Emilia Carnovale

Determination of folate vitamers in food and in Italian reference diet by high-performance liquid chromatography☆

A trienzyme treatment (conjugase, alpha-amylase, protease) followed by affinity chromatography and reversed-phase HPLC with UV and fluorescence detection was performed for the quantification of folate vitamers in legumes (chickpea and beans), processed meats (salami Milano and Parma ham) and in an Italian reference diet. This method allowed a good separation of six folate vitamers: 5-methyltetrahydrofolate, 5-formyltetrahydrofolate, folic acid, 10-formylfolic acid, 10-formyldihydrofolate and tetrahydrofolate within 30 min. Recovery, reproducibility and limits of detection of the method are reported. HPLC results were 24-52% lower than the microbiological assay findings.

Impact of processing on Fe dialysability from bean (Phaseolus vulgaris L.)

The influence of dehulling and cooking on in-vitro Fe dialysability from two varieties of Phaseolus vulgaris L. (mottled and white beans) was investigated. Fe and seed constituents (phytate, tannin, dietary fibre) were differently distributed between hull and cotyledon. Fe dialysability from mottled bean was 2.5%, from white bean 3.6%. Dehulling significantly decreased Fe dialysability (36%, P < 0.025) from both varieties. Cooking significantly reduced Fe dialysability from mottled bean (59%, P < 0.025), whereas in white bean no modifications were detected. On the other hand, cooking positively influenced Fe dialysability from cotyledon: compared with the raw samples, both varieties showed a significant increase (54%, P < 0.025) in Fe dialysability. This study showed that localization of both Fe and some seed constituents in seed affected Fe dialysability. Changes in food constituents (i.e. degree of protein digestion) account for the modifications in Fe dialysability subsequent to cooking.

Chemical evaluation of wild under-exploited Vigna spp. seeds

Abstract Eight wild Vigna spp. ( Vigna vexillata, Vigna vexillata macrosperma, Vigna luteola, Vigna oblongifolia, Vigna unguiculata dekindtiana, Vigna racemosa, Vigna reticulata, Vigna ambacensis ) were analysed for chemical characteristics (protein, amino acid profile, starch digestibility) and for antimetabolic compounds, such as trypsin inhibitors, cysteine proteinase inhibitors, lectins, phytic acid and tannins, in order to find useful material for improving the resistance and nutritional aspects of cowpeas. V. vexillata showed a high protein content of up to 293 g kg −1 , whereas all the accessions had high sulphur amino acids (2.05-3.63 g per 16 g N) and consequently a high chemical score. Moreover, the level of resistant starch was also high (64–75%). A wide variability was found in the trypsin inhibitors, tannins and lectins; V. luteola contained high levels of these compounds, whereas V. unguiculata dekindtiana, V. reticulata and V. ambacensis had very low levels. Significant positive correlations were found between bruchid resistance and trypsin inhibitor, tannin and resistant starch content.

Influence of protein components (G1, G2 and albumin) on Fe and Zn dialysability from bean (Phaseolus vulgaris L.)

The influence of bean proteins on in vitro Fe and Zn dialysability was studied. Albumin and globulins (G1, G2) from Phaseolus vulgaris were characterised by SDS-PAGE and disc electrophoresis. Fe and Zn dialysability from whole flour was 2.28 and 27.5% respectively. Among protein fractions, albumin showed the lowest mineral dialysability (0.4% for Fe, 2.5% for Zn) in spite of having the highest Fe and Zn content. Globulins (G1 and G2) differed mainly in Fe dialysability (2.99 and 5% respectively), while presenting a similar Zn dialysability (20.3 and 23.6% respectively). Protein dialysability from bean protein fractions showed the same trend observed for minerals (albumin < G1 < G2). Unlike the whole seed, in protein fractions protein and Fe solubility showed the same behaviour, i.e. rising in the pepsin phase of digestion and decreasing in the pancreatic phase. These differences suggest that the intermediate products of protein digestion are responsible for Fe binding and solubilisation from bean protein ...

Influence of the method of protein extraction on the in-vitro evaluation of mineral dialysability from legumes

Abstract The aim of this study was to investigate to what extent the in-vitro evaluation of iron, zinc and protein dialysability from legumes is influenced by the method of globulins extraction (G1, G2). According to classical methods, globulins were first extracted into salt solutions containing ascorbic acid. Because of the enhancing effect of ascorbic acid on iron availability, globulins extraction was also carried out in the absence of ascorbic acid. In the presence of ascorbic acid, a parallel reduction in total protein content and in iron and zinc content was detected, suggesting an interaction between minerals and protein components. Ascorbic acid markedly improved protein dialysability and G2 always showed a higher dialysability than G1. In the absence of ascorbic acid, iron dialysability was 3.0% from G1 and 5.5% from G2, while ascorbic acid caused up to a three-fold increase in iron dialysability. Ascorbic acid did not influence zinc dialysability (20% for G1 and 24% for G2). For both globulins, the higher the iron/protein ratio the higher the iron dialysability, indicating that the extent of interaction between iron and protein, as well as influencing protein digestion, likely affects in-vitro iron availability.

Relationship between in vitro Fe and Zn dialysability and peptide composition of albumin and globulins extracted from cooked bean (Phaseolus vulgaris L.)

In vitro dialysability of iron, zinc and protein was determined from whole bean (Phaseolus vulgaris), albumin and globulin (G1, G2) after cooking. Albumin showed the highest iron, zinc, protein and phytic acid content. Cooking increased iron and protein dialysability only in whole bean and albumin. Compared to globulins, albumin also presented a higher in vitro protein digestibility and cystine chemical reactivity. HPLC analysis of peptides in dialysates of bean and protein fractions suggested that some aggregation occurred during dialysis. The percentage of amino acids in dialysed peptides was found to be different between albumin and globulins. The difference in iron and zinc dialysability between albumin and globulins seems to depend on the phytic acid content of the albumin fraction and the protein properties of globulins.

13C NMR Study of the Natural Glycosides Vicine and Convicine

Abstract 13C NMR parameters have been obtained for vicine and convicine in DMSO, D2O/DMSO and D2O. Complete assignment of the spectra has been achieved. Interpretation of spin-lattice relaxation rates and heteronu-clear NOES has yielded evidence of intramolecular structuring in the case of vicine and not in that of ronvirine and also of a complex network of solute-solvent interactions.