Modelling the effect of asparaginase in reducing acrylamide formation in biscuits

The influence of asparaginase on acrylamide formation, as well as colour development, in short dough biscuits was studied. In particular, asparaginase concentration, incubation time and temperature were changed according to an experimental design. As acrylamide formation was found to vary significantly between biscuits obtained by using the same ingredients and process, a mixed effect model was used to model variation of acrylamide concentration. By contrast a fixed effect model was used for colour polynomial analysis. Within the range of study, the overall results allowed the best conditions for minimising acrylamide formation to be found. It can be suggested that acrylamide development was at a minimum at intermediate asparaginase concentrations, as well as at the lowest time and temperature of incubation. Asparaginase addition did not significantly affect the colour of the final product, although the quadratic term of the incubation temperature did slightly.     

Effect of crust temperature and water content on acrylamide formation during baking of white bread: Steam and falling temperature baking

The effect of crust temperature and water content on acrylamide formation was studied during the baking of white bread. To assess the effect of over-baking, we used a full factorial experimental design in which the baking time was increased by 5 and 10 min at each baking temperature. Additional experiments were performed with steam baking and falling temperature baking. Immediately after baking, the crust was divided into the outer and inner crust fractions, and the water content and acrylamide concentration of each fraction was measured. The outer crust had a significantly lower water content and higher acrylamide concentration than the inner crust did. Crust temperature in combination with water content had a significant effect on acrylamide formation, higher temperatures resulting in higher acrylamide concentrations. However, at very high temperatures and lower water contents, acrylamide concentration was observed to decrease, though the bread colour was then unacceptable for consumption. Steam and falling temperature baking, on the other hand, decreased the acrylamide content while producing bread crust with an acceptable colour. The lowest acrylamide values and an acceptable crust colour were produced by steam baking.     

Effect of formulation on the capacity of l-asparaginase to minimize acrylamide formation in short dough biscuits

The influence of the matrix composition and structure on the capacity of asparaginase to reduce acrylamide formation in biscuits was studied. In particular, formulations differing for water (10 to 20% on total weight) and fat (0 to 15% on total weight) content, fat type (margarine, palm oil) and lipid phase distribution were considered. In the latter case, palm oil was substituted with a monoglyceride–palm oil–water gel (hydrogel). The results showed that high water contents, by favoring precursor mobility, promoted acrylamide formation as well as the enzyme capability of reducing the toxic molecule levels in the final product. On the contrary, the presence of fat significantly reduced acrylamide development and enzyme activity as compared with the fat free formulation. It can be hypothesized that the presence of fat would hamper the interaction between the precursors in the aqueous phase, leading to lower amounts of acrylamide. By substituting fat with hydrogel, the biscuit behaved as a fat free system, where acrylamide formation as well as its reduction by means of asparaginase activity was higher than in the fat-containing biscuits. It is likely that the inclusion of palm oil in the dough through the hydrogel modified the system morphology, thus not hampering the encounter among reactants and consequently favoring acrylamide formation.     

A new approach to evaluate the risk arising from acrylamide formation in cookies during baking: Total risk calculation

From a food engineering point of view, a viable approach in evaluating the risk related to acrylamide formation in heated foods is still lacking. In this study, thermal process calculation procedure used to evaluate safe levels of microbial inactivation by means of time-temperature history of the product during processing was adapted to evaluate the risk associated with acrylamide formation in cookies during baking. The rate constants were determined in model cookies during baking at different temperatures. For a risk threshold value of 200 ppb of acrylamide, thermal formation times were calculated as 6.29, 0.20 and 0.03 min for 150, 200 and 250 °C, respectively. The F and z values were determined as 0.20 min and 30 °C, respectively, for acrylamide formation in cookies during baking. Calculated total risk values compared well with experimentally measured acrylamide concentrations of cookies baked under different conditions confirming the success of risk evaluation procedure.     

Effects of dough formula and baking conditions on acrylamide and hydroxymethylfurfural formation in cookies

The effects of dough formula and baking conditions on the formations of acrylamide and hydroxymethylfurfural (HMF) were studied in a cookie model system. Increasing the sugar concentration in the dough formula increased acrylamide formation during baking at 205 °C for 11 min. The effect of sugar on acrylamide formation was more pronounced for glucose than for sucrose, expectedly. Addition of citric acid into dough formula comprising sucrose increased the susceptibility of acrylamide formation, while it decreased acrylamide formation in the dough formula comprising glucose. Decreasing the pH of dough formula increased the tendency to surface browning and the formation of hydroxymethylfurfural in cookies during baking. The results suggest that a cookie with acceptable texture and colour, but having less than 150 ng/g of acrylamide, can be manufactured by lowering the baking temperature and avoiding reducing sugars in the recipe.     

Influence of a malolactic starter on the quality of the cider produced on an industrial scale

The application of starter culture technologies to induce the malolactic fermentation in cidermaking are not yet established, as is already the case in winemaking. In this work, a selected indigenous cider malolactic strain was tested as a starter culture to assess its implementation and its influence on cider production on an industrial scale (10,000 l). The results showed that the culture, under the fermentation conditions tested, allowed successful achievement of the malolactic fermentation. Analysis of L-malic acid in the fermenting apple must medium revealed a highly significant difference in the rate of consumption of this acid from the moment of bacterial inoculation when compared with that of the control. The concentration of the malolactic starter culture maintained the inoculation level (10⁶ cfu/ml) during the process, the level necessary to ensure the malolactic fermentation. Thus, the cider malolactic starter culture showed good adaptation to the harsh environmental conditions found in the fermenting apple must, such as low temperature and the presence of SO₂ and ethanol. Several parameters were monitored during the process (specific gravity, temperature, pH, free SO₂ content, microbiological count, malic acid degradation rate, lactic acid formation, other major organic acids and volatile compounds) under inoculated and not inoculated conditions.     

Impact of selected additives on acrylamide formation in asparagine/sugar Maillard model systems

The main purpose of this paper was to study the effect of selected additives, NaCl, NaHSO₃, ascorbic acid, cysteine and allicin, on acrylamide (AA) formation in asparagine/fructose (Asn/Fru) and asparagine/glucose (Asn/Glc) by microwave processing. Our results showed that NaHSO₃ and cysteine had the best reduction rate on AA formation, but the browning would be influenced by the addition of these additives. Ascorbic acid is another good inhibitor for AA formation both in Asn/Fru and Asn/Glc model systems, but the browning would be inhibited by the high concentration of ascorbic acid. Natural antioxidants are attractive candidates for the development of effective inhibitors for AA formation. In the present study, allicin effectively reduced AA formation and achieved a maximum reduction rate of > 50% for the use of allicin at a concentration of 0.0375% in Asn/Fru model system. While in Asn/Glc model system, allicin did not show good reduction rate. Through RSM study, the lowest AA content was 0.181 ??g/mL by the addition of allicin in Asn/Fru and 0.029 ??g/mL by the addition of ascorbic acid in Asn/Glc model system, respectively. The study could be regarded as a pioneer contribution on AA reduction in Maillard model system by the addition of allicin.     

Supercritical fluid extraction as a potential mitigation strategy for the reduction of acrylamide level in coffee

The removal of acrylamide from coffee through supercritical CO₂ extraction has been investigated for the first time. Two steps were performed: a pre-roasting treatment and a supercritical extraction process. The main aim of this first work was to investigate the feasibility of the process more than the impact of the treatment on the organoleptic properties of coffee. The efficiency of acrylamide removal was checked by measuring its content in the coffee beans before and after the supercritical treatment. The role of temperature, pressure, extraction time and the addition of a modifier (ethanol) was examined.     

Mitigating effect of amaranth (Amarantus hypochondriacus) protein on acrylamide formation in foods

The effect of addition of amaranth flour and amaranth protein isolate to both a glucose/asparagine model system and real foods (cookies, fried tortilla chips, and baked tortilla chips) was studied to analyse the acrylamide mitigating potential of this underexploited plant with attractive nutraceutical properties. Addition of amaranth flour, with a relatively low protein content (16.45%), did not mitigate acrylamide in either the model system or the studied foods. On the contrary, addition of amaranth protein isolate decreased acrylamide content by 35–40% in the model system, 89% in cookies, 51% in fried tortilla chips, and 62% in baked tortilla chips. This acrylamide reduction was obtained without change in the colour or the texture of the cookies. On the contrary, colour remained unchanged in tortilla chips, but the addition of amaranth protein isolate increased the hardness (16–36%) of the produced tortillas. Although a much more detailed sensory evaluation of cookies and tortilla chips prepared using amaranth protein isolate is needed, the above results suggest that the use of amaranth protein may be an interesting way to both mitigate acrylamide formation and improve nutritional properties of foods.     

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

Maillard reaction along with caramelisation are the main chemical reactions occurring in bakery products. They are referred to as non enzymatic browning. In this work, the effect of flour type (wheat, rye and whole-wheat flours) and process conditions were investigated by using a bread crisp model system made up of flour, water and yeast. The bread was toasted at different temperature for different times. In a second set of experiments several additives (glycine, 0.1% on flour; asparaginase, 2000 U kg⁻¹ of flour and an antioxidant extract from green tea) were added to the basic formulations in order to test their ability in reducing the formation of potentially harmful Maillard reaction compounds such as HMF and acrylamide. Browning development and water content along with antioxidant activity were also monitored.Rye model systems produced more HMF and acrylamide at all temperature tested, while wholewheat systems produced less HMF, but more acrylamide than wheat one. The addition of glycine was effective in reducing acrylamide formation, and it increased browning development, antioxidant activity and HMF formation. Asparaginase reduced acrylamide formation up to 88% and had no effect on browning development and antioxidant activity. The addition of exogenous antioxidant compounds from green tea did not produce clear effect on acrylamide formation, thus it was not useful as mitigation strategy in bakery products, likely because of the low fat content.     

Effect of ground ginger on dough and biscuit characteristics and acrylamide content

Food Science and Biotechnology - Effect of different contents of ground ginger [0%, 1%, 3%, 5%, and 7% (w/w)] on flour quality, dough and biscuit characteristic and acrylamide content were...     

Reduction of acrylamide content of ripe olives by selected additives

A model system based on alkali-treated olive juice heated at 121 °C for 30 min was used to screen different additives (salts, amino acids, antioxidants) for potential inhibition of acrylamide formation in ripe olives. The most-efficient inhibitors found were sodium bisulphite, l-cysteine, and l-arginine. These compounds, as well as other sulphur-containing compounds (N-acetyl-l-cysteine, reduced glutathione, methionine) and several natural products (tea, oregano, rosemary, garlic), were then added to black ripe olives prior to sterilisation to evaluate their effect on both the acrylamide content and the sensory quality of olives. Sodium bisulphite had the highest impact on the acrylamide level in black ripe olives without a negative repercussion on sensory quality. Arginine and blanched garlic showed promising results. SH-containing compounds such as l-cysteine, N-acetyl-l-cysteine, or reduced glutathione were as effective as sodium bisulphite in reducing acrylamide, but did generate unpleasant off-flavours.     

Effect of formulation and processing parameters on acrylamide formation: A case study on extrusion of blends of potato flour and semolina

Acrylamide formation in extruded snacks prepared using blends of potato flour:semolina in ratios ranging from 30:70 to 70:30 showed maximum acrylamide formation in the 70:30 blend. The extrusion was carried out at a screw speed of 120 rpm, temperature of 170 °C and moisture content of 18%. Further, the influence of extrusion processing parameters on the acrylamide formation in extruded snacks prepared from a 70:30 blend of potato flour:semolina was investigated using response surface methodology (RSM). The feed moisture was varied from 12.6% to 19.4%, die temperature from 163 to 197 °C and screw speed from 106 to 173 rpm. The extrudates so obtained showed acrylamide content ranging from 704 to 1560 μg/kg. The effect of different additives such as citric acid, calcium salts, amino acids, vitamins and their combinations on the mitigation of acrylamide formation showed calcium chloride at 50 μmol/g flour blend to reduce acrylamide formation by 65% without altering the sensory properties of the extrudates.     

Study of acrylamide mitigation in model system: Effect of pure phenolic compounds

Many natural antioxidant extracts were reported to potentially reduce the acrylamide formation during Maillard reaction. In this work, the effect of pure antioxidant molecules on acrylamide net amount was investigated in an equimolar asparagine–glucose system (10 mM) during heating (200 °C). All experimentations were performed in the newly designed test cell. Cinnamic acid and six phenolic compounds (gallic, ferulic, coumaric, caffeic acids, catechin, and epicatechin), displaying different antioxidant capacity, were added at 5 mM to the model system. The results indicated no reduction effect of the tested compounds on acrylamide net amount. Moreover, in the case of ferulic acid a slight but significant promoting effect was observed. An increase of antioxidant activity was also noticed during heating of model solution spiked with caffeic acid but the acrylamide level was not affected.     

Impact of extraction conditions on the content of acrylamide in model systems and food

It has recently been suggested that the analytical methods that have been developed to date for the determination of acrylamide (AA) may underestimate the concentration of AA in certain foods, because significantly higher results were obtained upon extraction of the food matrix under alkaline conditions. The present study employs food (potato, rye) and chemical model systems to better understand the tentative release of AA under high pH extraction conditions. The experimental design is based on the generation of AA in an environment containing an AA-isotopomer, and by comparing the ratio of AA, respectively the AA-isotopomer, after extraction at pHs 7 and 12. The results show that the additional AA released is not due to improved extractability of AA from the food matrix, and should therefore be regarded as an extraction artefact. Strongly alkaline conditions seem to induce net formation of AA from water-soluble precursors formed during thermolysis.     

Characterization and CFD modelling of air temperature and velocity profiles in an industrial biscuit baking tunnel oven

The industrial baking of cereal products is commonly performed in tunnel ovens, which give operators high flexibility for adjusting baking conditions to optimum values. This paper discusses the application of a CFD approach to predict the air temperature and velocity profiles inside the baking chamber of an industrial indirect gas-fired tunnel oven used for biscuit baking. We used two three-dimensional CFD models (one not covering the conveying band of biscuits and the other including it) to describe the complex air circulation resulting from the mechanisms of air input and exit at the ends of the oven and of air extraction through the different extraction points located along the oven length. Comparison of numerical results with experimental measurements shows a fairly close agreement in the qualitative prediction and a few inaccuracies in the quantitative prediction of the air temperature profiles within the baking chamber. Furthermore, the comparison also reveals great differences in the air velocity profiles.     

Effect of added calcium hydroxide during corn nixtamalization on acrylamide content in tortilla chips

This study has analyzed the influence of lime (Ca(OH)₂) concentration used during nixtamalization process on the physicochemical properties of nixtamalized corn flours and its effect on the acrylamide content in tortilla chips prepared from them. Flours prepared from nixtamalized corn with 0.5 and 1.0 g/100 g of Ca(OH)₂ showed higher levels of insoluble fiber, lower concentrations of calcium and ash, and a pH close to neutral. The acrylamide content of tortilla chips was correlated with the physicochemical properties of the flours. The results showed that acrylamide content was mainly affected by the ash, calcium, soluble fiber concentration in flour, as well pH value (p < 0.05). In comparison with tortilla chips made of flours prepared from nixtamalized corn with lime concentration of 1.0 g/100 g, a reduction of 52 and 36% in acrylamide content in tortilla chips made with flours prepared from nixtamalized corn with lime concentrations of 1.5 and 2.0 g/100 g, was obtained. The results suggest that controlling the concentration of Ca(OH)₂ during nixtamalization process can be used as an effective strategy for reducing acrylamide formation in fried products produced from nixtamalized corn flour.     

Impact of the roasting degree of coffee on the in vitro radical scavenging capacity and content of acrylamide

Due to the recognized toxicity of acrylamide, intensive efforts have been made to reduce the concentration of this undesired Maillard by-product in food. This work reports the results obtained from a series of experiments aimed at determining the concentration of acrylamide and the in vitro radical scavenging capacity in the same roasted and ground coffee samples, as it is well established that a significant part of the antioxidant activity in coffee is linked to the melanoidins, which are also considered as Maillard reaction products (MRPs). The radical scavenging capacity was measured using electroparamagnetic resonance (EPR). Coffee samples from the Robusta and Arabica varieties were roasted at 236 °C over different time periods to obtain very light, light, medium and dark roast. Color analyses were performed on all samples. Increasing the roasting degree led to a decrease in acrylamide concentration as well as radical scavenging capacity. The results of this work indicate that any mitigation efforts must also take into account the potential loss of desired food constituents and consequently changes to the risk/benefit characteristics of foods.     

Performance of a resistant starch rich ingredient in the baking and eating quality of short-dough biscuits

The effect of replacing part of the wheat flour with a resistant starch rich ingredient (RSRI) − a source of functional fibre with potential health benefits − was studied in short dough biscuits. A control with no replacement and 3 formulations in which 20, 40 and 60g of flour per 100 g were replaced by an RSRI (samples 20RSRI, 40RSRI and 60RSRI) were prepared. From a technological point of view, the RSRI level influenced the consistency of the raw dough and the ease of sheeting and cutting. Regarding the eating quality of the final product, addition of the RSRI increased the breaking strength and crumbliness and reduced the resistance to penetration. In the RSRI biscuits, both the surface and the crumb were paler. The sensory acceptance of the 20RSRI biscuits did not differ significantly from that of the control. 40RSRI reduced the acceptability of the colour, appearance and texture without altering the taste, sweetness and overall acceptance. Neither of these two levels significantly reduced the consumption intention. However, 60% flour replacement produced biscuits with lower sensory acceptability and a significant reduction in consumption intention. In general, the results could be interpreted in terms of the protein-diluting effect of the added ingredient and changes in the water content and water-retention capacity of flour mixtures containing RSRI. The present results proved that resistant starch rich ingredients (RSRI) have good potential for developing fibre-rich biscuits without changing their general features.     

Influence of the addition of Helianthus tuberosus L. fermented with different lactobacilli on acrylamide content in biscuits

The aim of the study was to investigate the effect of the addition of Helianthus tuberosus L. fermented with different lactobacilli (Lactobacillus sakei KTU05‐6, Pediococcus acidilactici KTU05‐7 and Pediococcus pentosaceus KTU05‐9) on acrylamide content in biscuits. Results of study indicated that submerged fermented Helianthus tuberosus L. tubers had the significantly (P ≤ 0.05) lower pH, higher total titratable acidity and from 1.2 to 1.3 times higher protease and from 1.2 to 2.0 higher alpha‐amylase activities compared with treated by solid‐state fermentation. The acrylamide content in all biscuit samples enriched with submerged fermented Helianthus tuberosus L. was measured lower than 10 μg kg^?1. Submerged fermentation with selected lactobacilli provided specific characteristics of fermented Helianthus tuberosus products which had effect on the asparagine reduction in plant additives, thus reducing acrylamide content in biscuits enriched with Helianthus tuberosus L.