17E-12 |
|
J. C. Ferreira, Food Science and Technology Departament, Santa Catarina Federal University, Rod. Admar Gonzaga 1346, Itacorubi, Florianópolis, 88034-001, Brazil, R. FETT, Departamento de Ciência e Tecnologia de Alimentos, Universidade Federal de Santa Catarina, Rodovia Admar Gonzaga, 1346, Florianopolis, 88040900, Brazil, M. L. Uvarova, Food Technology Departament, Campinas State University, Cidade Universitaria Zeferino Vaz, Campinas, 13881-970, Brazil, and D. Barrera-Arellano. The ability to form cohesive and stable foams is an important property in various food products. Protein foams are formed through the incorporation of air bubbles in a flexible protein film. The use of methods that modify the interfacial and surfactant nature of proteins is important, as a means of adding value to proteins of vegetable origin. A type of protein chemical modification is lipophilization, which permits a change in the functional properties related to hydrophilic/hydrophobic characteristics, through the incorporation of lipophilic groups in the protein molecules. Our objective was to evaluate the influence of lipophilization in different rates on foam expansion (FEX) and foam stability (FS) of peanut and cottonseed meals, comparing them to the properties of the non-modified raw materials. Lipophilization of peanut and cottonseed meals was carried out by direct addition of palmitic acid chloride in a basic medium (pH 9). The protein/chloride ratios studied were 1:0.5, 1:1 and 1:2 w/w and 1:0.25, 1:0.5 and 1:1 w/w for peanut and cottonseed meals, respectively. The determination of foaming properties was made according to Puski (1975) in 1% protein solutions at pH 7. FS was determined after 30 and 120 min. Statistical analyses were carried out using the STATISTIC 6.0 software. The results showed that in the peanut meal there was a significant reduction of FEX when compared to the non-modified raw material. This is probably due to a very efficient incorporation of fatty acids in original proteins. In cottonseed meal, FEX increased notably, more than 220%, 280% and 370% for the 1:0.25, 1:0.5 and 1:1 ratios, respectively. The increase in hydrophobicity promoted a reduction in interfacial tension. FES increased significantly for both lipophilized products, by the net increase of hydrophobicity and factors such as denaturation caused by lipophilization process and the formation of polymeric aggregates. These results suggest that lipophilization has a great effect on protein foaming properties, however, the modification does not depend solely on lipophilization rate but also on protein composition, distribution and conformation.
Session 17E, Food Chemistry: Proteins
|