The fruits of Cucurbita pepo L. var. melopepo Alef. are very much appreciated in low calory human diets, mainly for their delicate taste. Their carotenoid pattern has not yet been established, as both the epicarp and the mesocarp are white, suggesting that they contain no carotenoids. HPLC analysis of carotenoids from these fruits revealed a chromatographic pattern very similar to that of other fruits belonging to different varieties of Cucurbita pepo L. - a fact with great chemotaxonomic importance. The main carotenoids are lutein and ß-carotene; traces of violaxanthin, lactucaxanthin, ß-cryptoxanthin, 9Z-ß-carotene and 15Z-ß-carotene are also present. HPLC separation was achieved on a Nucleosil 120 - 5 C18 column, using the following mobile phases: A - acetonitrile : water (9 : 1) and B - ethyl acetate. The flow rate was 1 ml/min and the solvent gradient was as follows: from 0 to 16 min - 10 to 70% B, then from 16 to 25 min - 70 to 10% B. Quantification of the carotenoids was achieved by the internal standard method, using echinenone as internal standard. The total carotenoid content was found to be 1.12 µg carotenoids/g dry weight for the mesocarp and 3.62 µg carotenoids/g dry weight for the epicarp.
Authors:A. Păucean, D.C. Vodnar, V. Mureșan, F. Fetea, F. Ranga, S.M. Man, S. Muste, and C. Socaciu
The lactic acid bacteria are key microorganisms for the production and preservation of fermented dairy products, cheeses, sourdough bread, and lacto-fermented vegetables. This study was developed to monitor lactic acid produced by Lactobacillus plantarum ATCC 8014 and Lactobacillus casei ATCC 393, as single strains and combined, in fermenting media by Fourier Transform Infrared Spectroscopy coupled to multivariate statistical analysis. Media containing different mixtures of carbohydrates were chosen as model fermenting media for monitoring lactic acid concentration by infrared spectroscopy, due to the fact that vegetable and animal food matrices could contain different carbohydrates as carbon sources. Three different types of media were obtained by adding different carbohydrates to a basic MRS medium. HPLC was used as reference method for lactic acid quantification. The calibration set (n=36) was used for building model, while a validation set (n=13) for testing the robustness of the developed model. The coefficients of determination between predicted and reference values were 0.986 and 0.965, while root mean square error for calibration and validation sets recorded values of 0.127 and 0.263 g·l−1, respectively. Results confirmed the efficiency of FTIR spectroscopy combined with multivariate statistics, as a rapid, reliable, and cost-effective tool for routine monitoring of lactic acid.