The Antioxidant Potential of Various Wheat Crusts Correlates with AGE Content Independently of Acrylamide.

Epidemiological studies have indicated that the consumption of whole-grain products is associated with a reduced risk of cardiovascular diseases, type II diabetes, and cancer. In the case of bread, high amounts of antioxidants and advanced glycation end products (AGEs) are formed during baking by the Maillard reaction in the bread crust; however, the formation of potentially harmful compounds such as acrylamide also occurs. This study investigated the antioxidant responses of different soluble extracts from whole-grain wheat bread crust extracts (WBCEs) in the context of the asparagine, AGE, and acrylamide content. For that, we analyzed nine bread wheat cultivars grown at three different locations in Germany (Hohenheim, Eckartsweier, and Oberer Lindenhof). We determined the asparagine content in the flour of the 27 wheat cultivars and the acrylamide content in the crust, and measured the antioxidant potential using the induced expression of the antioxidant genes GCLM and HMOX1 in HeLa cells. Our study uncovered, for the first time, that the wheat crust's antioxidant potential correlates with the AGE content, but not with the acrylamide content. Mass spectrometric analyses of WBCEs for identifying AGE-modified proteins relevant to the antioxidant potential were unsuccessful. However, we did identify the wheat cultivars with a high antioxidant potential while forming less acrylamide, such as Glaucus and Lear. Our findings indicate that the security of BCEs with antioxidative and cardioprotective potential can be improved by choosing the right wheat variety.

Rye Bread Crust as an Inducer of Antioxidant Genes and Suppressor of NF-κB Pathway In Vivo.

Heat-processed food, like bread, containing high amounts of advanced glycation end products (AGEs), is controversially discussed regarding the effects on health and disease. In in vitro and in vivo experiments, AGEs can induce proinflammatory NF-κB and/or the anti-inflammatory NRF2 pathways. The aim of this study was to investigate how gene expression is influenced in vivo upon short as well as long-term feeding of mice with control and bread crust-food (BC). For that, the liver, kidney and heart from two days- and eight days-fed mice were isolated and gene arrays were performed. Fewer genes were affected in terms of expression after two days of BC feeding than after eight days. We observed, especially in the heart and to lesser extent in the liver, an induction of antioxidant response by BC. Among the significantly up-regulated genes identified in the heart were transcripts encoding for cardioprotective and antioxidative proteins like metallothionein 2, uncoupling protein 3 and pyruvate dehydrogenase kinase 4. In contrast, in the liver, genes encoding for inflammatory drivers like thioredoxin-interacting protein, lncRNA Mtss1 and ubiquitin-specific protease 2 were down-modulated. However, an increased expression of immunoglobulins was observed in the kidney. Furthermore, in vivo imaging analyses with NF-κB-luciferase-reporter mice uncovered a rather anti-inflammatory response, especially after three and seven days of the feeding study. Our results suggest that bread crust exerts antioxidant and anti-inflammatory effects in the model organism mouse in an organ-specific manner.

AGE-Rich Bread Crust Extract Boosts Oxidative Stress Interception via Stimulation of the NRF2 Pathway.

Advanced glycation end products (AGEs) result from a non-enzymatic reaction of proteins with reactive carbohydrates. Heat-processed food, such as bread, contains high amounts of AGEs. The activation of the NF-κB signaling pathway by bread crust extract (BCE) is well understood. However, it is largely unknown whether NRF2, the master regulator of oxidative stress resistance in mammalian cells, is affected by BCE. We have investigated the molecular mechanisms by which BCE induces antioxidant gene expression in cellular models. Our data showed that soluble extracts from bread crust are capable of stimulating the NRF2 signaling pathway. Furthermore, NRF2 pathway activation was confirmed by microarray and reporter-cell analyses. QRT-PCR measurements and Western blot analyses indicated an induction of antioxidative genes such as HMOX1, GCLM and NQO1 upon BCE treatment. Moreover, BCE pretreated cells had a survival advantage compared to control cells when exposed to oxidative stress. BCE induces phosphorylation of AKT and ERK kinase in EA.hy926 cells. By mass spectrometry, several new, potentially active modifications in BCE were identified. Our findings indicate that BCE activates NRF2-dependent antioxidant gene expression, thus provoking a protection mechanism against oxidative stress-mediated tissue injury. Hence, BCE can be considered as functional food with antioxidative and cardioprotective potential.

A fluorescence biosensor based on single-stranded DNA and carbon quantum dots for acrylamide detection.

As a potential carcinogen produced in food thermal processing, acrylamide (AM) can cause irreversible harm to human health. For the detection of AM in food products, a simple fluorescent biosensor based on single-stranded DNA (ssDNA) and carbon quantum dots (CQDs) was developed. Reduced fluorescence intensity of CQDs at 445 nm (excitation at 350 nm) was induced by the attachment of ssDNA. In the presence of AM, ssDNA was preferentially bound to AM by hydrogen bonding and the degree of fluorescence reduction was smaller than that without AM. Under optimized conditions, results showed that the sensing approach for detecting AM had a low detection limit of 2.41 × 10-8 M in the standard solution, and a linear relationship ranging from 5 × 10-3 to 1 × 10-7 M with the determination coefficient (R2) of 0.9895 was obtained. Furthermore, a good recovery percentage (91.36-98.11%) in bread crust showed the potential for practical applications of this proposed biosensor.

Mathematical modeling of weight loss and crust temperature of toast bread containing guar gum during baking process.

Baking is a combined process in which several interconnected chemical, biochemical, and physical phenomena such as starch gelatinization and formation of porous structures occur. These changes affect the ultimate quality of the product such as taste. In this study, effects of guar gum (at 1% level) and baking temperature (at 190, 200, 210, 220, and 230°C) on crust temperature and weight loss of toast bread samples during 40 min exposure were investigated. According to the results, raising the oven's temperature from 190°C to 230°C will rise the crust's temperature of toast bread samples both in the control group (from 128.5°C to 190.2°C) and test group (from 120.18°C to 164.8°C), as well as the percentage of weight loss in toast bread samples both in the control group (from 35.11% to 47.23%) and test group (from 20.37% to 29.57%). We also worked with polynomial functions, exponential functions, fractional functions, Gaussian functions, and MATLAB to model the percentage of weight loss and an increase in the crust temperature of toast bread samples during the baking process. And ultimately, the correlation coefficients of the models were calculated and compared to analyze the results of predictor functions.

Efficient Analysis of 2-Acetyl-1-pyrroline in Foods Using a Novel Derivatization Strategy and LC-MS/MS.

2-Acetyl-1-pyrroline (2-AP) is a key odorant in many foods, such as aromatic rice and wheat bread, with a very low odor threshold of 0.05 µg/L in water. The small molecule with a popcornlike, roasty odor is generated biologically or by Strecker degradation within the Maillard-reaction cascades during thermal food processing with methylglyoxal and 1-pyrroline as the main direct precursors. Numerous gas-chromatographic methods for the analysis of 2-AP have been published, but the reactivity of the compound leads to discrimination or degradation during sample workup. We developed a novel derivatization method for 2-AP with o-phenylenediamine followed by HPLC-MS/MS analysis of the resulting stable quinoxaline. The precision (7%), repeatability (14%), recovery (92%), linearity (0.79-500 µg/kg), limit of detection (LOD, 0.26 µg/kg), and limit of quantitation (LOQ, 0.79 µg/kg) were validated for rice matrix and were excellent as compared with those of methods published before. With the novel method, 2-AP levels in typical foods like aromatic rice (131 µg/kg), wheat bread (18 µg/kg), brown bread (18 µg/kg), rye bread (18 µg/kg), and popcorn (38 µg/kg) were determined.

Interactions of coffee and bread crust melanoidins with hydroxycinnamic and hydroxybenzoic acids in aqueous radical environment.

The interactions of coffee and bread crust melanoidins with hydroxycinnamic and hydroxybenzoic acids (HCA/HBA) containing different numbers of -OH and -OCH3 groups localized at different positions on the aromatic ring were investigated. By doing so, mechanism of the interactions was intended to be explained with a structural approach. Experimental studies were carried out in DPPH radical medium. Chemometric methods were used for experimental design and multivariate data analysis. Area under the curve (AUC) values calculated from the plots of time versus inhibition (%) for coffee and bread crust melanoidins and HCA/HBA derivatives were ranged between 6532 ±â€¯97-19,106 ±â€¯85, 3997 ±â€¯102-7565 ±â€¯159 and - 1678 ±â€¯81-22,486 ±â€¯119, respectively. Synergistic interactions were revealed for both coffee and bread crust melanoidins and HCA/HBA derivatives. The significance of the concentrations of coffee and bread crust melanoidins on radical scavenging activity was clearly centered from the scores plots obtained via Principal component analysis (PCA). Phases of radical scavenging reactions were also revealed from the loadings plots.

Analysis of volatile compounds in gluten-free bread crusts with an optimised and validated SPME-GC/QTOF methodology.

The aroma of bread crust, as one of the first characteristics perceived, is essential for bread acceptance. However, gluten-free bread crusts exhibit weak aroma. A SPME-GC/QTOF methodology was optimised with PCA and RSM and validated for the quantification of 44 volatile compounds in bread crust, extracting 0.75 g of crust at 60 °C for 51 min. LODs ranged between 3.60 and 1760 µg Kg-1, all the R2 were higher than 0.99 and %RSD for precision and %Er for accuracy were lower than 9% and 12%, respectively. A commercial wheat bread crust was quantified, and furfural was the most abundant compound. Bread crusts of wheat starch and of japonica rice, basmati rice and teff flours were also quantified. Teff flour and wheat starch crusts were very suitable for improving gluten-free bread crust aroma, due to their similar content in 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3(2H)-furanone compared to wheat flour crust and also for their high content in pyrazines.

Reduction of acrylamide content in bread crust by starch coating.

BACKGROUND: A technique of starch coating to reduce acrylamide content in bread crust was proposed. Bread was prepared in accordance with a conventional procedure and corn or potato starch coating was brushed on the surface of the fermented dough prior to baking. RESULTS: Corn starch coating caused a decrease in acrylamide of 66.7% and 77.1% for the outer and inner crust, respectively. The decrease caused by the potato starch coating was 68.4% and 77.4%, respectively. Starch coating reduced asparagine content significantly (43.4-82.9%; P < 0.01)in both the outer and inner crust. A lower temperature (difference of 10-20 °C) in combination with a higher moisture content (maximum difference of 8%) of bread crust were a result of starch coating, which effectively shortened the time span (4-8 min) over which acrylamide could form and accumulate. CONCLUSION: The present study demonstrates that starch coating could be a simple, effective and practical application for reducing acrylamide levels in bread crust without changing the texture and crust color of bread. © 2017 Society of Chemical Industry.

Evaluation of the Availability and Antioxidant Capacity of Maillard Compounds Present in Bread Crust: Studies in Caco-2 Cells.

Bread crust is one of the major contributors to the intake of Maillard reaction products (MRP). MRP improve the organoleptic properties of foods and can provide biological actions such as antioxidant properties. The transport and availability of Amadori compounds (measured as furosine) and hydroxymethylfurfural (HMF)-early and intermediary MRP-from enzymatically digested bread crust (BC) and from its soluble low-molecular weight (LMW) and high-molecular weight (HMW) fractions were investigated in the Caco-2 cell line. The absorption of the early and final MRP pool was tested by measuring the absorbance recovery (280 and 420 nm). The ability of soluble BC or its fractions to lessen the production of reactive oxygen species (ROS) was examined. Amadori compounds (furosine) were transported across Caco-2 cell monolayers from the soluble BC in percentages ranging between 40% and 56%; the lower amount of the compound supplied, the higher transport rate. However, HMF transport rate (35%) was unaffected by the initial amount of the compound. Amadori compounds and HMF contained in the LMW fraction were more efficiently transported than those present in the HMW fraction, suggesting improved absorption when supplied as free forms or linked to LMW compounds. Absorbance recovery at 280 nm was higher from the LMW fraction, whereas higher recovery was detected for the HMW fraction at 420 nm. The digested BC-but not its isolated fractions-was able to significantly reduce ROS production at basal conditions and after subjecting cells to an oxidant. A clear positive action of BC on the antioxidant defence is manifested, seemingly attributable to the combined presence of soluble LMW and HMW products.