythan others. Breakdown viscosity of the starches ranged from1673.0 (Faro 40) e 3155.5 cP (Faro 55). Breakdown viscosity is ameasure of the vulnerability or susceptibility of the cooked starchto disintegration. The higher the breakdown viscosity, the lowerthe ability of the starch sample to withstand heating and shearstress during cooking (Adebowale, Olu-Owolabi, Olawunmi, &Lawal, 2005; Ashogbon and Akintayo, 2011). Thus, Faro 40 starchmight be able to withstand more heating and shear stress thanother cultivars which possess higher breakdown values. Thesetback viscosity is a measure of the re-crystallization of gelati-nized starch during cooling (Ashogbon and Akintayo, 2011).Setback viscosity of the rice starches varied from 2279.5 (Faro 46)to 3605.5 cP (Faro 21), with Faro 21 showing signicantly highervalue (Table 4). This indicated that Faro 21 starch might have agreater tendency to retrogradation than other cultivar. Pastingtemperature of the isolated rice starches varied from 73.9 to80.0 C. This range was consistent with the ndings of Huaisan,Uriyapohgson, Rayas-Duaetz, Ali, and Srijesdarute (2009) whopreviously reported a pasting temperature range of 79.1e79.5 Cfor Asian rice gels.

Flours and starches of the rice cultivars showed patterns char-acteristics of rise in viscosity until peak, with subsequent decreasein viscosity at holding and thereafter a rise up to nal viscosity(Figs. 1 and 2). Peak paste viscosity of the ours and starchesshowed sharp peak curves. Pasting behaviours in starch-basedsystems have been classied as types A, B, C and D (Chen, Schols,temperatures obtained from the RVA data. Gelatinizationenthalpy (DHG) varied between 7.58 and 19.29 J/g. The Faro 21showed a lower value and displayed a single endotherm(Fig. 4a), however, other rice starches displayed a biphasic en-dotherms (Fig. 4bef). Vandeputte, Derycke, Geeroms, andDelcour (2003a, 2003b) and Lawal et al. (2011) reported gelati-nization temperatures of 7.7e19.2 and 18.0e29.1 J/g,respectively.

3.9. Starch granule morphology

Starch granules of the rice cultivars were found to be small, withan average length and width range of 5.37e9.25 mm and3.94e6.94 mm respectively (Table 5). These were consistent withthe granule size classication of Lindeboom, Chang, and Tyler(2004). The shapes of the granules were spherical and polyhedralwith some granules forming aggregates (Fig. 3aef). These size andshape of the granules were intrinsic properties and had an inu-ence on the functional and pasting proles of the rice starches aspreviously discussed.and non-starch components (e.g. as in sorghum) or high-amylosestarches may not change by increasing starch concentrations(Waramboi et al., 2011). Also, surface lipids and proteins, rehydra-tion time, method of sample preparation (e.g. milling and particlesize), presence of impurities, pH, type of cultivar, and presence ofendogenous enzymes can affect starch swelling, pasting and gela-tinization properties (Chen et al., 2003; Mahasukhonthachat,Sopade, & Gidley, 2010a, 2010b).

3.8. Thermal properties of the rice starches

Glass transition, identied by DSC, corresponds to a re-arrangement of the solid amorphous matrix involving thebreaking of bounds and creation of new ones. The glass transi-tion temperature for the rice starches ranged between 79.4 and105.0 C (Table 5). The change in the heat capacity (Cp) throughTg, occurred because the glassy and amorphous states haddifferent physical properties, including Cp. The glass transitiontemperature Tg (35.2e50.2 C) and gelatinization onset, To(50.8e68.8

C) varied with cultivar. These were similar to the

values (61.1e71.47 C) previously reported by Singh, Kaur,Sandhu, Kaur, and Nishinari (2006). Gelatinization peak (Tp)and gelatinization conclusion (Tc) of the starches varied from78.7 to 93.7 C and 116.4e127.6 C, respectively. These wereconsistent with the ndings of Lawal et al. (2011) who reportedTp (81.5e88.5 C) and Tc (147.1e156.2 C) for starches isolatedfrom West African rice cultivars. The high gelatinization peakdifferences in their patterns of pasting properties (Fig. 1), which canbe grouped to predict the cooking and other food utilizationproperties of the cultivars. Based on the breakdown ratio, Faro 21our showed slightly shear thinning (Type C) while ours of Faro40, 44, 46, 52, and 55 cultivars showed moderately shear thinning(Type B) behaviours (Fig. 1). However, starches of Faro 21, 52 and 55showed highly shear thinning (Type A) behaviours while the Faro44, 42 and 46 showed moderately shear thinning (Type B) behav-iours (Fig. 2). Both rice ours and starches did not show Type Dbehaviours. Some researchers proposed that types C and D pastingclasses were changeable by increasing the starch concentrations.

Table 8Pearson Correlation matrix between the functional, pasting and thermal properties of Nigerian rice starches.

g Mc

*

0.62 0.75 0.43 0.39 0.07 0.52 0.28 0.530.02 0.29 0.75 0.21 0.45 0.54 0.03 0.09

K.O. Falade, A.S. Christopher / Food Hydrocolloids 44 (2015) 478e490488Peak Trough Breakdown Finalvisc

Setback Peaktime

Pastintemp

Peak 1.00Trough 0.76 1.00Breakdown 0.35 0.87* 1.00Final viscosity 0.59 0.82* 0.75 1.00Setback 0.41 0.45 0.34 0.14 1.00Peak time 0.60 0.93** 0.89* 0.78 0.39 1.00Pasting Temperature 0.18 0.22 0.18 0.68 0.69 0.22 1.00Moisture content 0.66 0.28 0.09 0.01 0.48 0.05 0.22Packed bulk density 0.15 0.57 0.71 0.69 0.10 0.69 0.22WAC 0.14 0.49 0.81* 0.61 0.11 0.51 0.36OAC 0.10 0.18 0.34 0.38 0.29 0.50 0.47Gel consistency 0.02 0.27 0.37 0.20 0.78 0.34 0.82Swelling power 0.15 0.64 0.81* 0.77 0.10 0.82* 0.46Solubility 0.26 0.37 0.34 0.01 0.66 0.12 0.55Granule length 0.65 0.68 0.49 0.30 0.71 0.75 0.09Granule width 0.67 0.52 0.26 0.21 0.59 0.58 0.02L 0.01 0.29 0.43 0.52 0.31 0.59 0.49a 0.18 0.36 0.66 0.26 0.21 0.61 0.17b 0.17 0.12 0.05 0.36 0.36 0.16 0.80DE 0.12 0.42 0.52 0.63 0.26 0.68 0.45DC 0.17 0.11 0.28 0.18 0.47 0.14 0.75Hue angle 0.04 0.33 0.46 0.38 0.01 0.65 0.30To (C) 0.34 0.06 0.17 0.33 0.64 0.06 0.30Tp (C) 0.28 0.58 0.63 0.80 0.24 0.47 0.76Tc (C) 0.24 0.06 0.27 0.10 0.26 0.13 0.17Tg (C) 0.77 0.41 0.01 0.43 0.03 0.19 0.51DHG (J/g) 0.40 0.20 0.01 0.34 0.18 0.13 0.19DTG (Tc To) 0.49 0.03 0.33 0.27 0.47 0.02 0.19PHI(DHG/(Tp To) 0.45 0.30 0.10 0.22 0.87* 0.17 0.47*n Signicant correlations at 10% ; **n Signicant correlations at 5%.3.10. Fourier transform infra-red (FTIR) spectroscopy

The major functional groups in the samples displayed absor-bance peaks within a frequency band 350- 4000 cm1. The func-tional groups identied from each sample are highlighted inTable 6. Most of the a-1 / 4 gylcosidic linkages for the isolatedstarches were found within the spectral absorption bands1149.55e1023.00 cm1. Nikonenko, Buslov, Sushko, and Zhbankov(2002) stated that the characteristic of polysaccharides with1/ 4 glycosidic linkage is the appearance of absorption bands inthe 1175-1140 cm1 spectral range as compared to the spectra oftheir constituent monomers, which can be a spectroscopic mani-festation of glycosidic linkage formation; a fact used in identifyingdifferent structural transformations of polysaccharides withparticipation of glycosidic linkage. All of the starch samples showedthe presence of cyclodextrins, an indication of possible partialbreakdown of the long amylose/amylopectin chains during pHbalancing using acids or drying.

Pearson correlation of the measured parameters for rice oursand starches are shown in Tables 7 and 8, respectively. For the ours(Table 7), peak viscosity showed signicant (p < 0.05) correlationwith trough viscosity (0.97) while trough viscosity showed signif-icant (p < 0.05) correlation with CIE L (0.81). Breakdown viscositycorrelated signicantly (p < 0.05) with pasting temperature (0.90).Also, colour intensity showed signicant (p < 0.05) correlationwithCIE L (0.98), and hue angle showed signicant (p < 0.05) correlationwith CIE a (0.99). For the rice starches, trough viscosity showedsignicant (p < 0.05) with breakdown viscosity (0.87). Breakdown0.28 0.27 0.49 0.51 0.12 0.20 0.66 0.190.66 0.30 0.20 0.19 0.54 0.13 0.01 0.350.65 0.06 0.04 0.66 0.27 0.24 0.49 0.400.44 0.58 0.73 0.07 0.00 0.40 0.13 0.640.65 0.50 0.28 0.40 0.39 0.36 0.52 0.67oistureontent

Packedbulk density

WAC OAC Gelconsistency

Swellingpower

Solubility Granulelength

1.000.42 1.000.35 0.61 1.000.80 0.51 0.31 1.000.03 0.30 0.07 0.10 1.000.54 0.86* 0.72 0.78 0.12 1.000.66 0.00 0.19 0.74 0.57 0.23 1.000.20 0.11 0.04 0.32 0.39 0.35 0.08 1.000.27 0.12 0.24 0.28 0.15 0.17 0.08 0.95**0.76 0.68 0.38 0.97 0.06 0.87 0.66 0.290.63 0.78 0.55 0.61 0.64 0.77 0.01 0.280.14 0.22 0.12 0.47 0.74 0.23 0.60 0.240.65 0.83 0.41 0.88 0.03 0.91 0.51 0.290.05 0.44 0.17 0.21 0.89* 0.10 0.59 0.030.68 0.52 0.28 0.96** 0.12 0.79 0.58 0.55viscosity correlated signicantly (p < 0.05) with peak time (0.89),WAC (0.81) and swelling power (0.81), while swelling powershowed signicant correlation with breakdown viscosity (0.81),peak time (0.82) and packed bulk density (0.86). Chroma correlatedwith gel consistency (0.89), while gel consistency correlated withpasting temperature (0.82).

4. Conclusion

Physical, functional and physicochemical attributes of the ricevaried with cultivar and product ie our or starch. Generally, therice cultivars showed low to high milling recovery, and moderatestarch yield. The Faro 21 and Faro 44 were categorised as long grainrice while other were medium sized. The CIE L, a, b colour param-eters varied from ours to starches, starches exhibited higher de-gree of whiteness than the corresponding ours. Aside from Faro 40ours, other showed lighter colours. Isolated starches showed highlightness values and should not impart colour when utilized inproduct formulations. The isolated starches had restricted swellingand solubility patterns, presumably due to their granular charac-teristics. However, all the starch granules were small in size,spherical and mostly polyhedral in shape. Pasting properties of theours and corresponding starches also varied among the cultivars.Thermal properties of the isolated starches showed high gelatini-zation peaks (Tp) but lowglass transition temperatures (Tg); giving aclue into their behaviour under heating cycles expected in indus-trial processes.

To(C

10

0.27 0.56 0.11 0.08 0.58 0.14 0.48 00.53 0.19 0.66 0.59 0.17 0.70 0.18 0

00

0

od H0.37 0.50 0.50 0.21 0.32 0.01 0.720.81* 0.19 0.41 0.29 0.26 0.37 0.070.68 0.50 0.23 0.00 0.52 0.03 0.18Granulewidth

L a b DE DC Hueangle

1.000.21 1.000.02 0.67 1.00

0.42 0.36 0.29 1.000.17 0.97** 0.71 0.21 1.000.29 0.11 0.62 0.92 0.04 1.00

0.47 0.93 0.69 0.38 0.86 0.08 1.000.66 0.53 0.49 0.24 0.62 0.29 0.230.06 0.25 0.00 0.61 0.26 0.43 0.15

K.O. Falade, A.S. Christopher / FoAcknowledgements

Authors are grateful to the University of Ibadan for the SenateResearch Grant (SRG/FT/2010/7A) awarded to conduct this research.

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Physical, functional, pasting and thermal properties of flours and starches of six Nigerian rice cultivars1. Introduction2. Materials and methods2.1. Parboiling and milling of the rice cultivars2.2. Isolation of the rice starches using the alkaline extraction method2.3. Determination of moisture, protein and fat contents of the rice cultivars2.4. Physical properties2.4.1. Physical characteristics of rice kernels2.4.2. Determination of one thousand grain weight2.4.3. Determination of the colour parameters of rice flours and starches

2.5. Functional properties of rice flours and starches2.5.1. Determination of loose and packed bulk densities2.5.2. Determination of water (WAC) and oil (OAC) absorption capacities2.5.3. Determination of swelling power and solubility2.5.4. Determination of gel consistency2.5.5. Determination of the alkaline spreading value2.5.6. Determination of amylose content

2.6. Pasting properties of rice flours and isolated starches2.7. Fourier transform infrared spectrocopy (FTIR)2.8. Differential scanning calorimetry2.9. Starch granule morphology2.10. Statistical analysis

3. Results and discussion3.1. Total milling recovery and degree of milling (DoM) of rice cultivars3.2. Yield of rice starches3.3. Moisture contents of rice flours and starches3.4. Physical characteristics of rice paddy and milled rice3.5. CIE L, a and b, and other colour parameters of rice flours and starches3.6. Functional properties of rice flour and starches3.6.1. Water (WAC) and Oil (OAC) absorption capacity of rice flours and starches3.6.2. Loose and packed bulk density of rice flours and starches3.6.3. Swelling power, solubility and amylose content of rice starches

3.7. Pasting properties of rice flours and starches3.8. Thermal properties of the rice starches3.9. Starch granule morphology3.10. Fourier transform infra-red (FTIR) spectroscopy

4. ConclusionAcknowledgementsReferences