Effect of Steam Baking on Acrylamide Formation and Browning Kinetics of Cookies

Abstract: Effects of baking method and temperature on surface browning and acrylamide concentration of cookies were investigated. Cookies were baked in natural and forced convection and steam‐assisted hybrid ovens at 165, 180, and 195 °C and at different times. For all oven types, the acrlyamide concentration and surface color of cookies increased with increasing baking temperature. Significant correlation was observed between acrylamide formation and browning index, BI, which was calculated from Hunter L, a, and b color values, and it showed that the BI may be considered as a reliable indicator of acrylamide concentration in cookies. Acrylamide formation and browning index in cookies were considered as the first‐order reaction kinetics and the reaction rate constants, k, were in the range of 0.023 to 0.077 (min^?1) and 0.019 to 0.063 (min^?1), respectively. The effect of baking temperature on surface color and acrylamide concentration followed the Arrhenius type of equation, with activation energies for acrylamide concentration as 6.87 to 27.84 kJ/mol; for BI value as 19.54 to 35.36 kJ/mol, for all oven types. Steam‐assisted baking resulted in lower acrylamide concentration at 165 °C baking temperature and lower surface color for all temperatures. Steam‐assisted baking is recommended as a healthy way of cooking providing the reduction of harmful compounds such as acrylamide for bakery goods, at a minimal level, while keeping the physical quality. Practical Application: The kinetics of acrylamide formation and browning of cookies will possibly allow definition of optimum baking temperatures and times at convectional and steam‐assisted baking ovens. The kinetic model can be used by developing baking programs that can automatically control especially a new home‐scale steam‐assisted hybrid oven producing healthy products, for the use of domestic consumers.     

Halogen lamp–microwave combination baking of cookies

The effects of halogen lamp–microwave combination baking on the quality of cookies in terms of texture, color and spread ratio were studied. In addition, gelatinization and pasting properties of cookies baked in different ovens were assessed by using a Rapid Visco Analyzer. The hardness values of the cookies increased with increasing baking time and/or halogen power. The microwave power also contributed to cookie hardness. The lightness values of the cookies decreased, while the a* and E values increased linearly during baking at different halogen lamp and microwave powers. The spread ratio of conventionally baked cookies was significantly lower than that of the other cookies. Halogen lamp power, microwave power and baking time were found to have a significant effect on the spread ratio of the cookies. The moisture contents of the cookies decreased during baking as the halogen lamp and/or the microwave power level increased. The best baking condition in a halogen lamp–microwave combination oven to produce cookies having similar quality parameters as conventionally baked ones was baking at 70% halogen lamp and 20% microwave power levels for 5.5 min. The baking time of these cookies is half of that required in conventional baking.     

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.     

Effect of leavening agents and sugars on the formation of hydroxymethylfurfural in cookies during baking

The effects of recipe compositions in terms of leavening agent (ammonium and sodium bicarbonates) and sugars (sucrose and glucose), and baking conditions (temperature and time) on HMF formation in cookies were studied. Five recipes were prepared by varying the types of leavening agent and sugar. The cookies were baked at different temperatures (180, 200, 210 and 220 °C) for different time (10, 15, 20 and 25 min) to monitor physical and chemical changes in cookie composition in terms of water activity, pH, surface browning, sugar decomposition, and hydroxymethylfurfural (HMF) formation. Decreasing moisture to a level under a water activity of 0.4 appeared as the critical point in baking where the rate of HMF formation drastically increased after this point. After this stage, sucrose decomposed very rapidly if ammonium bicarbonate was used as the leavening agent at temperatures greater than 200 °C. Replacing ammonium bicarbonate with sodium bicarbonate maintained pH of cookies ranging between 9.0 and 10.0 during baking, which limited the decomposition of sucrose.     

Acrylamide formation in a cookie system as influenced by the oil phenol profile and degree of oxidation

The purpose of this study was to investigate the effect of the olive oil phenolic compounds as well as of thermoxidised oil on the formation of acrylamide in a cookies system. Three virgin olive oils having different phenolic profile and a thermoxidised sunflower oil were selected. Cookies were baked at 190 °C for different times (8–16 min) following a basic recipe where type of oil was the variable. Additionally to acrylamide (AA), other parameters such as colour, moisture, antioxidant activity (AOA), and hydroxymethylfurfural (HMF) were measured. Results showed that concentration and composition of phenolic moiety of virgin olive oil significantly affect the acrylamide formation, particularly at prolonged baking time. Virgin olive oil with a higher dihydroxy/monohydroxy ratio was more efficient in the AA mitigation and AA was reduced up to 20%. Colour and AOA were not significantly different among the three types of oils. However, AA is dramatically increased when thermoxidised oil is used with a parallel increase of browning and HMF. It was concluded that lipid oxidation products should be considered as an important factor in acrylamide formation during baking of fat-rich products.     

Mitigation of acrylamide formation in cookies by using Maillard reaction products as recipe modifier in a combined partial conventional baking and radio frequency post-baking process

This study aimed to mitigate acrylamide formation in cookies by lowering thermal energy input along with certain recipe modifications. Lowering temperature required longer cooking times as expected in order to achieve desired final moisture content. To shorten cooking time, conventional baking was combined with radio frequency post-baking process. Lack of development of surface browning in cookies during lower-temperature baking could be overcome by adding the Maillard reaction products (MRP) into dough. The MRP used to modify dough was prepared by heating a binary mixture of arginine and glucose at 100?°C for 6?h or by overbaking thin dough-layered disks. In comparison with control cookie baked at 205?°C for 11?min, combined conventional baking (205?°C for 8?min) and radio frequency post-drying process (45?s) decreased acrylamide formation in biscuits by up to 50?%. The use of Maillard reaction products to improve the visual acceptability of cookies to the consumer may have applications in food industry.     

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.     

Comparison of the effects of sucrose and hexose on furfural formation and browning in cookies baked at different temperatures

The influence of the type of sugar and baking temperature on sugar degradation, hydroxymethylfurfural (HMF) formation and browning was studied in model cookies. The baking process was characterised by the temperature in the cookie and the water content and activity. A reference browning was selected to compare the differently processed cookies. The accumulation of HMF was modelled at three temperatures for three formulas (sucrose (S-CK), glucose (G-CK) or fructose (F-CK)). HMF started to accumulate at a_w between 0.5 and 0.7 depending on the temperature and followed a first order kinetic, highly dependent on the baking temperature and type of sugar. Cookies baked at 200 °C accumulated 10–100 times less HMF than those baked at higher temperatures. Below 250 °C, S-CK produced less HMF than G- or F-CK, but the inverse was observed at 300 °C.     

Effect of Radio Frequency Postdrying of Partially Baked Cookies on Acrylamide Content,Texture, and Color of the Final Product

Abstract: Effect of radio frequency (RF) postdrying of partially baked cookies on acrylamide content, texture, and color of the final product was investigated in this study. Control cookies were prepared by baking in a conventional oven at 205 °C for 11 min. Cookies partially baked for 8 and 9 min were postdried in a 27.12 MHz RF tunnel oven until attainment of the moisture content of control cookies. Internal temperature of cookies was monitored during the experiments to better explain the results. Cookies were analyzed for acrylamide content using a liquid chromatography‐mass spectrometry (LC‐MS) method. Texture measurements were performed using a Texture Analyzer, while digital image analysis was used for color measurement. The results showed that RF postdrying of partially baked cookies resulted in lower acrylamide levels (107.3 ng/g for control cookies, 74.6 ng/g upon RF postdrying of cookies partially baked for 9 min, 51.1 ng/g upon RF postdrying of cookies partially baked for 8 min). Instrumental texture analysis showed no significant difference among the texture of cookies, whereas RF postdried samples had a lower degree of browning. According to sensory evaluation results, control had a more crumbly texture, and RF postdried sample that was conventionally baked for 8 min had a slightly uncooked flavor. Practical Application: Combining radio frequency and conventional baking may provide cookie manufacturers with ability to make cookies with lower levels of acrylamide.     

Influence of konjac flour on foaming properties of milk protein concentrate and quality characteristics of gluten‐free cookie

The effects of konjac flour (KF) for modifying the foaming properties of milk protein concentrate (MPC) and characteristics of gluten‐free rice cookies were investigated. The three variables of konjac concentration (0.1–0.4%), pH (pH 5–9) and NaCl concentration (0.2–0.6 м) were studied. Both KF and pH had considerable effects on the foaming capacity (FC) and foaming stability (FS) of MPC. The NaCl had a negligible effect. Lowered FC and FS observed at pH 9 and pH 5 were increased with the increase in KF addition. Batter characteristics (flowability and consistency), cookie quality (moisture, yield, spread ratio, specific volume, hardness and colour) and sensory acceptance were evaluated in gluten‐free cookies with 0%, 0.25% and 0.4% KF. Konjac supplementation increased batter characteristics, yield, specific volume and hardness, but decreased lightness. Panellist acceptance, especially regarding texture and overall acceptability, increased in gluten‐free cookies with 0.4% KF. A higher purchasing decision was found for cookies with added KF.     

Browning development in bakery products – A review

This paper presents a review regarding several aspects of the development of browning during baking of bakery products, mainly from an engineering point of view. During baking, the formation of colour is due to the Maillard reaction, and caramelization of sugars. Besides the major influence of this phenomenon on the initial acceptance of products by consumers, it is the responsible for other relevant changes occurring in food during baking, i.e. production of flavour and aroma compounds, formation of toxic products (e.g. acrylamide), and decrease of nutritional value of proteins. As well as baking, the development of browning in bakery products is a simultaneous heat and mass transfer process that occurs mostly in a non-ideal system under non-ideal conditions. In addition, the mechanisms of chemical reactions involved are still not elucidated completely, so the process is difficult to control and represents a major challenge for food engineers. Effects of browning on properties of products and experimental, modelling and technological aspects of colour formation during baking are reviewed.     

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.     

Incorporation of germinated mung bean flour with rice flour to enhance physical,nutritional and sensory quality of gluten-free cookies

Quality of the cookies substituted with germinated mung bean flour (GMF) to rice flour (RF) to produce gluten-free cookies were investigated in this study. The GMF was used to formulate with the RF to obtain the composite flours with different total protein contents of 6, 9, 12, 15, 18 and 21 (%, d.b). The increase in the substituted amounts of GMF contributed to the lower baking loss, diameter and spread ratio, but the higher thickness and hardness of the cookies as compared to the RF-based cookie. The cookies with more GMF substitution expressed lower lightness (L*) values, but higher redness (a*) and yellowness (b*) values than the others. The cookies substituted with 60% of the GMF (60-GMFC) exhibited similar baking loss, thickness, diameter, spread ratio and lightness values to the wheat flour (WF)-based cookies. The total amounts of essential amino acids and the sum of histidine, lysine and methionine of the composite flour-based cookies were 3.90% and 1.64%, significantly higher than those of the RF-based cookie (1.93% and 0.66%, respectively) or the WF-based cookie (1.70% and 0.58%, respectively). As a result, healthy gluten-free cookies could be prepared using the RF with the substitution of the germinated mung bean flour.     

Antioxidant activity of cookies and its relationship with heat-processing contaminants: a risk/benefit approach

Formation of both health promoting and potential harmful substances (acrylamide and hydroxymethylfurfural) has been associated to the extent of the Maillard reaction. The effects of recipe compositions in terms of leavening agent (ammonium and sodium bicarbonates) and sugars (sucrose and glucose), and baking conditions (temperature and time) on the antioxidant activity (AOA) in cookies were studied. The cookies were baked at different temperatures (180–220 °C) for different times (10–25 min). AOA was measured by the ferric reducing power (FRAP), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2,-diphenyl-1-picrylhydrazyl (DPPH) coloured radicals, and oxygen radical absorbance capacity (ORAC-fluorescein) in automated plate-reader assays. Net AOA varied regarding the assay applied, whereas higher AOA was always obtained for the ABTS assay and lower for DPPH assay, and ranging from 2 to 200 μmol Trolox/g sample. At higher temperature and baking times, higher AOA in cookies regardless of the formulation was recorded. Glucose enhances formation of compounds with higher AOA compounds as compared with sucrose recipes. Ammonium bicarbonate clearly promotes the formation of AOA for sucrose recipes but this effect is not observed in glucose recipes and varied with the AOA procedure applied. A risk/benefit index, based on the concomitant formation of neo-formed contaminants and substances with AOA (potentially health-promoting substances) is presented, and its application for recipe comparison is discussed. Risk/benefit index rapidly increased with increased temperature and time of baking.     

Evaluation of Gingerbread Cookies Supplemented with Sunflower Protein Concentrate

The protein content, baking characteristics, physical characteristics, and sensory characteristics of gingerbread cookies supplemented with sunflower protein concentrate were examined. Protein content increased from 7.2% to 15.9% as the substitution level increased from 0% to 30%. Supplementation resulted in higher moisture loss during baking and more compact inner structure of the cookies. Although the texture of supplemented cookies was slightly crispier and harder, evaluation showed that sensory characteristics were not significantly affected by the addition of sunflower protein concentrate.     

Modelling the browning of bread during baking

In this work, we study the development of browning at bread surface during baking. Computer vision is applied to follow the progress of browning at surface, while the variations of temperature and water activity are obtained by numerical simulation of a mathematical model previously validated. The formation of the bread crust is a complex process where temperature and water content change continuously during baking, making browning a non-isothermal process occurring in a non-ideal system. Minimum requirements for initiation of colour formation are temperature greater than 120 °C and water activity less than 0.6. We apply a non-isothermal kinetics approach to model the browning development at bread surface during baking, where the variation of local temperature and water activity is taken into account. The methodology presented here is suitable for modelling and predicting browning during baking; model parameters can be estimated by using a non-ideal system closer to real processing conditions.     

Accumulation of 5-hydroxymethyl-2-furfural in cookies during the backing process: Validation of an extraction method

During baking, complex chemical reactions take place in the cookies, such as the Maillard reaction (MR) and caramelisation (CR). Both reactions involve glucose and fructose, generated from starch and sucrose hydrolysis during baking. Among the many products formed, HMF a possible mutagen, seems particularly interesting because of a rapid accumulation during the process.     

Lipid changes during long-term storage of canned tuna (Thunnus alalunga)

 Lipid damage during prolonged storage of canned fish was studied. Albacore tuna was processed under two sterilization conditions (115°C, 74 min; 120°C, 40 min) and then stored for up to 6 years. Analyses (lipid oxidation and hydrolysis, browning and formation of fluorescent compounds) of the lipids extracted from the white muscle of the fish and the packing oils were carried out. Muscle lipids were partially extracted by the packing oil, so that an increase in the storage time produced higher levels of free fatty acids, browning and fluorescence development in the packing oils. As regards the types of muscle, little difference between them throughout the canned storage was detected. Received: 17 February 1997 / Revised version: 12 May 1997     

Bread browning kinetics during baking

The development of browning at bread surface during baking is an important quality index. In this paper, the colour (CIE L^*a^*b^* parameters) of bread surface was measured by computer vision. Also, the weight loss variation was determined during the process. Baking experiences were performed at 180, 200 and 220 °C under natural and forced convection. Linear trend was found between total colour change and weight loss of breads. A simple mathematical model was proposed to predict the development of browning during baking. The independent variables were the weight loss of breads and the baking temperature. For values of weight loss greater than 7%, the mean absolute estimation error of the proposed model was 6.23%.     

蜜枣在烘制过程中褐变相关因素分析

试验以新疆阿克苏地区不同成熟度的骏枣为试材，采用常压二次煮制渗糖工艺，55 ℃恒温烘制，以总酚、抗坏血酸含量、叶绿素含量、游离氨基酸总量、5-HMF含量等为评价指标，结合相关性分析与主成分分析方法，探究蜜枣在烘制阶段褐变情况。结果表明:不同成熟度原料的蜜枣随着烘制时间的延长，各项致褐变因子的含量变化不同。相关性分析发现三种成熟度蜜枣的色差与总酚、叶绿素等指标呈极显著正相关（P<0.01），抗坏血酸含量与5-HMF指标呈极显著负相关（P<0.01）。由主成分分析可知，成熟度、5-HMF、抗坏血酸含量等是影响蜜枣在烘制过程中褐变的主要因素。并且红枣经过（V_C 1.25 g/kg、焦性亚硫酸钠1.25 g/kg、柠檬酸3 g/kg、NaCl 25 g/kg）护色处理后与对照组相比有明显抑制褐变的作用。由此可见蜜枣的烘制阶段褐变情况是一个复杂的非酶褐变的过程，也为后续进一步研究提供了理论依据。