RESUMO

Research background: Controlled sprouting promotes physiological and biochemical changes in whole grains, improves their nutritional value and offers technological advantages for breadmaking as an alternative to traditional whole grains. The aim of this study is to find sprouting conditions for the grains of Klein Valor wheat variety (Triticum aestivum L.) that would increase the nutritional value without significantly affecting the gluten proteins, which are essential in wholegrain baked goods. Experimental approach: The chemical and nutritional composition, enzymatic activity and pasting properties of the suspensions of unsprouted and sprouted whole-wheat flour were evaluated. Results and conclusions: This bioprocess allowed us to obtain sprouted whole-wheat flour with different degrees of modification in its chemical composition. Sprouting at 25 °C resulted in an observable increase in enzymatic activity and metabolic processes, particularly α-amylases, which significantly affect the starch matrix and the associated pasting properties. Additionally, there was a smaller but still notable effect on the structure of the cell walls and the protein matrix due to the activation of endoxylanases and proteases. In contrast, sprouting at 15 and 20 °C for 24 h allowed for better process control as it resulted in nutritional improvements such as a higher content of free amino acid groups, free phenolic compounds and antioxidant capacity, as well as a lower content of phytates. In addition, it provided techno-functional advantages due to the moderate activation of α-amylase and xylanase. A moderate decrease in peak viscosity of sprouted whole-wheat flour suspensions was observed compared to the control flour, while protein degradation was not significantly prolonged. Novelty and scientific contribution: Sprouted whole-wheat flour obtained under milder sprouting conditions with moderate enzymatic activity could be a promising and interesting ingredient for wholegrain baked goods with improved nutritional values and techno-functional properties. This approach could avoid the use of conventional flour improvers and thus have a positive impact on consumer acceptance and enable the labelling of the product with a clean label.

RESUMO

The debranning process, at an industrial scale, was applied to grains of two wheat cultivars to determine its effect on Fusarium mycotoxin content and antioxidant activity. Grain samples from the BRS Marcante and BRS Reponte wheat cultivars, naturally contaminated by Fusarium, were used in the study. The dry wheat samples were processed on the polisher once or twice and evaluated by hardness index, chemical composition (moisture, protein, and ash), deoxynivalenol (DON) and zearalenone (ZON) levels, phenolic content, and antioxidant activity. In the BRS Marcante cultivar, the debranning process only slightly reduced the DON and ZON contents in whole-wheat flours compared with the previous cleaning treatment (no-debranned). In the BRS Reponte cultivar, the DON concentration decreased by 36% at a debranning ratio of 5%, obtained by polishing, compared with prior cleaning treatment (no-debranned). In addition, the polishing reduced the ZON level by 56% compared with the cleaned wheat. The debranning process did not reduce the antioxidant capacity. Therefore, debranning is a suitable technology to obtain safer and healthier food by minimizing the mycotoxin content and retaining antioxidant capacity.

Assuntos

RESUMO

The aims of this work were to assess the influence of the physicochemical composition of whole flour from soft and hard wheat genotypes on cookie and bread properties, as well as the ability of the prediction tests to estimate the whole meal flour end-use. Flours from hard and soft wheat genotypes proved to have different chemical composition and particle size distribution. Flours from hard wheat had lower particle average size and dietary fiber content, and higher lipid and wet gluten contents than flours from soft wheat. Particle size distribution, water absorption capacity and chemical composition of whole flours strongly influenced bread and cookie making performance. Considering prediction tests, flours from different wheat types were successfully discriminated using SDS-SI, SRC lac, and GI. However, rather weak correlations were found between the prediction test and the cookie and bread quality parameters. The prediction test, standardized for refined flours, showed a poor performance when whole flours were used. Nevertheless, grain texture and whole flour physicochemical properties did affect bread and cookie quality parameters, thus classical prediction tests should be modified in order to estimate the end-use performance of whole flours. Moreover, a standardization of the milling process should be considered.

RESUMO

Suitable conditions of temperature and humidity are required to maintain wheat grains quality, but during processing and storage, the grains can be exposed to adverse environmental conditions and presence of infectious fungi. Fusarium graminearum, the main causal agent of Fusarium head blight on wheat, affects crop yields and grain quality by alteration of their biochemical components and mycotoxin contamination, which reduces the possibilities of wheat end use and compromises food safety. Lipid degradation by hydrolytic, oxidative and microbial deterioration is the predominant cause of the loss of sensory acceptability, nutritional value and baking quality. The aim of this research was to determine the influence of adverse environmental conditions -as the increasing moisture - on lipid patterns of whole wheat flours contaminated with F. graminearum in relation to the infection degree. In vitro cultures of F. graminearum were carried out on wheat grains under different degrees of relative humidity (11, 50, 75 and 100%) throughout 45 days of incubation at 28 °C. The fungal biomass measured by q-PCR increased proportionally with the humidity. A decrease in the signals of saturated (palmitic and estearic) and unsaturated (oleic, linoleic and linolenic) fatty acids, analyzed as fatty acid methyl esters (FAMEs) by GC-MS, was observed in relation with the humidity and infection degree. The degradation rate of the lipids was high during the first 15 days of incubation, reaching the fatty acids content, values around 20-40% of those found in the control. From that moment on, the rate of degradation was slower or even null. It was observed that in all treatments, the linolenic acid reached the highest degradation ratio in comparison with the other fatty acids, which may be caused by the action of lipoxygenases. The lipase activity and the content of deoxynivalenol were also determinate on the flours. The lipase activity increased until day 25 of incubation reaching twice the initial value. The deoxynivalenol content also increased along incubation while fatty acids decreased. Our results demonstrated that the magnitude in the signal of fatty acids in whole wheat flours varied in relation to the degree of humidity and fungal infection of the grains from which they were obtained. Otherwise, lipids and their oxidation products are related with the pathogenesis and production of mycotoxins. These observations highlight the importance of an adequate manipulation of wheat grains on the processing chain to prevent quality changes and mycotoxins contamination.

Assuntos

RESUMO

BACKGROUND: Endo-1,4-ß-xylanases have marked hydrolytic activity towards arabinoxylans. Xylanases (xynA) produced by the anaerobic fungus Orpinomyces sp. strain PC-2 have been shown to be superior in specific activity, which strongly suggests their applicability in the bakery industry for the processing of whole-wheat flour containing xylans. In the present study, two xylanases from this source, the small wild-type xylanase SWT and the small mutant xylanase SM2 (V108A, A199T), were expressed in Escherichia coli, purified, characterized, tested for their ability to hydrolyze whole-wheat flour and applied in dough processing. RESULTS: Both purified SM2 and SWT showed high specific activity against oat spelt xylan and wheat arabinoxylan, exhibiting maximum activity at pH 3-7 and 60 °C. SM2 was more thermostable than SWT, which suggests that the mutations enhanced its stability. Both SWT and SM2 were able to hydrolyze whole-wheat flour, and evaluation of their applicability in dough processing by the sponge method indicated that use of these enzymes increased dough volume by 60% and reduced texture hardness by more than 50%, while gumminess and chewiness were reduced by 40%. CONCLUSION: The recombinant xylanases showed potential for application in bakery processing and can improve techno-functional properties in sponges. © 2018 Society of Chemical Industry.

Assuntos

RESUMO

This study aimed at investigating the effect of iron compounds used in whole wheat flour (WWF) fortification, both on rheological properties of the dough and on bread technological quality. Furthermore, bioaccessibility of iron (Fe), zinc (Zn) and calcium (Ca) in the final breads was determined. Rheological properties (mainly dough development time, stability, mixing tolerance index, resistance to extension and ratio number) of the dough and the technological quality of bread (mainly oven spring and cut opening) were altered. However, producing roll breads fortified with different iron compounds was still possible. NaFeEDTA (ferric sodium ethylene diamine tetra acetic acid) proved to be the most effective iron compound in the fortification of WWF, since it presented the highest levels of solubility (44.80%) and dialysability (46.14%), followed by microencapsulated ferrous fumarate (FFm). On the other hand, the microencapsulated ferrous sulfate (FSm) and reduced iron presented the lowest solubility (5.40 and 18.30%, respectively) and dialysability (33.12 and 31.79%, respectively). Zn dialysis was positively influenced by NaFeEDTA, FSm, and ferrous fumarate. As for Ca, dialysis was positively influenced by FSm and negatively influenced by FFm. The data indicated that there is a competitive interaction for the absorption of these minerals in whole wheat roll breads, but all studied minerals can be considered bioaccessible.

Assuntos