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 those allergic to proteins (phenylcetonurics), or to other products. It 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. On the other hand, it seems to be important to obtain new textures in food that can be highly appreciated by consumers as products for high gastronomy. For both purposes, edible surfactants can be useful. In this communication we present formulations where edible surfactants are included, on the one hand to obtain a substitute of mayonnaise without egg or milk, where mono-diglyceride (MDG) and lecithin (L) are used as surfactants, and on the other hand for obtaining foams, where lecithin and sucroesters (SE) are used instead.
Examples of recipes
Fig.1.
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.
Fig.2.
Frozen chocolate and milk air Milk air: 1L milk, 5g of soy lecithin. Hold the hand mixer in the surface of milk, to facilitate the incorporation of air bubbles. This will give a foaming and stable texture.
Aims
Chocolate air: 1L water, 400g noir chocolate, 50g hazelnut praliné and 5g of soy lecithin. Heat the water up to 90ºC and mix with the rest of ingredients using a hand mixer. Let cool to 45ºC and follow the same procedure as in the milk air.
The goals of this work were to optimize the formulations of mayonnaise substitute and several airs to obtain the desirable texture and taste with enough stability and a tolerable amount of edible surfactants.
Experimental
Mayonnaise substitute: A systematic study with several oil/water (O/W) ratios and several concentrations of surfactants (L and MDG) was done. The emulsions were characterized from the point of view of their rheological behavior and stability. Rheological measurements were performed in a HAAKE RS300 rheometer, using a serrated plate-plate to avoid slippage of the samples. Stability was assessed by measuring backscattering vs. time using TURBISCAN equipment MA2000. Food airs (light foams): Airs were obtained by holding a hand mixer on the surface of the liquid. Stability of foams was measured by means of Turbiscan. The surfactants (L and SE) concentration in water and the preparation methods were studied in order to determine the best conditions to obtain foams in aqueous systems for each recipe. For the optimum concentration, the influence of common salt, calcium ion, sugar and acidity on the properties and stability of foam was analized. Formation and stability of foams were investigated for fruit juices, vegetable juices, dairy foods, alcohol beverages and other the different kinds of foods.
Results and discussion Substitute of mayonnaise
Foams
For all the emulsions a clear predominance of storage modulus is observed, indicating that the elastic component predominates. As an example, the sample with an O/W ratio of 3/1 and 1wt% L+4wt%MDG is shown in Figures 3 and 4. This sample was the most similar to the conventional mayonnaise. Higher G’ and G” values are found at 4ºC, pointing out that emulsions are more stable when stored in the fridge. The rheological parameters also increase with the O/W ratio, as expected for an oil-in-water emulsion. G’ and G” increase with total concentration of surfactants, according to the formation of more but smaller droplets when this concentration increases. . Several %L:%MDG ratios. T=4ºC and 20ºC Fig. 1. G’G' ofvs. frequency sweep emulsions several O/W. T=20ºC and 4ºC. 1%wt L+4%wt MDG. 10000 O/W=3/1
G" vs. . Several %L:%MDG ratios. T=4ºC and T=20ºC 10000
1000
G" [Pa]
G' [Pa]
1000
100
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
Several airs were prepared and stability was measured. Results of backscattering for different positions of the tube can be represented versus time. Only as some examples, in figures 8-10 backscattering evolution with time for different systems are shown. Backscattering evolution with time 30
Backscattering (%)
A. Rheological measurements
20 15 mm bottom 25 mm botton 35 mm botton 45 mm bottom 10
0
100
0
10
20
30
40
Time (minutes)
Fig. 8. Backscattering evolution with time for water-sucroester foam. 0.5wt% L:2%MDG, 20ºC 0.75wt% L:3%MDG, 20ºC 1wt% L:4%MDG, 20ºC
1 0.01
0.1
1 [rad/s]
10
0.5wt% L:2%MDG, 4ºC 0.75wt% L:3%MDG, 4ºC 1wt% L:4%MDG, 20ºC
10
O/W=3/1 100
Fig. 3. G’ of frequency sweep emulsions at several %L:%MDG. T=20ºC and 4ºC. O/W=3/1.
1 0.01
Backscattering evolution with time 60
0.1
1 [rad/s]
10
100
Fig. 4. G” of frequency sweep emulsions at several %L:%MDG. T=20ºC and 4ºC. O/W=3/1.
B.Stability
50
Backscattering (%)
10
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 coalescence is less favored. However, these samples are unsalted. If salt is added to that samples, they become quite unstable due to coalescence (Fig.7), at least after the first hour. Then, salt should be added just some minutes before the serving of the dish.
40 15 mm bottom 25 mm botton 30
35 mm botton 40 mm bottom
20
10
0 0
5
10
15
20
Time (minutes)
Fig. 9. Backscattering evolution with time for milk-lecithin foam.
Backscattering evolution with time 60
Fig. 5. Back scattering of emulsions with O/W=4/1 and 1/L:4%MDG. T=20ºC.
Fig. 6. Back scattering of emulsions with O/W=3/1 and 1/L:4%MDG. T=20ºC.
Fig. 7. Back scattering of emulsions with O/W=3/1 and 1/L:4%MDG. T=20ºC. Salted.
Conclusions
A quite stable highly concentrated emulsion of olive oil in water, with texture, color and flavor similar to that of conventional mayonnaise can be obtained without egg nor milk, using edible surfactants as lecithin and monodiglycerid. Light foams with enough stability and quite homogeneous can be prepared with lecithin or sucroesters as surfactants and a variety of foods: Sodium Chloride facilitates foaming with lecithin, but it has a negative effect with sucroester at ambient temperatures, and it has no effect at higher temperatures.
Sugar has a negative effect with lecithin, and it has no effect with sucroester.
Acidity does not affect lecithin and sucroester foaming.
For clear fruit juices and L or SE, the presence of pulp avoid the foam formation.
Milk foams at ambient temperature are difficultly obtained. Higher temperatures facilitate the preparation of foam.
Alcoholic beverage foams can be prepared, but the less amount of alcohol, the more stability.
Backscattering (%)
50
40 30 mm bottom 35 mm botton
30
40 mm botton 45 mm bottom
20
10
0 0
2
4
6
8
10
Time (minutes)
Fig. 10. Backscattering evolution with time for gin-water-sucroester foam.
Acknowledgment Financial support from CYCYT CTQ2005-09063-C03-01/PPQ is gratefully acknowledged.