Effect of Bran Pre-Treatment with Endoxylanase on the Characteristics of Intermediate Wheatgrass (Thinopyrum intermedium) Bread

Abstract

Previous work indicated that bran removal promotes network formation in breads prepared from intermediate wheatgrass (IWG) flour. However, refinement reduces yields as well as contents of nutritionally beneficial compounds such as fiber. This study evaluated xylanase pretreatment of IWG bran as a processing option to enhance the properties of bread made with half of the original bran content. Xylanase pretreatment did not affect stickiness but significantly reduced hardness and increased specific loaf volumes compared to negative (without xylanase) and positive controls (with xylanase but without pretreatment). However, the surface of breads with pretreated bran was uneven due to structural collapse during baking. Fewer but larger gas cells were present due to pretreatment. Addition of ascorbic acid modulated these effects, but did not prevent uneven surfaces. Accessible thiol concentrations were slightly but significantly increased by xylanase pretreatment, possibly due to a less compact crumb structure. Endogenous xylanases (apparent activity 0.46 and 5.81 XU/g in flour and bran, respectively) may have been activated during the pretreatment. Moreover, Triticum aestivum xylanase inhibitor activity was also detected (193 and 410 InU/g in flour and bran). Overall, xylanase pretreatment facilitates incorporation of IWG bran into breads, but more research is needed to improve bread appearance.

Optimizing the extrusion conditions for the production of expanded intermediate wheatgrass (Thinopyrum intermedium) products

“…The remarkable progress made toward IWG development and improvement has resulted in efforts to utilize IWG for mainstream food applications. Previous studies have focused on the compositional and functional properties of IWG as impacted by varietal differences, bran content, storage conditions, and dough conditioners to enhance baking quality (Banjade et al., 2019; Marti et al., 2016; Rahardjo et al., 2018; Tyl & Ismail, 2019; Zhong et al., 2019a), determining the starch hydrolysis kinetics of IWG (Zhong et al., 2019b), establishing tempering conditions for the production of refined IWG flour (Tyl et al., 2019), and pretreating IWG bran with xylanase to enhance the properties of IWG bread (Dai et al., 2021). In one such study (Tyl & Ismail, 2019), it was shown that IWG had higher protein, dietary fiber, and antioxidant contents than wheat.…”

Effects of Selenium Enrichment on Dough Fermentation Characteristics of Baker’s Yeast

“…Furthermore, the gas retention capacity during dough fermentation by Se-enriched yeast (87.15 ± 0.22%) was higher than that for the original yeast strain (83.96 ± 0.25%) ( p < 0.05). It is reported that yeast plays a certain role in increasing gluten extension in dough fermentation [ 25 ]. Whenever CO 2 is released by yeast metabolism, these gases will disturb surrounding molecules, which will increase the chance for protein molecules to contact with water molecules, so that glutenin in flour will be properly changed.…”

“…Images were captured using an HD camera (Canon, Japan, 1x). The analysis of stomatal morphology in cross-sections of bread is based on a previous study [ 25 ], with a slight modification. The images were processed using ImageJ version 1.50i (National Institute of Health, Rockville, MD, USA).…”

Physicochemical and Nutritional Characterization of Bran-Enriched Products

“…Another strategy to modify bran is via incubation with enzymes. Dai et al [ 7 ] focused their efforts on intermediate wheatgrass, a perennial grain of interest due to its considerable root mass, which may help counteract environmental challenges associated with intensive cereal production. However, the combination of weak protein networks and high fiber contents limits its use in baked goods.…”

“…However, the combination of weak protein networks and high fiber contents limits its use in baked goods. Dai et al [ 7 ] used bran pre-treatment with xylanase to modify the fiber population, resulting in increased expansion, evidenced by higher specific volumes and differences in crumb structure. The effects on dough and bread were partially counteracted by ascorbic acid, added as a dough strengthener that also improved surface appearance.…”