Effect of flour type on Maillard reaction and acrylamide formation during toasting of bread crisp model systems and mitigation strategies

The impact of raw materials and baking conditions on Maillard reaction products, thiamine, folate, phytic acid and minerals in white bread

The aim of this study was to develop a white bread with improved nutrient contents and reduced levels of potentially harmful Maillard reaction products such as N(ε)-carboxymethyllysine (CML) and 5-hydroxymethylfurfural (HMF). Assays were carried out through a full factorial experimental design allowing the simultaneous analysis of four factors at two levels: (1) wheat flour extraction rates (ash content: 0.60%-0.72%), (2) leavening agents (bakers' yeast - bakers' yeast and sourdough), (3) prebaking and (4) baking conditions (different sets of time and temperature). The baking conditions affected HMF and CML as well as certain mineral contents. A reduced baking temperature along with a prolonged heat treatment was found to be favourable for reducing both the CML (up to 20%) and HMF concentrations (up to 96%). The presence of sourdough decreased the formation of CML (up to 28%), and increased the apparent amounts of calcium (up to 8%) and manganese (up to 17.5%) probably through acidification of the dough. The extraction rate of flours as well as interactions between multiple factors also affected certain mineral content. However, compounds like folate, thiamine, copper, zinc, iron and phytic acid were not affected by any of the factors studied.

Protein Bread Fortification with Cumin and Caraway Seeds and By-Product Flour

Malnutrition continues to be a key health problem in developing regions. The valorization of food waste appears as an ideal way to prevent malnutrition and improve people’s access to food. Cumin (Cuminum cyminum L.) and caraway (Carum carvi L.) oilseeds are commonly used for cuisine and medicinal purposes. However, remaining cakes after oil extraction are usually underutilized. In order to assess the usefulness of these by-products in food applications, this study investigated the effect of their addition to protein bread formulations. Different levels (2, 4 and 6%) of whole seeds and cakes flour were used in the study. Fortified protein bread samples were compared to control protein bread and evaluated for their sensory, color, moisture, hardness properties, nutritional values as well as their biological activity. Results indicated that bread fortification shows a significant effect on bread properties depending on fortification level. A higher acceptability was observed specially for bread fortified with by-products flour. Increased tendencies of color darkness, moisture content, bread hardness, nutritional values as well as total phenolic content and radical scavenging activity compared to control bread were observed as the percentage of fortification increased in both cases. The overall results showed that the addition of cumin and caraway seeds and by-product flour can improve the antioxidant potential and overall quality of protein bread.

Reduction of acrylamide in whole-wheat bread by combining lactobacilli and yeast fermentation

This study mainly focuses on a strategy for reducing acrylamide content in whole-wheat bread by combining lactobacilli and yeast in sourdough breadmaking. Combinations of sourdough (fermented dough using different Lactobacillus strains including Lactobacillus plantarum PTCC 1896 [probiotic], L. sakei DSM 20,017, L. rhamnosus DSM 20,021, and L. delbrueckii DSM 20,081) and yeast, in comparison with yeast alone, were used for breadmaking. The results showed that acrylamide levels in breads fermented using sourdough+yeast were in all cases much lower (6.9-20 μg/kg on a dry weight basis [d.b.]) than those in the yeast-only fermented bread (47.6 μg/kg d.b.). Significant (p < 0.05) correlations were also found between pH, total titratable acids (TTA) and lactic acid, and acrylamide content. Furthermore, the obtained results showed that the moisture content of dough directly influenced the formation of acrylamide in bread (r = 0.925, p < 0.0001). In addition, no significant correlations were observed between acrylamide content in breads and either the reducing sugar or free amino acid contents in dough samples. According to the different effects of Lactobacillus strains, it could be concluded that the acrylamide reducing potential of lactobacilli was strain-specific, with L. rhamnosus being the most effective. This suggests that sourdough fermentation with appropriate Lactobacillus strains can be used as an advantageous technology to reduce the acrylamide content of whole-wheat breads.

Microwave thawing and green tea extract efficiency for the formation of acrylamide throughout the production process of chicken burgers and chicken nuggets

BACKGROUND

Initially, we measured the acrylamide (AA) levels of chicken burgers (CBs) and chicken nuggets (CNs) purchased from fast food restaurants. After the determination of AA in these products, we aimed to investigate whether the use of green tea extract in the covering material, and microwave thawing before frying, mitigated the formation of AA in CBs and CNs during the production process.

RESULTS

According to our study, AA concentrations of CBs and CNs purchased from fast food restaurants were in the range of 13.43-118.97 and 32.92-134.90 ng g^-1 coating, respectively. In our experiment, AA levels varied between 19.61 and 40.08 ng g^-1 coating for CBs and 7.92-49.60 ng g^-1 coating for CNs. Green tea extract reduced the AA formation in CBs and CNs at the pan frying and steam oven cooking heat treatment steps (P < 0.05). However, microwave thawing did not affect AA level of CBs and CNs.

CONCLUSION

When the AA levels of commercial CBs and CNs are compared with those produced in our experiment, the use of green tea extract could be a novel, easy and practical application for fast food producers to minimise AA levels in the first two steps of the production without changes to the sensory properties of the final products. © 2016 Society of Chemical Industry.

Acrylamide and 5-hydroxymethylfurfural formation during biscuit baking. Part II: Effect of the ratio of reducing sugars and asparagine

This study investigated acrylamide and 5-hydroxymethylfurfural (HMF) formation during biscuit baking. Four types of wheat flour with different molar ratios of total fructose and glucose to asparagine were investigated. Nevertheless, the molar ratio in all four biscuit doughs exceeded one after proofing due to enzyme action. Data obtained after baking were used to develop a mechanistic model, based on the asparagine-related pathway, for acrylamide and HMF formation in the four baked biscuit types. Asparagine reacted with fructose to form a Schiff base before decarboxylation to produce acrylamide without Amadori rearrangement product and sugar fragmentation. Fructose contributed considerably to acrylamide formation and to HMF formation via caramelization in all four biscuit types. No clear correlation was found between acrylamide and HMF in baked biscuits, nor between asparagine and the sum of glucose and fructose concentrations in the wheat flour.

Mitigation strategies of acrylamide, furans, heterocyclic amines and browning during the Maillard reaction in foods

The Maillard reaction (MR) occurs widely during food manufacture and storage, through controlled or uncontrolled pathways. Its consequences are ambiguous depending on the nature and processing of the food products. The MR is often used by food manufacturer to develop appealing aromas, colour or texture in food products (cereal based food, coffee, meat…). However, despite some positive aspects, the MR could decrease the nutritional value of food, generate potentially harmful compounds (e.g. acrylamide, furans, heterocyclic amines) or modify aroma or colour although it is not desired (milk, fruit juice). This paper presents a review of the different solutions available to control or moderate the MR in various food products from preventive to removal methods. A brief reminder of the role and influence of the MR on food quality and safety is also provided.

A Comparison Study of Frying Conditions on Furan Formation in 3 Potato Varieties

Furan, a typical food contaminant formed by heating process, is classified as a possible carcinogen to humans. Many factors lead to the formation of furan in food processing. In our present study, 3 potato varieties, white potato, sweet potato, and purple potato were selected to investigate the effect of thermal processing temperature and time on furan formation. The results showed that the formation of furan was highly correlated with frying temperature and time. Among the 3 potato varieties, sweet potato resulted in the highest furan concentration when fried at 200 °C for 5 min. In addition, the frying temperature and time also influenced the water activity and the color of the 3 kinds of potato slices, which had significant correlation with the formation of furan. Furan concentration decreased along with the increasing of water activity in the 3 potato varieties and the changes presented regression relationships. Meanwhile, there was an inverse correlation between furan content and color changes in the 3 potato varieties. The level of furan decreased as total color changes (ΔE) increased and the changes also presented regression relationships. These results could be used to estimate the possibility of furan formation in the 3 varieties of potato slices systems.

Evaluation of acrylamide-removing properties of two Lactobacillus strains under simulated gastrointestinal conditions using a dynamic system

The aim of this study was to evaluate the capability of Lactobacillus reuteri NRRL 14171 and Lactobacillus casei Shirota to remove dietary acrylamide (AA) under simulated gastrointestinal conditions using a dynamic system. The effects of different AA levels or bacteria concentration on toxin removal by Lactobacillus strains were assessed. Thereafter, AA-removing capability of bacteria strains under either fasting or postprandial simulated gastrointestinal conditions was evaluated. Commercial potato chips were analyzed for their AA content, and then used as a food model. Average AA content (34,162μg/kg) in potato chips exceeded by ca. 34-fold the indicative values recommended by the EU. Toxin removal ability was dependent on AA content and bacterial cell concentration. A reduction on bacterial viability was observed in the food model and at the end of both digestive processes evaluated. However, bacteria survived in enough concentrations to remove part of the toxin (32-73%). Both bacterial strains were able to remove AA under different simulated gastrointestinal conditions, being L. casei Shirota the most effective (ca. 70% removal). These findings confirmed the risk of potato chips as dietary AA exposure for consumers, and that strains of the genus Lactobacillus could be employed to reduce the bioavailability of dietary AA.

Acrylamide: inhibition of formation in processed food and mitigation of toxicity in cells, animals, and humans

Potentially toxic acrylamide is largely derived from the heat-inducing reactions between the amino group of the amino acid asparagine and carbonyl groups of glucose and fructose in plant-derived foods including cereals, coffees, almonds, olives, potatoes, and sweet potatoes. This review surveys and consolidates the following dietary aspects of acrylamide: distribution in food, exposure and consumption by diverse populations, reduction of the content in different food categories, and mitigation of adverse in vivo effects. Methods to reduce acrylamide levels include selecting commercial food with a low acrylamide content, selecting cereal and potato varieties with low levels of asparagine and reducing sugars, selecting processing conditions that minimize acrylamide formation, adding food-compatible compounds and plant extracts to food formulations before processing that inhibit acrylamide formation during processing of cereal products, coffees, teas, olives, almonds, and potato products, and reducing multiorgan toxicity (antifertility, carcinogenicity, neurotoxicity, teratogenicity). The herein described observations and recommendations are of scientific interest for food chemistry, pharmacology, and toxicology, but also have the potential to benefit nutrition, food safety, and human health.

The kinetics of the inhibition of acrylamide by glycine in potato model systems

BACKGROUND

Acrylamide (AA) is a potential carcinogen which widely exists in heat-processed foods. The addition of glycine (Gly) has been shown to reduce the formation of AA. The objective of this work was to investigate the kinetics of the inhibition of AA by Gly in both asparagine (Asn)/glucose (Glc) and Asn/Glc/Gly potato model systems during heating at 160 °C, 180 °C, and 200 °C.

RESULTS

The simplified two consecutive first-order kinetic model fitted well to the changes of AA in both systems. No significant difference in rate constant (kF) and apparent activation energy (EaF) was observed for AA formation between the two systems (P > 0.05). Whereas EaE and only kE at 200 °C for AA elimination in the Asn/Glc/Gly system was significantly higher than Asn/Glc system (P < 0.05). The elimination reaction between Gly and AA was confirmed by the identification of their major reaction product 2-((3-amino-3-oxopropyl)amino)acetic acid in the Asn/Glc/(15)  N-Gly system.

CONCLUSION

The reduction of AA by Gly is predominantly attributed to the elimination reaction between Gly and AA.

Influence of water biscuit processing and kernel puffing on the phenolic acid content and the antioxidant activity of einkorn and bread wheat

The whole meal flour of wheat is rich in phenolic acids, which provide a relevant antioxidant activity to food products. Aim of this research was to assess the influence of processing on phenolic acid content and antioxidant activity of whole meal flour water biscuits and puffed kernels of einkorn and bread wheat. To this end, the evolution of syringaldehyde, ferulic, vanillic, syringic, p-coumaric, p-hydroxybenzoic, and caffeic acids was studied during manufacturing. Overall, from flour to water biscuit, the total soluble conjugated phenolic acids increased slightly in einkorn, while the insoluble bound phenolic acids decreased in all the accessions as a consequence of losses during the mixing step. In the puffed kernels, instead, the total soluble conjugated phenolic acids increased markedly, while the bound phenolics did not show any clear change, evidencing their high thermal stability. The antioxidant activity, measured by FRAP and ABTS, increased during processing and was highest under the most drastic puffing conditions.

Characterization of the quality of novel rye-buckwheat ginger cakes by chemical markers and antioxidant capacity

The total phenolics and flavonoids, rutin, early, advanced and finalMaillard reaction products, and antioxidative capacity determined against 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) radical cation and superoxide anion radicals were used for the characterization of the quality of novel rye-buckwheat ginger cakes enriched with rutin (quercetin rutinoside). The cakes were prepared substituting 30 % of rye flour by light buckwheat flour or flour from roasted buckwheat dehulled grains and employing a dough fermentation-like incubation step. Enrichment of ginger cakes with rutin showed protective effect on lysine blockage, improved antioxidant properties, inhibited the formation of furosine and free fluorescent compounds thus stimulating the Maillard reaction progress towards melanoidin formation. The loss of the nutritional quality of cakes enriched with rutin was related to the formation of fluorescent compounds linked to protein and carboxymethyllysine at an advanced stage of the Maillard reaction. It can be concluded that free fluorescence intermediatory compounds, carboxymethyllysine and browning are the best chemical markers for the characterization of the quality of this novel type of ginger cakes. This study also indicates that rye-buckwheat ginger cakes enriched with rutin can be recommended for wider consumption since daily consumption of 250 g of these cakes may have a prophylactic or therapeutic effect corresponding to typical pharmacological drugs with rutin as the active component.

Acrylamide mitigation strategies: critical appraisal of the FoodDrinkEurope toolbox

Not all the strategies proposed in FoodDrinkEurope toolbox have equal value in terms of efficacy and cost/benefit ratio.

Investigations on the effect of antioxidant type and concentration and model system matrix on acrylamide formation in model Maillard reaction systems

The formation of acrylamide in model Maillard reaction systems containing phenolic compounds was examined, with regards to phenolic type, concentration, and model system matrix. In dry glyoxal/asparagine waxy maize starch (WMS) systems, 9 out of 10 examined phenolics demonstrated an inhibiting effect, with the most significant reductions (55-60%) observed for caffeoylquinic acids. In WMS glucose/asparagine systems, examination of three different concentrations (0.1, 0.5 and 1 μmol/g WMS) suggested a 'minimum effective concentration' for epicatechin and caffeic acid, whilst addition of caffeoylquinic acids resulted in dose-dependent acrylamide reduction (25-75%). The discordant results of further studies utilising different matrices (dry and wet-to-dry) indicated that, apart from the nature and chemical reactivity, the matrix and the physical state of the reactants might be important for acrylamide formation.

Effects of formulation, extrusion cooking conditions, and CO₂ injection on the formation of acrylamide in corn extrudates

BACKGROUND

Acrylamide is a possible carcinogen and known to form in heat-treated carbohydrate-rich foods. This study was designed to investigate the effects of different ingredients (reducing sugars, chemical leavening agents, citric acid), processing conditions (feed moisture content: 22, 24 or 26%, exit die temperature: 110, 150 °C), and extrusion cooking methods (with or without CO2 injection) on acrylamide formation.

RESULTS

The type of reducing sugar did not have a considerable effect on acrylamide formation, while increased exit die temperature had a promoting effect. Addition of chemical leavening agents (sodium bicarbonate and ammonium bicarbonate) into formulations increased acrylamide formation levels. The addition of citric acid prevented acrylamide formation, but its effect on textural properties was detrimental. Acrylamide levels of extrudates decreased gradually with increasing feed moisture in all formulations. Acrylamide content of extrudates produced with 22% feed moisture decreased by 61% in the CO2 injection method compared to conventional extrusion. Furthermore, an 82% decrease in acrylamide content was observed with the combined effect of CO2 injection and increasing feed moisture content from 22 to 24% and decreased below the limit of quantification with a further increase in feed moisture.

CONCLUSION

A substantial decrease in final acrylamide level is probably due to restriction of two major steps of acrylamide formation: dehydration and decarboxylation.

Effects of extrusion, infrared and microwave processing on Maillard reaction products and phenolic compounds in soybean

BACKGROUND

The Maillard reaction indicators furosine, hydroxymethylfurfural (HMF), acrylamide and color were determined to evaluate heat effects induced during extrusion, infrared and microwave heating of soybean. In addition, the present paper aimed to study changes in the phenolic compounds, as well as in the overall antioxidant properties of different soybean products in relation to heating at 45-140 °C during the processes.

RESULTS

Soybean proteins were highly sensible to Maillard reaction and furosine was rapidly formed under slight heating conditions during extrusion and infrared heating. Microwave heating at lower temperatures for a longer time yielded lower acrylamide levels in the final soybean products, as a result of its partial degradation. However, during infrared heating, acrylamide formation greatly increased with decreasing moisture content. After a short time of extrusion and infrared heating at 140 °C and microwave heating at 135 °C for 5 min, concentrations of HMF increased to 11.34, 26.21 and 34.97 µg g(-1), respectively.

CONCLUSION

The heating conditions caused formation of acrylamide, HMF and furosine in high concentration. The results indicate that the complex structure of soybeans provides protection of phenolic compounds from thermal degradation, and that Maillard reaction products improved the antioxidant properties of heat-treated soybean.

Current issues in dietary acrylamide: formation, mitigation and risk assessment

Acrylamide (AA) is known as a neurotoxin in humans and it is classified as a probable human carcinogen by the International Agency of Research on Cancer. AA is produced as by-product of the Maillard reaction in starchy foods processed at high temperatures (>120 °C). This review includes the investigation of AA precursors, mechanisms of AA formation and AA mitigation technologies in potato, cereal and coffee products. Additionally, most relevant issues of AA risk assessment are discussed. New technologies tested from laboratory to industrial scale face, as a major challenge, the reduction of AA content of browned food, while still maintaining its attractive organoleptic properties. Reducing sugars such as glucose and fructose are the major contributors to AA in potato-based products. On the other hand, the limiting substrate of AA formation in cereals and coffee is the free amino acid asparagine. For some products the addition of glycine or asparaginase reduces AA formation during baking. Since, for potatoes, the limiting substrate is reducing sugars, increases in sugar content in potatoes during storage then introduce some difficulties and potentially quite large variations in the AA content of the final product. Sugars in potatoes may be reduced by blanching. Levels of AA in different foods show large variations and no general upper limit is easily applicable, since some formation will always occur. Current policy is that practical measures should be taken voluntarily to reduce AA formation in vulnerable foods since AA is considered a health risk at the concentrations found in foods.

Toxic compounds in honey

There is a wealth of information about the nutritional and medicinal properties of honey. However, honey may contain compounds that may lead to toxicity. A compound not naturally present in honey, named 5-hydroxymethylfurfural (HMF), may be formed during the heating or preservation processes of honey. HMF has gained much interest, as it is commonly detected in honey samples, especially samples that have been stored for a long time. HMF is a compound that may be mutagenic, carcinogenic and cytotoxic. It has also been reported that honey can be contaminated with heavy metals such as lead, arsenic, mercury and cadmium. Honey produced from the nectar of Rhododendron ponticum contains alkaloids that can be poisonous to humans, while honey collected from Andromeda flowers contains grayanotoxins, which can cause paralysis of limbs in humans and eventually leads to death. In addition, Melicope ternata and Coriaria arborea from New Zealand produce toxic honey that can be fatal. There are reports that honey is not safe to be consumed when it is collected from Datura plants (from Mexico and Hungary), belladonna flowers and Hyoscamus niger plants (from Hungary), Serjania lethalis (from Brazil), Gelsemium sempervirens (from the American Southwest), Kalmia latifolia, Tripetalia paniculata and Ledum palustre. Although the symptoms of poisoning due to honey consumption may differ depending on the source of toxins, most common symptoms generally include dizziness, nausea, vomiting, convulsions, headache, palpitations or even death. It has been suggested that honey should not be considered a completely safe food.

Industrially applicable strategies for mitigating acrylamide, furan, and 5-hydroxymethylfurfural in food

Acrylamide and furanic compounds, such as furan and 5-hydroxymethylfurfural (HMF), are formed in a variety of heat-treated commercial foods. They are known to be toxic and, according to the International Agency for Research on Cancer, "possibly carcinogenic to humans". As this gave rise to concern, research was carried out to study their metabolism and toxicity and elucidate the mechanistic pathways of formation. So far, many papers have been published on acrylamide, furan, and HMF occurrence, precursors and mechanisms of formation, toxicity, and detection methods, as well as on possible routes to reduce their levels in food and, thus, consumer intake. This paper reviews the interventions suggested in the literature to mitigate the presence of acrylamide and furanic compounds in food. In particular, some technological measures potentially exploitable at the industrial level are discussed extensively. These are (i) preventive strategies based on the use of asparaginase and thermal input reduction (i.e., low temperature-long time dehydration; dielectric heating) and (ii) removal intervention by means of vacuum treatment, aimed to remove the already formed acrylamide and furanic compounds from the finished product.

Acrylamide and 5-hydroxymethylfurfural formation in reconstituted potato chips during frying

In our present paper, the effect of water activity and processing conditions in reconstituted potato chips was considered as a model to investigate the changes of acrylamide (AA) and 5-hydroxymethylfurfural (HMF). The results suggested that the formation of AA and HMF was highly correlated with frying temperature and time. Water activity could also influence the formation of AA and HMF. Meanwhile, the formation of HMF has significant correlation with the formation of AA in reconstituted potato chips. A typical exponential growth curve was observed by plotting AA levels vs HMF content which were all determined under different heating condition: [Formula: see text]. The model could be used as a tool for estimating the formation of AA when the content of HMF was known.

Okara promoted acrylamide and carboxymethyl-lysine formation in bakery products

Soybeans are widely used in bakery products because of their technological advantages and, recently, soybean-containing products have been marketed as functional foods thanks to several health benefits. Okara is a soybean-based ingredient obtained after elimination of the water-soluble component from ground soybeans. In this paper the effect of okara addition to bakery products on the formation of some potentially harmful Maillard reaction products was evaluated. Cookies obtained by replacing 15% of wheat flour with okara showed a visible browning increase and a more intense Maillard reaction development as shown by higher concentrations of 5-hydroxymethyl-2-furaldehyde (HMF) (+100%), acrylamide (+60%), and carboxymethyl-lysine (CML) (+400%) with respect to the control. This phenomenon could be related to the presence in okara of about 50% of insoluble dietary fiber: the fiber reduces water activity during cooking, thus promoting Maillard reaction. To confirm this hypothesis, cookies obtained by replacing 7% of wheat flour with three different types of dietary fiber (cellulose, chitosan, and pea fiber) were prepared: these experimental cookies showed higher Maillard reaction product concentration with respect to the control and, in particular, HMF and CML values were directly related to the fiber water-holding capacity (WHC). To extend the observation to the food market, a sampling of soybean-containing commercial bakery products was analyzed by comparing the concentrations of Maillard reaction products with those of similar bakery products without soy. Soybean-containing samples showed higher concentrations of acrylamide and CML than corresponding controls.