Effects of Combined α-Amylase and Endo-Xylanase Treatments on the Properties of Fresh and Frozen Doughs and Final Breads

Investigation of in situ and ex situ mode of lactic acid bacteria incorporation and the effect on dough extensibility, bread texture and flavor quality during shelf-life

Lactococcus lactis subsp. diacetylactis, Lactobacillus delbrueckii subsp. bulgaricus, and Lb. rhamnosus were evaluated for their efficiencies in preserving bread texture and flavor during shelf-life. The investigated LABs exhibited efficiency during preliminary screening in expressing selected enzymes (protease, xylanase, α-amylase, laccase, and glucose oxidase) and producing exopolysaccharide (EPS). Dough samples were supplemented with either sourdough starters containing live LAB cells or LAB cell lysates. Prolonged fermentation further enhanced the protective advantage of sourdough starter incorporation. During the 5-day shelf-life period, in situ enrichment with Lb. rhamnosus led to a mere 12.5-35.4 % hardness change and 13.8-20.7 % overall texture change. Furthermore, sourdough bread with live LAB cell supplementation displayed a more diverse and intense flavor profile, with high concentration of bread key odorants maintained during shelf-life, including 2,3-butanedione, 2-acetyl-1-pyrroline, and 3-methylbutanal. Meanwhile, no significant improvement was found in bread enriched with LAB cell lysates during shelf-life.

Frozen dough steamed products: Deterioration mechanism, processing technology, and improvement strategies

Fresh dough products lead to instability in product quality, high production costs, and more production time, which seriously affects the industrial production of the food industry. The frozen dough technology mitigates the problems of short shelf-life and easy deterioration of quality during storage and transportation. It has shown a series of advantages in large-scale industrialization, high-quality standardization, and chain operation. However, the further development of frozen dough is restricted by the deterioration of the main components (gluten, starch, and yeast) caused by freezing. This review summarizes the main production process of frozen steamed bread and buns, and the deterioration reasons for the main component of frozen dough. The improvement mechanisms of raw ingredients, processing technology, processing equipment, and additives on frozen dough quality were analyzed from the perspective of improving gluten network integrity and yeast freeze tolerance. From prefermented frozen raw to steamed products without thawing has become the preferred production process to improve production efficiency. Wheat flour mixed with other flour can maintain the gluten network continuity of frozen dough. The freeze tolerance of yeast was improved by treatment with yeast suspension, yeast cell encapsulation, screening hybridization, and genetic engineering. Process optimization and new technology-assisted fermentation and freezing effectively reduce freezing damage. Various additives improve the freeze resistance of the gluten-starch matrix by promoting protein cross-linking and inhibiting water migration. In addition, ice structural proteins and ice nucleating agents have been proven to change the growth morphology and formation temperature of ice crystals. More new technologies and additive synergies need to be further explored.

Recent advances in enzymatic modification techniques to improve the quality of flour-based fried foods

Flour-based fried foods are among the most commonly consumed foods worldwide. However, the sensory attributes and nutritional value of fried foods are inconsistent and unstable. Therefore, the creation of fried foods with desirable sensory attributes and good nutritional value remains a major challenge for the development of the fried food industry. The quality of flour-based fried foods can sometimes be improved by physical methods and the addition of chemical modifiers. However, enzyme modification is widely accepted by consumers due to its unique advantages of specificity, mild processing conditions and high safety. Therefore, it is important to elucidate the effects of enzyme treatments on the sensory attributes (color, flavor and texture), oil absorption and digestibility of flour-based fried foods. This paper reviews recent research progress in utilizing enzyme modification to improve the quality of flour-based fried foods. This paper begins with the effects of common enzymes on the physicochemical properties (rheological property, retrogradation property and specific volume) of dough. Based on the analysis of the mechanism of formation of sensory attributes and nutritional properties, it focuses on the application of amylase, protease, transglutaminase, and lipase in the regulation of sensory attributes and nutritional properties of flour-based fried foods.

Effects of maltogenic α-amylase on physicochemical properties and edible quality of rice cake

Maltogenic α-amylase (MA) are commercially used in the baking industry to retard starch retrogradation. However, whether MA can be used to modify rice flour during the fermentation process to improve the quality of rice flour remains unclear. In this study, MA was introduced during rice cake (RC) processing, and the modification effect and underlying mechanism were explored. Mn showed a decreasing trend except for 4.0 × 10-3 U/g sample. Chain length distribution data showed that MA effectively hydrolyzed long chains in amylopectin and increased the concentration of amylopectin chain length with a degree of polymerization of ≤ 9. High-performance liquid chromatography results suggested that the maltose content increased to 3.14% at an MA concentration of 9.5 × 10-3 U/g, which affected the fermentation effect of MA-treated RC. MA effectively reduced the viscosity of RC, and the gelatinization enthalpy of RC changed to 0.835 mJ/mg. MA also reduced the hardness and chewiness of RC after storage for 7 d. Moreover, rapidly digestible starch and slowly digestible starch contents of MA-treated RC decreased and increased, respectively, and resistant starch contents were remained unchanged. These results indicate that MA exerts a significant and effective antiretrogradation effect on RC. Combining the above results with sensory evaluation findings, an MA concentration of 4.0 × 10-3 U/g was the best supplemental concentration for obtaining RC with better edible quality. These findings suggest that MA treatment to rice flour during the fermentation process not only preserved the edible quality of RC but also retarded its retrogradation, thus, providing a novel processing method for the industrial production of RC.

A combined use of different functional additives for improvement of wheat flour quality for bread making

BACKGROUND

Low-protein wheat flour can produce bread with poor texture and appearance, reducing its nutritional value and market appeal. This is a growing concern for both the food industry and consumers relying on wheat as a dietary staple. The present study evaluated the individual and combined effects of bacterial xylanase (BX), maltogenic α-amylase (MG), vital gluten (VG) and ascorbic acid (AA) with respect to improving weak flour properties for bread making.

RESULTS

BX, VG and AA improved gluten Index (GI), whereas MG was employed for optimizing amylolytic-activity in flour. VG increased the water absorption (WA) capacity of flour and prolonged dough development time (DDT). The dough stability (DST) was increased by BX and VG. BX and MG decreased crumb firmness (CF) and showed anti-staling effect. All additives reduced bake loss, increased loaf volume (LV) and retained or improved sensory attributes of bread. However, MG at 60 mg kg-1 (MG60), BX at 30 mg kg-1 (BX30), VG at 5% (VG5) and AA at 50 mg kg-1 (AA50) were found to be the most suitable for evaluating in combinations. Ternary combinations of MG60, BX30, VG5 or AA50 imparted significantly (P < 0.05) positive impacts on GI, WA, DDT, DST, CF, LV and sensory attributes compared to control, individual and binary combinations.

CONCLUSION

The PCA suggested that a combination of MG60 + VG5 was more similar to MG60 + BX30 + VG5, whereas, MG60 + BX30 and MG60 + AA50 were more related to MG60 + BX30 + AA50 combination, but all of these combinations showed the improvement in the characteristics compared to control flour. © 2023 Society of Chemical Industry.

From Waste to Taste: Application of Fermented Spent Rootlet Ingredients in a Bread System

The process of upcycling and incorporating food by-products into food systems as functional ingredients has become a central focus of research. Barley rootlets (BR) are a by-product of the malting and brewing industries that can be valorised using lactic acid bacteria fermentation. This research investigates the effects of the inclusion of unfermented (BR-UnF), heat-sterilised (BR-Ster), and five fermented BR ingredients (using Weissella cibaria MG1 (BR-MG1), Leuconostoc citreum TR116 (BR-TR116), Lactiplantibacillus plantarum FST1.7 (BR-FST1.7), Lactobacillus amylovorus FST2.11 (BR-FST2.11), and Limosilactobacillus reuteri R29 (BR-R29) in bread. The antifungal compounds in BR ingredients and the impact of BR on dough rheology, gluten development, and dough mixing properties were analysed. Additionally, their effects on the techno-functional characteristics, in vitro starch digestibility, and sensory quality of bread were determined. BR-UnF showed dough viscoelastic properties and bread quality comparable to the baker's flour (BF). BR-MG1 inclusion ameliorated bread specific volume and reduced crumb hardness. Breads containing BR-TR116 had comparable bread quality to BF, while the inclusion of BR-R29 substantially slowed microbial spoilage. Formulations containing BR-FST2.11 and BR-FST1.7 significantly reduced the amounts of sugar released from breads during a simulated digestion and resulted in a sourdough-like flavour profile. This study highlights how BR fermentation can be tailored to achieve desired bread characteristics.

Assessment of properties of gluten-based edible film formulated with beeswax and DATEM for hamburger bread coating

Using edible films and coatings is one of the effective methods of improving the quality of bread. The aim of the present work was the development of gluten-based films containing lipids to be applied as bread coating, intending to improve quality and delay staleness. In this study, two types of lipids including beeswax and DATEM (diacetyl tartaric ester monoglycerides) were incorporated into gluten film at different levels. The findings showed that inserting both lipids together into gluten for film preparation, weakened the developed films in terms of mechanical and moisture barrier properties. Adding DATEM to the gluten film formulae decreased the elongation at the break and the tensile strength of the film. Using gluten-beeswax coatings for hamburger bread, compared to gluten-DATEM coatings, indicated a significant decrease in the hardness and staling feature. Moreover, applying sorbate as a preservative along with the solvents used in the film preparation prevented the growth of mold during the bread shelf life. In conclusion, the findings in this study indicated that the type and levels of lipids added to the edible gluten-based films and coatings affected the film properties and coated hamburger bread quality, significantly.

Effect of Xylanase and Pentosanase Enzymes on Dough Rheological Properties and Quality of Baguette Bread

The wheat flour baguette bread is one of the most important foods throughout the world. Therefore, improving the quality of this type of white bread has always been of interest. In this study, the effect of xylanase and pentosanase enzymes on the rheological properties of dough and baguette bread characteristics was investigated. Adding xylanase and/or pentosanase had led to improve rheological properties of the dough. Using 0.2 gr pentosanase in 100 g flour significantly strengthened the gluten network of the dough. Also, this treatment had the lowest extensibility and the highest resistance ratio number. The treatment containing 0.6 g xylanase and 0.1 g pentosanase in 100 g flour had a higher moisture content on the first, third, and fifth days of storage time. Regarding the color of the crust of the produced bread, it was found that the addition of both enzymes at higher levels, especially in enzyme mixtures, decreased the brightness of the bread crust. Due to the organoleptic features of breads, adding xylanase and pentosanase enzymes could improve the volume and crumb texture of the bread, but no significant difference was observed in baking uniformity, physical shape, taste, and odor of bread crumbs. In conclusion, the findings in this study indicated that the type of enzymes added and enzyme levels affected dough rheology, bread properties, and quality of the baguette bread significantly.

A review on mechanistic aspects of individual versus combined uses of enzymes as clean label-friendly dough conditioners in breads

Numerous dough improvers are used alone or in combination to enhance the quality of baked goods such as breads. While modern consumers demand consistent quality, the expectations for ingredients have changed over the past few years, and reformulations have taken place to provide "clean label" options. However, the effects and mechanisms of blended dough conditioners suitable for such baked products have not been systematically summarized. In this review, dough and bread properties as affected by different improver combinations are examined, with a focus on additive or synergistic interactions between enzymes or between enzymes and ascorbic acid. The combination of enzymes that hydrolyze starch and cell wall polysaccharides has been shown to reduce textural hardness in fresh and stored bakes goods such as breads. Enzymes that hydrolyze arabinoxylans, the main nonstarch polysaccharide in wheat, have synergistic effects with enzymes that result in cross-linking of wheat flour biopolymers. In some studies, the effects of bread improvers varied for wheat flours of different strength. Overall, bread products in which wheat is used in whole grain form or in a blend with other flours especially benefit from multiple improvers that target different flour constituents in doughs.

Conversion of Wheat Bran to Xylanases and Dye Adsorbent by Streptomyces thermocarboxydus

Agro-byproducts can be utilized as effective and low-cost nutrient sources for microbial fermentation to produce a variety of usable products. In this study, wheat bran powder (WBP) was found to be the most effective carbon source for xylanase production by Streptomyces thermocarboxydus TKU045. The optimal media for xylanase production was 2% (w/v) WBP, 1.50% (w/v) KNO₃, 0.05% (w/v) MgSO₄, and 0.10% (w/v) K₂HPO₄, and the optimal culture conditions were 50 mL (in a 250 mL-volume Erlenmeyer flask), initial pH 9.0, 37 °C, 125 rpm, and 48 h. Accordingly, the highest xylanase activity was 6.393 ± 0.130 U/mL, 6.9-fold higher than that from un-optimized conditions. S. thermocarboxydus TKU045 secreted at least four xylanases with the molecular weights of >180, 36, 29, and 27 kDa when cultured on the WBP-containing medium. The enzyme cocktail produced by S. thermocarboxydus TKU045 was optimally active over a broad range of temperature and pH (40–70 °C and pH 5–8, respectively) and could hydrolyze birchwood xylan to produce xylobiose as the major product. The obtained xylose oligosaccharide (XOS) were investigated for 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and the growth effect of lactic acid bacteria. Finally, the solid waste from the WBP fermentation using S. thermocarboxydus TKU045 revealed the high adsorption of Congo red, Red 7, and Methyl blue. Thus, S. thermocarboxydus TKU045 could be a potential strain to utilize wheat bran to produce xylanases for XOS preparation and dye adsorbent.