Effects of controlled germination on selected physicochemical and functional properties of whole-wheat flour and enhanced γ-aminobutyric acid accumulation by ultrasonication

Reduction of phytic acid, aflatoxins and other mycotoxins in wheat during germination

BACKGROUND

Wheat grains are susceptible to infection by various toxigenic fungal species that produce toxic metabolites called mycotoxins. This makes wheat one of the most important daily dietary sources of mycotoxins for consumers. As germination is popularly used to improve the nutritional quality of grains, the present study was carried out to understand its effect on the toxin content of wheat seeds. For this purpose, wheat grains were spiked with ochratoxin A (OTA; 5 μg kg^-1 ), aflatoxins B2 and G2 (5 μg kg^-1 ), zearalenone (ZEA; 20 μg kg^-1 ), aflatoxins B1 and G1 (20 μg kg^-1 ) and deoxynivalenol (DON; 50 μg kg^-1 ) in separate experiments. Thereafter, the grains were germinated and analyzed for toxin content during 14 days of germination using a high-performance liquid chromatography (HPLC) method.

RESULTS

ZEA content did not change significantly until 14 days. The maximum reductions of DON, OTA and aflatoxins at days 10-14 of germination were 39, 38, 41 (B1), 60 (B2), 33 (G1) and 62% (G2) respectively. A 63% reduction of phytic acid at 14 days was observed, according to Fe²⁺ bioavailability. For all toxins (except ZEA), there were no significant differences in reduction after day 10.

CONCLUSION

Germination for 10 days might be sufficient to achieve an appropriate decrease in toxin content. © 2019 Society of Chemical Industry.

Comparative Study on the Bread Making Quality of Normoxia- and Hypoxia-Germinated Wheat: Evolution of γ-Aminobutyric Acid, Starch Gelatinization, and Gluten Polymerization during Steamed Bread Making

To explore the bread making characteristics of germinated wheat flour, the current study focused on the componential evolution throughout the steamed bread making process. Hypoxia-germinated wheat (HGW) dough produced the maximum γ-aminobutyric acid as a result of high glutamic acid decarboxylase activity during fermentation compared to normoxia-germinated wheat (NGW) and sound wheat (SW). HGW was superior to NGW in terms of rheological properties and restored the organoleptic characteristics as SW bread. Blocking of α-amylase activity and protein polymerization demonstrated that the decline in pasting and gelation properties was not caused by changes in intrinsic starch and protein properties. Polymerization of α- and γ-gliadin to glutenin was facilitated in germinated wheat bread, while the cross-linking degree of glutenin-gliadin was suppressed. In comparison to NGW bread, more high-molecular-weight glutenin subunits but less α-gliadin fractions polymerized upon steaming of HGW dough. Results demonstrate that HGW has great potential to be exploited as a nutritious functional ingredient for wheat-based food.

Wheat bran stabilization and its effect on cookies quality

Wheat bran are widely used as a source of dietary fiber with enhanced health benefits. However, its hight application level in bakery products caused lower quality of these products (eg. reduced volume and increased hardness of product). Different mechanical, physical or chemical methods are used for modification of wheat bran physicochemical properties. Wheat bran obtained from two wheat variety was used to evaluate the effect of bran stabilization process on qualitative properties of baked goods. Stabilization was performed using hot air and microwave heating. Threated and unthreated wheat bran were blended with wheat flour at 5, 10 and 15% substitution level. Influence of bran addition on rheological properties was evaluated using Mixolab 2. Stabilized wheat bran increased water absorption up to 11.7% (hot air stabilization) and 11.9% (microwave stabilization), respectively. Hot air stabilization of wheat bran improved heat resistance of dough proteins during mixing and the stability of hot gel during heating. Stabilization process of wheat bran using both methods also increased the volume and spread ratio values of enriched cookies. Cookies incorporated with hot air treated bran were significantly softer than cookies contained raw bran. Sensory evaluation showed that addition of stabilized bran improved the shape and taste of cookies. Additionally, it was concluded that the most acceptable cookies were obtained at 5% addition level of bran stabilized using microwave heating.

Changes in Bread Quality, Antioxidant Activity, and Phenolic Acid Composition of Wheats During Early-Stage Germination

This study reported changes in baking properties, total phenolic content (TPC), antioxidant activity, and phenolic acid composition of three hard red winter wheat varieties during the early stage of seed germination. The wheats were sprouted at 30 °C and 95% relative humidity to achieve different germination levels based on falling number ranges (550 s for control flour; 350 s [low], 250 s [medium], and 120 s [high] for sprouted flours, respectively). Average germination times were 7, 8, and 10 hr for the low, medium, and high germinated samples, respectively. Most baking properties of sprouted whole flour were comparable to the control flour. However, TPC, flavonoid content, phenolic acids, and antioxidant activity of sprouted flour were lower than the control flour. To our knowledge, this is the first study that reported both baking properties and antioxidant potential of sprouted whole wheat flour from early-stage germination. The study deepens the understanding of seed germination and the potential use of sprouted flour in baking industry. PRACTICAL APPLICATION: This study evaluates the baking quality and nutraceutical value of sprouted whole wheat flour, which are key factors determining the application of sprouted flour in the baking industry. The results will contribute to the production of quality bakery products with enhanced nutraceutical benefits.

The compositional, physicochemical and functional properties of germinated mung bean flour and its addition on quality of wheat flour noodle

Despite sprouted grains have high nutritional and functional properties, their exploration in mung bean and application in traditional foods are limited. The effects of germination of mung bean for 12, 24, 36, 48, 60 and 72 h on compositional, physicochemical and functional properties of its flour were investigated. The effects of incorporation of germinated mung bean flour at different levels (0, 10, 20 and 30%) on noodles making properties of wheat flour were evaluated 0. The protein content increased while the amylose increased initially and then decreased with increase in germination time. Water absorption index, oil binding capacity and water retention capacity increased, while water soluble index initially increased and then decreased. The germinated mung bean flour became darker with increase in germination time. The protein bound to starch in noodlesed to increase in hardness, cohesiveness, gumminess, chewiness, resilience and cooking time of noodles. Additionally, the water absorption, cooking loss, adhesiveness and springiness of raw noodles and springiness, cohesiveness and chewiness of cooked noodles decreased with the addition of germinated flour.

Physicochemical properties of germinated dehulled rice flour and energy requirement in germination as affected by ultrasound treatment

Limited data are published regarding changes in the physicochemical properties of rice flours from germinated de-hulled rice treated by ultrasound. This work was undertaken to evaluate the effect of ultrasound treatment (25 kHz, 16 W/L, 5 min) on starch hydrolysis and functional properties of rice flours produced from ultrasound-treated red rice and brown rice germinated for up to 36 h. Environmental Scanning Electron Microscopy (ESEM) microimages showed that the ultrasound treatment altered the surface microstructure of rice, which helped to improve moisture transfer during steam-cooking. The flours from sonicated germinated de-hulled rice exhibited significantly (p < .05) enhanced starch hydrolysis, increased the glucose content, and decreased falling number values and viscosities determined by a Rapid Visco Analyzer. The amylase activity of the germinating red rice and brown rice displayed different sensitivity to ultrasonic treatment. The ultrasonic pre-treatment resulted in a significant reduction in energy use during germination with a potential to further reduce energy use in germinated rice cooking process. The present study indicated that ultrasound could be a low-power consumption method to modify the rheological behavior of germinated rice flour, as well as an efficient approach to improve the texture, flavor, and nutrient properties of steam-cooked germinated rice.