Effects of recombinant lipoxygenase on the rheological properties of dough and the quality of noodles

Assessing the Impact of Arabinoxylans on Dough Mixing Properties and Noodle-Making Performance through Xylanase Treatment

This study examined the impact of xylanases, focusing on the hydrolysis of water-extractable (WE-AX) and water-unextractable arabinoxylans (WU-AX) and on the quality and noodle-making performance of flours with varying gluten strengths. Flours categorized as strong (S), medium (M), and weak (W) were treated with two xylanases (WE and WU) at concentrations ranging from 0.01% to 0.2%. Parameters such as solvent retention capacity (SRC), SDS sedimentation volume, dough mixing properties, and noodle characteristics were measured. The SRC revealed that flour S had the highest water-holding capacity, gluten strength, and arabinoxylan content. Xylanase treatment reduced water SRC values in flour S and increased the SDS sedimentation volume, with a greater effect from xylanase WU, indicating the potential enhancement of gluten strength. The impact of xylanases was pronounced at higher enzyme concentrations, with differences in dough mixing properties, resistance, and extensibility of fresh noodles, producing softer and stretchable noodles. Cooked noodles made from flours treated with xylanase were softer and had decreased firmness and chewiness, especially those made from flours S and M. This study concludes that WE-AX and WU-AX influence noodle texture; therefore, controlling their degradation with xylanases can produce noodles with varied textures, depending on the gluten strength of the flour.

Improved catalytic performance and molecular insight for lipoxygenase from Enterovibrio norvegicus via directed evolution

Lipoxygenase (LOX) holds significant promise for food and pharmaceutical industries. However, albeit its application has been hampered by low catalytic activity and suboptimal thermostability. To address the drawbacks, a directed evolution strategy was explored to enhance the catalytic activity and thermostability of LOX from Enterovibrio norvegicus (EnLOX) for the first time. After two rounds of error-prone polymerase chain reaction (error-prone PCR) and one generations of sequential DNA shuffling, all of four different mutants showed a significant increase in the specific activity of EnLOX, ranging from 132.07 ± 9.34 to 330.17 ± 18.54 U/mg. Among these mutants, D95E/T99A/A121H/S142N/N444W/S613G (EAHNWG) exhibited the highest specific activity, which was 8.25-fold higher than the wild-type enzyme (WT). Meanwhile, the catalytic efficiency (K cat /K m) of EAHNWG was also improved, which was 13.61 ± 1.67 s-1 μM-1, in comparison to that of WT (4.83 ± 0.38 s-1 μM-1). In addition, mutant EAHNWG had a satisfied thermostability with the t 1/2,50 °C value of 6.44 ± 0.24 h, which was 0.4 h longer than that of the WT. Furthermore, the molecular dynamics simulation and structural analysis demonstrated that the reduction of hydrogen bonds number, the enhancement of hydrophobic interactions in the catalytic pocket, and the improvement of flexibility of the lid domain facilitated structural stability and the strength of substrate binding capacity for improved thermal stability and catalytic efficiency of mutant LOX after directed evolution. Overall, these results could provide the guidance for further enzymatic modification of LOX with high catalytic performance for industrial application.

Starch-based noodles: Current technologies, properties, and challenges

Starch noodles are gaining interest due to the massive popularity of gluten-free foods. Modified starch is generally used for noodle production due to the functional limitations of native starches. Raw materials, methods, key processing steps, additives, cooking, and textural properties determine the quality of starch noodles. The introduction of traditional, novel, and natural chemical additives used in starch noodles and their potential effects also impacts noodle quality. This review summarizes the current knowledge of the native and modified starch as raw materials and key processing steps for the production of starch noodles. Further, this article aimed to comprehensively collate some of the vital information published on the thermal, pasting, cooking, and textural properties of starch noodles. Technological, nutritional, and sensory challenges during the development of starch noodles are well discussed. Due to the increasing demands of consumers for safe food items with a long shelf life, the development of starch noodles and other convenience food products has increased. Also, the incorporation of modified starches overcomes the shortcomings of native starches, such as lack of viscosity and thickening power, retrogradation characteristics, or hydrophobicity. Starch can improve the stability of the dough structure but reduces the strength and resistance to deformation of the dough. Some technological, sensory, and nutritional challenges also impact the production process.

Characterization and Preliminary Application of a Novel Lipoxygenase from Enterovibrio norvegicus

Lipoxygenases have proven to be a potential biocatalyst for various industrial applications. However, low catalytic activity, low thermostability, and narrow range of pH stability largely limit its application. Here, a lipoxygenase (LOX) gene from Enterovibrio norvegicus DSM 15893 (EnLOX) was cloned and expressed in Escherichia coli BL21 (DE3). EnLOX showed the catalytic activity of 40.34 U mg-1 at 50 °C, pH 8.0. Notably, the enzyme showed superior thermostability, and wide pH range stability. EnLOX remained above 50% of its initial activity after heat treatment below 50 °C for 6 h, and its melting point temperature reached 78.7 °C. More than 70% of its activity was maintained after incubation at pH 5.0-9.5 and 4 °C for 10 h. In addition, EnLOX exhibited high substrate specificity towards linoleic acid, and its kinetic parameters of Vmax, Km, and Kcat values were 12.42 mmol min-1 mg-1, 3.49 μmol L-1, and 16.86 s-1, respectively. LC-MS/MS analysis indicated that EnLOX can be classified as 13-LOX, due to its ability to catalyze C18 polyunsaturated fatty acid to form 13-hydroxy fatty acid. Additionally, EnLOX could improve the farinograph characteristics and rheological properties of wheat dough. These results reveal the potential applications of EnLOX in the food industry.

Effects of anabaena lipoxygenase on whole wheat dough properties and bread quality

The effects of the purified recombinant anabaena lipoxygenase (ana-rLOX) on the rheological characteristics of whole wheat dough and the quality of bread were investigated. The lightness of whole wheat dough supplemented with ana-rLOX was improved, which is superior to that of dough treated with benzoyl peroxide. The effect of ana-rLOX on the strength of dough was analyzed by farinograph, extensograph, and dynamic rheological tests. Compared with the control, the stability time of dough treated with 40 IU/g ana-rLOX increased by 35.4% and the farinograph quality number increased by 27.4%. In addition, the resistance to extension, as well as the elastic and viscous modulus, was improved by ana-rLOX in a dose-dependent manner. The height and specific volume of bread treated with ana-rLOX increased by 17.3 and 15.2%, respectively, compared with the control, and the lightless, whiteness, and other textural parameters, such as hardness, springiness, chewiness, resilience, and gumminess, were significantly improved. Overall, the results of this study suggest the promising application of ana-rLOX in enhancing quality of whole wheat flour.