Dietary fiber from Cassava pulp

Transcription

1 A-O-008 Dietary fiber from Cassava pulp Pornariya Chirinang a, Ratchadaporn Oonsivilai *a, Natta Kachenpukdee a a School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand *roonsivi@sut.ac.th phone fax ABSTRACT Cassava pulp is a high value by-product from cassava starch industry that contain high amount of neutral detergent fiber (NDF) at 31.40% (w/w). Response surface methodology was applied for optimization of extraction parameters. Three parameters such as -amylase concentration, protease concentration, and amyloglucosidase concentration including three levels for each parameter were studied. The optimum condition for the highest NDF preparation by enzymatic digestion was at 0.1% of -amylase (w/v), 1% of protease (v/v) and 0.1% of amyloglucosidase (v/v). Dietary fiber from cassava pulp contained 40.24% (w/w) crude fiber, 79.03% (w/w) neutral detergent fiber (NDF),.14% (w/w) acid detergent fiber (ADF) and high content of cellulose at 58.55% (w/w). In addition, the hydration properties of dietary fiber prepared were investigated. The results showed that the dietary fiber prepared exhibited 4.82 ml/g swelling capacity, 8.36 g/g water retention capacity and 8.17 g/g water holding capacity. The major monosaccharide constituent of dietary fiber prepared was glucose, together with other neutral sugars. The FTIR spectrum of dietary fiber prepared was similar to cassava pulp spectrum with showing the sharp peak at cm -1 that is usually the fingerprint of polysaccharides. Finally, scanning electron microscopy (SEM) of cassava pulp revealed a lot of starch granule embedded within cell wall material of cassava pulp. Otherwise, there was no starch granule appeared in dietary fiber prepared after enzymatic digestion. In conclusion, as physicochemical properties of dietary fiber prepared from cassava pulp by enzymatic digestion described above, cassava pulp could be used as a rich source of useful dietary fiber and could be applied to many food products. Keywords: Cassava pulp, Neutral detergent fiber, Hydration properties 15

2 1. INTRODUCTION Dietary fiber (DF) is defined as non-digestible carbohydrate and lignin that are the part of plants that have beneficial physiological effects in humans. The broader definition of dietary fibers may include fibers of animal origin and modified or synthetic non-digestible carbohydrate polymers (Polymerization Degree 3) [1]. Cassava (Manihot esculenta) is the third-largest source of food carbohydrates in the tropics.thailand is the third largest producer of cassava starch, which yielded around 22.2 million tons per year.consequently, there are a lot of byproducts from the cassava processing which the important one is cassava pulp. Cassava pulp is fine and white mainly composed of carbohydrate, around 55-56%. Starch remaining in the pulp may approximately be 50-60% of its dry weight, in which the starch mostly be trapped inside ligno-cellulose [2]. Thus, the alternative way is to produce the value added cassava pulp is dietary fiber production.the purpose of this study was tostudy the optimize condition of NDF production by response surface methodologyandphysicochemical properties of dietary fiber prepared from cassava pulp. 2. MATERIALS AND METHODS Materials and samples preparation Cassava pulp was purchased from tapioca starch industry in the local area of NakhonRatchasimaprovince, Thailand. Heat-stable -amylase (Cat. No. A3306), amyloglucosidase (Cat. No. A9913) from Aspergillusnigerand protease (Cat. No. P1236) from Bacillus amyloliquefaciens (0.80 AU/g) were obtained from Sigma-Aldrich, Sigma Chemical, S. t. Louis, MO. All chemicals using were of reagent grade. Extraction optimization Determination of factors affecting the optimized yield of NDF was carried outwith Box-Behnken design. Response surface methodology was applied to obtain maximum extraction of NDF. All experimental data were statistically analysed with Design Expert software (Version , Stat-Ease, Inc. Minneapolis, MN). Three level of three independent variables are -amylase concentration, X 1 ( % w/v), protease concentration, X 2 ( % v/v) and amyloglucosidase concentration, X 3 ( % v/v) were applied. The selected dependent variables were cumulative neutral dietary fiber (NDF) percentage (Y1). Compositional analysis Dried cassava pulp and dietary fiber was analyzed for moisture, ash, protein, fat and crude fiber contents according to the methods of AOAC [3].The contents of neutral dietary fiber (NDF), acid detergent fiber(adf) and acid detergent lignin (ADL) were investigated using the detergent method according to Van Soest[4]. Analyses were conducted using a Fibertec System 2010 apparatus(foss Tecator, Höganäs, Sweden).Monosaccharide compositions were analyzed using a DionexHPAEC system (Archemica international, Co. Ltd., Sunnyvale, CA, USA) equipped with a pulsed amperometric detector (PAD).Gradient elution was carried using 250 mmnaoh and deionized water at the flow rate of 0.2 ml/min. Hydration properties determination Swelling capacity (SWC), water retention capacity (WRC) and water holding capacity (WHC) of NDF prepared from cassava pulp were determined using the method of Robertson et al. [5]. Fourier transform infrared spectroscopy Cassava pulp and dietary fiber were dried and stored in desiccators prior to FTIR analysis. FTIR spectra were recorded using a golden-gate diamond single reflectance ATR on a Bruker T27/Hyp 2000 FTIR spectrophotometer. The spectra were recorded in the transmittance mode from 4000 to 400 cm -1 (mid-infrared region) at a resolution of 4 cm -1 ; and 64 scans were collected. At least triplicate spectra readings for each sample were obtained [6]. Scanning electron microscope (SEM) The cassava pulp and dietary fiber, spread on a double side conducting adhesive tape, pasted on a metallic stub, coated with gold in a sputter coating unit for 8 min and observed in a JEOL JSM-6010LV electron microscope (JEOL ltd., Tokyo, Japan). Statistical analysis All experiments were performed in triplicate and mean values (on dry basis) with standard deviations are reported. The experimental data were analyzed using an analysis of variance (ANOVA). SPSS software (version 16, SPSS Inc., Chicago, IL, USA) was used to perform all the statistical calculations.in addition, response surface method was applied for optimization study. 16

3 3. RESULTS Effect of enzyme concentration on NDF extraction The effect of three independent parameters on the yield percentage of NDF from cassava pulp is investigated and data are shown in Table 1. The statistical analysis indicated that the second-order polynomial model correlated three variables in this study was obtained in Eq.(1) below: NDF = x X x X xX xx 1 x X x X 1 x X x X 2 x X x X x X x X 3 2 (1) Statistical significance of the model was checked by the F-test and model F-value of implied that the model to be significant (p< 0.05). The regression coefficient (R 2 = ) of experimental model also indicated the suggested model to be a good fit for NDF extraction. The optimum condition was 0.1% w/v. 1% v/v and 0.1% v/v for concentration of -amylase, protease and amyloglucosidase, respectively. Table 1. Effects of extraction conditions on percentage NDF of dietary fiber from cassava pulp. Trt. -amylase (%w/v) X 1 Independent variables protease (%v/v) amyloglucosidase (%v/v) X 2 X 3 %NDF ± 0.25 fg ± 1.49 g ± 1.96 bc ± 2.26 bc ± 2.62 cde ± 1.10 bcd ± 1.95 fg ± 2.01 def ± 1.51 ef ± 1.51 cde ± 4.95 ef ± 4.44 ef ± 0.42 b ± 0.59 b ± 0.55 a Note: Each value is mean ± SD a,b Data in the same row with different superscripts are significantly different (p < 0.05). 17

4 a b c NDF NDF B: protease C: C: amyloglucosidase C: amyloglucosidase C: amyloglucosidase A: amylase neutrase A: -amylase B: protease A: -amylase Figure 1. Contour plots of the effect of independent parameters on NDF yields percentage. (a) The effect of concentration of -amylase and proteaseon the NDF yields percentageat concentration of 0.1% amyloglucosidase. (b) The effect of concentration of -amylase and amyloglucosidaseon the NDF at concentration of 1% protease. (c) The effect of concentration of protease and amyloglucosidaseon the NDF yields percentageat concentration of 0.1% -amylase. Chemical compositions The proximate analysis of cassava pulp powder and dietary fiber are shown in Table 2. The major composition of cassava pulp and dietary fiber was carbohydrate at.15 and 48.46% respectively. Cassava pulp still contains high starch contents while dietary fiber contains high cellulose with insoluble form. Moreover, dietary fiber showed higher contents of NDF, ADF, ADL, cellulose and hemicellulose when it passed through extraction process due tohydrolysis properties of enzymes applied. Kosoom et al.[8] reported that cassava pulp from many cassava starch manufacturing plants in Thailand contain average crude fiber, NDF, ADF, lignin and starch at 13.99, 40.62, 27.65, 3.60 and 50.19%, respectively. Oonsivilai et al. [7] studied on enzymatic digestion of dietary fiber from cassava pulp, the results showedthat NDF content of cassava pulp extraction was highest at 13.96%. Sugar profile of cassava pulp and dietary fiber showed that glucose was the most abundant composition. In dietary fiber, glucose was present in the highest amounts followed by galactose, rhamnose, xylose, arabinose and mannose, respectively. The results showed that glucose contents of dietary fiber decrease perceptibly when compared with raw material. It might be due to starch contents decreased with enzyme activity. Hydration properties correlate with both physiological and technological point of view and could influence the incorporation of fiber-enriched ingredients into food products. Hydration properties of dietary fiber such asswelling, water retention capacity and water holding capacity of dietary fiber showed the value of 4.82 ml/g, 8.36 g/g dry weight and 8.17g/g, respectively. Fourier transform infrared spectroscopy FTIR spectrum of dietary fiber exhibited similarities in absorption pattern to raw material. The sharp peak was appearing at around 1031 and 1005 cm -1 which showed the indication of stretching vibration of pyranose. The band at 1239 cm -1 of dietary fiber was indication of acetyl group substitution of some of the OH groups present [8].The bands at 1318 cm -1 indicated ring breathing with C O stretching. Both cassava pulp and dietary fiber are composed of protein which usually has specific absorption bands in the cm -1 region. The carbonyl (C=O) stretching was at 1736 and 1606cm -1. The band at 2936 and 2906 cm -1 was indeed characteristic of C-H stretches associated with the ring hydrogen atoms. An intense peak at 3336 and 3291 cm -1 was OH stretching peak. 18

5 Table 2. Chemical compositions (%) of cassava pulp powder and dietary fiber (dry weight basis) Components Cassava pulp (%) Dietary fiber (%) Crude protein 2.02 ± ± 0.10 Fat 0.21 ± ± 0.06 Moisture 6.63 ± ± 0.09 Ash 3.76 ± ± 0.04 Crude fiber ± ± 2.22 Carbohydrate Starch ± ± 0.31 Neutral detergent fiber (NDF) ± ± 0.51 Acid detergent fiber (ADF) ± ± 0.40 Acid detergent lignin (ADL) 4.16 ± ± 0.01 Cellulose a Hemicellulose b Monosaccharide (mg/g dry sample) Galactose ± ± 0.21 Glucose ± ± 1.45 Xylose ± ± 0.67 Mannose 6.03 ± ± 0.86 Rhamnose ± ± 1.33 Arabinose ± ± 1.03 a ADF-ADL, b NDF-ADF Scanning electron microscope (SEM) From the SEM results, the pulp showed hugely starch granules embedded well inside the matrix which related to starch contents as above (Figure 3a). For dietary fiber, after hydrolysis by -amylaseand amyloglucosidase enzyme, the results showed that there was no starch granule embedded inside the fiber matrix (Figure 3b). This NDF produced from cassava pulp showed higher purification than starch. Its fiber structure seems to have high porosity. Sowhagya et al. [9] extracted dietary fiber from spent residue cumin. They found that the fiber matrix appeared to have a typical honey comb structure, almost avoid of starch granules. a b Figure 3. Scanning electron micrographs of cassava pulp (a) and dietary fiber (b) at 400x. 19

6 4. CONCLUSIONS Cassava pulp could be the new source of NDF production by enzymatic extraction at the optimal conditions of 0.1% w/v, 1% v/v and 0.1% v/v for concentration of -amylase, protease and amyloglucosidase enzyme, respectively. In addition, NDF prepared from cassava pulp contained 79.03%and high contents of cellulose. The physical properties as hydration properties of dietary fiber such as swelling, water retention capacity and water holding capacity of dietary fiber showed the value of 4.82 ml/g, 8.36 g/g dry weight and 8.17g/g, respectively.finally, there was no starch granule embedded inside the fiber matrix that suggests high porosity of fiber structure. The application of dietary fiber in food products system should be interested topic for the future study. ACKNOWLEDGEMENT This research was supported by Research and Development Institute Funds, Suranaree University of Technology, Nakhon Ratchasima province and National Research Council Thailand. REFERENCES 1. Iain AB The physiological roles of dietary fiber. Food Hydrocolloid. 25(2), Elleuch M, Bedigian D, Roiseux O. Besbes S, Blecker C,Attia H Dietary fiber and fiber-rich byproducts of food processing: characterization, technological functionality and commercial applications: A review. Food Chem. 124, AOAC Official Methods of Analysis, AOAC International. 18 th ed. Gaithersburg, USA, ISBN Van Soest PJ Use of detergents in the analysis of fibrous feeds. IV. Determination of plant cell wall constituents. J. AOAC Int. 50, RobertsonJA, Monredon FD, Dysseler P, Guillon F, Amado R,Thibault JF Hydration properties of dietary fiber and resistant starch: a European collaborative study. Lebensm. Wiss. Technol. 33, Kosoom W, Charoenwattanasakun N, Ruangpanit Y, Rattanatabtimtong S, Attamangkune S Physical, chemical and biological properties of cassava pulp. Proc. of the 47 th Kasetsart University Annual Conference. Kasetsart Oonsivilai R, Chanphuak C, Srisutor P, Kulrattanarak T, Sutheerawattananond M, Oonsivilai A Dietary fiber prepared from cassava byproduct. World Acad Sci Eng Technol Mathlonthi M, Koenig JL Vibrational spectra of carbohydrates. Adv. Carbohydr. Chem. Biochem. 44, Sowbhagya HB, Florence Suma P, Mahadevamma S, Tharanathan RN Spent residue from cumin-a potential source of dietary fiber. Food Chem. 104,