Partial Replacement of Egg White Proteins with Whey Proteins in Angel Food Cakes

This study was conducted to investigate the effects of partial replacement of egg white proteins (EWP) with whey protein isolate (WPI) on the appearance, structure, texture, and sensory properties of angel food cakes baked in conventional and microwave/conventional ovens. Factors studied were: 1) replacement of 25% or 50% of EWP with WPI; 2) added xanthan gum (XG), methyl cellulose (MC), cupric sulfate (Cu⁺²) or sodium phosphate (PHOS); and 3) conventional vs microwave/conventional oven baking. EWP replacement cakes without additives were generally inferior to 100% EWP control cakes, whereas EWP replacement cakes with added XG were most similar to 100% EWP control cakes with respect to appearance, texture, and sensory properties and those with added MC exhibited air cell size distributions that most closely resembled control cakes. The other additives and microwave/ conventional vs conventional baking had minor effects on the quality of EWP replacement cakes.     

Cake Baking in Conventional, Impingement and Hybrid Ovens

White layer cakes were baked in three types of air impingement ovens, a hybrid (microwave/air impingement) oven, and a reel oven. Cakes were evaluated based on volume, crust color, and texture. Oven heat transfer rates were measured directly, and ranged from 22.8 to 84.8 J/s m²C° for top and from 17.4 to 110.9 for bottom surfaces, exposed in the different ovens, with the conventional reel oven having the lowest values. An RSM design was used to establish optimum baking conditions for each oven. For air impingement ovens, baking time was reduced by almost half but produced cakes very similar to those from the control (reel) oven. Incorporating microwaves enabled a further reduction in baking time, to one fourth. Cakes baked with microwaves had similar color, but had 15% less volumes and firmer textures than control cakes.     

Quality characteristics of egg-reduced pound cakes following WPI and emulsifier incorporation

The effect of partial (50 wt%) or total liquid egg replacement by whey proteins in combination with emulsifiers, i.e. hydroxypropylmethylcellulose (HPMC) and sodium stearoyl-2-lactylate (SSL), on the quality of pound cakes was investigated. Cakes containing whey protein isolate (WPI) solutions of varying concentrations (i.e. 20, 17 and 14% w/v) were first prepared. Complete egg replacement by WPI led to the preparation of cake batter of increased specific gravity as well as to final cake products of inferior quality with regard to volume, texture and hardness increase upon storage, compared to the control. In the case of partial liquid egg replacement by WPI solutions, cakes with acceptable sensory and quality characteristics were obtained, which were further improved following the addition of emulsifiers. During a storage period of four days the egg-reduced cakes exhibited a significantly lower staling rate depending mainly on the concentration of WPI and the presence of emulsifiers. Finally, the analysis of cake microstructure confirmed the positive effect of the co-addition of whey proteins and emulsifiers in egg-reduced cakes. This work made it possible to develop an alternative, egg-reduced cake of satisfactory quality, by using a combination of whey proteins with two common baking additives.     

Effect of processing conditions on the stability of annatto (Bixa orellana L.) dye incorporated into some foods

Annatto dye is an orange-yellow pigment extensively used in dairy products. Studies were carried out to determine the stability of bixin (oil-soluble dye) during different treatments and processing in traditional foods of India. The annatto dye was exposed to heat treatments in a baking oven at 100, 150 and 180 °C for time periods up to 60 min; deep fat heating at 160, 180 and 200 °C for periods ranging from 30 to 120 s; microwave oven at 300 and 700 W for periods ranging from 15 to 60 s; and in a pressure cooker for a 15-min period. The losses in bixin concentration during these experiments were compared with the losses of bixin in the preparation of products like cakes, chegodis, biscuits and fried rice. The mass fractions of bixin lost were maximum when the dye was exposed directly to heating in a baking oven (0.54) and in deep fat heating (0.47). The mass fraction of bixin lost was 0.30 in cakes and negligible losses were observed in biscuits (0.015). In case of the deep fat fried snack, the dye leached in to the oil, which resulted in maximum loss (0.65). Microwaves did not affect the bixin in the dye when exposed directly or in the products. Pressure cooking resulted in mass fractions of bixin lost (0.25–0.33) comparable to those of other products.     

Effect of Substitution of Melon with Soybean on the Nutrient Content and Sensory Properties of Traditional Cakes

Traditional cakes were prepared from a blend of melon and soybean meal. The blended meal contained 10% and 20% soybean respectively while unblended meal contained 100% melon meal which served as control. Cakes obtained from the blends were analysed for proximate composition, amino acid content and organoleptic properties. The moisture content and protein content of the cakes increased significantly (p < 0.05) as the level of soybean inclusion was increased while the fat, ash and crude fibre contents of the cakes decreased significantly (p < 0.05) as the level of soybean inclusion was increased. Inclusion of as little as 10% soybean increased the quantity of amino acids in the cake than the control cake. The organoleptic properties of the cakes were also acceptable at 10% level of soybean inclusion.     

Optimization of microwave baking of model layer cakes

 Response surface methodology was used to optimize the formulation of microwave-baked cakes. The independent variables were water content, emulsifier content baking time, oven power, shortening content and starch type. The quality factors evaluated were specific gravity of batter and volume index, uniformity index and tenderness of the crumb. Constraints for quality factors were obtained by conventional baking of American Association of Cereal Chemists high-ratio cake formulation. Multiple contour plots showed the optimum region for various water and shortening combinations at different emulsifier, time and power levels. Cakes formulated with wheat starch, containing 0.3% polysorbate 60, 133.7% water and 45.2% shortening (flour substitute basis), baked for 6 min at 100% power yielded acceptable cakes that can compete with conventionally baked cakes. Rice and corn cakes had lower quality than conventionally baked high-ratio cakes. Power was found to be the most efficient independent variable affecting all the dependent variables. Received: 26 August 1999 / Revised version: 11 October 1999     

Effects of Microwave/Convection Baking and Pan Characteristics on Cake Quality

The quality of devil's food cake baked in a microwave/convection oven using different oven conditions and pan characteristics was assessed by sensory and objective methods. The most important factors were the number of layers baked at a given time and the baking pan characteristics, followed by initial oven temperatures. Crust color, moistness and cake symmetry were affected by these conditions. For example, single layers received a lower sensory score and had sticky and less red crusts than double layers. Cakes baked in glass-polyester microware pans were peaked, whereas those baked in aluminum pans were flat. Although slight differences in quality were found by both sensory and objective evaluations, all cakes were acceptable.     

Effects of sucrose on egg white protein and whey protein isolate foams: Factors determining properties of wet and dry foams (cakes)

The effects of sucrose on the physical properties of foams (foam overrun and drainage ½ life), air/water interfaces (interfacial dilational elastic modulus and interfacial pressure) and angel food cakes (cake volume and cake structure) of egg white protein (EWP) and whey protein isolate (WPI) was investigated for solutions containing 10% (w/v) protein. Increasing sucrose concentration (0–63.6 g/100 mL) gradually increased solution viscosity and decreased foam overrun. Two negative linear relationships were established between foam overrun and solution viscosity on a log–log scale for EWP and WPI respectively; while the foam overrun of EWP decreased in a faster rate than WPI with increasing solution viscosity (altered by sucrose). Addition of sucrose enhanced the interfacial dilational elastic modulus (E′) of EWP but reduced E′ of WPI, possibly due to different interfacial pressures. The foam drainage ½ life was proportionally correlated to the bulk phase viscosity and the interfacial elasticity regardless of protein type, suggesting that the foam destabilization changes can be slowed by a viscous continuous phase and elastic interfaces. Incorporation of sucrose altered the volume of angel food cakes prepared from WPI foams but showed no improvement on the coarse structure. In conclusion, sucrose can modify bulk phase viscosity and interfacial rheology and therefore improve the stability of wet foams. However, the poor stability of whey proteins in the conversion from a wet to a dry foam (angel food cake) cannot be changed with addition of sucrose.     

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.     

Influence of yeast and vegetable shortening on physical and textural parameters of frozen part baked French bread

The objective of this project was to study the influence of yeast and vegetable shortening on physical and textural parameters of frozen part baked French bread stored for 28 days and to produce a frozen part baked bread with physical and textural characteristics similar to those of the fresh one. Four formulations were used with different quantities of yeast and vegetable shortening. Dough was prepared by mixing all ingredients in a dough mixer at two speeds. After resting, the dough was divided into 60 g pieces, molded and proofed. The bread was partially baked for 7 min at 250°C, in a turbo oven. After cooling, it was frozen until the core temperature reached −18°C and stored at the same temperature up to 28 days. Once a week, samples were removed from the freezer to complete the baking process, without previous thawing. Mass, volume, water content, firmness, cohesiveness and springiness were measured 1 h after final baking. Resistance to extension and extensibility of dough were measured after mixing. Specific volume and chewiness were determined. Bread with higher yeast content presented a higher specific volume, whereas vegetable shortening reduced its crumb firmness and chewiness.     

Optimization of Baking of Rice Cakes in Infrared–Microwave Combination Oven by Response Surface Methodology

In this study, response surface methodology was used to design gluten-free cakes made from rice flour to be baked in infrared-microwave combination oven. Two types of cake formulations containing different types of gums were used in the experiments, which were xanthan gum and xanthan–guar gum blend. The independent variables were emulsifier content (0, 3, and 6% of flour weight), upper halogen lamp power (50, 60, and 70%), and baking time (7, 7.5, and 8 min). Specific volume, surface color change, firmness and weight loss of the cakes were determined for optimization. Cakes formulated with xanthan gum had better quality characteristics than cakes containing xanthan–guar gum blend. Cakes formulated with xanthan gum and 5.28% emulsifier and baked using 60% halogen lamp power for 7 min had the most acceptable quality.     

Water vapor transport properties during staling of bread crumb and crust as affected by heating rate

In order to develop a mathematical model to simulate mass transfer occurring between the crumb and the crust during bread staling, water vapor sorption properties, i.e., moisture diffusivity, WVP and sorption of bread crumb and crust were investigated at 15 °C. Two types of bread baked with two heating rates (7.39 °C/min and 6.32 °C/min) were considered. Sorption and desorption isotherms were determined using Dynamic Vapor Sorption (DVS) and FF and GAB models were applied in the range of 0–0.95 a_w, to fit isotherm curves. Diffusivity was determined from sorption isotherms by using Fick's law and WVP was measured by two methods (gravimetric and from sorption data). Results exhibited maximum values of D_eff in the range of 0.1 and 0.14 g/g d.b. moisture contents. They varied between 0.88 × 10^? 10 and 0.92 × 10^? 10 m²/s for the crust and between 2.24 × 10^? 10 and 2.64 × 10^? 10 m²/s for the crumb, baked respectively at 220 °C and 240 °C. Results of WVP showed that the crust baked at 240 °C was significantly more permeable than the crust baked at 220 °C. This fact was attributed to the difference in porosity and the molecular structure due to heating effects. Also, the presence of steam in the oven atmosphere enhanced the development of higher porosity in the crust, leading to different structures and properties. Moreover, SEM images showed that starch granules were intact and less swelled in the upper crust when baking at 240 °C, resulting in higher WVP.     

Comparison of properties of oil-in-water emulsions stabilized by coconut cream proteins with those stabilized by whey protein isolate

Coconut cream protein (CCP) fractions were isolated from coconuts using two different isolation procedures: isoelectric precipitation (CCP1-fraction) and freeze–thaw treatment (CCP2-fraction). The ability of these protein fractions to form and stabilize oil-in-water emulsions was compared with that of whey protein isolate (WPI). Protein solubility was a minimum at ∼pH 4, 4.5 and 5 for CCP1, CCP2, and WPI, respectively, and decreased with increasing salt concentration (0–200 mM NaCl) for the coconut proteins. All of the proteins studied were surface active, but WPI was more surface active than the two coconut cream proteins. The two coconut cream proteins were used to prepare 10 wt% corn oil-in-water emulsions (pH 6.2, 5 mM phosphate buffer). CCP2 emulsions had smaller mean droplet diameters (d₃₂ ≈ 2 μm) than CCP1 emulsions (d₃₂ ≈ 5 μm). Corn oil-in-water emulsions (10 wt%) stabilized by 0.2 wt% CCP2 and WPI were prepared with different pH values (3–8), salt concentrations (0–500 mM NaCl) and thermal treatments (50–90 °C for 30 min). Considerable droplet flocculation occurred in the emulsions near the isoelectric point of the proteins: CCP2 (pH ∼ 4.3); WPI (pH ∼ 4.8). Emulsions with monomodal particle size distributions, small mean droplet diameters, and good creaming stability could be produced at pH 7 for WPI, but CCP2 produced bimodal distributions at this pH. The CCP2 and WPI emulsions remained relatively stable to droplet aggregation and creaming at NaCl concentrations ⩽50 and ⩽100 mM, respectively. In the absence of salt, both CCP2 and WPI emulsions were quite stable to thermal treatments (50–90 °C for 30 min).     

Extending shelf life of chapatti by partial baking and frozen storage

The effect of conventional and partial baking and storage at two different temperatures (ambient and −18 °C) on the texture of wheat flour chapatties was evaluated using tensile deformation and the extent of retrogradation was studied using DSC. The extensibility of the conventionally baked chapatti decreased by 58.7% and 20.15%, respectively after storage of 24 h at ambient and frozen temperature. The partially baked chapatti showed a much lower decrease of 3.7% and 0.01% in extensibility when stored under the same conditions. Chapatties, both conventionally and partially baked stored at ambient temperature showed higher retrogradation enthalpy than their counterparts kept at −18 °C. Extended frozen storage of the chapattis from partially baked chapatti resulted in a progressive increase in the extensibility whereas the extensibility of the conventionally baked chapatties was not affected. Lowest water absorption index of 4.60 was observed in partially baked chapatti stored for 24 h at ambient temperature indicating that maximum retrogradation (4.19 J/g) had taken place. Frozen partially baked chapatties after thawing and rebaking exhibited texture equivalent to that of conventionally baked chapatties therefore they could be considered a better option than frozen conventionally baked chapatties for retarding staling.     

Apparent Heat Transfer in a Forced Convection Oven and Properties of Baked Food

Parameters for expressing the heating performance and baking results of sponge cakes dependent on heating performance in a forced convection oven were studied. The heating performance of a forced convection oven may be expressed by the apparent heat transfer coefficient which was measured at various air temperatures and velocities. Both the air velocity and temperature of the circulating air affected the apparent heat transfer coefficient in a forced convection oven and determined the final properties of the baked food. The effects of these parameters on sponge cakes baked in the forced convection oven were observed.     

X-ray diffraction analysis of lactose crystallization in freeze-dried lactose–whey protein systems

Water sorption, time-dependent crystallization and XRD patterns of lactose and lactose–WPI mixtures were studied with glass transition data. The results indicated that the sorbed water of lactose–WPI mixtures was fractional and water content of individual amorphous components in lactose–WPI mixtures at each a_w from 25 °C to 45 °C could be calculated. Crystallization occurred in pure lactose whereas partial crystallization was typical of lactose–WPI mixtures (protein content ≤ 50%) at intermediate and high a_w (> 0.44 a_w) from 25 °C to 45 °C. The extents of crystallization were significantly delayed by WPI. The T_g values of lactose–WPI systems showed the composition-dependent property in systems and might indicate the occurrence of phase separation phenomena during 240 h storage. XRD showed no anhydrous β-lactose and mixed α-/β-lactose with molar ratios of 4:1 crystals in crystallized lactose–WPI systems (70:30 and 50:50 solids ratios). Reduced crystallization in the presence of WPI was more pronounced possibly because of reduced nucleation and diffusion during crystal-growth. The present study showed that WPI could present an important role in preventing sugar crystallization.     

Influence of emulsifier type on in vitro digestibility of lipid droplets by pancreatic lipase

The objective of this study was to investigate the influence of interfacial composition on the in vitro digestion of emulsified lipids coated by various emulsifiers by pancreatic lipase. Sodium caseinate, whey protein isolate (WPI), lecithin and Tween 20 were used to prepare corn oil-in-water emulsions (3 wt% oil). Pancreatic lipase (1.6 mg/mL) and/or bile extract (5.0 mg/mL) were added to each emulsion and the particle charge, droplet aggregation, microstructure and free fatty acids released were measured. In the absence of bile extract, the amount of free fatty acids released per unit volume of emulsion was much lower for lipid droplets coated by Tween 20 (13 ± 16 μmol ml⁻¹) than those coated by lecithin (75 ± 20 μmol ml⁻¹), sodium caseinate (220 ± 24 μmol ml⁻¹) or WPI (212 ± 6 μmol ml⁻¹). In the presence of bile extract, there was an appreciable increase in the amount of free fatty acids released in all the emulsions, with the most appreciable effects being observed in the Tween 20-stabilized emulsions. The stability of the emulsions to droplet flocculation and coalescence during hydrolysis was also strongly dependent on emulsifier type, with the WPI emulsions being the least stable and the Tween 20 emulsions being the most stable. Our results suggest that the access of pancreatic lipase to emulsified fats decreases in the following order: proteins (caseinate and WPI) > phospholipids (lecithin) > non-ionic surfactants (Tween 20). These results may have important consequences for the design of foods with either increased or decreased lipid bioavailability.     

Acrylamide and 5-hydroxymethylfurfural formation during baking of biscuits: NaCl and temperature–time profile effects and kinetics

The present study aimed to investigate the effect of recipe and temperature–time on the formation of acrylamide and 5-hydroxymethylfurfural (HMF) during biscuit baking. Baking experiments were performed with biscuits of two different recipes, with and without NaCl, at 180 °C, 190 °C and 200 °C. Acrylamide and HMF reached highest concentrations at 200 °C for both recipes. The presence of NaCl in the biscuit formulation lowered acrylamide concentrations at 180 °C and 190 °C but not at 200 °C, and led to higher concentrations of HMF at all the tested temperatures. Sucrose hydrolysis was a key step in acrylamide and HMF formation during biscuit baking, even though a significant amount of acrylamide already had formed before the onset of sucrose hydrolysis. A lag phase was observed before sucrose hydrolysis occurred, which might depend on the melting of crystalline sucrose occurring at approximately 180 °C.A mathematical model based on the chemical reaction pathways was developed for the recipe with NaCl baked at 200 °C. The model described the chemical evolution during the last part of biscuit baking, and accurately predicted acrylamide and HMF content at the end of baking. The model showed the significant contribution of the reducing sugars to the formation of both acrylamide and HMF. The model could not be extended to the entire baking period because it was not possible to incorporate the lag phase observed before sucrose hydrolysis. The results reported in this study confirm that the kinetics of acrylamide and HMF formation in real food and dry systems may depend on the physical state of their precursors.     

Effect of Flour Type and Baking Temperature on Cake Dynamic Height Profile Measurements During Baking

A dynamic height profile method using digital imaging of cakes at 2 min intervals during baking was used to analyze changes in volume during baking for cakes made with three different flour types (plain flour, heat-treated cake flour, and strong white flour) and baked at three different temperatures (175°C, 190°C, and 205°C). The cakes made from the different flours showed, with some exceptions, a similar trend in the shape and development of the top contour during baking. In the first 4–6 min of baking, there was relatively little expansion followed by a period of rapid expansion to the maximum volume and a period of contraction up to the end of baking. For the three flour types, volume peaked at 16–17 min for the medium and high baking temperatures and at 20 min for the low baking temperature. Cakes made from heat-treated cake flour and strong white flour baked at low and high temperatures produced cakes where the center of the cake was lower than the surrounding pins resulting in a final undesirable dimpled cake contour. A higher baking temperature caused the cake to rise more rapidly. Baking at high temperature produced cakes which shrank the most (P < 0.001) during cooling. Among all combinations of flour type and different temperature treatments, cake made from heat-treated cake flour baked at the middle temperature produced the best final cake in terms of a final dome-shape contour, an appreciable volume during baking, less volume shrinkage during baking, and maximum cross-sectional area of the half cake after 1 h cooling.     

Optimization of halogen lamp–microwave combination baking of cakes: a response surface methodology study

The main objective of this study was to optimize processing conditions during halogen lamp–microwave combination baking of cake by using response surface methodology. The independent variables were the power of the upper halogen lamp (50, 60, and 70%), the power of the lower halogen lamp (50, 60, and 70%), the power of the microwaves (30, 40, and 50%), and the baking time (4, 5, and 6 min). Weight loss, specific volume, color, and the texture profile of the cakes were determined. The upper halogen lamp power, the microwave power, and the baking time were found to have a significant effect on the weight loss, the specific volume, and the firmness of the cakes. Cakes baked for 5 min at 60% upper halogen lamp power, 70% lower halogen lamp power, and 30% microwave power had quality comparable with conventionally baked ones, except for color. By the usage of a halogen lamp–microwave combination oven it was possible to obtain high-quality cakes by reducing the conventional baking time by about 79%.