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Title: Content, bioavailability, bioconversion and antioxidant activities of carotenoids in some Sri Lankan fruits and green leafy vegetables
Keywords: Nutrition
Issue Date: 2004
Publisher: University of Sri Jayawardenepura: USJ(MED).
Citation: CHANDRIKA, UG, Content, bioavailability, bioconversion and antioxidant activities of carotenoids in some Sri Lankan fruits and green leafy vegetables , University of Sri Jayawardenepura USJ(MED), 2004: xxv,223[15]p.
Abstract: The aim of this study was to evaluate the content and bioavailability/bioconversion of pro-vitamin A carotenoids in selected fruits and green leafy vegetables (GLV) from Sri Lanka and to elucidate the effects of different processing and preparation methods. The fruits used in this study was papaya, palmyrah, jak, lavalu and beal. GLV used in this study were kathurumurunga (Sesbania grandiflora). Mukunuwanna (Alternathera sesessilis) gotukola (Centella asoatica). Manioc (Manihot esculenta), sarana (Triathema konogyna), nivithi (Spinacea oleracea) and and thampala (Amaranthus caudatus). In the caase of papaya, palmyrah and jakfruits content of caroenoids were determines using MPLC and visible spectrophotometry and in the case of lavalu and GLV by HPLC method. The vitamin A and á- carotene status in Wistar rats was assessed with and without fat in the diet in the case of papya and mukunuwann leaves using HPLC method. An in vitro method that simulates human digestion was used to measure the fraction of pro-vitamin A carotenoids that is release for absorption (bioaccessible) from selected GLV using HPLC method. Separation and quantification of the carotenoids in two major varieties of Carica papaya grown in Sri Lanka indicated that red- and yellow-fleshed varieties had different carotenoid profiles. Yellow-fleshed papaya contained three major carotenoids. i.e. á-carotene. ?cryptoxanthin and C-carotene. In addition to these three carotenoids, red-fleshed papaya also contained lycopene and á-carotene-5,6 epoxide. It is interesting to note that red-fleshed papaya has significantly higher á-carotene and lycopene than yellow -fleshed variety. Hence the calculated mean retinol equivalent (RE) was 506.7 ñ 54.9 ægkg-1 fresh weight (FW) in yellow -fleshed papaya, whereas in red-fleshed papaya it was 202 ñ 48 ægkg-1 FW. Study with Wistar rats has shown that notwithstanding the colour of the flesh a significant increase of serum vitamin A is shown only if papaya is fed incorporated to standard diet (p\<0.001) rather than given separately (with out incorporated to standard diet ). Red-fleshed variety shows higher (66.7ñ 4.2 æg/g) á-carotene levels in the liver compared to the yellow fleshed variety (5.4ñ 1.0 æg/g. p\<0.001). Six carotenoids were detected in jackfruit kernel. The carotenes are á-carotene. a-carotene. á-zeacarotene. a-zeacarotene, á-carotene 5, 6 epoxide and a dicarboxylic carotenoid crocetin were identified. This corresponds theortically 25.5 RE/100g FW. Our study indicated that jackfruit is a souce of pro-vitamin A carotenoids, but not as good as papaya. Serum retinol concentrations of rats supplemented with jackfruit kernel shown to be significantly higher (p=0.008) compared with control group. The same is true for liver retinol (p=0.006). Quantification was carried out by RP-HPLC. This results shows biological conversion of pro-vitamin A in jackfruit kernel appears satisfactory. Thus increased consumption of ripe hak fruits could be advocated as a part of a strategy to prevent and control of vitamin A deficiency in Sri Lanka. Four major carotenoids were detected in palmyrah fruit pulp (PFP). The carotenoids are a-carotene, ?-carotene. Lycopene and á-zeacarotene and this corresponds to 22.3 RE/100g. FW. The results of in vivo bioavailability and bioconversion studied showed that pro-vitamin A carotenoids from PFP were also bioavailable and bioconvertible. The major carotenoid in lavalu (Chrysophyllum roxhburgii) was trans-violaxanthin (113 percent). Also present was cisviolaxanthin ( 19 percent) neoxanthin (3 percent). ?-cryptoxanthin monoepoxide ( 11percent) lutein á-cryptoxanthin, ?-carotene and á-carotene. The retinol equivalent of the pulp was only 13.8 RE/100g FW. The study shows that lavalu is not a good source of pro vitamin A. Further the structural properties of the carotenoids make bioconversion studies with animals or humans futile. So that the best use of lavalu carotenoids is as a food colourent for oil based foods.In the case of beli (Aegle marmelos) there were only trace amount of caroenoids and cannot be used as a pro vitamin A supplement. The all-trans á-carotene content in fresh GLV ranged from 63.1 æg/g FW in leaves of mukunuwanna to 133.8 æg/g FW in the thampala. Cooking of fresh leaves resulted in some losses of all-trans-á-carotene and retention ganging from 56 to 76 pecent in the malluma and 27 to 73 percent in the fried preparation. Cooking with water or coconut milk resulted in retentions ranging from 36 to 88 percent . The in vitro accessibility of all-trans-á-carotene in cooked vegetables ranged from 14 to 43 percent in malluma, and from 12 to 36 percent in the fried preparation. In the GLV cooked with coconut milk the in vitro accessibility ranged from 12 to 26 percent compared with 4 to 8 percent when cooked with water. The á-carotene content, retention and in vitro accessibility widely varied between different varieties of green leaves. The three types of different traditional cooking procedures show about the same retention. Preparations with oil scraped coconut and coconut milk had improved in vitro á-carotene accessibility. In conclusion, the green leafy vegetables and fruits studied have variable contents and in vitro accessibility of pro-vitamin A carotenoids and thus contribute in various degrees to recommended daily allowance (RDA) of vitamin A. For green leafy vegetables such as kathurumurunga, mukunuwanna, manioc, gotukola sarana, thamplala an adequate contribution to RDA of vitamin A can be obtained by consumption of green leafy vegetables (100g, FW) with high pro-vitamin A content judging from in vitro accessibility and traditional prepatation methods of Sri Lanka with addition of coconut, coconut milk or coconut oil. None of fruits studied would cover the total vitamin A requirement if consumed in normal amounts. Papaya, jack and palmyrah should be considered as good sources of pro-vitamin A carotenoids, as they would be a sound vitamin A contributing complement to the diet. This study also revealed that some fruits such as lavalu and beli are not good sources of pro-vitamin A as believed by the general population. These findings can be useful in dietary intervention programmes to alleviate vitamin A deficiency in Sri Lanka as well as other developing countries.
Description: Dissertation: PhD, University of Sri Jayawardenepura: USJ(MED), 2004.
Appears in Collections:University of Sri Jayawardenepura

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