Effects of alkylresorcinols on volume and structure of yeast-leavened bread

Effect of alkylresorcinols on the formation of Nε-(carboxymethyl)lysine and sensory profile of wheat bread

Alkylresorcinols (ARs) are important bioactive components in wheat bran which have been used as biomarkers for whole grain wheat consumption. In this study, the impact of ARs on the formation of Nε-(carboxymethyl)lysine (CML), the main component of dietary advanced glycation end products which could induce chronic disease was analyzed. Moreover, the influence of the addition of ARs on the sensory profiles of wheat bread was evaluated. ARs supplementation (0.03%, 0.1%, and 0.3% w/w) could significantly decrease the formation of CML by 21.70%, 35.11%, and 42.18%, respectively, compared with the control. Moreover, ARs-supplemented bread achieved a higher score in overall acceptability and buttery-like aroma through sensory evaluation. The volatile compounds in bread supplemented with ARs were characterized by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), among which acetoin, 2,3-butanedione, 3-methyl-1-butanol, 2-phenylethanol, and 2-methylbutanal were confirmed as the main volatile compounds through determination of odor activity value. In addition, ARs supplementation had no negative impact on the chewiness, hardness, and springiness of bread. These findings demonstrated that ARs could be applied as potential food additives to improve the quality and sensory profile of bread.

The role of rye bran acidification and in situ dextran formation on structure and texture of high fibre extrudates

High insoluble dietary fibre content causes challenges with structure and texture in extrusion. This paper focused on studying the structure of extrudate enriched with rye bran modified in different ways. Fermentation of rye bran with dextran-producing Weissella confusa (with 10 g/100 g, 5 g/100 g and 0 g/100 g added sucrose as substrate for dextran production), in situ enzymatic production of dextran in the bran and chemical acidification of bran with lactic acid were compared in extrusion trials. Endosperm rye flour was the base in extrusion, of which 32 g/100 g was substituted for rye bran. Fermentation with dextran production showed similar improvement in extrudate expansion as chemically acidified bran samples (489 and 493%), in comparison with native bran (420%). Similarly, these treatments decreased extrudate hardness and increased crispiness index (CI) (16 N, 0.06 and 14 N, 0.071 respectively) compared to the control (39 N, 0.008). Enzymatically produced dextran did not affect expansion, although it decreased hardness (26 N) and increased CI compared to the control (0.023). Chemical changes in the fermented and acidified rye bran included reduction in insoluble dietary fibre (DF) (19 g/100 g → 17 g/100 g) and increase in soluble DF (5.17 g/100 g → 5.51-7.19 g/100 g), as well as soluble protein (8 g/100 g → 11 g/100 g) content. Lactic acid bacteria fermentation or acidification is therefore a promising method to increase the functionality of rye bran in extrusion.

Solid state fermentation by Fomitopsis pinicola improves physicochemical and functional properties of wheat bran and the bran-containing products

Wheat bran was solid state fermented by Fomitopsis pinicola. The results showed that the processing properties were increased by fermentation and the content of total phenol and alkylresorcinols was 5.91 and 1.55 times of the unfermented bran respectively by the 6th day. The total antioxidant capacity was 5.73 times of the unfermented sample by the 4th day. Electronic nose analysis showed that the fermented wheat bran had a special flavor. GC-MS analysis found that 4-ethyl-2-methoxy-phenol was the main flavor substance, which was sharply increased during the fermentation. Furthermore, the textural properties of the dough and bread containing fermented bran were significantly improved. The content of phytic acid in the bread was significantly decreased, while the protein, total phenol and alkylresorcinols contents were significantly increased. Results suggest that solid state fermentation by Fomitopsis pinicola is a promising way to improve wheat bran to a nutritious and flavorful cereal food ingredient.

Structuring colloidal oat and faba bean protein particles via enzymatic modification

Oat and faba bean protein isolates were treated with transglutaminase from Streptomyces mobaraensis and tyrosinase from Trichoderma reesei to modify the colloidal properties of protein particles in order to improve their colloidal stability and foaming properties. Transglutaminase crosslinked faba bean protein extensively already with 10nkat/g enzyme dosage. Oat protein was crosslinked to some extent with transglutaminase with higher dosages (100 and 1000nkat/g). Transglutaminase increased the absolute zeta-potential values and reduced the particle size of oat protein particles. As a result, the colloidal stability and foaming properties were improved. Tyrosinase had limited crosslinking ability on both plant protein materials. Tyrosinase greatly reduced the solubility of oat protein despite limited crosslinking. Tyrosinase did not have effect on zeta-potential or colloidal stability of either protein, but it impaired foaming properties of both. Thus, the crosslinking enzymes studied caused significantly different end product functionality, presumably due to the different mechanism of action.