Emulsions in novel foods: new textures and new formulations for protein allergic groups Aguilera, Y.1, Gutiérrez, J. M.1, Maestro, A.1, Castells, P.2, Farré, I.2, Biarnés, J.2, and González, C.1 1 Departament d’Enginyeria Química, Universitat de Barcelona; 2 Fundació Alicia Tlf: 34 93 402 9013 Fax: 34 934021291 e-mail: carme.gonzalez@ub.edu
Introduction There are some groups of people that are allergic or intolerant to different foods, like that allergic to proteins (phenylcetonurics ), or to other products. It (phenylcetonurics), is important to find some foods similar to the conventional ones in flavor, aspect and texture, but without including the components that they cannot eat. In this communication we present a substitute of mayonnaise without egg nor milk. This new food consists on a highly concentrated oiloil-inin-water emulsion (O/W). The edible surfactants used for the stabilization of the emulsion emulsion are monomonodiglyceride (MDG) and lecithin (L). A systematic study with several O/W ratios ratios (2/1, 3/1 and 4/1), and several concentrations of surfactants (0.5%L/2%MDG, (0.5%L/2%MDG, 0.75%L/3%MDG, and 1%L/4%MDG), was done. The emulsions were characterized characterized from the point of view of their rheological behavior and stability. Moreover, we explored foods with new textures, like a texturized oil prepared with MDG, that can be spread on a slice like a cream.
Fig.1.
Fig.2.
Recipes Highly concentrated emulsion as a substitute of mayonnaise (asparagus with foam of mayonnaise alicia and mustard) Asparagus: Cut the fibrous stem of the asparagus. Peel them, and boil for 3 min. Cool in water with ice. Mayonnaise: Warm 75 ml of oil with 4g of monodiglyceride. Dissolve 1g of lecithin in 25ml of water. Add little by little the oil (with monodiglyceride) to the water (with lecithin). Put the mayonnaise in the siphon with cartridge of CO2. Serve: Foam the mayonnaise on the plate and put the asparagus and touches of mustard.
Texturized oil (pa amb tomà tomàquet) quet) Texturized oil: 200 g of olive oil, 20g monodiglyceride. Heat the mixture up to 60ºC until monodiglyceride is completely dissolved. Let cool in the refrigerator. Bread: Cut a loaf of bread in thin slices and toast for one side. Extract the seeds from the tomatoes. Serve: Tomato over the bread with small amount of texturized oil. If desired, add some herbs (oregano, parsley, etc).
Experimental
Fig.3. Emulsions prepared with olive oil, water (3/1), L and MDG were very viscous. A hydrophobic colorant (Sudan IV) and a hydrophilic one (methylene blue) were poured on the emulsion, and only the hydrophilic one penetrated the emulsion by diffusion, confirming the emulsion was a direct O/W one.
O/W emulsions were prepared at several O/W ratios and several total total surfactant concentrations, using in all cases a L:DMG ratio=1:4. ratio=1:4. Rheological measurements were performed in a HAAKE RS300 rheometer, rheometer, using a serrated plateplate-plate to avoid slippage of the samples. Rheological experiments were carried out at controlled temperatures of 4º 4ºC (temperature in the fridge), and 20º 20ºC (mean temperature of the dish when it is served). Dynamic frequency sweep measurements were were performed in the linear viscoelastic regime, which was previously determined by dynamic stress sweep measurements. Stability was assessed assessed by measuring the increase in backscattering using TURBISCAN equipment MA2000.
Results and discussion Substitute of mayonnaise
Texturized oil
A. Rheological measurements For all the emulsions, comparison of G’ G’ with the corresponding G” G” (Fig.3(Fig.3-Fig.4; Fig.5Fig.5-Fig.6) points out a clear predominance of storage modulus, indicating that the elastic component component predominates. Moreover, higher G’ G’ and G” G” values are found at 4º 4ºC. This increase could take to higher stability when the emulsion emulsion is stored into the fridge. On the other hand, the rheological parameters also increase with the O/W ratio, as expected for an oiloil-inin-water emulsion. G’ G’ and G” increase with total concentration of surfactants, according to the formation of more but smaller droplets when this concentration increases. The sample with an O/W ratio of 3/1 and 1wt% L+4wt%MDG was the most similar to the conventional mayonnaise. G" vs. frequency. Several O/W ratios. T=4ºC and 20ºC
G' vs. frequency. Several O/W ratios. T=4ºC and 20ºC 10000
O/W=2/1, 4ºC O/W=3/1, 4ºC O/W=4/1, 4ºC
G' [Pa] G" [Pa] G',G"(Pa)
G" [Pa]
G' [Pa]
O/W=2/1, 20ºC O/W=3/1, 20ºC O/W=4/1, 20ºC
O/W=2/1, 4ºC O/W=3/1, 4ºC O/W=4/1, 4ºC
1000
Texturized oil. T=20ºC 10000
10000 O/W=2/1, 20ºC O/W=3/1, 20ºC O/W=4/1, 20ºC
Rheology of the texturized oil was measured at 4º 4ºC (temperature in the fridge) and 20º 20ºC (temperature of the oil when it is served). It can be seen that the addition of MDG to the oil gives to it an important important viscoelastic behavior with a clear predominance of storage modulus. It can be explained because the MDG is dissolved into the oil at high temperature, but when the mixture is cooled, it solidifies. G’ G’ and G” G” are higher in the fridge (4º (4ºC) than when the dish is served (20º (20ºC). The resultant rheology at room temperature allows to spread the oil on a slice like a cream. The systems were were very stables.
1000
100 0.001
wt% L:wt% MDG=1:4 0.1
1 ω [rad/s]
10
100 0.01
100
Fig. 3. 3. G’ of frequency sweep emulsions at several O/W. T=20ºC and 4ºC. 1%wt L+4%wt MDG.
G" [Pa]
G' [Pa]
1000
0.1
1 ω [rad/s]
0.01
0.1 1 ω (rad/s)
10
100
Fig. 8. 8. Frequency sweep of texturized oil prepared as said in recipe 2. T=20ºC.
Texturized oil. T=4ºC
0.5wt% L:2%MDG, 20ºC 0.75wt% L:3%MDG, 20ºC 1wt% L:4%MDG, 20ºC
0.5wt% L:2%MDG, 4ºC 0.75wt% L:3%MDG, 4ºC 1wt% L:4%MDG, 4ºC
10000
G' [Pa] G" [Pa] 100 0.01
O/W=3/1 100
Fig. 5. 5. G’ of frequency sweep emulsions at several %L:%MDG. T=20ºC and 4ºC. O/W=3/1.
1000
100
10
0.5wt% L:2%MDG, 4ºC 0.75wt% L:3%MDG, 4ºC 1wt% L:4%MDG, 20ºC
10
100
10000
100
1 0.01
10
G" vs. ω. Several %L:%MDG ratios. T=4ºC and T=20ºC
1000
0.5wt% L:2%MDG, 20ºC 0.75wt% L:3%MDG, 20ºC 1wt% L:4%MDG, 20ºC
1 ω [rad/s]
Fig. 4. 4. G” of frequency sweep emulsions at several O/W. T=20ºC and 4ºC. 1%wt L+4%wt MDG.
ω. Several %L:%MDG ratios. T=4ºC and 20ºC Fig. 1. ofvs. frequency sweep emulsions several O/W. 1. G’G' T=20ºC and 4ºC. 1%wt L+4%wt MDG. 10000 O/W=3/1
10
0.1
G',G"(Pa)
100 0.01
1000
1 0.01
0.1
1 ω [rad/s]
10
0.1
1 ω (rad/s)
10
100
Fig. 9. 9. Frequency sweep of texturized oil prepared as said in recipe 2. T=4ºC. 100
Fig. 6. 6. G” of frequency sweep emulsions at several %L:%MDG. T=20ºC and 4ºC. O/W=3/1.
B.Stability The stability of emulsions was measured for all the samples. It can be seen that the stability increases when O/W decreases (Fig.5 and 6), since less dispersed phase is present and and coalescence is less favored. favored. However, these samples are unsalted. If salt is added to that samples, they become quite quite unstable due to coalescence (Fig.7), at least after the first hour. Then, salt should be added some minutes before the serving of the dish.
Conclusions AAquite quitestable stablehighly highlyconcentrated concentratedemulsion emulsion of of olive oliveoil oilin in water, water,with withtexture, texture, color color and andflavor flavor similar similar to tothat that of of conventional mayonnaise can be obtained without egg nor conventional mayonnaise can be obtained without egg nor milk, . monodiglycerid milk, using usingedible edible surfactants surfactantsas aslecithin lecithinand andmonodiglycerid. monodiglycerid. Traditional pa amb Traditionalrecipes recipeswith withnovel noveltextures textures(e.g. (e.g. ““pa amb tomà àquet” tom quet”) can tomàquet”) canbe bedeveloped developedthrough throughaaproper proper preparation preparation of of texturized texturizedoil oilwhen whenaa10wt% 10wt%of of monodiglycerid monodiglyceridis isadded. added.
Acknowledgment Fig. 5. 5. Back scattering of emulsions with O/W=4/1 and 1/L:4%MDG. T=20ºC.
Fig. 6. 6. Back scattering of emulsions with O/W=3/1 and 1/L:4%MDG. T=20ºC.
Fig. 7. 7. Back scattering of emulsions with O/W=3/1 and 1/L:4%MDG. T=20ºC. Salted.
Financial support from CYCYT CTQ2005CTQ2005-0906309063-C03C03-01/PPQ is gratefully acknowledged.
1