Wheat flours samples

For the application of indirect calibration methods, one should have several samples available with known constitution. These samples should be of exactly the same type as the unknown sample. For example for the determination of the fat, water and protein content in wheat by near infrared reflectance spectrometry, one should have available a number of wheat flour samples of which the amount of fat, water and protein is known, or determined by a conventional method. 

The target sequence for the buckwheat was clearly detected in the 0.001 to 100% mixed samples when we tested the mixed wheat flour samples containing 0, 0.0001, 0.001, 0.005, 0.01, 0.1, 1, and 100% of the buckwheat flour powder. This evidence suggests that buckwheat flour contamination as low as 0.001% can be detected in an unprocessed food. 

One important remaining question to be discussed in relation to sample preparation of HR MAS NMR is the choice of solvent and exposure time to the solvent. We found that especially mature dry seeds tend to absorb the added deuterated water (D2O) and exchange it with internal water (H2O). The result of this process is a poorer shimming and in turn increasingly lower quality spectra over time. In order to evaluate if another solvent with advantage could be used to replace D2O, wheat flour samples were measured using deuterated DMSO with h HR MAS NMR (Figure 4). DMSO was chosen, since most... 

Figure 4 HR MAS NMR spectra of mature wheat flour samples (Shamrock) soaked in either DMSO or D2O at spinning rate 7000 Hz. Spectra were measured at t = 25°C and normalised to similar noise level.

LAB were obtained from durum wheat flour samples and screened for roseoflavin-resistant variants to isolate natural riboflavin-overproducing strains (Capozzi et al. 2011). Two riboflavin-overproducing strains of Lact. plantarum were used for the preparation of bread (by means of sourdough fermentation) and pasta (using a prefermentation step) to enhance their vitamin B content. The applied approach resulted in a considerable increase of vitamin B content (about 2- and... 

Fe in duplicate diet samples ETAAS NIST SRM 1567, Wheat flour Van Cauwenbergh et al. 1997... 

System or sample Whole blood Wheat flour... 

Bread Sample Preparation. The recipes for making white bread consisted of wheat flour (regular, 1 kg), water (520 ml), baker s yeast (25 g), improver mix (24 g), salt (20 g) and soya flour (0 or 30 g). For studying the shelf-life of soya containing improver mixtures (20 C, 80 % rH) an improver paste with 0.5 % and an improver powder with 2.5 % soya flour were used in the recipe without further soya flour addition. 

For measuring water absorption by the excess water method, the techniques developed by Janicki and Walczak (described by Hamm, 21) for meats and by Sosulski (22) for wheat flour are modified. Lin et al. (17) modified the Sosulski technique for use with sunflower and soy meal products. This modified procedure has been employed for much of the research on water absorption of plant protein additives. Water absorption capacities of a soy flour, two soy concentrates, and two soy isolates were compared by Lin et al. (17) to those of a sunflower flour, three sunflower concentrates, and one sunflower isolate. The percent water absorption of the soy products increased as the total protein content of the samples increased from flour to isolate. The soy flour absorbed 130% water, the soy concentrates absorbed an average of 212% water, and the soy isolates absorbed an average of 432% water. No calculations were made, however, that related the percent water absorbed to protein content of the samples. The sunflower products, though similar in protein content, did not respond in the same magnitude or direction as the soy products. 

Figure 1. A typical sequence of sample preparation manipulations for a procedure of Soxhlet extraction followed by preparative column chromatography for a solid sample - e.g., glycolipids out of wheat flour. Note that equivalently complex processes are encountered with "simple liquid-solid or liquid-liquid extractions followed by a series of back extractions - e.g., pesticides from fish tissue. (Reproduced with permission by Hewlett-Packard, HP Publication (43)5091-2102E, (1991), in preparation.)...

Comparative study of amino acid composition of commercial samples of a high-protein and a low protein and a low-protein wheat flour. Contribs. Boyce Thompson Inst., 18, 477 (1957). With R. H. Mandl. 

In one word, a possibly low in vitro extraction efficiency does not necessarily go together with low Se bioavailability. The powdered basic samples of Se speciation (Se-enriched yeast, Allium ssp., wheat flour, etc.) - albeit they are food materials or food supplements - are far less complex than real foodstuffs. At the same time, they facilitate sample preparation and the assessment of Se supply from prepared food materials through the analysis of some raw food materials. 

Figure 5. Cumulative MWDs of the high protein wheat flour control and an extruded sample (G39).

Oyster tissue, milk powder, wheat flour (total) Digestion of sample with HN03 and heat in closed container in microwave over reduction with SnCI2 and TBP purging of mercury to gold-coated sand absorber to preconcentrate desorption to detector CVAAS 0.84 ng/g 93-111 Vermeir et al. 1989... 

Wheat flour, citrus leaves, pine needles (total) Digestion of sample using K2Cr207 and H2S04 heating and dilution CVAAS 6 ng/g 91-108 Landi et al. 1990... 

A 0.7121 g sample of a wheat flour was analyzed by the Kjeldahl method. The ammonia formed by addition of concentrated base after digestion with H2SO4 was distilled into 25.00 mL of 0.04977 M HCl. The excess HCl was then back-titrated with 3.97 mL of 0.04012 M NaOH. Calculate the percent protein in the flour. 

The dietary fiber content of various Norwegian wheat flours (9) with different extraction rates were analyzed. To analyze the dietary fiber content we used a gravimetric method, based on digestion of the samples with pepsin and pancreatin. The method is a modification of the procedure described by Hellendorn et al. and modified by Asp et al (10). The pepsin digestion was carried out at pH 1.5 for 1 hr, and the pancreatin digestion at pH 6.8 for 1 hr. 

Analytical approach to more reliable quantification of Se in biological materials. Results showed that SeMet was the main Se species in both matrices (59% of total Se for wheat flour and of 68% for yeast). Inorganic Se was detected in yeast samples, but not in wheat flour... 

---