Acrylamide formation and antioxidant level in biscuits related to recipe and baking

Heated plant foods may contain compounds with adverse health effects (e.g. acrylamide). On the other hand, health-promoting compounds (e.g. antioxidants) have also been identified in such foods. Therefore, a baking experiment with biscuits was carried out to study the potential impact of both acrylamide and antioxidants in that food. Two different wheat flour types - wholemeal (WMF) and white flour type 550 (T550; 0.55% mineral content) - as well as recipe (fat and leavening agent) and thermal input (temperature?×?time) were changed. Furthermore, the effect of an enzymatic asparagine hydrolysation was tested. Antioxidants were determined with two independent procedures ABTS - (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate)) and FRAP-assay (ferric reducing ability of plasma). WMF samples resulted in an unchanged acrylamide level, but in a significantly higher antioxidant concentration when compared with T550 samples (149 and 141?μg?kg(-1) acrylamide and 9.1 and 5.1?mmol?TE?kg(-1) FW ABTS for WMF and T550, respectively). A reduced fat content yielded in an increased volume. Raising agents had no effect on acrylamide levels, but antioxidants were higher in samples with sodium bicarbonate (SBC) than with ammonium bicarbonate (ABC). Thermal input (temperature?×?time; 150°C?×?25?min to 240°C?×?9?min) indicated an exponential acrylamide increase especially at higher temperatures (from 75 to 236?μg?kg(-1)), whereas antioxidant increase was linear (from 7.0 to 7.7?mmol?TE?kg(-1) FW, ABTS). FRAP and ABTS values were correlated on a low level, whereas acrylamide content of biscuits was correlated with FRAP and lightness (R (2?)=?0.62 and 0.47, and 0.71 and 0.85 for WMF and T550, respectively). The enzyme asparaginase reduced acrylamide formation by about 50% for both raising agents (SBC and ABC, respectively), whereas antioxidant levels were not affected. An evaluation of recipe variants with low acrylamide and high antioxidants indicated the advantage of wholemeal biscuits.     

Acrylamide formation and antioxidant level in biscuits related to recipe and baking

Heated plant foods may contain compounds with adverse health effects (e.g. acrylamide). On the other hand, health-promoting compounds (e.g. antioxidants) have also been identified in such foods. Therefore, a baking experiment with biscuits was carried out to study the potential impact of both acrylamide and antioxidants in that food. Two different wheat flour types – wholemeal (WMF) and white flour type 550 (T550; 0.55% mineral content) – as well as recipe (fat and leavening agent) and thermal input (temperature?×?time) were changed. Furthermore, the effect of an enzymatic asparagine hydrolysation was tested. Antioxidants were determined with two independent procedures ABTS – (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate)) and FRAP-assay (ferric reducing ability of plasma). WMF samples resulted in an unchanged acrylamide level, but in a significantly higher antioxidant concentration when compared with T550 samples (149 and 141?µg?kg^?1 acrylamide and 9.1 and 5.1?mmol?TE?kg^?1 FW ABTS for WMF and T550, respectively). A reduced fat content yielded in an increased volume. Raising agents had no effect on acrylamide levels, but antioxidants were higher in samples with sodium bicarbonate (SBC) than with ammonium bicarbonate (ABC). Thermal input (temperature?×?time; 150°C?×?25?min to 240°C?×?9?min) indicated an exponential acrylamide increase especially at higher temperatures (from 75 to 236?µg?kg^?1), whereas antioxidant increase was linear (from 7.0 to 7.7?mmol?TE?kg^?1 FW, ABTS). FRAP and ABTS values were correlated on a low level, whereas acrylamide content of biscuits was correlated with FRAP and lightness (R ^2?=?0.62 and 0.47, and 0.71 and 0.85 for WMF and T550, respectively). The enzyme asparaginase reduced acrylamide formation by about 50% for both raising agents (SBC and ABC, respectively), whereas antioxidant levels were not affected. An evaluation of recipe variants with low acrylamide and high antioxidants indicated the advantage of wholemeal biscuits.     

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.     

Quantification in starch microstructure as a function of baking time

The purpose of this study was the characterization of micro structural and thermal aspects of starch gelatinization in wheat dough/crumb during bread baking. The microstructure of starch granules was examined by confocal-laserscanning-microscopy (CLSM) and evaluated by an image analyzing tool. Supporting crystallinity changes in wheat dough/crumb were analyzed by differential-scanning-calorimetry (DSC) and calculated by the content of terminal extent of starch gelatinization (TEG). The micrograph of processed CLSM data showed starch structure changes during baking time. After gelatinization the starch fraction itself was inhomogeneous and consisted of swollen and interconnected starch granules. Image processing analyses showed an increment of mean granule area and perimeter of the starch granules. The results of DSC were examined to present an equation which provides a mean of predicting TEG values as a function of baking time. CLSM and DSC measurements present high significant linear correlation between mean starch granule area and TEG (r = 0.85). The possibility to combine CLSM with thermal physical analytical techniques like DSC in the same experiments is useful to obtain detailed structural information of complex food systems like wheat bread. Finally, it offers the option to enlarge the knowledge of microstructural starch changes during baking in combination with physicochemical transformation of starch components.     

The influence of time and storage temperature on resistant starch formation from autoclaved debranched banana starch

Debranching and autoclaving processes of banana starch were carried out for obtaining a resistant starch-rich powder with functional characteristics. Debranching was carried out using pullulanase for 24 h and the autoclaving was done at 121 °C for 30 min, the samples were then cooled down and stored between 24 and 48 h, and temperatures between 4 and 60 °C. The resistant starch level increased due to the debranching and autoclaving processes. The water absorption index values decreased when the storage time increased, pattern that agrees with the higher RS content. The water solubility index (WSI) was affected by the storage temperature but not by the storage time. The autoclaved sample was hydrolyzed to a lesser extent than native starch. The RS-rich powder presented also crystallinity because the process of autoclaving and storage induced starch retrogradation. The procedure proposed might be used for production of a RS-rich powder from banana starch with high RS level and functional properties.     

Dietary fibre in bread and corresponding flours--formation of resistant starch during baking

Dietary fibre, assayed with an enzymatic/gravimetric method, was higher in wheat/rye bread than in the corresponding flours. The increase was most pronounced in crumbs from bread baked with mainly low-extraction-rate flour, and could be accounted for to a large extent as "resistant starch", i.e. a starch fraction available to amyloglucosidase only after solubilization with 2 m-KOH. The resistant starch was formed at dough-making and/or baking and did not increase further during freezing or storage at room temperature. The chemical modifications leading to resistant starch formation remain to be investigated. Starch-lipid complexes are probably not involved, since these are hydrolyzed by the heat-stable amylase used in the dietary fibre assay.     

Comparison of the expansion ability of fermented maize flour and cassava starch during baking

The modifications occurring during the fermentation (at 20 or 35 °C) and drying (under the sun or in an oven at 40 °C) of maize flour (ogi) and cassava starch along with their expansion ability during baking were characterised and compared. A high temperature accelerated the fermentation but favoured lactic acid synthesis for maize ogi and butyric acid for cassava starch. The increase in acidity was higher for maize, but dried maize ogi did not evidence any expansion ability whatever the experimental conditions. Cassava starch that had been fermented at 20 °C then sun‐dried presented the highest expansion ability. It was associated with low paste viscosities and high swelling and solubilisation values. When the fermentation was carried out at 35 °C, an annealing of cassava starch occurred that delayed starch gelatinisation and which could be involved in its lower baking expansion ability. © 2000 Society of Chemical Industry     

Dietary fibre in bread and corresponding flours —Formation of resistant starch during baking

Dietary fibre, assayed with an enzymatic/gravimetric method, was higher in wheat/rye bread than in the corresponding flours. The increase was most pronounced in crumbs from bread baked with mainly low-extraction-rate flour, and could be accounted for to a large extent as “resistant starch”, i. e. a starch fraction available to amyloglucosidase only after solubilization with 2m-KOH. The resistant starch was formed at dough-making and/or baking and did not increase further during freezing or storage at room temperature. The chemical modifications leading to resistant starch formation remain to be investigated. Starch-lipid complexes are probably not involved, since these are hydrolyzed by the heat-stable amylase used in the dietary fibre assay.     

The impact of baking time and bread storage temperature on bread crumb properties

Two baking times (9 and 24 min) and storage temperatures (4 and 25 °C) were used to explore the impact of heat exposure during bread baking and subsequent storage on amylopectin retrogradation, water mobility, and bread crumb firming. Shorter baking resulted in less retrogradation, a less extended starch network and smaller changes in crumb firmness and elasticity. A lower storage temperature resulted in faster retrogradation, a more rigid starch network with more water inclusion and larger changes in crumb firmness and elasticity. Crumb to crust moisture migration was lower for breads baked shorter and stored at lower temperature, resulting in better plasticized biopolymer networks in crumb. Network stiffening, therefore, contributed less to crumb firmness. A negative relation was found between proton mobilities of water and biopolymers in the crumb gel network and crumb firmness. The slope of this linear function was indicative for the strength of the starch network.     

Resistant starch from processed cereals: the influence of amylopectin and non-carbohydrate constituents in its formation

The effect of removal of protein and lipids on the resistant starch (RS) content of processed rice and ragi has been studied. The percent recovery of RS increased significantly (over 2–3-fold) after defatting and autoclaving. However, deproteinization did not show any major difference. Prolonged storage of gelatinized starch suspensions showed considerably more undigested mass even after extended α-amylolysis, probably due to the involvement of long unbranched chains of amylopectin in the formation of RS. Thermal characteristics of these processed flours/starches showed variable enthalpy values. X-ray diffraction data revealed both B- and V-type diffraction patterns for the isolated RS.     

Effect of baking temperature/time conditions and dough thickness on arabic bread quality

A new scoring system for the evaluation of Arabic bread is presented which allows discrimination between flour samples. This system is suitable for the evaluation of bread in commercial bakeries. Dough thickness and baking temperature/time conditions were varied: doughs sheeted to <3.0 mm thick require baking temperatures higher than 500°C whereas doughs that are thicker than this will benefit from temperatures lower than 500°C. Thinner doughs baked at higher temperatures for shorter times produced better quality bread. The processing variables identified as being optimal in this study were incorporated into a test baking method. This method gave reproducible results and greater discrimination between flour samples than a previous method.     

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.     

Properties and applications of starch modifying enzymes for use in the baking industry

Enzyme technology has many potential applications in the baking industry because carbohydrate-active enzymes specifically react with carbohydrate components, such as starch, in complex food systems. Amylolytic enzymes are added to starch-based foods, such as baking products, to retain moisture more efficiently and to increase softness, freshness, and shelf life. The major reactions used to modify the structure of food starch include: (1) hydrolysis of α-1, 4 or α-1, 6 glycosidic linkages, (2) disproportionation by the transfer of glucan moieties, and (3) branching by formation of α-1, 6 glycosidic linkage. The catalytic reaction of a single enzyme or a mixture of more than two enzymes has been applied, generating novel starches, with chemical changes in the starch structure, in which the changes of molecular mass, branch chain length distribution, and the ratio of amylose to amylopectin may occur. These developments of enzyme technology highlight the potential to create various structured-starches for the food and baking industry.     

Combined effects of freezing rate, storage temperature and time on bread dough and baking properties

This study compares the effects of freezing temperature and rate as well as storage temperature and time on the quality of frozen dough. Yeasted bread dough was frozen using four freezing rates (19-69 °C/h), then stored at −10, −20, −30, or −35 °C for up to 180 days. Dough strength diminished with longer storage time and higher storage temperatures. Cryo-SEM showed that dough stored at −30 and −35 °C had the least damaged gluten network. NMR studies showed that more rapidly frozen dough, and that stored at lower temperatures had lower transverse relaxation (T₂) times (9-10 ms). However, dough stored at −20 °C displayed the highest yeast activity among samples. Bread loaf volume decreased with storage time, and bread made from dough stored at −20 °C showed the highest loaf volume. Breads produced from −30 and −35 °C stored dough displayed less change in the texture profile during storage as well as less change in T₂ values. Response surface analysis showed that optimal properties occurred at freezing rates of around 19-41 °C/h and storage temperatures of −15 to −20 °C.     

Effects of time/temperature treatments on potato (Solanum tuberosum) starch: a comparison of isolated starch and starch in situ

Previously, time/temperature treatments of starch have been performed mainly on starch/water systems. In this study the same time/temperature treatments were applied to starch/water systems and to potato starch in situ. Two potato varieties (Solanum tuberosum cultivars Asterix and Bintje) were used. The effect of time/temperature treatments on gelatinisation behaviour was evaluated using differential scanning calorimetry (DSC). A blanching process was simulated by heating samples to 74 °C and then cooling them to 6 °C. A DSC scan showed that starch was completely gelatinised after this treatment. Retrogradation of amylopectin increased during storage at 6 °C from 0 to 24 h after blanching. Annealing of starch, with the aim of altering cooking properties, was performed by heating samples to temperatures below the gelatinisation onset temperature. Treating samples at 50 °C for 24 h caused a shift in gelatinisation onset temperature of 11–12 °C for isolated starch and 7–11 °C for in situ samples. The extent of the annealing effect depended on the difference between onset and annealing temperatures, and prolonged treatment time increased the effect. Starch/water systems and tissue samples behaved similarly when exposed to time/temperature treatments. The most apparent difference was the shift of gelatinisation to higher temperatures in tissue samples. Copyright © 2003 Society of Chemical Industry     

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.