Fusarium head blight: Effect on white salted and yellow alkaline noodle properties

Fusarium head blight: Effect on white salted and yellow alkaline noodle properties D. W. Hatcher, M. J. Anderson, R. M. Clear, D. G. Gaba, and J. E. Dexter Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main St. Winnipeg, Manitoba, Canada R3C 3G8 (e-mail: dhatcher@grainscanada.gc.ca). Paper no. 841 of the Grain Research Laboratory, received 17 December 2001, accepted 16 July 2002. Hatcher, D. W., Anderson, M. J., Clear, R. M., Gaba, D. G. and Dexter, J. E. 2003. Fusarium head blight: Effect on white salted and yellow alkaline noodle properties. Can. J. Plant Sci. 83: 11 21. Composite samples of Canada Western Red Winter wheat (CWRW) with varying levels of Fusarium head blight damage (0.5 9.6%) were prepared from the 1998 Western Canadian harvest survey and milled to yield both patent (60% extraction) and straight grade (~76%) flours. The mycotoxin deoxynivalenol (DON) levels in the flours ranged from 0.21 to 2.6 ppm with no significant influence due to flour extraction. No differences were attributable to Fusarium damage (FD) in the amount of work required to sheet either yellow alkaline (YA) or white salted (WS) noodles. The color of the raw (YA) noodles was adversely affected by FD as a significant loss in noodle brightness (L*) and an increase in redness (a*) were observed for noodles prepared from both patent and straight grade flour. Straight grade YA noodles, prepared from wheat with FD levels above acceptable limits for milling grades, displayed a significant loss in yellowness (b*) after aging for 24 h. Differences in noodle brightness of raw WS noodles were observed between the control and 9.6% FD samples for both patent and straight grade noodles at 24 h. Analysis of YA and WS noodles indicated a significant linear relationship between the number of specks and the quantity of FD in the wheat. YA and WS noodles displayed significant loss in cooked noodle texture with increasing FD levels. Maximum cutting stress and recovery declined with increasing FD for both noodle types whether made from patent or straight grade flour. Maximum wheat FD tolerances below 2% are required in order to ensure optimum noodle quality. Key words: Fusarium damage, noodles, color, texture and image analysis Hatcher, D. W., Anderson, M. J., Clear, R. M. Gaba, D. G. et Dexter, J. E. 2003. La brûlure de l épi causée par la fusariose : conséquences sur les propriétés des nouilles blanches salées et jaunes alcalines. Can. J. Plant Sci. 83: 11-21. Les auteurs ont prélevé des échantillons composites de blé rouge d hiver de l Ouest canadien aux épis plus ou moins attaqués par la fusariose (0,5 à 9,6 %) lors d une enquête effectuée à la moisson de 1998, dans l Ouest. Ils ont moulu ces échantillons pour obtenir de la farine fleur (extraction à 60 %) et de la farine ordinaire (~ 76 %). La concentration du désoxynivalénol venant de la mycotoxine variait de 0,21 à 2,6 ppm dans la farine et l extraction n influe pas sensiblement sur ce facteur. La durée du pétrissage nécessaire à l obtention de la pâte servant à la fabrication de nouilles jaunes alcalines (JA) ou blanches salées (BS) ne varie pas avec les dommages causés par Fusarium (DF). La couleur des nouilles JA brutes ne se détériore pas avec la proportion de DF. Bref, elle n entraîne pas une perte importante de brillance (L*) ni une hausse de la rougeur (a*), que les nouilles soient faites de farine fleur ou de farine ordinaire. Les nouilles JA de classe ordinaire confectionnées avec la farine de blé présentant une proportion de DF supérieure au seuil de tolérance pour le grain destiné à la meunerie se décolorent sensiblement (b*) au terme de 24 heures. La brillance des nouilles BS brutes n est pas la même quand la farine vient de l échantillon témoin ou de celui présentant 9,6 % de DF. Cette remarque s applique autant aux nouilles faites de farine fleur que de farine ordinaire, au bout de 24 heures. L analyse des nouilles JA et BS révèle une corrélation linéaire significative entre le nombre de tachetures et la proportion de DF dans le blé. La texture des nouilles JA et BS se détériore sensiblement à la cuisson quand la proportion de DF augmente. La résistance maximale au cisaillement et la restauration des deux types de nouilles diminuent avec la hausse des DF, qu il s agisse de farine fleur ou de farine ordinaire. Pour faire des nouilles de qualité optimale, on fixe le seuil de tolérance pour les DF dans le blé à moins de 2 %. Mots clés : dommages causés par la fusariose, nouilles, couleur, texture, analyse d images Fusarium head blight (FHB), also known as scab, can reduce the yield and grade of wheat. There are also potential health implications should mycotoxins be produced by the causal species. The principal FHB pathogen in North America, Fusarium graminearum Schwabe, has been associated with the production of the mycotoxin deoxynivalenol (DON). Correlations between DON levels and Fusarium damage for hard red winter wheat, r = 0.75 (Shotwell et al. 1985) and hard red spring wheat, r = 0.74 (McMullen et al. 1993) have been reported for different areas of the United States. DON has been observed to be partitioned in varying concentrations among screenings, mill feeds and flour streams (Scott et al. 1983, 1984; Seitz et al. 1985). 11 Unfortunately, DON remains stable during both milling (Scott et al. 1983; Seitz et al. 1985) and baking (Tanaka et al. 1986; Boyacioglu et al. 1993) processes, thereby presenting a potential health concern. Severely infected wheat kernels are visually distinguishable as very thin, shriveled, chalky white kernels, often referred to as tombstone kernels. These seeds are produced Abbreviations: CWRW, Canada Western Red Winter wheat; DON, deoxynivalenol; 15 ADON, 15-acetyl deoxynivalenol; FD, Fusarium damage; FHB, Fusarium head blight; MCS, maximum cutting stress; REC, noodle recovery; WS, white salted; YA, yellow alkaline

12 CANADIAN JOURNAL OF PLANT SCIENCE when pathogenic Fusarium spp. infect the wheat head at anthesis or up to 3 wk post anthesis (Atanasoff 1920). Fusarium damaged kernels have a significantly lower kernel density (1.08 g cm 3 ) than healthy kernels (1.28 g cm 3 ) (Martin et al. 1998). This is consistent with the results of Tkachuk et al. (1991), in which the severely FD kernels were concentrated in the least dense wheat fraction prepared from specific gravity tables. Dexter et al. (1997) indicated that FD also had a negative impact on durum wheat kernel weight and test weight. Wheat kernels infected with F. culmorum (W.G. Smith) Sacc. were found to be damaged more extensively than those infected by F. graminearum, F. avenaceum (Fr.) Sacc. or F. nivale (Fr.)Ces. (Chelkowski et al. 1990). Fusarium mycelium growth was found to be highest between the pericarp and aleurone layers. Micrographs of wheat kernels infected by FHB (F. graminearum) indicated degraded starch granules, storage proteins and cell walls (Bechtel et al. 1985). Significant compositional changes in carbohydrates, lipids and proteins were also reported by Boyacioglu and Hettiarachchy (1995) with moderate infection by F. graminearum. Adverse effects of FHB on milling (flour color and yield) have been reported (Tkachuk et al. 1991; Dexter et al. 1996). Inferior baking quality attributable to wheat gluten degradation was noted for wheat infected by F. culmorum (Meyer et al. 1986), and a decrease in loaf volume was observed in severely infected (F. graminearum) American hard red winter wheat (Seitz et al. 1986) and Canadian hard red spring wheat (Dexter et al. 1996). Fusarium damage in durum wheat resulted in reduced semolina yield and inferior semolina color (Dexter et al. 1997). Although FD reduced gluten strength, no significant effect on pasta texture was detected, although pasta color was adversely effected. The negative impact of FD on pasta color was also observed in durum wheat from North Dakota (Moore 1994). The quality of wheat endosperm protein determines the viscoelastic and processing characteristics (baking or pasta making) of the flour dough or semolina. Nightingale et al. (1999) determined that although scanning electron microscope images showed visible endosperm protein degradation and reduced total wheat storage protein content in F. graminearum Schwabe and F. avenaceum infected wheat, no qualitative differences in protein were detectable by either reverse phase high performance liquid chromatograpy (RP-HPLC) or sodium docedyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Use of size exclusion (SE) HPLC on a mixture of cultures of F. graminearum in the presence of wheat storage protein, however, did indicate hydrolysis of the protein. Enzyme inhibition studies carried out during their research suggested that the F. graminearum protease was a heat sensitive alkaline protease. Decreased dough consistency and resistance to extension were evident on farinograph and extensograph curves, respectively. Inferior baking quality, attributable to wheat gluten degradation, was also noted for wheat infected by F. culmorum. (Meyer et al. 1986). The impact of FD on the quality of Asian noodles is not documented in the literature. In Canada, a maximum tolerance of 2% FD kernels by weight is allowed in the milling grades of CWRW wheat to ensure the safety of the grain and subsequent end products (Canadian Grain Commission 2001). A common end product of this wheat class is Asian noodles. The discriminating consumer is concerned with noodle appearance, both color and the degree of speckiness, as well as the mouthfeel or texture associated with the cooked noodle (Hatcher 2001). It is quite common for raw noodles to be stored for 24 h prior to consumption. Therefore, the reported deterioration of pasta color (Dexter et al. 1997) in conjunction with the hydrolysis of gluten protein (Nightingale et al. 1999) suggested that FD would have a significant deleterious impact on both the color and texture of oriental noodles. The objective of this study was to examine the effect of FD (0.5 to 9.6%) on the quality characteristics of WS and YA noodles prepared from CWRW wheat at two levels of flour refinement. MATERIALS AND METHODS Wheat and Flour Commercially grown CWRW wheat samples, from southern Manitoba, Canada, where the predominant grading factor was FD, were selected from the 1998 harvest survey and stored at 15 C. Composite samples were prepared by combining samples with similar FD to give eight samples with a FD range of 0.5 to 9.6%. Varietal composition was confirmed electrophoretically by the method of Thachuk and Mellish (1980) to be CDC Kestrel at greater than 90% purity for all samples. The top CWRW No.1 milling grade has an FD limit of 2.0%, and as such, the sample with 0.5% FD was considered to be a representative commercial CWRW control wheat. Patent (60%) and straight grade (~76%) extraction flours were prepared using a tandem Buhler pilot mill as described by Martin and Dexter (1991). Analytical Methods Protein content (%N 5.7) was determined by combustion nitrogen analysis using a LECO, Model FP-248 Dumas combustion nitrogen analysis analyzer (LECO Corp. St. Joseph, MI) calibrated with EDTA. Test weight was determined using a Schopper chondrometer equipped with a 1-L container. Ash content, starch damage and farinograph analyses were determined by American Association of Cereal Chemists (2000) Approved Methods 08-01, 76-31 and 54-20, respectively. Wet gluten was determined by the ICC standard method no. 137 (ICC 1999) using the Glutomatic system. Flour grade color was determined by a Simon Series IV Flour Colour Grader (Satake UK, Stockport, UK) following the Flour Testing Panel Method No. 007/4 (Flour Milling and Baking Research Association 1991), and expressed in Satake International units. Levels of the mycotoxins deoxynivalenol (DON) and 15- acetyl deoxynivalenol (15 ADON) were determined using a gas chromatograph (Varian, Model 3400, Mississauga, ON) with a DB35MS capillary column (30 m 0.25 mm i.d. 0.25 µm) attached to a Saturn 3 ion trap mass spectrometer detector (Tacke and Casper 1996). Isobenzan, also known as Telodrin (Shell Chemical Co., New York, NY), was used as an internal standard. Due to limited sample material only

HATCHER ET AL. FUSARIUM EFFECT ON NOODLE PROPERTIES 13 single analyses of the wheat and flour samples were undertaken and are presented solely to characterize the material. The causal species of FD in the composite samples were determined by whole seed plating of a random selection of 100 seeds and 10 selected FD kernels per composite sample as per Dexter et al. (1996). Noodle Preparation Noodles were prepared using the method previously described by Kruger et al. (1994). Kansui reagent (9:1 sodium and potassium carbonate mixture) or salt (NaCl), dissolved in water, was added to 200 g of flour to yield a 1% alkaline or salt (wt/wt) dough at a water absorption of 32% (14% m.b.). The materials were incorporated by a Hobart N50 mixer (Hobart Canada, North York, ON) using a 4 stage mixing regime over 5 min. The mixture was sheeted on an Ohtake laboratory noodle machine (Ohtake, Tokyo, Japan) with an initial gap setting of 3.0 mm. Two passes were made at this setting with the noodle sheet folded between passes to ensure homogeneity. A 25-cm-long section was cut from the noodle sheet and subjected to seven reduction passes (3.0 1.1 mm) with work input requirements measured and expressed on a per-gram of dough basis (Kruger et al. 1994). Noodle sheets for each sample were prepared on 2 separate days as per the experimental design. The noodle sheet was divided for further testing. One portion was cut into noodles and underwent immediate cooking and subsequent textural analysis. The remaining portion was retained as a sheet for time-dependent color measurements and image analysis. Noodle Color, Image and Textural Analyses A Labscan II spectrocolorimeter (HunterLab, Reston, VA) equipped with a D65 illuminant using the CIE 1976 brightness, L*, redness, a*, and yellowness, b* color scale was used to measure raw noodle color. The noodle sheet was folded into three layers, placed on the spectrocolorimeter opening (4.9 cm 2 ), and enclosed within a blackened container to remove ambient light. Measurements were made in triplicate at each of two locations on the noodle sheet surface for each sample. Color measurements were carried out at 0, 1, 2 and 24 h after production. The raw noodle sheet was stored in a sealed plastic bag at 25 C over the 24 h examination period. Colorimeters provide an average of L*, a* and b* over a defined area, but are incapable of discerning the impact of individual specks on these values. Images of the raw noodle sheets were captured at the same time interval using a commercial scanner (Model 3, Microtek, Canada) and analyzed using in-house developed software based on KS-400 (Carl Zeiss Vision, Echting, Germany) as per Hatcher et al. (1999) to determine noodle speckiness, which is a key component for consumer acceptance. Textural measurements were carried out on raw and cooked noodles using an Instron Universal Testing Machine (IUTM model 4201, Instron, Canton, MA) with fixtures and procedures described by Oh et al. (1983, 1985) and Kruger et al. (1994). Table 1. Properties of Fusarium-damaged Canada Western Red Winter (CWRW) wheat samples Fusarium 15-Acetyl Flour damage DON z DON z Test weight Protein yield (%) (ppm) (ppm) (kg h L 1 ) (%) (%) 0.5 0.4 ND ty 78.5 10.2 76.0 1.0 1.7 0.10 77.6 10.3 76.3 2.1 1.8 ND 78.8 10.7 76.8 3.2 1.9 0.10 78.3 10.3 76.5 3.7 3.6 0.16 77.6 10.6 76.8 4.9 2.8 0.11 78.8 10.7 77.7 5.5 4.7 0.16 75.3 10.5 76.6 9.6 6.4 0.26 76.1 10.5 75.1 SE 0.30 0.04 0.9 0.02 0.38 z DON = deoxynivalenol. y ND = below detectable limit. Experimental Design A noodle sheet was prepared on 2 separate days for each FD sample following a randomized block design. Noodles cut from each sheet were cooked in duplicate 10 min apart. Texture measurements were performed using three noodle strands lying perpendicular to the testing blade. Replicated texture measurements (5) were performed on the noodles strands for each cooking. Fresh noodles were used for each replicated measurement. The cutting test was performed 10 min after rinsing and the compression test at 15 min. The results were averaged for each of the four cookings (Kruger et al. 1994). All statistical analyses were carried out using SAS (SAS Institute, Inc., Cary, NC), Version 6.12 employing PROC ANOVA invoking a Fisher s least significant difference (LSD) test. The use of significance throughout the manuscript is based upon P < 0.05 unless stated otherwise. RESULTS AND DISCUSSION Wheat and Flour Characteristics The milling grades of CWRW wheat have a maximum allowable FD content of 2.0%, whereas Canada Feed wheat has a maximum allowable limit of 5.0% (Canadian Grain Commission 2001). Therefore, only two of the composite samples would qualify as CWRW milling wheat, four were acceptable for feed, and the remaining two would be confined to industrial use (i.e., sample grade)(table 1). This wide range in FD was chosen to determine the level at which a detrimental impact on noodle quality was detectable. The wheat samples displayed a narrow protein content range. DON levels (0.4 to 6.4 ppm) in the wheat increased with increasing FD. The mycotoxin 15-ADON was detected at a maximum level of 0.26 ppm for the 9.6% FD wheat but much lower levels were in the remaining samples. Fuarium. graminearum, a well known producer of DON and 15 ADON, was the main causal agent of the FD in all the composite samples, infecting between 80 and 100% of the selected FD kernels. It also infected between 5% (in the 0.5% FD composite sample) and 39% (5.5% FD composite) of randomly selected, visually assessed non-fd seeds. A noticeable drop in the wheat test weight was observed for the 5.5 and 9.6% FD samples. No consistent effect attributable to FD was detected for straight grade flour milling

14 CANADIAN JOURNAL OF PLANT SCIENCE Table 2. Characterization of Fusarium-damaged Canada Western Red Winter patent (60%) flours used for noodle evaluation Mixograph Flour protein Ash content Flour colour Wet gluten DON Peak time Peak FD (%) (%) z (%) (SIU) z (%) (ppm) z (min) resistance w Work w Band width w 0.5 9.2 0.39 2.2 25.2 0.3 3.5 43.2 270 12.7 1.0 9.3 0.38 1.7 24.5 0.6 3.0 40.4 265 12.8 2.1 9.5 0.38 1.7 26.6 1.0 2.9 39.5 261 11.1 3.2 9.4 0.38 1.7 25.8 0.8 3.7 38.4 239 11.6 3.7 9.4 0.39 1.5 26.8 1.1 2.8 37.2 239 10.4 4.9 9.4 0.39 1.5 26.2 1.0 4.2 40.5 264 11.0 5.5 9.3 0.40 0.6 26.1 1.6 2.8 38.0 246 11.2 9.6 9.2 0.42 0.3 25.1 2.4 4.6 37.2 244 10.5 SE 0.09 0.01 0.2 0.41 0.30 0.20 1.2 21 0.5 z Protein expressed on a 14.0% moisture basis. y SIU = Satake International Units. x DON = deoxynivalenol. w Arbitrary units. yield, which was consistent with Dexter et al. (1996). Flour ash content, however, increased with increasing FD in both patent and straight grade flours (Tables 2 and 3), while flour color significantly declined (grade color increased), which is consistent with Dexter et al. (1996). The patent and straight grade flours reflected increasing DON levels with increasing FD, although differences due to flour extraction level were minimal (Tables 2 and 3). This observation agrees with Seitz et al. (1985) who found a narrow range of DON concentration among flour mill streams for US hard red winter wheat and little difference between patent, straight grade and poorer quality, high ash clear flours. The protein content of both flours derived from the FD wheat exhibited a narrow range (9.2 9.9%) (Tables 2 and 3). Mixograph curve data (Tables 2 and 3) indicated a moderate loss in dough strength as evident from the significant decrease in maximum peak resistance and bandwidth for both patent and straight grade flours. This was consistent with the findings of Dexter et al. (1996, 1997) and Nightingale et al. (1999). No discernible effect due to FD was observed on wet gluten content for either flour type Processed Noodles General Processing Characteristics Neither the total amount of work nor the amount of work/gram of dough sheet required to sheet the respective doughs displayed a statistically significant effect due to FD for either flour extraction or noodle type (results not shown). Noodle water uptake and loss of solids during cooking also indicated no significant effect due to FD% (results not shown). Yellow Alkaline Noodles Raw Noodle Color A general decline in brightness (L*) was observed with increasing FD for the patent flour YA noodles at 2 h (Fig. 1a). The 0.5% FD sample displayed the highest L* (78.5). It was significantly brighter than the samples prepared from wheat with a FD of 3.7% or greater. The 9.6% FD sample displayed the lowest L* (76.5), which was significantly darker than the majority of samples. Aging 24 h resulted in a loss of brightness for all samples (Fig. 1d). The 0.5% FD prepared patent flour noodle remained the brightest (73.5) and the 9.6% FD flour sample (70.4) remained the darkest. A significant loss in brightness due to FD was only detected above the 2% FD level. Although the enzyme polyphenol oxidase is believed to play a role in enzyme discoloration by oxidizing phenolic compounds, previous work by Hatcher and Kruger (1993) found that milling could remove 96% of the enzyme in a CWRW straight grade flour and 98% in a patent flour. CWRW has very low polyphenol oxidase activity compared to other Canadian wheat classes (Hatcher and Kruger 1993), so it would not play a significant role in the observed noodle discoloration of these high quality flours. Redness (a*) is an indicator of the formation of undesirable discoloration on the noodle surface. The redness is due to reactions between labile quinones, formed by enzymes or autooxidation of phenolic compounds, and the amines or sulfhydryl groups of proteins (Taylor and Clydesdale 1987). Patent flour YA noodles showed no clear effect due to FD at 2 h, although the 0.5% FD sample had the lowest red a* value. Aging for 24 h resulted in an increase in the a* values for all samples. The 0.5% FD sample, however, was significantly less red than all other samples, while the 5.5 and 9.6% FD noodles displayed the highest a* values. Addition of alkali causes endogenous colorless flavanoids to undergo a chromophoric shift to yield a bright yellow color (Hatcher 2001). Yellowness (b*) of a YA noodle is a critical characteristic for consumer acceptance. Ideally the noodle should be bright, clear and maintain a strong yellow color for 24 h or longer. The 0.5% FD patent flour YA noodles displayed the maximum b* value at 2 h (36.3) while the 5.5% and 9.6% were significantly lower at 33.1 and 33.8, respectively. Aging the noodles for 24 h resulted in a decrease in b* values for all FD samples (Fig. 1f). The 0.5% FD prepared noodle, however, retained the maximum yellowness, while the 5.5 and 9.6% FD samples displayed lower b* values than the other samples. Preparation of the YA noodles using straight grade flour showed the effects on color due to FD (Fig. 2). At 2 h, the 0.5% FD noodles were significantly brighter than all other prepared noodles, while the 9.6% FD sample was significantly darker than the rest. Aging for 24 h resulted in a significant loss in brightness for all the samples. The extent of the decline in straight grade noodles (mean = 6.72 ± 0.82)

HATCHER ET AL. FUSARIUM EFFECT ON NOODLE PROPERTIES 15 Table 3. Characterization of Fusarium-damaged Canada Western Red Winter straight grade flours (~76%) flours used for noodle evaluation Mixograph Flour protein Ash content Flour colour Wet gluten DON Peak time Peak FDK (%) (%) z (%) (SIU) z (%) (ppm) z (min) resistance w Work w Band width w 0.5 9.5 0.46 0.2 25.0 0.2 3.0 42.5 269 11.7 1.0 9.7 0.47 0.2 24.9 0.7 3.1 40.3 262 12.0 2.1 9.9 0.47 0.0 27.0 0.9 2.5 41.3 274 11.4 3.2 9.6 0.46 0.2 26.6 1.1 3.3 41.0 266 11.4 3.7 9.8 0.47 0.5 27.0 1.2 2.9 40.5 264 11.7 4.9 9.8 0.47 0.3 26.4 1.2 3.0 39.8 254 10.9 5.5 9.6 0.47 0.9 26.1 1.9 3.3 39.0 250 10.8 9.6 9.5 0.52 1.7 25.1 2.6 2.7 36.4 238 10.6 SE 0.1 0.01 0.2 0.4 0.3 0.2 1.2 21 0.5 z Protein expressed on a 14.0% moisture basis. y SIU = Satake International Units. x DON = deoxynivalenol. w Arbitrary units. Fig. 1. CWRW patent flour raw yellow alkaline (YA) noodle color characteristics over time. (A) Brightness at 2 h. (B) Redness at 2 h. (C) Yellowness at 2 h. (D) Brightness at 24 h. (E) Redness at 24 h. (F) Yellowness at 24 h. LSD = least significant difference at P = 0.05 level. was larger than that observed in the corresponding patent flours (mean = 5.31 ± 0.51) over the same time period. A general loss of brightness was noted with increasing FD. The 0.5% FD sample again retained a significantly brighter noodle than all other samples, while the 9.6% FD sample was significantly darker than the rest. Redness (a*) of the straight grade YA noodles, although higher than that observed for the patent flours, demonstrated

16 CANADIAN JOURNAL OF PLANT SCIENCE Fig. 2. CWRW straight grade flour raw yellow alkaline (YA) noodle color characteristics over time. (A) Brightness at 2 h. (B) Redness at 2 h. (C) Yellowness at 2 h. (D) Brightness at 24 h. (E) Redness at 24 h. (F) Yellowness at 24 h. LSD = least significant difference at P = 0.05 level. Fig. 3. Relationship between noodle specks and FD level in CWRW yellow alkaline (YA) noodles. patent flour 2 h. Average standard deviation for this series ±4.8 specks. patent flour 24 h. Average standard deviation for this series ±10.1 specks. straight grade flour 2 h. Average standard deviation for this series ±12.2 specks. straight grade flour 24 h. Average standard deviation for this series ±14.6 specks. the same pattern at 2 and 24 h. At both times the 0.5% FD sample displayed significantly lower a* values than all other samples. Aging (24 h) of the noodles increased all sample a* values with the differences between samples increasing relative to 2 h. No clear effect on YA noodle yellowness due to FD was detected at 2 h, with the exception of the 9.6% FD sample, which displayed a significantly lower b* value. However by 24 h, a very consistent trend of lower b* as FD increased was observed. The 0.5% FD (35.0) sample retained a significantly higher b* value than the remaining samples, while the 5.5% (31.8) and 9.6% FD flour noodles (30.8) were significantly different from each other and lower than the remaining samples. In many countries throughout S.E. Asia, straight grade flours are used for noodle production to minimize their unit price. At 2 h the 0.5% FD CWRW sample was significantly brigher than the 1.0% FD sample, and at both 2 and 24 h it was significantly less red than the 1.0% FD sample. These data suggest a maximum FD limit below 2% in the wheat intended for high-quality noodle markets to ensure optimum noodle quality when made from straight grade flour.

HATCHER ET AL. FUSARIUM EFFECT ON NOODLE PROPERTIES 17 Fig. 4. Texture characteristics of patent and straight grade CWRW yellow alkaline (YA) cooked noodles. (a) Maximum cutting stress g mm 2. (b) Recovery % LSD = least significant difference at P = 0.05 level. Image Analysis Consumer acceptance of a noodle is influenced by its color. The L*, a* and b* values, however, provide only an indication of the overall average noodle color. The discriminating consumer, however, is also strongly influenced by the degree of speckiness in the product. The preferred product should be bright, clear, and free from specks for at least 24 h. Image analysis provides the ability to quantitate or characterize the visual impact that specks have on consumer perception of noodle quality (Hatcher and Symons 2000a, b). YA noodles prepared from either patent or straight grade flours displayed a significant increase in the number of specks/noodle sheet image with increasing FD (Fig. 3). As previously observed (Hatcher and Symons 2000a, b) each patent flour displayed fewer specks than its corresponding straight grade flour, although the regression lines are almost parallel at the 2 h reading. The relationship between specks and FD for the patent flour (r 2 = 0.55) was somewhat weaker than for the straight grade noodle (r 2 = 0.68), although both were significant at P < 0.025. Aging for 24 h retained the relationship between noodle specks and FD for both flours (r 2 = 0.61 and 0.63). However, it was noted that while the aged low FD (0.5%) patent flour noodle displayed significantly fewer specks than the corresponding straight grade flour, as the level of FD increased, the difference due to flour refinement was reduced. At the highest FD level (9.6%), no difference was detected in the number of specks/image due to flour refinement, thus negating the normal benefits of using a low extraction flour. Cooked Noodle Textural Attributes Although no influence due to FD was detected on patent CWRW YA cooked noodle thickness (data not shown), its

18 CANADIAN JOURNAL OF PLANT SCIENCE Table 4. Color readings over 24 h of Fusarium-damaged Canada Western Red Winter WS noodles prepared from patent and straight grade flours Patent Flour Noodles Straight Grade Flour Noodles FDK Brightness Redness Yellowness Brightness Redness Yellowness (%) L* a* b* L* a* b* Time 2 h 24 h 2 h 24 h 2 h 24 h 2 h 24 h 2 h 24 h 2 h 24 h 0.5 80.0ab 75.1a 3.17b 3.44e 31.0a 29.4bc 78.1a 70.4ab 3.67b 4.29b 29.9a 28.1ab 1.0 79.6bcd 74.2ab 3.28ab 4.11b 30.4a 30.8a 77.1bc 70.9a 3.83ab 4.41b 30.3a 27.3ab 2.1 79.2cd 75.2a 3.31ab 3.60de 30.6a 28.1de 77.1bc 70.7a 3.84ab 4.56b 29.8a 27.3ab 3.2 80.5a 74.0ab 3.18b 3.73cd 28.2b 27.3ef 78.0a 68.8bc 3.59b 4.45b 27.1b 26.1b 3.7 79.5bcd 73.9ab 3.35ab 3.82c 30.3a 29.1bcd 76.9bc 69.8abc 3.99a 4.66ab 30.5a 28.3a 4.9 79.6bc 73.9ab 3.27ab 3.60de 30.6a 28.5cd 76.8c 70.6ab 4.00a 4.72ab 30.4a 27.3ab 5.5 78.9d 72.7b 3.44a 4.28a 30.5a 29.6b 76.2d 69.3abc 3.97a 5.05a 30.2a 27.84ab 9.6 79.1cd 73.2b 3.36ab 3.57de 30.0a 27.0f 76.2d 68.3c 4.01a 4.58ab 29.5a 26.3ab a e Values, the mean of two replicates, within the same column having the same letter are not significantly different at the P = 0.05 level. bite or maximum cutting stress (MCS) displayed a decline with increasing FD (Fig. 4a). Previous work on durum wheat and red common wheat has shown that FD resulted in the breakdown of glutenin polymers responsible for gluten strength (Nightingale et al. 1999). Mixograph results for the CWRW samples in this study (Tables 2 and 3) indicated a moderate loss in dough strength with increasing FD. Noodles prepared from patent flours with lower FD (0.5 and 1.0%) displayed the greatest MCS values, being significantly different from all but the 2.1% FD sample (Fig. 4a). The higher FD samples (5.5 and 9.6%) displayed the minimum values, confirming the detrimental impact of FD on noodle texture. As was the case for color, YA noodles prepared from straight grade flour showed a significant decline in MCS above the 0.5% FD level, although no clear discernible trend was detected in the remaining samples (Fig. 4a). Noodle recovery (REC, %), which reflects the noodle s chewiness and springiness, also showed the effects of deterioration in protein quality, as there was a general decline in REC with increasing FD (Fig. 4b). Patent noodle flours had a maximum REC observed in the 0.5% FD sample (25.3%) with significantly lower values for the 4.9 9.6% FD samples. REC values for YA prepared from straight grade flour mirrored MCS behavior, as a very significant decline in REC was observed in samples with greater than 0.5% FD (Fig. 4b). No effect due to FD was detected in the resistance to compression of either the patent or straight grade flour YA noodles (data not shown). White Salted Noodles Raw Noodle Color Ideally a WS noodle should be bright, free of discoloration, and depending upon regional preferences, display minimal to no yellowness. Unlike the YA noodles, no consistent effects due to increasing FD levels were detected in 2 or 24 h aged WS noodles for L*, a* or b* prepared from patent flours (Table 4). Straight grade flour noodles displayed a significant FD influence on noodle brightness at 2 h as the control was significantly brighter than noodles prepared from flours derived from wheat with 3.7% or greater FD. This effect was minimized on aging (24 h) as only the control and 9.6% FD sample displayed significant differences in noodle brightness. Straight grade noodle redness was also significantly lower in the control noodle than samples prepared from 3.7% or greater Fig. 5. Relationship between noodle specks and FD level in CWRW WS noodles. patent flour 2 h. Average standard deviation for this series ±5.6 specks. patent flour 24 h. Average standard deviation for this series ±8.6 specks. straight grade flour 2 h. Average standard deviation for this series ±6.8 specks. straight grade flour 24 h. Average standard deviation for this series ±9.7 specks. FD at 2 h, although this effect was lost by 24 h. No influence was detected in b* values due to FD at either 2 or 24 h. Image Analysis Although minimal effects were detected on WS noodle color due to FD, the appearance of the noodle was significantly affected. The WS noodles prepared from patent or straight grade flours displayed fewer specks/image than their YA noodle counterparts at either 2 or 24 h (Fig. 5). No significant relationship was detected due to FD and the number of specks/noodle image for the patent flour at 2 h, but a significant relationship (r 2 = 0.65) was detected between FD level and specks/noodle image for noodles made from straight grade flour (P < 0.025). Noodles made from straight grade flours displayed a significantly greater number of specks/image than the corresponding patent flour noodles at 2 h, which was consistent with previous findings (Hatcher and Symons 2000a). Aging for 24 h allowed FD levels to exert a significant, detrimental effect on the speckiness of WS noodles prepared from either patent or straight grade flours (Fig. 5).

HATCHER ET AL. FUSARIUM EFFECT ON NOODLE PROPERTIES 19 Fig. 6. Texture characteristics of patent and straight grade white salted CWRW (WS) cooked noodles. (a) Maximum cutting stress g mm 2. (b) Recovery % LSD = least significant difference at P = 0.05 level. The level of FD influenced noodle speckiness (r 2 = 0.61) to a lesser extent in the patent flours (56 97 specks/ image), than the straight grade noodles (112 238 specks/ image), as would be anticipated by the lower bran content associated with the higher degree of flour refinement. Aging the WS noodles did not invoke the same loss of flour refinement effect on speck count as observed for the YA patent noodles. Significantly higher values and a much larger range in the number of specks/image were observed within the WS straight grade noodles than for the WS patent noodles. The aged (24 h) WS straight grade noodle specks/image data indicated a progressive deterioration (r 2 = 0.63) in noodle appearance with increasing FD. It was important to note that all aged straight grade WS noodles displayed significantly higher specks/image than the control sample. Cooked WS Noodle Texture Fusarium damage displayed a significant influence on patent WS noodle textural characteristics (Fig. 6a). Maximum MCS for the patent flour noodles was observed for the 0.5% FD sample (17.5 g mm 2 ). A significant decline at the 1% FD level (16.1 g mm 2 ) was followed by lower MCS values for the remaining samples, although no further trend due to FD could be identified. A similar trend was noted for straight grade WS noodles. Maximum MCS (17.1 g mm 2 ) was again observed for the 0.5% FD sample with a significant lowering and a general decline associated with increasing FD. A significant effect on REC was observed at FD levels above 0.5% (Fig. 6b). The 0.5% patent prepared noodle had a significantly higher REC than the other samples, while the 5.5 and 9.6% FD noodles had the lowest. Comparable trends were observed for the straight grade flour noodles.

20 CANADIAN JOURNAL OF PLANT SCIENCE As was the case for YA noodles, no discernible effect attributable to FD could be detected on patent or straight grade flour WS noodle resistance to compression (data not shown). CONCLUSIONS Fusarium damage significantly affected both patent and straight grade flour characteristics. The levels of DON in the respective CWRW flours were found to increase with increasing FD, although no influence due to flour extraction rate was detected. Ash content, flour color and dough strength, which are all critical to an acceptable noodle, deteriorated with increasing FD levels in both flours. Yellow alkaline noodle color characteristics, L*, a* and b* were adversely effected by FD at both 2 and 24 h. Patent and straight grade YA noodles displayed a significant increase in redness (a*) and a significant loss in noodle brightness (L*) with increasing FD. WS patent noodle color characteristics (2 h) did not display a consistent significant FD effect, although by 24 h a significant difference in brightness was detected between the control (0.5% FD) and both the 5.5 and 9.6% FD noodles. Straight grade flour noodles, however, made a significantly brighter control noodle at 2 h than those prepared from flour derived from wheat with 3.7% or greater FD. The effect on L* was minimized with aging (24 h), as a significant difference was only detected between the control and the 9.6% noodle. A significant linear relationship existed between FD and CWRW noodle speckiness for both noodle types, particularly after 24 h, using either patent or straight grade flour. YA and WS noodles displayed a significant loss in cooked noodle texture with increasing FD. The impact was primarily on noodle bite, MCS, noodle chewiness, and REC. Athough an alkaline protease had been implicated in FD degradation (Nightingale et al. 1999), the YA noodles did not display any preferential loss of noodle texture relative to WS. This may be due to insufficient moisture in raw noodles in combination with the limited time from production to cooking for the enzyme to degrade gluten proteins to the same extent as observed during bread dough fermentation. Our results, however, indicate that although the mode of deterioration is not clearly understood, FD has a significant detrimental impact on the quality of both YA and WS noodles. In addition to considering the serious health implications of increasing DON levels in flour from FD wheat, FD tolerances are required in order to ensure acceptable noodle quality. For preparation of high-quality noodles, FD tolerances less than 2% would be desirable. ACKNOWLEDGMENTS The authors gratefully acknowledge the assistance of H. Facto, S. Patrick, R. Desjardins, D. Saydak and J. 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