Underlying mechanism governing the influence of peanut oil addition on wheat dough viscoelasticity and Chinese steamed bread quality

Effects of oil and heating on the physicochemical and microstructural properties of gluten-starch dough

Oil has crucial applications for improving the quality of some wheat products during dough formation and heat-processing. Herein, the influence of oil modification and thermal-mechanical treatment on dough prepared mainly with wheat starch and gluten was investigated. Oils with different structures addition reduced the hardness but improved the tensile strength of dough and inhibited starch retrogradation. Oil also reduced the disulfide bond, hydrogen bond and hydrophobic interactions whilst changed the rheology of dough. The X-ray diffraction patterns were characterised by new weak peaks at approximately 12.9°, and 19.8°, indicating that thermal-mechanical treatment promoted the formation of V-type complexes. Oil modification impaired dough short-range ordered structure, but prevented part starch granule crystallinity degradation caused by thermal-mechanical treatment. Scanning electron microscopy revealed oil modification and thermal-mechanical treatment synergistically affected starch-gluten agglomeration. Our findings contributed to elucidate the influence of oil modification and thermal-mechanical treatment on dough functionality.

Influence of sesame cake on physicochemical, antioxidant and sensorial characteristics of fortified wheat breads

Incorporation of two sesame cake preparations, differing in fat, 11 % (LF) and 17 % (HF), and protein, 51 % (LF) and 44 % (HF), contents, respectively, into breads at 6, 12 and 20 % wheat flour substitution levels, led to enriched end-products with antioxidants, suitable also to carry the 'high protein' and 'fiber source' nutrition claims (at ≥ 12 % substitution level). Sesame cake decreased wheat dough resistance to mixing and extension, and peak viscosity (empirical rheology), in a concentration-dependent manner, being more pronounced for LF formulations. Breads with LF incorporation ≥ 12 % had lower specific volumes and harder crumb (texture analysis) throughout storage, than control (100 % wheat flour); however, such adverse effects were diminished in HF bread formulations due to the plasticizing and emulsifying action of the sesame cake fat. Calorimetry showed that the sesame cake had no effect on starch retrogradation, but enhanced amylose-lipid complex formation. Antioxidant activity (ABTS, DPPH and FRAP assays), and phenolic acids (ferulic, p-coumaric and sinapic) and lignan (sesaminol glucosides and sesamolin) contents, determined by HPLC-DAD-MS, were higher in LF breads than their HF counterparts. The presence of some sulfur (off-flavor) and pyrazine (nutty flavor) compounds (SPME-GC-MS), as well as the sesame flavor and bitterness (sensory analysis) were of higher intensity in HF breads, while the 6 % LF product received the highest overall acceptability score among all fortified products. Overall, the sesame cake can be a promising ingredient for production of functional wheat bread depending on its composition and fortification level.

Effect of Tea Polyphenols on the Storage Stability of Non-Fermented Frozen Dough: Protein Structures and State of Water

The usage of tea polyphenols (TPs) as a natural food additive into non-fermented frozen dough (NFFD) has rarely been investigated, and results have been controversial. Hence, this study investigated the effect of TPs at various levels (0, 0.5, 1, and 2%) on the quality of NFFD stored from 0 to 4 weeks. The rheological characteristics, water state, protein, and its microstructure were analyzed by DSC, LF-NMR, SDS-PAGE, FT-IR, and SEM, respectively. Results showed that the 0.5% TP group delayed the deterioration of protein and inhibited the water migration in dough throughout the whole frozen storage period. In addition, the 0.5% TP group enhanced the rheological properties of NFFD and stabilized the sulfhydryl content and the secondary structure in the gluten network. On the contrary, opposite phenomena were found in the 1 and 2% TP groups, which might be due to the induction of excess hydroxyl groups from TPs. In conclusion, our results suggested that a proper addition of TPs, but not an excessive amount (>1%), exhibited beneficial effects in maintaining the quality of NFFD during the 4-week frozen storage. Moreover, this paper elucidated the mechanism of TPs in influencing the protein structure and water state of NFFD during storage and provided new insight into its application in dough-based foods.