Statistical design of experiments (DOE) applied to the study of new functional cheese derivatives

HÉCTOR STURNIOLO.; SONIA BARBERIS.; JORGE MAGALLANES.

Buenos Aires

Jornada; IV Jornadas Internacionales de Proteínas y Coloides Alimentarios; 2007

Universidad de Buenos Aires

The enzymatic protein hydrolysis is an attractive way to improve nutritional, functional and sensorial properties of foods. At the moment, it is applied to meats, cheeses, milk and its derivatives, in the preparation of salads, soups, sauces, drinks and pastes. From the nutritional point of view the protein hydrolysis is important in the formulation of special diets where it is necessary that the nutrients quickly are absorbed, as in the case of dysfunctions of the digestive system. From the sensorial point of view, the proteins in their natural state do not contribute chemically to the formation of flavors in foods. However, the hydrolysis products containing peptides and amino acids increase the flavor and they are more reactive with other food components such as sugars and fats, creating specific flavors. From the technological point of view, the used enzymes for obtaining protein hydrolyzed show excellent advantages on the chemical treatments; because of the last ones use drastic conditions of reaction, show low specificity and the residual reagents are difficult to eliminate. On the contrary, the enzymatic reactions are carried out in smooth conditions and with high specificity. In enzymatic processes of protein hydrolysis numerous variables should be considered (pH, temperature, time of hydrolysis, added amount of water, enzyme: substrate ratio, etc.) and so, it is necessary to carry out the efficient measurement of a several functional parameters of those hydrolyzed, with a suitable economy of trials, time and costs. In addition, these measurements must provide sufficient precision. Then, the aim of this work was carry out to a statistical design of experiments (DOE) for studying the functional parameters of protein hydrolyzed from goat cheese, which will be evaluated and modeled by means of chemometric techniques. A Doehlert statistical design was carried out, which has a fundamental characteristic: the factors have different numbers of levels. For more than three factors the number of levels is 3, for one of them is 5 and for all the rest are 7. This design allows assigning a greater number of levels to those factors that need more description and a minor number of levels to those factors that are difficult to change experimentally. In addition, this design allows increasing the number of parameters initially considered in the design. The following parameters were varied in this hydrolysis process: pH: 5 to 9, (7 levels). Temperature: 35 to 70 °C, (7 levels). Time of hydrolysis: 30 to 270 min., (7 levels). Amount of added buffer: 10 to 30 (g of buffer/protein g), (3 levels). Enzyme: substrate ratios: 5.5.10-3 to 0.22 (g /g of casein of the cheese), (5 levels). Then, 10 responses (functional parameter) were measured in 31 run (by duplicate): soluble proteins, free amine nitrogen, emulsifying properties (emulsifying activity index and emulsifying stability index), viscosity, water holding capacity, gel capacity, surface hydrophobicity and foaming properties (foam capacity and foam stability). The developed statistical design allowed obtaining the optimization of a multivariate process as the enzymatic hydrolysis of the goat cheese.