An isocratic reversed-phase HPLC separation of the stereoisomers of the provitamin A carotenoids (α- and β-carotene) in dark green vegetables

Nyambaka, Hudson; Ryley, J. W.

doi:10.1016/0308-8146(95)00093-3

Cited by 50 publications

(38 citation statements)

References 20 publications

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“…In order to properly assess the biological variability in carotenoid content of these foods, a systematic sampling strategy covering a range of geographic and (micro)climatic conditions is required, but was beyond the scope of the present study. The carotenoid profile of vegetables is much more complex than previously recognized, with the proportion and forms occurring as different carotenoids varying considerably according to growing conditions, storage and processing (Nyambaka & Ryley, 1995). It is noteworthy that the wild green vegetables described in this paper would typically be collected and eaten within several hours.…”

Section: Discussionmentioning

confidence: 93%

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Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil

Itsiopoulos

et al. 2002

Eur J Clin Nutr

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Objective: To characterize the carotenoid content of selected components of the Mediterranean diet commonly eaten by Greek migrants to Melbourne, a population group maintaining a traditional dietary regimen, and who exhibit relatively high circulating carotenoid concentrations and low cardiovascular disease mortality. Design and specimens: Opportunistic sampling of wild (sow thistle, amaranth, purslane and dandelion, collected from roadsides and home gardens) and commercially available (chicory, endive) green leafy vegetables and figs in season. Foods were selected on the basis that they are commonly eaten by Greek migrants but not by Anglo-Celtic persons, and had not previously been well-characterized with respect to their carotenoid contents. Extra virgin, cold-pressed olive oil and 'extra light' olive oil were obtained from commercial sources. Specimens were extracted with tetrahydrofuran (or chloroform:methanol for olive oil) and carotenoid contents were quantified using HPLC with UV detection. Two to six specimens of greens and figs were analysed. Dietary intake was assessed by food frequency questionnaire. Results: Wild green vegetables contained high concentrations of lutein (sow thistle > amaranth > purslane > dandelion) and bcarotene (sow thistle > amaranth > purslane ¼ dandelion). Sow thistle and amaranth contained lutein (15 and 13 mg=100 g, respectively) and b-carotene (3.3 and 4.0 mg=100 g, respectively) at concentrations greater than that seen in the commercially available species of chicory and endive. Figs contained all major carotenoids appearing in plasma, albeit at low concentrations. Extra virgin cold-pressed olive oil contained substantial quantities of lutein and b-carotene, but the more-refined 'extra light' olive oil did not. Conclusions: These components of the traditional Mediterranean diet contribute to the higher circulating concentrations of carotenoids in Greek migrants compared to Anglo-Celtic Australians.

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Section: Discussionmentioning

confidence: 93%

“…Wild green vegetables and figs were extracted by a modification of published methods (Khachik et al, 1992;Nyambaka & Ryley, 1995). Two to six specimens of each plant species were collected, homogenized as a single sample, and two aliquots analysed (each in duplicate).…”

Section: Preparation and Extraction Of Food Samplesmentioning

confidence: 99%

Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil

Itsiopoulos

et al. 2002

Eur J Clin Nutr

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“…The reduction in beta-content in the vegetables during dehydration results in a significant amount of β-carotene lost, with the extent of loss determined by the amount of heat involved in the dehydration process 11 . The degradation of beta-carotene during processing and storage of vegetables may be attributed to the oxidation reactions triggered by metal catalysts present in the food material 9,13,20 . However, some studies have reported that conventional blanching and cooking result in a significant increase in the concentration of carotenoids in the cowpea, peanut and pumpkin leaves, attributed to the inactivation of enzymes responsible for β-carotene degradation 9,21,22 .…”

Section: Resultsmentioning

confidence: 99%

“…The degradation of beta-carotene during processing and storage of vegetables may be attributed to the oxidation reactions triggered by metal catalysts present in the food material 9,13,20 . However, some studies have reported that conventional blanching and cooking result in a significant increase in the concentration of carotenoids in the cowpea, peanut and pumpkin leaves, attributed to the inactivation of enzymes responsible for β-carotene degradation 9,21,22 . The extent of reduction of beta-carotene in various food matrices is determined by several factors, including species, variety, presence of enzymes, seasonality, maturity and losses between harvesting and analysis periods 9,21,22 .…”

Section: Resultsmentioning

confidence: 99%

“…Dark green leafy vegetables are important sources of micronutrients (pro-VA, vitamin C, vitamin E, zinc, iron) and dietary fibre 7,8 . Among the pro-VA carotenoids, beta-carotene is the most important and abundant carotenoid with high pro-VA activity 9 . The DGLVs are fairly acceptable among the population and although they are season dependent, they are known to be effective in combating VAD, enhancing immunity and combating other diseases such as cancer and coronary diseases 5,10 .…”

Section: Introductionmentioning

confidence: 99%

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Use of kitchen steel wool as oxygen absorber improves storage retention of beta-carotene in solar-dried vegetables

Nyambaka¹,

Nderitu²,

Nawiri³

et al. 2012

Mediterr.J.Chem.,

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Vitamin A deficiency remains a major health concern in developing countries whereas the season availability of vegetables could provide for vitamin A. Dehydration is widely used to preserve dark green leafy vegetables (DGLV) but storage in normal atmosphere condition losses beta-carotene by oxidation, therefore requiring use of an oxygen absorber. The study examined use of kitchen steel wool as an oxygen absorber in reducing the loss of beta-carotene content in three indigenous DGLVs that were solar dried and stored for a period of 168 days in four different packing conditions. Fresh vegetables contained between 781.94 to 1047.42 μg/g dry matter (DM) beta-carotene, reducing significantly (p=0.01) to between 653.63 to 712.99 μg/g DM after dehydration. Steel wool oxygen absorber significantly improved (p = 0.02) beta-carotene retention, recording a loss of 19.5 to 37.6% compared to 47 to 72% in normal conditions. Storage of DGLVs under kitchen steel wool oxygen absorber preserves vegetables and retains high levels of beta-carotene.

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Use of column temperature to optimize carotenoid isomer separation by C30 high performance liquid chromatography

Böhm¹

2001

J. Sep. Science

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Five xanthophylls and six carotenes were eluted from a YMC C30 column with a binary mobile phase gradient consisting of methyl tert‐Butyl ether and methanol. The effect of column temperature on the separation was tested between 15°C and 25°C. A mixture of prominent lycopene isomers was additionally analyzed to optimize their separation in relation to the main xanthophylls and carotenes. At column temperatures below 20°C (15Z)‐β‐carotene co‐eluted with echinenone, a frequently used internal standard. For most carotenoids an optimal separation was achieved at 23 ± 1°C within one hour. In contrast, some (Z)‐isomers of lycopene showed a better resolution at higher column temperatures. While these isomers were separated at 30°C and at 35°C, another (Z)‐isomer co‐eluted with (E)‐lycopene at 35°C. Thus, column temperature is a noteworthy parameter in high performance liquid chromatography of carotenoids.

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An isocratic reversed-phase HPLC separation of the stereoisomers of the provitamin A carotenoids (α- and β-carotene) in dark green vegetables

Cited by 50 publications

References 20 publications

Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil

Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil

Use of kitchen steel wool as oxygen absorber improves storage retention of beta-carotene in solar-dried vegetables

Use of column temperature to optimize carotenoid isomer separation by C30 high performance liquid chromatography

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