Popescu Stela’s scientific contributions

We processed a batch from the Romanian wheat of the 2008 harvest in the mill, obtaining flour type 550, flour type 800 and bran. Both for the initial batch of wheat, and for each product obtained after its processing, we analyzed: moisture, ash content, total content of aflatoxins, ochratoxin A content and the content of heavy metals (cadmium and lead). We identified total amounts of aflatoxins from 3.74 ppb in flour type, 550 to 87.71 ppb in bran, while the content of ochratoxin A and heavy metals was situated below the limits set by the European health legislation. We also noted that the distribution of the concentration of contaminants was correlated with the extraction degree, namely: higher concentrations of contaminants were identified in the products of higher extraction.

One hundred flour samples of Romanian wheat, from the crops of the years 2005, 2006 and 2007 have been tested by determining the main physical and chemical quality parameters (moisture, wet gluten, gluten index, protein, ashes, Falling number) and viscoelastic parameters, specific to the alveographic method. Our results were included into a mathematical simulation, in order to elaborate predictive models for estimating the value of the alveographic parameters - mechanical work (W), resistance (P) and extensibility (L) – based on main physical and chemical quality parameters. Two predictive multifactorial models were developed, having the multiple determination coefficients (R2) bigger than 0.965, for each of the alveographic parameters. As for the mechanical work (W), all the physical and chemical parameters of the flour may be significant regressors for the predictive simulation of its value. The extensibility (L) parameter can also be estimated, taking into consideration all the parameters, excepting the gluten index parameter, which is an insignificant regressor. The alveographic resistance (P) can be modelled taking into consideration the parameters: Moisture, Protein, Falling number and ashes; the parameters Gluten index and Wet Gluten are insignificant regressors.

94 samples of white unbottled wine have been analyzed. The samples were derived from three varieties of grapes (White Feteasca, Blanc Sauvignon, Italian Riesling) grown in SC Ostrov S.A. The following quality parameters were determined for each sample: d 20 20 ,, alcohol (% vol), total dry extract (mg/l), free sugar (g/l), unreducing extract (g/l), total acidity (g/l C 4 H 6 O 6), free SO 2 (mg/l) and total SO 2 (mg/l). Statistical analysis showed that the best regressors for the studied white wines are the parameters Free sugar and Total dry extract. These regressors are involved in 2 of the 3 significant correlations between the quality parameters that are common to all analyzed varieties, namely: total dry extract-free sugar, total dry extract – unreducing extract and free sugar-alcohol content. For each of the three studied varieties we established a number of specific correlations. Thus, for the variety of White Feteasca wine, Total acidity was correlated with the Density parameter (r = 0.45 **), Total dry extract (r = 0.57 ***) and Dry unreducing extract (r = 0.49 **). For the wine of the Italian Riesling variety, Alcohol content was correlated with Total dry extract (r = 0.58 ***), with Unreducing extract (r = 0.47 **) and with Free sugar (r = 0.58 * **). The Blanc Sauvignon variety was characterized by correlations of the indices related to wine sulphitation, with other parameters. Thus, Free SO 2 correlated with the percentage of Alcohol (r = 0.38 *) and Total SO 2 with the Total dry extract (r = 0.82 ***) and with the Unreducing extract (r = 0.53 **).

There have been analyzed 670 wheat samples from the 2002, 2003, 2004 and 2005 crops, in order to establish the quality characteristics' yearly evolution. Our results show that Romanian wheat crops have been characterized by high values for the variation coefficients, associated with the quality parameters which describe the seed enzymatic activity (gluten deformation and falling number). The most constant quality parameters of Romanian wheat are Hectolitric Weight (Test Weight), Moisture and Protein Content. The most different crops from a qualitative point of view are those obtained in 2002 and 2005, which were years characterized by completely different climatic conditions. The medium (multiannual) mean coefficient for establishing the relationship between the protein content. and the wet gluten was 0.750 for Romanian wheat, value corresponding to a medium correlation coefficient of 0.866.

In order to obtain biscuits, there were used flours with different characteristics, from those used for obtaining other bakery products. In this way, the flours are treated with important quantities of L-cystein and/or proteases. Our investigations followed the evaluation of L-cystein (Cisto Pan), protease (Veron W) and their combinations addition impact, upon the alveographic parameters of the flour resulted from Romanian wheat. Our results showed that the L-cystein addition increases the dough extensibility (L), reduces the resistance (P) and the absorbed energy in the kneading process (W). The using of protease in combination with L-cystein cancells its effect upon the extensibility parameter (L) and emphasizes all the alveographic parameters' decrease (P, W, G, Ie, P/L).