CHAPTER IV EFFECT OF ADDITION OF WATER SOLUBLE PENTOSANS ON FUNCTIONALITY OF WHOLE WHEAT FLOUR AND CHAPATI QUALITY

Transcription

1 CHAPTER IV EFFECT OF ADDITION OF WATER SOLUBLE PENTOSANS ON FUNCTIONALITY OF WHOLE WHEAT FLOUR AND CHAPATI QUALITY 130

2 4.1. INTRODUCTION Carbohydrate is the major component present in wheat flour and among the carbohydrates starch is the major component and pentosans are the minor components (Shalini & Laxmi, 2007). Pentosan contents vary from 5 to 8% of the whole grain flour (Pritchard et al, 2011) while in refined wheat flour its content is very low (2-3%). Pentosans are the major non-starch polysaccharides present in wheat (Wang et al, 2006) and they located in the cell walls of wheat grains (Fincher & Stone, 1986). Due to their high water binding capacity, pentosans are known to play an important role in rheological properties of dough (Michniewicz et al, 1991) retrogradation of starch and breadmaking quality (Delcour et al, 1991; Izydorczyk & Biliaderis, 1995). Addition of water soluble pentosans to refined wheat flour significantly increased the farinograph water absorption and dough development time and also increased bread quality parameters like loaf volume, crumb structure and decreased staling characteristics (Amado & Neukom, 1985; Meuser & Suckow, 1986). Pentosans from various cereals and different plant tissues share the same general molecular structures. However, they differ in the fine structural features, which may affect their physico-chemical properties (Courtin & Delcour, 1998). These differences are reflected in the degree of polymerization, ratio of arabinose to xylose residues, relative proportions and sequence of various glycosidic linkages, pattern of substitution of the xylan backbone with arabinose residues 130

3 and the presence and amount of other substituents, such as feruloyl groups or glucuronic acid residues. Since, pentosans are not under strict genetic control, even polymers isolated from a single plant or tissue exhibit structural microheterogeneity (Izydorczyk & Biliadreis, 1993; Saulnier et al, 2007). The ratio of arabinose to xylose residues indicates degree of branching in these polysaccharides. Depending upon the origin of arabinoxylans, the ratio of Ara/Xyl may vary from 0.3 to 1.4, but large variations were observed among the cereals. The water-extractable pentosans from wheat bran were found to have lower degree of substitution and lower molecular weights, compared to their alkaliextractable counterparts. The ratio of A/X indicates degree of branching in arabinoxylans. However, it does not reveal detailed structural features of these polymers (Cleemput et al, 1993). Although considerable work has been reported with respect to the role of pentosans on bread quality, no reports are available with respect to whole wheat flour products such as parotta, chapati, roti, etc. Therefore, the present work was undertaken 1. To study the effect of added water soluble pentosans isolated from good and poor chapati making wheat varieties on rheological properties of dough 2. To study the effect of added water soluble pentosans isolated from good and poor chapati making wheat varieties on chapati making quality. 131

4 4.2. MATERIALS AND METHODS Wheat Varieties Ten (Triticum aestivum) wheat varieties namely GW-322, HD- 2189, HD-2781, HD-2501, K-9644, MACS-2496, NIAW-34, and NI were procured from Agharkar Research Institute, Pune and DWR-162 and DWR-39 were procured from Dharwad University, India, for the studies Chemical Analysis Moisture, total protein, total sugars and damaged starch of whole wheat flour were determined according to the standard AACC methods (2000). Values reported are the average of triplicate determinations Isolation of pentosans Water soluble pentosans from whole-wheat flour of different wheat varieties were isolated according to the method described by Santos et al (2002). Whole-wheat flours were fractionated into starch, gluten and water-solubles (Czuchajowska & Pomeranz, 1993). Watersoluble pentosans were isolated and purified. The pentosans present in the water solubles were precipitated from the supernatant at 80% ethanol. The precipitate was then washed and dried by exchange of solvents, followed by drying at 30ºC (Izydorczyk et al, 1990; Vinkx et al, 1993) Analytical methods Estimation of total sugars was carried out according to the method described by Dubois et al (1956) and uronic acids were 132

5 estimated according to the method described by Dische (1947). Sugar composition in the flour and water-insoluble fractions were analysed after solubilization with 72% sulphuric acid (in ice-cold temperature) followed by hydrolysis in 10% sulphuric acid at boiling water bath temperature for 6-8 h. The water-soluble fractions were hydrolysed with 2N trifluroacetic acid in sealed tubes at 100ºC for 5-6 h. The sugars were analysed by gas liquid chromatography as alditol acetates (Sawardekar et al, 1967) on OV-225 column at column temperature at 200ºC using Shimadzu GLC. Pentosan content was determined according to the method described by Albaum & Umbreit (1947) Rheological characteristics Farinograph characteristics of whole wheat flours were determined according to AACC (2006) method using Brabender Farinograph E (Brabender OHG, Duisburg, Germany). Whole wheat flours were enriched with 0.25% and 0.5% of water soluble pentosans and their farinograph characteristics were studied. The amylograph characteristics of whole wheat flours were determined using Micro Visco Amylograph (Brabender OHG, Duisburg, Germany). Whole wheat flours were enriched with 0.25% and 0.5% of water soluble pentosans and their amylograph characteristics were studied. Whole wheat flours (15g on 14% moisture basis) were suspended in 100 ml of distilled water and heated in the visco-amylograph from 30 to 92º C at a rate of 5ºC/min, held at 92ºC for 5 min, cooled to 50ºC and then held at 50ºC for 1 min 133

6 under constant stirring (250 rpm). Torque measuring range was 300 cmg. The viscosity was expressed in Brabender Units (BU) Chapati making quality Chapati was prepared by incorporating 0.25 and 0.5% water soluble pentosans of same variety and other varieties according to the procedure given in Section Objective & subjective evaluation of chapati Objective evaluation such as height and texture, subjective like sensory evaluation was done according to the procedure described in Sections & Statistical analysis and graphical representation The experimental data, including sensory scores of chapati, were treated statistically by Duncan s new multiple range test (DMRT) to determine the significance of results (Steel & Torrie, 1980). 134

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8 4.3. RESULTS AND DISCUSSIONS Section A Composition of Water Soluble Pentosans and their effect on Dough Rheology Composition of whole wheat flour Carbohydrate profile of DWR-162, DWR-39, GW-322, NI-5439, NIAW-34, HD-2501, HD-2781, K-9644, HD-2189 and MACS-2496 whole wheat flours are given in Table 4.1. The total sugar (carbohydrate) content varied from 70.3 to 79.7% in the whole wheat flours. The pentosan contents of DWR-162, DWR-39, GW-322, NI and NIAW-34 wheat varieties were 4.7%, 4.1%, 4.1%, 3.9% and 3.8%, respectively, which were higher than the other varieties (3 to 3.4%). The arabinose-xylose ratios were high in DWR-162, DWR-39, GW-322 and NI-5439 varieties ( %) indicating that it might be due to higher degree of branching in these pentosans. Higher degree of branching was reported in few Canadian wheat flours of variable bread making quality (Izydorczyk & Biliaderis, 1995). The arabinosexylose ratios (A/X) in remaining wheat varieties were low indicating that it might be due to lower degree of branching in these pentosans (Dupont and Selvendran, 1987). 136

9 Table 4.1: Chemical Characteristics of Whole Wheat Flour Wheat Varieties Pentosans (%) Total Sugar (%) Uronic Acid (%) Arabinose (%) Xylose (%) Glucose (%) A/X Ratio DWR d ± b ± f ± DWR c ± b ± b ± GW c ± c ± c ± NI b ± d ± b ± NIAW b ± b ± b ± HD a ± c ± b ± HD a ± a ± a ± K a ± d ± c ± HD a ± c ± d ± MACS a ± a ± e ± Data expressed as mean ±SD; Means followed by different letters in the same column differ significantly (p<0.05). 137

10 Composition of water soluble pentosans The yields of water soluble pentosans isolated from DWR-162, DWR-39, GW-322, NI-5439 and NIAW-34 whole wheat flours were high compared to the water soluble pentosans isolated from the remaining whole wheat flours (Table 4.2). The water soluble pentosans were lesser than the native pentosan contents in whole wheat flours. The total sugar content of water soluble pentosans varied from 80 to 88%. The uronic acid contents were very less in water soluble pentosans compared to that of whole wheat flour (Tables 4.1 & 4.2). Water soluble pentosans did not show the presence of glucose, when subjected to gas liquid chromatography. The arabinose-xylose ratios of water soluble pentosans isolated from DWR-162 and DWR-39 wheat varieties which are known to have good chapati making property were high (1.7) indicating that it might be due to higher degree of branching in these pentosans. Saxena et al (2000) have also reported that the contents of arabinose and xylose were higher in the polysaccharide fractions of varieties of wheat that has good tandoor roti making quality. The arabinose-xylose ratios of water soluble pentosans isolated from K-9644, HD-2189 and MACS-2496 wheat varieties which are poor in chapati making were low. 138

11 Table 4.2: Chemical Characteristics of Water soluble Pentosans Wheat Varieties Yield of WSP* (%) Total Sugar (%) Uronic Acid (%) Arabinose (%) Xylose (%) Glucose (%) A/X Ratio DWR e ± b ± DWR c ± a ± GW e ± b ± NI a ± a ± NIAW a ± d ± HD b ± c ± HD b ± c ± K d ± b ± HD d ± c ± MACS f ± c ± Data expressed as mean ±SD; Means followed by different letters in the same column differ significantly (p<0.05). *WSP Water soluble pentosans 139

12 WWF: Whole wheat flour; WSP: Water soluble pentosan. Fig. 4.1A: GC profiles of whole wheat flours and water soluble pentosans of DWR-162 and DWR-39 wheat varieties. 140

13 WWF: Whole wheat flour; WSP: Water soluble pentosan. Fig. 4.1B: GC profiles of whole wheat flours and water soluble pentosans of GW-322 and NI-5439 wheat varieties. 141

14 WWF: Whole wheat flour; WSP: Water soluble pentosan. Fig. 4.1C: GC profiles of whole wheat flours and water soluble pentosans of NIAW-34 and HD-2781 wheat varieties. 142

15 WWF: Whole wheat flour; IP: Water soluble pentosan. Fig. 4.1D: GC profiles of whole wheat flours and water soluble pentosans of HD-2501 and K-9644 wheat varieties. 143

16 WWF: Whole wheat flour; WSP: Water soluble pentosan. Fig. 4.1E: GC profiles of whole wheat flours and water soluble pentosans of HD-2189 and MACS-2496 wheat varieties. 144

17 Section B Chapati Making Quality of Whole Wheat flour on Addition of Water Soluble Pentosans Effect of added pentosans on the farinograph characteristics of whole wheat flour Water soluble pentosans isolated from whole wheat flours were incorporated at 0.25 and 0.5% in the same variety of whole wheat flours and farinograph characteristics of were studied (Table 4.3). Water absorption increased from 77.8 to 80, 82.2% for DWR- 162 whole wheat flour, 75.5 to 77.5, and 80.5% for DWR-39 whole wheat flour while the increase in water absorption for GW-322 whole wheat flour was from 70.9 to 72.5 and 74.1% on incorporation of 0.25 and 0.5% pentosans of the same variety, respectively. The increase in water absorption was 2.0 to 5% for these two good chapati making variety whole wheat flours, whereas only 0.3 to 0.6% increase in water absorption was observed for poor chapati making whole wheat flours obtained from HD-2189, K-9644, HD-2501 and MACS-2496 varieties. Dough development time decreased from 3.7 to 3.3 for DWR-162 whole wheat flour, 3.9 to 3.4 min for DWR-39 whole wheat flour, while the decrease in dough development time for MACS-2496 whole wheat flour was from 6.2 to 6.0 on incorporation of 0.5% water soluble pentosans of the same variety, respectively. 145

18 Table 4.3: Farinograph Characteristics of Whole Wheat Flour on incorporation of Pentosans Wheat Varieties Variations (Pentosans) Water Absorption (%) Dough Development Time (min) Stability (min) Tolerance Index (BU) DWR-162 Control % % DWR-39 Control % % GW-322 Control % % NI-5439 Control % % NIAW-34 Control % % HD-2781 Control % % HD-2501 Control % % K-9644 Control % % HD-2189 Control % % MACS-2496 Control % % Data expressed as means of two determinations. 146

19 Farinograph characteristics of whole wheat flours on addition of pentosans of same wheat variety Water soluble pentosans isolated from whole wheat flours were incorporated at 0.25 and 0.5% in the same variety of whole wheat flours and farinograph characteristics of were studied (Table 4.3). Water absorption increased from 77.8 to 80, 82.2% for DWR- 162 whole wheat flour, 75.5 to 77.5, and 80.5% for DWR-39 whole wheat flour while the increase in water absorption for GW-322 whole wheat flour was from 70.9 to 72.5 and 74.1% on incorporation of 0.25 and 0.5% pentosans of the same variety, respectively. The increase in water absorption was 2.0 to 5% for these two good chapati making variety whole wheat flours, whereas only 0.3 to 0.6% increase in water absorption was observed for poor chapati making whole wheat flours obtained from HD-2189, K-9644, HD-2501 and MACS-2496 varieties. Dough development time decreased from 8.7 to 8.3 for DWR-162 whole wheat flour, 7.9 to 7.4 min for DWR-39 whole wheat flour, while the decrease in dough development time for MACS-2496 whole wheat flour was from 6.2 to 6.0 on incorporation of 0.5% water soluble pentosans of the same variety, respectively. Marginal changes were observed in dough stability for all the varieties. A marginal increase in dough stability was observed in HD-2781, NIAW-34, GW-322, NI-5439 and K-9644 varieties on addition of water soluble pentosans. Marginal changes were observed in mixing tolerance index (MTI) of flours, obtained from all the wheat varieties on addition of water soluble pentosans. 147

20 Farinograph characteristics of whole wheat flours on addition of pentosans from good chapati making quality whole wheat flour to poor chapati making quality whole wheat flour and vice-versa Water absorption increased by 0.3% and 0.6% on incorporation of 0.25 and 0.5% water soluble pentosans isolated from HD-2189 whole wheat flour to DWR-162 whole wheat flours, respectively. Similarly water absorption increased by 0.3% and 0.7% on incorporation of 0.25 and 0.5% pentosans from MACS-2496 whole wheat flour in DWR-39 whole wheat flour, respectively. However, water absorption increased by 2.1 and 4.2 on addition of 0.25 and 0.5% DWR-162 whole wheat flour pentosans, respectively to HD-2189 whole wheat flour. Similarly, water absorption increased by 2.0 and 4.1 on addition of 0.25 and 0.5% DWR-39 whole wheat flour pentosans, respectively, to MACS-2496 whole wheat flour (Fig. 4.4). The results clearly indicated that pentosans from good chapati making quality whole wheat flour exhibited higher water absorption. Dough development time decreased by 0.1 and 0.2 min on incorporation of 0.25 and 0.5% pentosans, respectively from poor chapati making quality whole wheat flour to good chapati making quality whole wheat flour while dough development time decreased by 0.5 to 1.1 min when pentosans from good chapati making quality whole wheat flour were incorporated in poor chapati making quality whole wheat flour. The decrease in dough development time and dough stability is mainly due to increased water absorption of flour. However, variations on the influence of dough development time and 148

21 Wheat Varieties DWR-162 DWR-39 HD-2189 MACS dough stability by good or poor chapati pentosans may be due to the differences in their pentosan. Table 4.4: Farinograph Characteristics of Whole Wheat Flour on addition of Water Soluble Pentosans isolated from different Wheat Varieties Variations (Pentosans) Water Absorption (%) Dough Development Time (min) Stability (min) Tolerance Index (BU) Control % % %WSP-HD %WSP-HD Control % % %WSP-MACS %WSP-MACS Control % % %WSP-DWR %WSP-DWR Control % % %WSP-DWR %WSP-DWR Data expressed as means of two determinations. *P-Pentosans. Increase in dough stability was observed when water soluble pentosans isolated from DWR-39 and DWR-162 whole wheat flours were added to HD-2189 and MACS-2496, respectively (Table 4.4). Although increase in water absorption was observed upon addition of pentosans in all the cases, it was more with the addition of water soluble pentosans isolated from good chapati making quality whole 149

22 wheat flour, which might be due to their high arabinose content. There was a positive effect observed in poor chapati making quality whole wheat flour on adding water soluble pentosans from good chapati making quality whole wheat flour. Pentosans imbibe and hold water with the crosslinking density of the gel network and thus increase farinograph water absorption (Jelaca & Hlynka, 1971; Cleemput et al, 1993; Vanhamel et al, 1993; Izydorczyk & Biliaderis, 1992). Jelaca & Hlynka (1971) reported that pentosan addition bring about changes in whole wheat flour stability. During dough mixing, pentosans act during the agglomeration of gluten following the breakdown of gluten structures and this may be the reason for alterations in rheological properties of whole wheat flour (Wang et al, 2004) Effect of pentosans on the amylograph characteristics of whole wheat flour Amylograph characteristics of whole wheat flours on addition of pentosans of same wheat variety Water soluble pentosans were added at 0.25 and 0.5% in the same variety of whole wheat flour and amylograph characteristics of whole wheat flour was studied (Table 4.5). Pasting temperatures were higher for HD-2189 and MACS-2496 which are poor chapati making varieties. However, in all the varieties pasting temperatures decreased upon addition of pentosans. Pasting temperature (PT) decreased from 67.7 to 67.3, 67.1 º C for DWR-162 flour and 64.7 to 62.1, 62.1 for GW-322 whole wheat flour upon addition of 0.25 and 0.5% pentosans from the same variety of wheat varieties. 150

23 Table 4.5: Amylograph Characteristics of Whole Wheat Flour on addition of Water Soluble Pentosans Wheat Varieties Variations (Pentosans) Pasting Temperature (⁰C) Peak Viscosity (BU) Hot Paste Viscosity (BU) Cold Paste Viscosity (BU) DWR-162 Control % % DWR-39 Control % % GW-322 Control % % NI-5439 Control % % NIAW-34 Control % % HD-2781 Control % % HD-2501 Control % % K-9644 Control % % HD-2189 Control % % MACS-2496 Control % % Data expressed as means of two determinations. Higher reduction in pasting temperature was observed for poor chapati making quality wheat varieties. For example, for HD- 151

24 2189 it decreased from 74.5 to 73.9, 72.6 º C and for MACS-2496 it was decreased from 75.8 to 74.0 and 73.7 º C, upon addition of 0.25 and 0.5% water soluble pentosans, respectively. Paste viscosity increased from 470 to 712, 864 BU and 530 to 776, 842 BU upon addition of 0.25, 0.5% pentosans from same variety of wheat for DWR-162 flour and DWR-39 flour, respectively. Paste viscosity increased from 472 to 523, 620 BU and 285 to 308, 333 BU upon addition of 0.25, 0.5% pentosans from same variety of wheat for HD flour and MACS-2496 flour, respectively. Upon addition of pentosans, the increase in paste viscosity was high in DWR-162 and DWR-39, which are good chapati making quality varieties. Similarly, increase in cold paste viscosity was also high for these good chapati making varieties (Table 4.5) Amylograph characteristics of whole wheat flours on addition of pentosans from good chapati making quality whole wheat flour to poor chapati making quality whole wheat flour and vice-versa Pasting temperature decreased from 67.7 to 66.4, 65.6 º C for DWR-162 flour upon addition of 0.25 and 0.5% water soluble pentosans from HD-2189 flour and 67.3 to 66.2, 65.7 º C for DWR-39 flour upon addition of 0.25 and 0.5% pentosans from MACS-2496 flour, respectively. Pasting temperature decreased from 74.5 to 71.0, 70.2 º C for HD-2189 flour upon addition of 0.25 and 0.5% pentosans from DWR-162 flour, and 75.8 to 73.1, 72.0 º C for MACS-2496 flour upon addition of 0.25 and 0.5% pentosans from DWR-39 flour, respectively. 152

25 Table 4.6: Amylograph Characteristics of Whole Wheat Flour on addition of Water Soluble Pentosans isolated from Different Wheat Varieties Wheat Varieties Variations (Pentosans) Pasting Temperature (ºC) Peak Viscosity (BU) Hot Paste Viscosity (BU) Cold Paste Viscosity (BU) DWR-162 Control % a-dwr % a-dwr % a-hd % a-hd DWR-39 Control % a-dwr % a-dwr %a-MACS % a-macs HD-2189 Control % a-hd % a-hd % a-dwr % a-dwr MACS-2496 Control % a-macs % a-macs % a-dwr % a-dwr Data expressed as means of two determinations. 153

26 Higher reduction in pasting temperature was observed for poor chapati making quality whole wheat flours when pentosans from good chapati making quality whole wheat flours were added. Paste viscosity increased from 470 to 536, 601 BU for DWR-162 whole wheat flour upon addition of 0.25 and 0.5% pentosans from HD-2189 flour, and 530 to 552, 679 BU for DWR-39 whole wheat flour upon addition of 0.25 and 0.5% pentosans from MACS-2496 flour, respectively. Paste viscosity increased from 472 to 786, 840 BU for HD-2189 flour upon addition of 0.25 and 0.5% pentosans from DWR-162 flour and 285 to 428, 498 BU for MACS-2496 flour upon addition of 0.25 and 0.5% pentosans from DWR-39 flour, respectively. The increase in paste viscosity was high when pentosans from good chapati making quality whole wheat flours were added in poor chapati making quality whole wheat flours. Similarly increase in CPV was also high of BU for poor chapati making quality whole wheat flours upon 0.5% addition of pentosans from good chapati making quality whole wheat flours and it was low ( BU) for good chapati making quality whole wheat flours upon addition of 0.5% pentosans from poor chapati making quality whole wheat flours. It was observed that when wheat flours were added with water soluble pentosans isolated from good chapati making quality whole wheat flours, which have high arabinose-xylose ratio, the cold paste viscosity was very high compared to other variations (Table 4.6). Yin and Walker (1992) reported that water soluble pentosans when added to 154

27 wheat flour exhibited positive effect on rheological properties by increasing dough paste viscosity Chapati making quality of whole wheat flour on incorporation of water soluble pentosans isolated from same variety Objective evaluation of chapatis Chapatis were prepared from whole wheat flours upon addition of 0.25 and 0.5% pentosans. The puffed height of chapatis increased significantly on addition of water soluble pentosans isolated from same variety to the whole wheat flours (Table 4.7). The puffed height of chapatis prepared from DWR-162, DWR-39, GW-322, K-9644 and HD-2189 wheat varieties upon adding 0.25% water soluble pentosans of same variety increased by 0.7, 0.8, 0.3, 0.3, 0.5cm, respectively. The shear force of chapatis prepared from DWR-162, DWR-39, GW-322, K-9644, HD-2189 and MACS-2496 wheat varieties upon addition of 0.25% water soluble pentosans isolated from same variety decreased by 1.0, 0.9, 0.3, 0.2, 0.3 and 0.4 N, respectively; upon addition of 0.5% water soluble pentosans isolated from same variety decreased by 1.9, 1.9, 0.8, 0.7, 1.0, and 0.8 N, respectively. The shear force of chapatis prepared from other wheat varieties NI-5439, NIAW-34, HD-2781 and HD-2501 decreased by 0.6, 1.0, 0.9 and 0.7 N upon addition 0.5% water soluble pentosans isolated from same variety (Table 4.7). 155

28 Table 4.7: Chapati Making Quality of Whole Wheat Flours on addition of Water Soluble Pentosans isolated from the same Variety Wheat Varieties Variations Puffed height (cms) Shear force (N) DWR -162 Control 5.5 a ± a ± % pentosan 6.2 b ± b ± % pentosan 6.5 c ± c ± 0.1 DWR - 39 Control 5.3 a ± a ± % pentosan 6.1 b ± b ± % pentosan 6.4 c ± c ± 0.2 GW Control 4.9 a ± a ± % pentosan 5.2 b ± b ± % pentosan 5.4 b ± c ± 0.2 NI Control 4.8 a ± a ± % pentosan 5.0 b ± b ± % pentosan 5.2 b ± c ± 0.2 NIAW - 34 Control 5.2 a ± a ± % pentosan 5.5 b ± b ± % pentosan 5.7 c ± c ± 0.2 HD 2781 Control 5.1 a ± a ± % pentosan 5.4 b ± b ± % pentosan 5.6 c ± c ± 0.4 HD Control 4.9 a ± a ± % pentosan 5.1 b ± b ± % pentosan 5.3 c ± c ± 0.3 K 9644 Control 4.8 a ± a ± % pentosan 5.1 b ± b ± % pentosan 5.3 c ± c ± 0.1 HD-2189 Control 4.8 a ± a ± % pentosan 5.3 b ± b ± % pentosan 5.6 c ± c ± 0.1 MACS Control 4.6 a ± a ± % pentosan 4.9 b ± b ± % pentosan 5.1 c ± c ± 0.1 *Data expressed as mean ±SD; Means followed by different letters in the same column box differ significantly (p<0.05). 156

29 Subjective evaluation of chapatis The different sensory characteristics as judged by ten panellists are presented in Table 4.8. There were no significant changes in appearance in chapatis prepared from whole wheat flours containing added pentosans. The scores for appearance of chapatis prepared from wheat flours having good chapati making quality had high scores around 8 and chapatis prepared from wheat flours having poor chapati making quality had less scores around 7. Tearing strength of chapatis improved upon addition of pentosans indicating that the chapatis were soft which was also evident from objective measurement of shear force. Tearing strength values of chapatis prepared from whole wheat flours having good chapati making quality were high as such and further improved upon addition of water soluble pentosans. Tearing strength of chapatis prepared from wheat flours having poor chapati making quality was also improved on adding water soluble pentosans. The scores for pliability, aroma and eating quality increased on addition of water soluble pentosans. The improvement in tearing strength and pliability reflected on the improvement in aroma and eating quality of chapati. The chapatis giving soft texture and better pliability are likely to give wholesome taste and better chewing properties, thus on addition of pentosans chapatis had better acceptability (Table 4.8). 157

30 Table 4.8: Sensory Properties of Chapatis prepared on addition of Water Soluble Pentosans isolated from Same Wheat Variety Wheat Varieties Pentosans Appearance (10) Tearing strength (10) Pliability (10) Aroma (10) Eating quality (20) Overall Quality (60) DWR-162 Control 8.6 a ± c ± c ± a ± c ± c ± % WSP 8.7 a ± b ± b ± a ± b ± b ± % WSP 8.7 a ± a ± a ± a ± a ± a ± 0.7 DWR-39 Control 8.7 a ± d ± c ± c ± b ± d ± % WSP 8.7 a ± b ± a ± b ± a ± b ± % WSP 8.9 a ± a ± a ± a ± a ± a ± 0.2 GW-322 Control 8.2 a ± a ± a ± a ± a ± a ± % WSP 8.3 a ± b ± b ± b ± b ± b ± % WSP 8.3 a ± c ± c ± c ± c ± c ± 0.7 NI-5439 Control 8.2 a ± a ± a ± a ± a ± a ± % WSP 8.3 a ± b ± b ± b ± b ± b ± % WSP 8.5 a ± c ± c ± c ± c ± c ± 0.9 NIAW-34 Control 8.8 a ± a ± a ± a ± a ± a ± % WSP 8.9 a ± b ± b ± b ± b ± b ± % WSP 8.9 a ± c ± c ± c ± b ± c ± 0.5 HD-2781 Control 7.9 a ± a ± a ± a ± a ± a ± % WSP 8.1 a ± b ± b ± b ± b ± b ± % WSP 8.2 a ± c ± c ± c ± c ± c ± 0.5 HD-2501 Control 7.7 a ± a ± a ± a ± a ± a ± % WSP 7.9 a ± b ± b ± b ± b ± b ± % WSP 7.9 a ± c ± c ± c ± c ± c ± 0.5 K-9644 Control 7.1 a ± a ± a ± a ± a ± a ± % WSP 7.4 a ± b ± b ± b ± a ± b ± % WSP 7.5 a ± c ± c ± c ± b ± c ± 0.8 HD-2189 Control 7.3 a ± e ± d ± b ± c ± e ± % WSP 7.4 a ± d ± c ± b ± c ± d ± % WSP 7.4 a ± c ± b ± b ± b ± c ± 0.2 MACS-2496 Control 7.3 a ± e ± e ± a ± c ± c ± % WSP 7.4 a ± d ± d ± a ± c ± b ± % WSP 7.4 a ± c ± c ± a ± b ± bc ± 1.0 *Data expressed as mean ±SD; Means followed by different letters in the same column box differ significantly (p<0.05). 158

31 Chapati making quality of whole wheat flours on addition of water soluble pentosans isolated from good chapati making quality whole wheat flours to poor chapati making quality whole wheat flours and vice-versa Objective evaluation of chapatis The puffed height of chapatis prepared from DWR-162 whole wheat flour and DWR-39 whole wheat flour on addition of water soluble pentosans of HD-2189 whole wheat flour and MACS-2496 whole wheat flour increased by 0.2 to 0.6 cm. The puffed height of chapatis prepared from HD-2189 whole wheat flour and MACS-2496 whole wheat flour on addition of water soluble pentosans of DWR- 162 whole wheat flour and DWR-39 whole wheat flour increased by cms and cms, respectively (Table 4.9). The increase in puffed height was more when treated with pentosans of good chapati making quality whole wheat flours than the pentosans of poor chapati making quality whole wheat flours. The shear force of chapatis prepared from DWR-162 whole wheat flour and DWR-39 whole wheat flour on addition of water soluble pentosans of HD-2189 whole wheat flour and MACS-2496 whole wheat flour decreased by and N, respectively. The shear force of chapatis prepared from HD-2189 whole wheat flour and MACS-2496 whole wheat flour on addition of water soluble pentosans of DWR-162 whole wheat flour and DWR-39 whole wheat flour decreased by and N, respectively (Table 4.9). 159

32 Table 4.9: Chapati Making Quality of Whole Wheat Flours on addition of Water Soluble Pentosans isolated from different Wheat Variety Wheat Variations Puffed height Cutting force Varieties (cms) (N) DWR -162 Control 5.5 a ± a ± % pentosan 6.2 c ± c ± % pentosan 6.5 d ± d ± % HD-2189 pentosan 5.8 b ± b ± % HD-2189 pentosan 6.0 bc ± c ± 0.1 DWR - 39 Control 5.3 a ± a ± % pentosan 6.1 c ± c ± % pentosan 6.4 d ± d ± %MACS-2496 pentosan 5.5 b ± b ± % MACS-2496 pentosan 5.9 c ± c ± 0.1 HD 2189 Control 4.8 a ± a ± % pentosan 5.3 b ± b ± % pentosan 5.6 c ± c ± % DWR-162 pentosan 6.0 d ± d ± % DWR-162 pentosan 6.3 d ± e ± 0.1 MACS Control 4.6 a ± a ± % pentosan 4.9 b ± b ± % pentosan 5.1 c ± c ± % DWR-39 pentosan 5.3 d ± d ± % DWR-39 pentosan 5.6 d ± e ± 0.1 *Data expressed as mean ±SD; Means followed by different letters in the same column box differ significantly (p<0.05). The decrease in shear force was more when treated with pentosans of good chapati making quality whole wheat flour than the pentosans of poor chapati making quality whole wheat flour. Lower shear force denotes that the chapatis have softer texture, hence, easy to tear (Haridas Rao, 1993). Soft texture is a desirable character of chapatis that makes them easy to chew. 160

33 Subjective evaluation of chapatis Chapatis prepared from whole wheat flours of good chapati making varieties, DWR-162 and DWR-39 upon adding water soluble pentosans of HD-2189 whole wheat flour and MACS-2496 whole wheat flour, respectively showed increase in the scores for tearing strength, pliability, aroma and eating quality. However, there was no significant difference in appearance of chapatis prepared from whole wheat flours containing added water soluble pentosans. Chapatis prepared from HD-2189 whole wheat flour and MACS-2496 whole wheat flour on adding water soluble pentosans of DWR-162 whole wheat flour and DWR-39 whole wheat flour, respectively showed no significant difference in the appearance and aroma of chapatis. Significant improvement was observed in the tearing strengths and pliability of chapatis prepared from HD-2189 whole wheat flour and MACS-2496 whole wheat flour on adding water soluble pentosans of DWR-162 whole wheat flour and DWR-39 whole wheat flour, respectively (Table 4.10). Eating quality is an attribute observed during chewing and biting of chapatis. Chapatis having moderate tearing strength and more pliability result in a product requiring lesser effort to chew the chapatis. Tougher chapatis require more effort for biting, chewing and tearing action and such a mouthfeel is less desirable. 161

34 Table 4.10: Sensory Properties of Chapatis prepared from addition of Water Soluble Pentosans isolated from different Wheat Varieties Wheat Varieties Pentosans Appearance (10) Tearing strength (10) Pliability (10) Aroma (10) Eating quality (20) Overall Quality (60) DWR -162 Control 8.6 a ± c ± c ± a ± c ± c ± % WSP 8.7 a ± b ± b ± a ± b ± abc ± % WSP 8.7 a ± a ± a ± a ± a ± a ± % HD-2189 WSP 8.6 a ± c ± c ± a ± b ± bc ± % HD-2189 WSP 8.6 a ± b ± b ± a ± b ± abc ± 0.4 DWR - 39 Control 8.7 a ± d ± c ± c ± b ± d ± % WSP 8.7 a ± b ± a ± b ± a ± b ± % WSP 8.9 a ± a ± a ± a ± a ± a ± % MACS-2496 WSP 8.7 a ± cd ± b ± b ± b ± c ± % MACS-2496 WSP 8.7 a ± c ± b ± b ± b ± bc ± 0.5 HD 2189 Control 7.3 a ± e ± d ± b ± c ± e ± % WSP 7.4 a ± d ± c ± b ± c ± d ± % WSP 7.4 a ± c ± b ± b ± b ± c ± % DWR-162 WSP 7.4 a ± b ± a ± a ± a ± b ± % DWR-162 WSP 7.4 a ± a ± a ± a ± a ± a ± 0.2 MACS Control 7.3 a ± e ± e ± a ± c ± c ± % WSP 7.4 a ± d ± d ± a ± c ± b ± % WSP 7.4 a ± c ± c ± a ± b ± bc ± % DWR-39 WSP 7.4 a ± b ± b ± a ± a ± bc ± % DWR-39 WSP 7.4 a ± a ± a ± a ± a ± a ± 0.7 *Data expressed as mean ±SD; Means followed by different letters in the same column box differ significantly (p<0.05). 162

35 Sensory scores for eating quality increased significantly for HD whole wheat flour and MACS-2496 whole wheat flour chapatis on adding water soluble pentosans of DWR-162 whole wheat flour and DWR-39 whole wheat flour, respectively. Water soluble pentosans of DWR-162 and DWR-39 treated whole wheat flours had positive impact on chapatis. Possible explanation would be that as water soluble pentosans of DWR-162 and DWR-39 varieties had high arabinosexylose ratio which exerts their functional role by means of their molecular structure, gelling capacity and hence influence the water distribution and water availability, thereby influence the chapati quality. Earlier studies carried out on bread indicated that textural properties of bread are attributed to the presence of pentosans in wheat as water absorption are governed by both protein and pentosan content and their interactions (Shogren et al, 1987). Chapati water absorption and damaged starch are critical factors in determining the quality of chapati (Prabhasankar et al, 2002; Haridas Rao et al, 1989). It is also reported that pentosans exert their functional role by means of their molecular structure, gelling capacity and influence the water distribution and water availability and thereby influence the loaf volume and in turn the bread quality (Courtin & Delcour, 1998). In the present study, whole wheat flour characteristics upon addition of pentosans had improved, which was evident by increase in water absorption and viscosity. The positive impact on whole wheat flour rheology has brought about positive impact in chapati quality which is evident from textural and sensory property. 163