Maillard reaction products profile and intake from Spanish typical dishes

The Mediterranean diet is proposed as one of the healthiest dietary models, but its contribution to Maillard reaction products (MRP) intake is unknown. Several Spanish dishes typical of the Mediterranean diet (paella, Spanish omelette, salmorejo or churros) were selected to evaluate MR extension and the presence of MRP. CIELab colour, browning at different wavelengths, furosine, hydroxymethylfurfural, furfural and acrylamide were determined, and content/serving was calculated. Development of MR was affected by ingredients: when protein levels were high and carbohydrates low, early MRP were formed, regardless of the culinary process. There was found a correlation between acrylamide and hydroxymethylfurfural. The possible underestimation of deterministic calculations of acrylamide dietary exposure is discussed. This study presents a first approximation to enable the MRP intake from the Mediterranean diet to be calculated, taking into account the moisture content and the serving size of dishes.     

Maillard reaction indicators in diets usually consumed by adolescent population

Contents of some indicators of the Maillard reaction (MR) in two diets adjusted to the adolescent requirements are compared: the A-diet, usually consumed by the adolescent population containing their preferred foods cooked by the culinary techniques more frequently chosen; and the B-diet, with the same foods, except those industrially processed and with high content of Maillard reaction products (MRP), cooked in softer processes to minimise the MR. Aliquots of a lunch-dinner (LD) and breakfast-afternoon (BA) snack pools separately from both diets were ground and lyophilised. Fluorescence associated to MRP, CIELAB colour parameters, furosine, hydroxymethylfurfural (HMF), carboxymethyllysine (CML) and sugar contents were investigated in the samples. Significant losses of lightness were manifested in A samples compared to the B ones. Fluorescence intensity was significantly higher in the LD and BA samples from the A-diet. Furosine measured in the A-diet was similar to that found in the B-diet. However, HMF content was significantly higher in the A-diet, as well as CML. Data showed significant higher levels of advanced MRP in the usual diet. Thus, MRP intake associated to alimentary pattern in the adolescence population might be studied in order to assess the health implications of the MRP consumption and its possible synergic effect with endogenous advanced glycation endproducts.     

Usefulness of some Maillard reaction indicators for monitoring the heat damage of whey powder under conditions applicable to spray drying

The Maillard reaction (MR) rate was observed according to available lysine loss, furosine, hydroxymethylfurfural (HMF), furfural, and brown colour during the heating of freeze-dried nano-filtered whey at 60, 75, and 90 °C and water activities of 0.11, 0.33, 0.43, and 0.73. The physical state of lactose was measured and associated with MR rate. The values obtained for available lysine, furosine, HMF and browning index ranged between, respectively, 11.3 and 1.63 (g 100 g⁻¹ protein), 0.44 and 11.1 (g 100 g⁻¹ protein), not detected and 57.7 (mg 100 g⁻¹ protein) and 0.0104 and 0.1707. The greatest heat damage occurred with low moisture content and high temperature. The MR rate was influenced by the physical state of lactose, heating temperature and the moisture content of the whey. This occurred to a greater extent during the initial and intermediate stages of the MR as opposed to during the formation of coloured compounds.     

Effect of digestive process on Maillard reaction indexes and antioxidant properties of breakfast cereals

Extrusion, drying and toasting are the most representative manufacturing processes suffered by breakfast cereals, conjugating thermal/moisture conditions that allow the Maillard reaction (MR) and caramelisation development, as well as the destruction of thermally labile antioxidant compounds. However, other compounds – like Amadori products and hydroxymethylfurfural (HMF) – are originated from the MR and caramelisation, showing different biological activities, as the antioxidant activity. But breakfast cereals are ingested and then affected by the digestive process, and so that the aim of this work was to analyse the effects of the digestion on the bioaccessibility of certain MR products (Amadori compound and HMF) and on the antioxidant activity of corn-based breakfast cereals, using a standardized in vitro gastrointestinal digestion. After digestion approx. 90% HMF remained soluble, but in some cases HMF distribution between soluble/insoluble fractions was higher than the initial HMF measured in the raw cereal, suggesting a release of initially bound Amadori products and its conversion to HMF during the digestion process. The Amadori compound was uniformly distributed between both fractions. The antioxidant activity of the soluble fraction was always higher than that from the raw cereal in any of the antioxidant method employed; therefore the digestion increased the solubility of the antioxidant compounds.     

Study of hydroxymethylfurfural and furfural formation in cakes during baking in different ovens,using a validated multiple-stage extraction-based analytical method

A procedure for extraction of hydroxymethylfurfural (HMF) and furfural from cakes was validated. Higher yield was achieved by multiple step extraction with water/methanol (70/30) and clarification with Carrez I and II reagents. Oven type and baking time strongly influenced HMF, moisture and volatile profile of model cakes, whereas furfural content was not significantly affected. No correlation was found between these parameters. Baking time influenced moisture and HMF formation in cakes from traditional and microwave ovens but not in steam oven cakes. Significant moisture decrease and HMF increase (3.63, 9.32, and 41.9 mg kg⁻¹ dw at 20, 40 and 60 min, respectively) were observed during traditional baking. Cakes baked by microwave also presented a significant increase of HMF (up to 16.84 mg kg⁻¹ dw at 2.5 min). Steam oven cakes possessed the highest moisture content and no significant differences in HMF and furfural. This oven is likely to form low HMF and furfural, maintaining cake moisture and aroma compounds.     

Effect of storage conditions on furosine formation in milk–cereal based baby foods

The effect of storage during 9 months at 25, 30 and 37 °C on furosine formation in three milk–cereal based baby foods was studied to evaluate development of the Maillard reaction. Furosine was measured by HPLC-UV. Immediately after the manufacturing process, furosine contents were 310–340 mg/100 g protein and at the 9th storage month were 426–603 mg/100 g protein. Storage time and temperature have a significant increase (p < 0.05) of furosine content during storage. Furosine contents were higher in sample containing honey than in those without honey. Interactions (p < 0.05) between storage time and temperature or type of sample were found. A predictive model equation of the evolution of furosine during storage explaining 80% of the variability in furosine content was obtained. The blockage of lysine through storage calculated using the furosine and total lysine provided values ranged from 9.5% to 18.1% for analysed baby foods.     

Analysis of glycative products in sauces and sauce-treated foods

Content of Maillard reaction products (MRPs) such as pentosidine, carboxymethyllysine and furosine in soybean sauce, sour-sweet sauce, tomato sauce, barbecue sauce, and sauce-treated chicken, pork, beef, salmon and cod was analysed. In test sauces, MRP content was in the range of 10–692 μg/100 mL sample. MRP content in raw, boiled, fried and baked foods was in the range of 10–76 μg/100 g sample. Boiling, frying and baking caused significantly higher MRP levels in test foods (P < 0.05). MRP levels in soybean sauce, sour-sweet sauce and barbecue sauce-treated foods were in the range of 1094–2424, 1494–3146 and 1400–2926 μg/100 g sample. The interactions of sauce, heating and frying oil markedly enhanced the formation of MRPs in sauce-treated foods. Because MRPs are glycative products; thus, patients with glycation associated diseases may consider limiting the dietary use of these sauces.     

Does the pelleting process affect the nutritive value of a pre‐starter diet for suckling piglets? Ex vivo studies on mineral absorption

BACKGROUND: The effects of pelleting on the extent of the Maillard reaction (MR) and on calcium, magnesium and zinc solubility and absorption were analysed in a conventional pre‐starter diet for suckling piglets. Development was tested measuring colour, absorbance (280/420 nm), fluorescence, residual free lysine, furosine, hydroxymethylfurfural (HMF) and furfural contents before and after pelleting. Fluorescence, absorbance and mineral solubility were also measured after in vitro digestion of diets. The effects on mineral absorption were tested using Caco‐2 cells. RESULTS: MR indexes confirmed the development of the reaction during the pelleting of this particular diet compared with the meal diet. The CIE‐Lab colour parameters showed a decrease in luminosity (L*) and progress of the colour to the red zone (a*) in the pelleted diet. A 36% decrease in free lysine content was observed. Significant correlations were observed between fluorescence intensity and furosine levels, HMF and furfural. The pelleting process did not modify calcium and magnesium solubility after in vitro digestion, but soluble zinc increased. The efficiency of calcium and zinc transport across Caco‐2 cell monolayers was greater in the pelleted diet. CONCLUSIONS: Evidence of MR development is shown, resulting in various nutritional consequences. Optimisation of pelleting could result in a better formulation of diets for feedstuffs. Copyright © 2010 Society of Chemical Industry     

Study on fluorescence of Maillard reaction compounds in breakfast cereals

During the advanced stage of the Maillard reaction (MR) in food processing and cooking, Amadori rearrangement products undergo dehydration and fission and fluorescent substances are formed. Free and total (free + linked to the protein backbone) fluorescence (FIC) due to Maillard compounds in 60 commercial breakfast cereals was evaluated. Pronase was used for efficient release of linked fluorescent Maillard compounds from the protein backbone. Results were correlated with some heat-induced markers of the extent of the MR or sugar caramelisation during cereal processing, such as hydroxymethylfurfural, furfural, glucosilisomaltol and furosine. The effect of sample composition (dietary-fibre added, protein, etc.) on levels of FIC, expressed as fluorescence intensity (FI) per milligram of sample, is discussed. FIC is significantly correlated to the protein content of the sample and fluorescent Maillard compounds are mainly linked to the protein backbone. The ratio of total-FIC to free-FIC was 10.4-fold for corn-based, wheat-based and multicereal-based breakfast cereals but significantly higher in rice-based samples. Addition of dietary fibre or honey increased the FIC values. Data support the usefulness of FIC measurement as an unspecific heat-induced marker in breakfast cereals.     

Occurrence of furosine and hydroxymethylfurfural as markers of thermal damage in dehydrated vegetables

The presence of furosine and hydroxymethylfurfural (HMF) as markers of thermal damage in commercial dehydrated vegetables has been studied. Furosine was measured in all the analysed samples whereas HMF was detected only in garlic, onion, and tomato groups and some other individual vegetables. Furosine, as indicator of the first steps of the Maillard reaction, ranged from 1.12 to 923 mg/100 g protein (depending on the vegetable species and thermal treatment applied) and was well correlated with the browning development in not severely heat-treated samples. In addition, the results seem to indicate that reducing sugars play an important role in the formation of furosine in some vegetable species but not HMF at the conditions used for the dehydration process. The findings of this study show the usefulness of furosine as a quality indicator for sensitive control of the dehydration process in vegetables.     

Indirect competitive ELISA based on monoclonal antibody for the detection of 5-hydroxymethyl-2-furfural in milk,compared with HPLC

In this study, a method for rapid detection of 5-hydroxymethyl-2-furfural (HMF) was investigated. Monoclonal antibody (anti-HMF) was prepared and evaluated by an indirect competitive ELISA (ic-ELISA) format. The optimized standard curve was y = -0.2097 x + 1.0432 [where x is the logarithm (base 10) of the values of the HMF concentration and y is the absorbance of ic-ELISA results tested at 490 nm] and the linear detection range was 0.008 to 32.768 mg/L. The percentage of cross-reactivity of HMF with 5 major furfural derivatives was less than 2.92%. Finally, the established ic-ELISA format was used to test HMF in milk, and compared with the result obtained by HPLC, which produced an error of about 0.3%. Based on the data in this experiment, we concluded that the established ic-ELISA format was reliable with a high specificity.     

A comparison study between antioxidant and mutagenic properties of cysteine glucose-derived Maillard reaction products and neoformed products from heated cysteine and hydroxymethylfurfural

It was previously reported that Maillard reaction products (MRP) obtained from glucose with cysteine (1 M/0.25 M) mixtures and compounds generated during the mixing of heated cysteine with HMF solutions (Mix) were prone to inactivate various vegetal polyphenoloxidases (PPO). In this study, antioxidant properties of these model systems were compared using in vitro assays (AAPH°, DPPH° and TMM tests). Results showed that antioxidant activity observed in MRP and the Mix could be attributed to the sulfhydryl group of cysteine. The Mix behaved like a non-competitive inhibitor towards eggplant PPO (K_i = 0.7 μM). A highly active fraction, devoid of thiol compound and HMF, was obtained after fractionation of the Mix by SPE. The Mix was as efficient as metabisulfite in preventing enzymatic browning of apple puree (CIE-La^∗b^∗). MRP, the Mix and HMF could not be considered as mutagenic in the Salmonella microsome assay using Salmonella typhimurium TA98 and 102 strains.     

焦糖化与美拉德反应中DDMP、HMF及糠醛的生成研究

食品热加工中广泛存在的美拉德反应除赋予食品色香味外,还会生成有害或有异味物质,2,3-二氢-3,5-二羟基-6-甲基-4(H)-吡喃-4-酮（DDMP）、5-羟甲基糠醛（5-hydroxymethylfurfural,HMF）及糠醛就是其中重要的产物。本文分别建立了3种焦糖化和3种美拉德反应体系,研究DDMP、HMF和糠醛的生成规律。结果表明,HMF和糠醛分别容易在果糖和木糖焦糖化体系中生成,在美拉德反应体系中,赖氨酸的参与抑制了HMF和糠醛生成,促进了DDMP的生成。结合中间产物和终末产物的表征,单糖的结构差异是影响三种化合物生成的主要因素,赖氨酸会竞争性抑制单糖降解的焦糖化途径,从而抑制HMF和糠醛的生成。本文可对食品热加工业中DDMP、HMF和糠醛的生成、控制及定向合成提供指导。     

Effect of toasting time on the browning of sliced bread

Slices of wheat bread were toasted for different times until a distinct intensity of brown colour was reached. Two assays were carried out: prolonged toasting times (5–60 min) and reduced toasting times (0.5–5 min). The browning indicators (furosine, available lysine, hydroxymethylfurfural (HMF), colour and absorbance at 284 and 420 nm) were determined. The precision of all indicators used was high (CV < 4%). No furosine or HMF was detected in the dough before baking. The furosine content increased until 7 min (299 mg per 100 g protein) and then decreased to 2.9 mg per 100 g protein at 60 minutes. For the first toasting times (0.5, 1 and 2 min) the furosine content decreased slightly. Available lysine reached losses of 50% after 25 min of heating. The toasting of bread increased HMF values from 12 to 2025 mg kg^?1 for the assay at prolonged times of heating and from 1.3 to 4.2 mg kg^?1 at reduced times (0.5–5 min). The HMF content decreased (1000 mg kg^?1) when the sliced bread was toasted until it burnt. Colour (ΔE, 100 ? L*) and absorbance at 284 and 420 nm always increased. High linear correlations (r² > 0.860) were obtained between browning indicators and time (A₂₈₄/time, A₄₂₀/time, 100 ? L*/time and HMF/time). © 2001 Society of Chemical Industry     

Inhibition of polyphenoloxidase activity by mixtures of heated cysteine derivatives with carbonyl compounds

It had previously been shown that soluble Maillard reaction products (MRP) made from thiol compounds and glucose or fructose contained powerful inhibitors of various fruit and vegetable polyphenoloxidase (PPO) activity. In MRP from cysteine and glucose, the amount of hydroxymethylfurfural (HMF) formed increased with the increase in glucose concentration (0-1 M), particularly under acidic (pH 2) conditions. Using model mixtures containing a preheated cysteine-derived compound and a carbonyl component, especially HMF, furfural and benzaldehyde, we showed that the neoformed compounds produced exhibited a stronger inhibitory potency toward PPO activity of eggplant, apple, and mushroom than former MRP. Optimal reaction conditions for the formation of inhibitory compounds when HMF reacted with preheated cysteine were investigated. It was found that a reactants molar ratio of 1:1 and a reaction time exceeding 1 h were the most efficient reaction conditions to generate inhibitory compounds. The stability of the newly formed products, evaluated during storage, showed that their inhibitory potency was globally kept at 4, 21, and 37 degrees C for 72 h but was unstable when stored at -20 degrees C and lost when exposed to UV radiations for 24 h.     

Contribution to the characterisation of honey-based Sardinian product abbamele: Volatile aroma composition,honey marker compounds and antioxidant activity

Sardinian abbamele is a typical product obtained from the honey recuperation from combs (traditional procedure) or by concentration of the honey diluted in water (industrial procedure). Seven abbamele samples were obtained to study the volatiles’ composition, the presence of honey marker compounds and their relationship with the production procedures. The long thermal treatment applied in abbamele production caused very high (1007.0–4405.8 mg/kg) HMF content (HPLC-DAD), while glucose and fructose amounts were quite similar to the honey ones (HPLC-RI). Total antioxidant activity (FRAP assay) of the samples ranged between 13.3 and 71.2 mmol Fe²⁺/kg, while antiradical activity (DPPH assay) ranged between 3.8 and 23.3 mmol TEAC/kg. Such high antioxidant values were linearly correlated with total phenol amount (1297.8–4469.5 mg GAE/kg) determined by Folin–Ciocalteau method. Thermally derived furan derivatives and terpenes were abundant among the headspace volatiles (HS-SPME), particularly limonene (0.5–76.0%) that probably originated from citrus rinds’ addition during abbamele production. GC and GC–MS analyses of USE isolates revealed HMF predominance as well as the honey marker compounds (if/when existing) such as methyl syringate (up to 49.2%), marker of Asphodelus microcarpus honey. High isophorone percentage (up to 30.9%) determined by HS-SPME followed by minor percentage of 4-ketoisophorone and norisoprenoids in one sample indicated Arbutus unedo L. honey use in the production. HPLC-DAD analysis confirmed the presence of specific honey markers: two samples showed high methyl syringate concentrations (150.4–120.1 mg/kg) while homogentisic acid and other specific markers of A. unedo honey were found in one sample. The compared GC–MS and HPLC-DAD data proved to be useful to obtain information about the use of specific honey in the production and to verify citrus addition.     

Combined use of HMF and furosine to assess fresh honey quality

BACKGROUND: The quality of honey can be affected by practices such as adulteration, inadequate storage or the application of severe heat treatments. Because hydroxymehylfurfural (HMF) is an indicator of honey freshness and furosine (ε‐2‐furoylmethyl lysine) has proved to be a useful chemical indicator of the progress of the Maillard reaction in foods, the aim of this work was to assess their usefulness as indicators of fresh honey quality. The effect of heat treatment, storage and adulteration with different types of syrups on HMF and furosine content has been studied. RESULTS: In fresh honey, HMF and furosine values ranged from 0.9 to 14.6 mg kg^?1 of product and from 3.06 to 12.06 g kg^?1 of protein, respectively. Heating of honey samples with different pH (3.76 and 5.14) produced slight increases in HMF content and negligible changes were detected in furosine values. The storage of fresh honey for 2 years caused a high increase in the HMF level, reaching values above EU limits. However, furosine showed a different behavior depending on the type of honey sample. Adulteration assays using different syrups produced an increase in HMF and a decrease of furosine values by dilution effect. HMF content of adulterated honey samples with syrup of known origin did not exceed EU limits. CONCLUSION: These results show the influence of long periods of storage or adulteration, using different percentages of corn or invert sugar syrups, on HMF and furosine content of fresh honey. This seems to indicate that the combination of HMF and furosine may be useful for evaluating the quality of fresh honey. Copyright © 2009 Society of Chemical Industry     

Studies on the formation of furosine and pyridosine during acid hydrolysis of different Amadori products of lysine

The behavior of different lysine Amadori compounds during acid hydrolysis was investigated in order to determine the molar yield of furosine and the other hydrolysis products. Based on this, the conversion factors for calculating the content of Amadori compound and lysine modification before hydrolysis can be derived. For that purpose, the peptide-bound Amadori compounds N^k-(1-deoxy-D-fructosyl)-, N^k-(1-deoxy-D-tagatosyl)-, N^k-(1-deoxy-D-lactulosyl)- and N^k-(1-deoxy-D-maltulosyl)hippuryllysine as well as free N^k-(1-deoxy-D-fructosyl)lysine were synthesized. For isolation of peptide-bound Amadori compounds, an optimized enzyme-enhanced reversed phase-high pressure liquid chromatography procedure was developed. Pyridosine and N^k-(carboxymethyl)hippuryllysine were synthesized as reference materials. After acid hydrolysis with 6 M hydrochloric acid the, molar yields of furosine were determined to be 32% for fructosyllysine, 34% for lactulosyl- and maltulosyllysine and 42% for tagatosyllysine. Hydrolysis with 8 M hydrochloric acid resulted in a higher yield of furosine for Amadori compounds containing a fructosyl-moiety, 46% for fructosyllysine, 50% for lactulosyllysine and 51% for maltulosyllysine. Compared with this, the molar yield for furosine was not affected by concentration of hydrochloric acid in the case of tagatosyllysine. Based on these conversion factors a reliable calculation of the amount of Amadori compound or lysine modification and with it the evaluation of the progress of the "early" Maillard reaction in foods and biological samples is possible via the quantification of lysine and furosine after acid hydrolysis.     

Forty years of furosine - forty years of using Maillard reaction products as indicators of the nutritional quality of foods

The Maillard reaction products (MRPs) most widely used as markers of the nutritional quality of foods are furosine, N(epsilon)-carboxymethyllysine (CML), hydroxymethylfurfural, pyrraline, pentosidine and pronyl-lysine. One of the MRPs identified first was furosine, which was quantified in foods 40 years ago as a chemical indicator of the Amadori compound N(epsilon)-fructoselysine. Since then, furosine has gained broad attention by food chemists and biomedical researchers, as its formation upon heat treatment is well characterised. Moreover, it represents the Amadori products from early Maillard reactions in which amino acids react with reducing carbohydrates, resulting in a loss of their availability. This is of importance for the essential amino acid lysine, which is also the limiting amino acid in many proteins. In order to evaluate the nutritional quality of a protein, the concomitant analysis of free - and nutritionally available - lysine and the amount of lysine reacted to form the respective MRP is essential, even for mildly processed foods. The other chemical markers of heat treatment such as CML, pyrraline, pentosidine or pronyl-lysine seem to be useful markers of the advanced stages of Maillard reactions. Compared to the conditions in which furosine is formed, these compounds are generated under more severe conditions of heat treatment. However, the concentrations analysed are significantly lower than those of furosine. Therefore, the nutritional evaluation of a food protein should include not only furosine, but also other chemical markers of heat treatment such as, for example, CML, pyrraline and pentosidine.     

The potential of biodetoxification activity as a probiotic property of Lactobacillus reuteri

Previous work on the metabolism of Lactobacillus reuteri ATCC 55730 anticipated a variability in the use of organic electron acceptors as a means to relieve metabolic redox problems. Therefore, investigations focusing on this unique metabolism of L. reuteri may reveal a basis for new probiotic properties. For instance, L. reuteri may use reactive aldehydes and ketones as electron acceptors to balance their redox metabolism, which opens the possibility to exploit this bacterium for in vivo bioreduction of deleterious compounds in the gastrointestinal tract (GIT). Herein we demonstrate that L. reuteri ATCC 55730 cultures on glucose are able to use furfural (1 g/L), and hydroxymethylfurfural (HMF) (0.5 g/L), as electron acceptors. The former enhances the growth rate by about 25% and biomass yield by 15%, whereas the latter is inhibitory. Furfural is stoichiometrically reduced to furfuryl alcohol by the culture. The conversion of furfural had no effect on the flux distribution between the simultaneously operating phosphoketolase and Embden-Meyerhof pathways, but initiated a flux to acetate production. In addition to furfural and HMF, cellular extracts showed potential to reoxidize NADH and/or NADPH with acrolein, crotonaldehyde, and diacetyl, indicating that conversion reactions take place intracellularly, however, utilization mechanisms for the latter compounds may not be present in this strain. The strain did not reduce other GIT-related reactive compounds, including acrylamide, glyoxal, and furan.