Effects of Transglutaminase on the Protein Network and In Vitro Starch Digestibility of Asian Wheat Noodles

Effect of a Bacterial Laccase on the Quality and Micro-Structure of Whole Wheat Bread

The gluten protein content in whole-wheat flour is low, which affects the elasticity and viscosity of the dough. Enzymatic modification of the protein may result in a network that mimics gluten, which plays an important role in the processing of whole-wheat foods. In this study, the effects of Halomonas alkaliantartica laccase (LacHa) on the quality parameters of whole-wheat bread were investigated. The optimum dosage of LacHa was 4 U/100 g of whole-wheat flour. At this dosage, whole-wheat bread exhibited the best specific volume and optimum texture parameters. Laccase also extended the storage duration of whole-wheat bread. We analyzed the micro-structure of the dough to determine its gluten-free protein extractable rate and free sulfhydryl group content, and verify that LacHa mediates cross-linking of gluten-free proteins. The results demonstrated that the cross-linking of gluten-free protein by LacHa improves the texture of whole-wheat bread. As a flour improver, LacHa has great developmental and application potential in baked-food production.

Modified whey protein isolate gel prepared by thermal aggregation combined with transglutaminase crosslinking achieves Casein-like slow digestion in vitro and in vivo

Our study aimed to fabricate a modified slow-digestive whey protein isolate (WPI), which can supply enough branched-chain amino acids (BCAAs) during long-term fasting. The WPI aqueous solution (10 % w/v) was treated by heat (80 ℃) to unfold the protein tertiary structure, and subsequently treated with transglutaminase to form a gel via cross-linking. The powder of the WPI gel was obtained by spray drying, which can dissolve in water easily and self-assemble into gels again. This modified WPI contained protein aggregates with high molecular weight, and kept a stable gel-like structure under simulated gastric digestion conditions (pH = 3, 37 ℃). A dense honeycomb internal microstructure of the freeze-dried gel was observed. Further, we found that the WPI gel successfully achieved a casein-like digestible ratio (37.37 %) and released more BCAAs (0.18 mg/mL) than casein during the 4 h of in vitro simulated digestion based on the INFOGEST method. Finally, our results showed that the C57BL/6 mice oral administrated with the modified WPI gel had consistently higher BCAAs concentration (0.052 mg/mL) in their blood serum than the mice with normal WPI intake during the 6 h of in vivo digestion.

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.

Potential application of enzymes to improve quality of dry noodles by reducing water absorption of inferior-quality flour

This study has investigated the characteristics of dry noodles made with Korean domestic wheat flours using enzyme treatment for reducing water absorption to improve noodle-making performance. The water solvent retention capacity (SRC) values of flour treated with α-amylase and xylanase significantly decreased with increasing enzyme concentrations up to 0.025% (flour weight basis), which confirmed the enzyme effect on reducing the water absorption capacity of damaged starches and arabinoxylans. Enzyme-treated cooked noodles showed changes in textural characteristics, depended on the enzyme type, water amount, and drying method. Applying α-amylase for reducing the water absorption capacity of flour could mitigate the issue of inferior dry-noodle-making performance. Sensory evaluation showed improved preference attributes of cooked noodles with α-amylase treatment. In conclusion, the α-amylase application could improve the quality of dry-noodle made of Korean domestic wheat flour by diminishing the undesirable effect of damaged starch in flour related to noodle quality.

Effect of biscuits formulated with high-amylose maize flour on satiety-related sensations and food intake

The amount of amylose within a food may elicit lower glycemic and insulin postprandial responses and thus potentially modulate the satiating effect. In this context, the effect of biscuits formulated with high amylose starch (HAS) flour on satiety-related sensations and food intake was studied. Three types of biscuits were produced: control biscuit (CRT, 0% of HAS), Amy-25 (25% HAS), and Amy-50 (50% HAS). Fifteen healthy volunteers were enrolled to conduct two in vivo experiments. In experiment 1, volunteers consumed biscuits ad libitum and their sensations of satiety and food intake were evaluated. In experiment 2, volunteers received a quantity of biscuits equivalent to the 20% of the daily estimated energy requirements, and both satiety-related sensations and food intake were checked at subsequent meal. The Amy-50 significantly reduced food intake at subsequent meal (p ˂ 0.05), compared to Amy-25 and CRT. The satiety-related sensations were not significantly affected in both experiments, excepted for intra-meal hunger variation induced by Amy-25 which resulted significantly higher (p ˂ 0.05) than Amy-50 and CRT. These findings support the need to reformulate carbohydrate rich foods commonly consumed in a dietary context, to provide consumers healthier alternatives to prevent and tackle obesity and related chronic diseases.

Influence of protein type, content and polymerization on in vitro starch digestibility of sorghum noodles

The impacts of protein type, content and polymerization on in vitro starch digestibility of cooked sorghum noodles were investigated. Results showed that addition of exogenous proteins decreased the starch hydrolysis rate. The noodles added wheat protein (WP) exhibited the highest amount of resistant starch, followed by whey protein isolate (WPI) and egg white protein (EWP). In each group, the hydrolysis kinetic parameters were the lowest when protein addition amounts were 5% WP, 3% EWP and 3% WPI, respectively. These changes were ascribed to the interactions of starch-proteins and protein-proteins, as proved by the enhancement of protein polymerization and starch short-range structure. The increase of protein polymerization degree induced by disulfide cross-links reduced the starch digestion rate of noodles. Additionally, the confocal laser scanning microscope observations demonstrated that the strengthening of protein network had a positive effect on decreasing starch digestibility by preventing the accessibility of enzymes to starch.