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Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/authorsrights Author's personal copy Journal of Cereal Science 58 (2013) 437e445 Contents lists available at ScienceDirect Journal of Cereal Science journal homepage: www.elsevier.com/locate/jcs Effects of endoxylanases, vital wheat gluten, and gum Arabic on the rheological properties, water mobility, and baking quality of whole- wheat saltine cracker dough Juan Li a,b, Gary G. Hou b,*, Zhengxing Chen a,**, Kathleen Gehring b a School of Food Science and Technology, National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, Jiangsu 214122, PR China b Wheat Marketing Center, Inc., 1200 NW Naito Parkway, Suite 230, Portland, OR 97209, USA article info abstract Article history: The aim of this study was to improve the baking quality of whole-wheat saltine cracker (WWSC) using Received 14 June 2013 endoxylanases, vital wheat gluten (VWG), and gum Arabic. SRC results showed both water-SRC and Received in revised form sucrose-SRC of soft white whole-wheat flour (SWWW) were significantly reduced by gum Arabic 26 August 2013 (r ¼ 0.94, P < 0.05). Alveograph results indicated that the tenacity and extensibility of the whole-wheat Accepted 8 September 2013 dough (WWD) were increased by VWG. Rheometer G0 and G00 moduli increased with higher addition levels of endoxylanases, VWG, and gum Arabic. Low-field nuclear magnetic resonance (LF-NMR) detected Keywords: three CPMG proton populations (T , T , and T ) in WWD. T peak area ratio (tightly bound water) Whole wheat saltine cracker 21 22 23 21 Endoxylanases reduced and T22 peak area ratio (less tightly bound water) increased with the levels of each additive. LF- Rheological properties NMR results revealed increased water mobility from T21 population to T22 population with addition of Water mobility these additives, which was beneficial for gluten to form a continuous network. Both stack height and Baking quality specific volume of WWSC were improved by the use of endoxylanases, VWG, and gum Arabic, but the breaking strength varied. The results of Orthogonal experimental design showed that the most-improved quality WWSC could be produced by combining 0.035% endoxylanases, 1.5% VWG, and 1.5% gum Arabic into SWWW flour. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction application of WWF in saltine cracker has not been reported else- where in the scientific literature. Crackers are low-moisture content products that have a unique In the manufacture of whole-grain flour products, high water crispy texture. In commercial production of saltine crackers, flour of absorption and weak gluten strength of WWF present many chal- low water absorption but relatively strong gluten strength is lenges in processing and product quality attributes. Loaf volume of required (Kweon et al., 2011). As a result, soft wheat is commonly whole-wheat bread tends to be lower than that of bread made from used for cracker flour, but hard red winter wheat offers some white flour (Bruckner et al., 2001). In the case of whole-wheat quality characteristics that are desired for making saltine crackers saltine crackers (WWSC), additional water is required in the for- by providing gluten strength (Slade et al., 1994). Whole-wheat flour mula and weak gluten strength of soft white whole-wheat flour (WWF) is rich in dietary fiber, phenolic compounds, enzymes, vi- (SWWW) increases the difficulty of cracker dough preparation and tamins, minerals, and phytoestrogens. The regular consumption of reduces puffiness and breaking strength (more fragile) (Li et al., whole-grain flour can provide health benefits such as the reduced 2013). Additional water of whole-wheat dough (WWD) must be risk of cardiovascular disease, type II diabetes, and cancers (Liu, baked out through baking evaporation, which results in prolonged 2007). However, to the best of our knowledge, the practical baking time and energy consumption (Rogers and Hoseney, 1987). Arabinoxylans (AX) are the major non-starch polysaccharides in wheat endosperm cell walls and the primary components responsible for water absorption in WWF. Wheat flour contains approximately 1.5e2.5% AX, of which 25e30% is water extractable * Corresponding author. Tel.: þ1 503 2950823; fax: þ1 503 295 2735. AX (WE-AX) and 70e75% is water unextractable AX (WU-AX) ** Corresponding author. Tel.: þ86 510 85917205; fax: þ86 510 85867273. E-mail addresses: [email protected], [email protected] (G.G. Hou), (Courtin and Delcour, 2002). WE-AX can form highly viscous so- [email protected] (Z. Chen). lutions, whereas WU-AX has a high water-holding capacity 0733-5210/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jcs.2013.09.006 Author's personal copy 438 J. Li et al. / Journal of Cereal Science 58 (2013) 437e445 (Meuser and Suckow, 1986). The water holding capacity of AX has OR). Baking soda (ARM & HAMMER Div. of Church & Dwigh, Co., Inc., been demonstrated to have significant influences on dough rheo- Princeton, NJ), mineral yeast food (ADM Arkady Inc., Olathe, KS), salt logical behaviors and quality attributes of baked products (Courtin (Morton Salt, Inc., Chicago, IL), Crisco vegetable shortening (trans-fat and Delcour, 2002). Bettge and Morris (2000) reported a negative free) (J.M. Smucker Company, Orrville, OH) and instant dry yeast relationship between cookie diameter and WE-AX in soft wheat (Lesaffre Yeast Corporation, Milwaukee, WI) were purchased from a flour, as dough viscosity (mainly controlled by WE-AX) appears to local supermarket (Portland, Oregon). A sourdough starter was control cookie spread; low-viscosity cookie dough tends to spread originally supplied by Oregon State University and was fed daily more and yields larger diameter (Guttieri et al., 2001). using old starter (50 g), HRW flour (100 g), and distilled water (50 g) In general, endoxylanases (EC 3.2.1.8) hydrolyze the glycosidic during the course of the study. bonds within the xylans, degrading the WU-AX into high molecular weight WE-AX, and/or decomposing the latter into low molecular 2.2. WWF blends preparation weight WE-AX (Sunna and Antranikian, 1997); therefore, it was stated that endoxylanases decrease the water holding capacity of Different levels of endoxylanases (0.01%, 0.02%, 0.03%, and 0.04%), AX and redistribute water in a dough system (Courtin et al., 1999). VWG (1.0%, 2.0%, 3.0%, and 4.0%) and gum Arabic (0.5%,1.0%, 2.0%, and In addition, endoxylanases were shown to improve dough handling 3.0%) (flour basis) were blended into the SWWW flour, respectively. and machinability (Slade et al., 1994), which are beneficial to The addition levels of each ingredient were based on the usage ranges WWSC dough preparation. Vital wheat gluten (VWG) is tradition- recommended by ingredient suppliers and confirmed by our own ally noted for its functional properties in various bakery applica- trials. Each blending was done in a blender (model 71, IMER Inter- tions, such as improving strength and network forming of dough, national Inc., Poggibonsi, Italy) for 20 min to achieve uniform mixture reducing breakage in snack products, improving gas retention and prior to dough preparation. Control flour was 100% SWWW flour. product volume, and improving structure in whole-grain products (Kalin, 1979). It is expected that VWG may improve the quality of 2.3. SRC testing WWSC by increasing gluten strength of SWWW flour and oven spring during baking. Gum Arabic was reported to bring many To determine the effects of endoxylanases, VWG, and gum benefits to bakery products in terms of processing, texture and Arabic on water absorption of SWWW flour, the SRC values of flour shelf life due to its moisture regulation and film-forming properties blends added with different ingredients described in Section 2.2 (Thevenet, 2010). The use of gum Arabic in WWSC is expected to were tested. The SRC values with four solvents as lactic acid SRC make positive contributions to its quality. (LA-SRC), sodium carbonate SRC (SC-SRC), sucrose SRC (Suc-SRC), The molecular mobility of water and biopolymers in food and water SRC (W-SRC) were determined according to the AACC products can be studied with proton nuclear magnetic resonance International Approved Method 56-11.02. (1H NMR). It was successfully applied to examine the water mobility between macromolecule complexes in various dough 2.4. Rheological measurements systems. By determining the spinespin relaxation time (T2) with LF-NMR, Lu and Seetharaman (2013) used a 1H NMR spinespin 2.4.1. Alveograph analysis relaxation time (T2) to study the water mobility in various dough Alveograph parameters of different dough samples were systems containing barley flour. Bosmans et al. (2012) investigated determined by the Alveo-Consistograph (Chopin, Villeneuve-La- starchewater, glutenewater, and flourewater model systems as Garenne, France) according to the AACC International Approved well