Hussein G. Daood

Determination of antioxidant vitamins in tomatoes

This study was conducted to investigate the antioxidant vitamin (vitamin E, vitamin C and β-carotene) content of one of the most important vegetables, tomato, using modern analytical techniques. High-performance liquid chromatographic procedures allowed the separation and quantification of these vitamins as well as their analogues in different cultivars. Carotenoid extract could be fractionated into 14 components, including lycopene, β-carotene and lutein as the major ones. Paired-ion liquid chromatography provided excellent separation of ascorbic acid with high peak purity. In addition to different analogues of tocopherol, ubiquinone-10 could also be separated and sensitively detected by normal-phase chromatography and fluorescence detection. The highest concentrations (3.15–3.98 μg g−1) of total tocopherol (mainly α-analogue) were found in tomato fruits of Katinka, Gitana and Floriset cultivars. The vitamin C content was maximal (36–48 mg per 100 g) in DRW 3126, Primato, Tampo and Monika cultivars. The highest values for β-carotene were found in Monika, Ultimo and Falcato cultivars (3.5–3.9 μg g−1). The dynamics of fruit ripening were also examined.

Antioxidant vitamin content of spice red pepper (paprika) as affected by technological and varietal factors

Abstract A study was conducted to investigate [by high-performance liquid chromatography (HPLC)]the antioxidant vitamin content of paprika during ripening, processing and storage. The most biologically effective antioxidant vitamins, such as ascorbic acid, tocopherols and carotenoids, were separated, identified and quantitated in different samples. The rate of in vivo synthesis of the three antioxidants increased after onset of the ripening process was induced in the climacteric fruits. As ripeness advanced, antioxidant vitamins tended to increase proportionally except that ascorbic acid reached a maximum level at the colour break-II stage and then declined. During drying and storage there was a dramatic decrease in the concentration of tocopherol and ascorbic acid as a result of active antioxidation performance, while carotenoid content decreased at a lower rate. Application of a forced-air drying technique resulted in a significantly high retention of antioxidant vitamins by dried or ground paprika. The different cultivars showed significant differences in their antioxidant vitamin contents.

High-performance Liquid Chromatography with Photodiode-array Detection of Carotenoids and Carotinoid Esters in Fruits and Vegetables

Summary A procedure for the simultaneous, one-step analysis of polar xanthophylls, xanthophyll mono- and diesters and geometric isomers of carotenes in selected fruits and vegetables using high-performance liquid chromatography (HPLC) and photodiode-array detector is described. The separation of carotenoid extracts was first performed on a column of 6 μm particles using different mobile phases and variable wavelength detectors to monitor column effluents. This procedure had limitations regarding separation efficiency and ease of spectrum analysis during the chromatographic run. The method was further developed by using a column of 6 μm particles and a mobile phase consisting of acetonitrile-isopropanol-methanol-water (39:52:5:4 v/v/v). This development permitted the isocratic separation of about 45 components in less than 50 minutes. Rapid and precise identification of the individual carotenoids was achieved by using photodiode-array detector under the control of chromatographic software which also allowed for rapid test of peak purity and complete mapping of the whole separation profile including major lipid classes and fat-soluble materials. A wide variety of carotenoids and carotenoid fatty acid esters were separated and quantified in selected fruits and vegetables such as spice red pepper, tomato, carrot, orange and apricot. cis isomers of β-carotene, the most effective provitamin A, were also separated and differentiated from their corresponding trans forms.

Chromatographic investigation of carotenoids, sugars and organic acids from Diospyros kaki fruits

Abstract A study was conducted to separate and determine carotenoid-type pigments, sugars and organic acids in persimmon fruits using high-performance liquid chromatography (HPLC) under isocratic conditions. The carotenoids were identified as cis-mutatoxanthin, antheroxanthin, zeaxanthin, neolutein, cryptoxanthins, α-carotene and β-carotene and fatty acid esters of cryptoxanthin and zeaxanthin. The fruits were found to be an excellent source of vitamin A: 1 g of edible portion provides about 54 IU of this vitamin. With respect to soluble sugars, the fruit contained mainly glucose, fructose and an unidentified oligosaccharide, but no sucrose could be detected in both unripe and ripe fruits. Ionpair HPLC allowed the separation and quantification of malic, isocitric, citric, ascorbic, fumaric and gallic acids, with malic acid being predominant. When fully ripe, metabolic processes led to a considerable loss in soluble sugars and organic acids in the fruit.

Effect of irrigation on yield parameters and antioxidant profiles of processing cherry tomato

A two-year (2010 and 2011) open field experiment was conducted to study the effect of drip irrigation and seasonal variation on the yield parameters and main bioactive components, carotenoids (mainly all trans, cis lycopene, and β-carotene), polyphenols (chlorogenic acid, caffeic acid, gallic acid, quercetin, rutin, naringin, etc.), and tocopherols of processing Strombolino F1 cherry tomatoes. The irrigated plants (STI) gave a higher marketable yield (61% and 101% respectively), and rain fed plants showed a yield loss. Water supply had a strong positive (R2=0.98) effect on marketable yield in 2011, but weak (R2=0.69) in 2010. In both years, the antioxidant concentration (all carotenoids, total polyphenols, tocopherols) showed a decrease with irrigation. Water supply affected the composition of carotenoids to a considerable extent. The optimum water supply treatment gave a lower proportion of lycopene than the rain fed control (STC) treatment. We observed significant negative correlation between rutin concentration and irrigation. The α-tocopherol concentration was significantly higher in STC treatments. Irrigation negatively influenced antioxidant concentrations of cherry tomato fruits, but higher yield could account for the concentration loss of individual fruits by higher antioxidant production per unit area.

HPLC Analysis of Carotenoids from Tomatoes Using Cross-Linked C18 Column and MS Detection

This study was conducted to analyze carotenoids from tomatoes by high-performance liquid chromatography using reversed-phase C18 silica having cross-linked end-capping with diode array and mass spectrometric detection. An efficient gradient elution system was developed to achieve good and reliable separation of both major and minor carotenoids as well as their isomers. Resolution of lycopene, β-carotene and their isomers was 0.91-3.97 and 1.02-2.86 with cross-linked and conventional C18 column, respectively. The % recovery for zeaxanthin, lycopene and β-carotene was found to be in the range of 89-97%. Limits of detection and quantification of 19.44 and 64.79 ng/mL for zeaxanthin, 15.6 and 52.4 ng/mL for lycopene and 8.28 and 27.61 ng/mL for β-carotene were determined. More carotenoid compounds could be separated and detected with the new method as compared with conventional C18 column. Hyphenation of HPLC with photodiode array and mass spectrometry detectors assisted in detection of tetra-dehydrocarotenoid and fatty acid diesters of xanthophylls in tomato products. Content of all-trans-lycopene, β-carotene and total carotenoid in different industrial tomatoes tested was found to range between 41.87 and 84.65, 0.89 and 1.50 and 53.22 and 112.60 µg/g fresh weight, respectively.

Effect of environmental conditions and water status on the bioactive compounds of broccoli

Four experiments were carried out in 2010 and 2011 to determine how cultivation period (spring or autumn), harvest season (summer or autumn), and plant water status (irrigated or rainfed) influenced content and composition of broccoli cultivar Parthenon F1 with respect to sulforaphane and phenolics under field conditions in Gödöllő, Hungary. Sulforaphane content was significantly higher in the autumn harvests, regardless of irrigation treatments. Harvest season also influenced total phenolics content, with the highest values occurring in the spring season. Harvest season also affected trolox equivalent antioxidant capacity (TEAC) and this capacity was also the greatest in spring. Caffeic acid glucoside was a major phenolics component in both spring and autumn season harvests. The season and irrigation related changes in other phenolic component contents were also characterised in this study.

HPLC Determination of Capsaicinoids with Cross-Linked C18 Column and Buffer-Free Eluent

A simple and efficient high-performance liquid chromatographic method was developed and validated for the separation and determination of capsaicin and its major dihydro- and homoderivatives in spice paprika products in 20 min with fluorescent and 35 min with mass-spectrometric detection. The separation was performed on reversed-phase chromatographic adsorbent of cross-linked endcapping with eluent consisting of 1:1 acetonitrile-water or acetonitrile-0.1% formic acid under isocratic conditions. Excellent separation of all the major and minor capsaicinoids with resolution index between 1.08 and 7.34 was achieved. The detection and quantification limits of capsaicinoids in standard material solutions were between 2 and 10 ng/mL. The lowest detectable amount of capsaicin, with fluorescent detection, was found to be <1 µg/g non-pungent spice paprika powder. The naturally occurring capsaicinoids could be distinguished from the non-capsaicinoids compounds appeared on liquid chromatography-fluorescence profile of extract from drastically processed paprika by applying mass spectroscopic detection. Hungarian spice paprika were evaluated as mild to very hot (capsaicinoid content: 334-1,660 µg/g) and chili products as very or extremely hot products (1,543-2,818 µg/g).

Determination of Polyphenols, Capsaicinoids, and Vitamin C in New Hybrids of Chili Peppers

Six hybrids were subjected to chromatographic analyses by HPLC for the determination of phytochemicals such as capsaicinoid, polyphenol, and vitamin C. The dynamics of ripening of 4 of the hybrids were also characterised. Seven capsaicinoids could be separated and determined; the major compounds were nordihydrocapsaicin, capsaicin, and dihydrocapsaicin, while homocapsaicin and homodihydrocapsaicin derivatives were detected as minor constituents. Capsaicin content ranged between 95.5 ± 4.15 and 1610.2 ± 91.46 μg/g FW, and the highest value was found in Bandai (C. frutescens) at the green ripening stage. The major capsaicinoids had a decreasing tendency in Bandai and Chili 3735 hybrids, while no change was observed in Beibeihong and Lolo during ripening. Nine polyphenol compounds were detected including 8 flavonoids and a nonflavonoid compound in the pods of all hybrids. The major components were naringenin-diglucoside, catechin, and vanillic acid-derivative and luteolin-glucoside. Naringenin-diglucoside ranged from 93.5 ± 4.26 to 368.8 ± 30.77 μg/g FW. Except vanillic acid-derivative, dominant polyphenols increased or remained unchanged during ripening. As for vitamin C, its content tended to increase with the advance in ripening in all hybrids included in this study. The highest value of 3689.4 ± 39.50 μg/g FW was recorded in Fire Flame hybrid.

The simultaneous determination of capsaicinoids, tocopherols, and carotenoids in pungent pepper powder

ABSTRACT From nutritional points of view, carotenoids, capsaicinoids, and tocopherols are valuable constituents in pungent peppers. A rapid and reliable high performance liquid chromatography (HPLC) method for the simultaneous determination of phytonutrients in spice red peppers and chili products was developed and validated. The method included simultaneous detection by fluorescence and diode-array detectors. The major capsaicinoids, two tocopherols and 43 carotenoid components, were simultaneously separated, detected, and identified in the appointed pepper powder (containing Capsicum annuum and Capsicum frutescens) for method validation. The separation was performed on a Nucleosil C18 reverse phase column and optimized gradient elution. Resolution ranged between 0.96 and 1.46 with the highest values corresponding to γ-tocopherol and α-tocopherol. The limits of detection and quantification of target compounds ranged between 18.77 and 148.08 ng mL−1. Recoveries were between 89.83–100.26 and 79.72–88.86% when standard materials were spiked at low and high amounts, respectively. The most sufficient extraction of the different phytonutrients was achieved by mixture of methanol and acetone, although it was only slightly better than the mixture of methanol and acetonitrile. These results suggest that the developed method could be used for rapid, one-step determination of a wide range of phytonutrients in chili and pepper powders. GRAPHICAL ABSTRACT