| || || Maharaj, Prayna P.P.|
| || || Folate analysis of some commonly consumed Fijian vegetables and the first comprehensive study on the effects of cooking|
Author:Maharaj, Prayna P.P.
Institution: University of the South Pacific.
Subject: Folic acid in human nutrition -- Fiji, Food -- Vitamin content -- Fiji
Call No.: Pac QP 772 .F6 P73 2014
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: Folate is a biologically significant, water soluble vitamin of the B complex, found in a variety of foods especially green vegetables. Folate deficiency is linked to a number of health problems such as megaloblastic anaemia, depression, cancer, neurological disorders, neural tube defects and cardiovascular ailments. The daily intake of adequate folate by humans thus becomes vital which can be fulfilled through the adequate consumption of folate rich foods or fortified food products. Since vegetables are considered to be folate-replete, it is imperative to analyze them for folate content so that daily need of folate is achieved by increasing the consumption of these vegetables rather than relying on fortified food products. The analysis of the local Fijian vegetables (many of which is also commonly consumed in the South Pacific region) is very important to help in setting Recommended Daily Intake (RDI) for the various age groups and for the determination of the folate status in the South Pacific countries. Boiling and frying are the two commonly practiced cooking methods in the Pacific and folate analysis on most of these Fijian vegetables have not been conducted until now to investigate the effect of these cooking methods. It is imperative to conduct research in this area, so that ailments related to folate deficiency can be prevented in Fiji and the South Pacific regions. This thesis, thus, focuses on: the analysis of undeconjugated folate and total folate content of ten commonly consumed fresh vegetables that contribute to the Fijian diet, the determination of the effect of boiling and frying on folate retention in these foods, and the analysis of cooking water to ascertain the leaching of folate and the extent of leaching (to determine if significant folate content present in the cooking water) Folate content was determined by microbiological assay (Lactobacillus casei subsp. rhamnosus) and tri-enzyme treatment with the use of CRM 485; Lyophized mixed vegetables. The culture was optimized prior to sample analysis. The aliquots of 0.25 mL of Inoculum Load (IL) and 50 μL of Culture Volume (CV) was the best combination and were used as an inoculum for the assay. Of the ten vegetables selected, six were green leafy vegetables while four were non-leafy fruit vegetables. The range of undeconjugated folate and total folate content was 2.3 ± 0.1 iv μg/100 g – 196.6 ± 19.0 μg/100 g and 18.0 ± 2.1 μg/100 g – 485.0 ± 16.7 μg/100 g, respectively. The coefficient of variation for total folate was 1.7–11.6 %. The highest folate content was found in Drumstick leaves (Moringa oleifera). Two of the ten vegetables analysed had total folate content over 200.0 μg/100 g (Long bean (Vigna sesquipedalis) and Drumstick leaves (Moringa oleifera)) while in five vegetables the folate content was in the range 50.0 μg/100 g – 200.0 μg/100 g; Chinese cabbage (Brassica chinensis), Taro (Colocasia esculenta), Bele (Abelmoschus manihot), French bean (Phaseolus vulgaris) and Okra (Abelmoschus esculentus (L.)). Folate losses varied between vegetables and ranged from 10–64 % in boiling and 1–50 % in frying. Of the two cooking methods, generally greater loss was seen in boiling. The cooking water was also analysed to ascertain leaching of folate due to boiling. The folate content in water ranged from 3.32 ± 0.31 μg/100 mL – 61.59 ± 2.51 μg/100 mL. The loss of folate was accounted for in the cooking water for the boiled vegetables. Thus, boiling may still be the better choice of cooking most vegetables in terms of folate intake, provided the cooking water is consumed together with the vegetables. The data collected indicates that the studied local vegetables are rich sources of folate which can be utilized to meet the recommended daily requirement, however, significant losses occurs upon cooking which varies between vegetables and cooking methods. Therefore, public health efforts to increase folate intake in order to improve folate status should incorporate practical advice on cooking. Efforts should be directed to advice and encourage consumption of the cooking water along with the vegetables. This project therefore helps to quantify for both consumers (especially pregnant as well as breast feeding mothers) and clinician/nutritionists the amount of folate present in the selected common Fiji foods before and after cooking and also indicates optimal cooking methods for the retaining of folates. Since reliable information was lacking on the folate content of uncooked/cooked vegetables in Fiji, this thesis being the first comprehensive project on folate analysis of local vegetables in terms of cooking effects, provides a valuable source of data for public health purposes.