| Popis: |
The colour of the pasta, an important quality aspect of this product depends mainly on the content of natural yellow pigment in the flour as well as on a number of eggs used [1]. Nowadays, pastas produced with or without eggs are being marketed ; the yellow colour of a former category is more pronounced than that of pastas containing no eggs. The yellowness of pasta is due to the presence of carotenoids in flour (and the eggs among which lutein, zeaxantine and b-carotene are dominating [2, 3]. The profile of carotenoids in flour depends on a wheat variety (botanical origin, growing conditions, processing etc.) or durom estivume. On the other hand it is the feed and a few other parameters that affect the profile of caroteonids in eggs. Several methods are currently in use to quantify yellow pigments in flours, eggs and pastas. Next to the time consuming, costly but a highly specific method such as the HPLC, there is a variety of the nonspecific techniques (examples are spectrophotometry, colorimetry, Raman spectrometry and photothermal methods) possessing the potential for a rapid assessment of total carotenoid content. This paper describes a study conducted on 13 commercially available dried pastas by several direct (no extraction) methods (such as colorimetry, Raman spectrometry and photoacoustic spectroscopy) and spectrophotometry. The pastas (all produced in Hungary) were purchased in Hungarian supermarkets. In addition to a pasta prepared without eggs, pastas made with 2, 4 and 8 eggs respectively have also been studied. For the clarity reasons, numbers 2, 4 and 8 refer to the actual number of eggs added to a 1 kg flour. To assure the unformity of samples when presented for the analysis, different pastas, normally produced in various shapes were crushed (coffee grinder) to a powder of a very fine grain size.. All direct methods show very good overall performance. The magnitude of the photoacoustic signal, the transformed colorimetric index DE* and the intensity of the Raman peak all exhibit a high degree of linear correlations with the pasta’ s total carotenoid content as determined by the conventional, spectrophotometry. |
