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1.
Food Chem ; 305: 125436, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514047

RESUMO

The physicochemical properties of wheat bran have an effect on its technofunctional and nutritional profile. The possibility to induce physicochemical modifications in wheat bran using microfluidisation was investigated. An I-optimal experimental design was used to investigate the effect of microfluidisation processing parameters (pressure, number of passes, bran concentration and initial particle size) on important properties of wheat bran (particle size, microstructure, chemical composition, water retention capacity (WRC), extractability, viscosity and sedimentation). With the parameters used in this study, microfluidisation reduced wheat bran median particle size to 14.8 µm and disintegrated starch granules from the attached endosperm. This coincided with an increased extractability of starch and arabinoxylan. While the initial particle size was of minor importance, a higher pressure, larger number of passes and lower bran concentration during microfluidisation resulted in a smaller particle size, higher WRC and extractability, and an increased viscosity and stability in a 2% wheat bran suspension.

2.
J Agric Food Chem ; 64(44): 8324-8332, 2016 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-27734675

RESUMO

To obtain detailed knowledge on possible changes in the properties of starch, proteins, and arabinoxylan as a result of field preharvest sprouting (PHS), three wheat varieties were harvested at maturity and several weeks later when severe PHS had occurred. Falling number values of flour dropped from 306 to 147 s (Sahara), 382 to 155 s (Forum), and 371 to 230 s (Tobak). Blocking of α-amylase activity demonstrated that the decline in falling number and changes in RVA pasting and gelation properties were not caused by changes in intrinsic starch properties as a result of PHS. PHS had no influence on the SDS-extractability and molecular weight distribution of the proteins. For arabinoxylan, incipient breakdown was noticed, leading to a higher amount and average degree of polymerization of water extractable arabinoxylan. Results show that strategies to cope with severely PHS in wheat should focus on blocking enzyme activities.


Assuntos
Farinha , Proteínas de Plantas/análise , Triticum/química , Xilanos/metabolismo , Agricultura/métodos , Carboidratos/análise , Farinha/análise , Análise de Alimentos/métodos , Qualidade dos Alimentos , Germinação , Peso Molecular , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Amido/análise , Amido/química , Triticum/fisiologia , alfa-Amilases/química , alfa-Amilases/metabolismo
3.
J Agric Food Chem ; 64(28): 5644-52, 2016 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-27341479

RESUMO

To date, research on preharvest sprouted (PHS) wheat has mostly been conducted on kernels germinated under laboratory conditions, which differ widely from conditions in the field. To obtain detailed knowledge of the evolution of hydrolytic enzyme activities in PHS wheat (Triticum aestivum), a broad collection of samples from three varieties was obtained by harvesting before, at, and after maturity. Delaying harvest time coupled with periods of heavy rainfall caused sprouting in the kernels, observed as a drop in Falling Number and an increase in α-amylase activity. The appearance of α- and ß-amylase, peptidase, and endoxylanase activity during field sprouting was independent from each other. Consequently, Falling Number could not be used to predict activity of other hydrolytic enzymes. When differentiating endogenous from kernel-associated microbial enzymes, results showed that α- and ß-amylase and peptidase activity of PHS kernels were predominantly of endogenous origin, whereas endoxylanase activity was largely from microbial origin.


Assuntos
Proteínas de Plantas/metabolismo , Sementes/enzimologia , Triticum/crescimento & desenvolvimento , Endo-1,4-beta-Xilanases/análise , Endo-1,4-beta-Xilanases/metabolismo , Germinação , Peptídeo Hidrolases/análise , Peptídeo Hidrolases/metabolismo , Proteínas de Plantas/análise , Sementes/química , Sementes/crescimento & desenvolvimento , Triticum/química , Triticum/enzimologia , alfa-Amilases/análise , alfa-Amilases/metabolismo , beta-Amilase/análise , beta-Amilase/metabolismo
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