WELCOME

Presented By

Sultana JahanExamination Roll: 116Registration No. 6298

M.S. Examination- 2011Course No. FN-508Session: 2010-11

Department of Food and Nutrition Science Bangladesh Home Economics college,

Dhaka

Title of Seminar PresentationCarotenoids retention in leafy vegetables

based on cooking methods

Chang, S.K., Nagendra Prasad, K. and Amin, I.

Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia

Chemical Engineering Discipline, School of Engineering, Monash University, Selangor, Malaysia

Laboratory of Halal Science Research, Halal Products Research Institute, Universiti Putra Malaysia, Selangor, Malaysia

Contents Introduction Rationale of The Topic Objectives Materials and Methods Results Discussion Limitation of The Study Conclusion References

Introduction Many vegetables and fruits contain significant amounts of β-carotene and other provitamin A that can be absorbed and converted to vitamin A in the human body.

About 5 to 78 % of the β-carotene degraded when vegetables are prepared using different cooking methods.

Several reports have documented the losses of β-carotene of vegetables after boiling, stewing, frying, blanching and pressure cooking.

Among these conventional methods boiling and stir-frying are selected for this study.

Rationale of the Topic It is mostly important to determine the

percentage of labile nutrients and other health-promoting food components of vegetables that is retained or lost during cooking practices.

The factors that enhance or reduce degradation can be recommended to minimize losses of nutrients in foods.

This study will provide guidance in healthy food preparation methods that did not deplete nutrient content in vegetables.

Indirectly, this also contribute in recommending healthy cooking methods to the general public.

Objectives of the study

General Objective To study the Carotenoids retention in leafy

vegetables based on various cooking methods.

Specific Objectives To determine the effects of different domestic

cooking methods on carotenoids retention in commonly consumed leafy vegetables.

The study is aimed to evaluate the extent of loss of lutein and β-carotene form the main carotenoids contributing to the health benefits in human.

To compare the effect of boiling and stir-frying at different cooking durations on raw and cooked leafy vegetables.

Materials and Methods Seven types of green leafy vegetables were selected

based on popular consumption by Malaysian people.

These vegetables were Chinese cabbage, swamp cabbage, spinach, Ceylon spinach, red spinach, white spinach and tapioca shoots.

One kilogram was taken and divided into three portions with 300 g for each application.

One portion was retained raw and others were cooked in different methods which were boiled and stir fried.

Images of Sample

Methods The β-carotene and lutein were extracted according

to the method AOAC.

The sample (10 g) was added with 40 ml of ethanol and 10 ml of potassium hydroxide, with 0.1% BHT and homogenized for 3 min.

The carotenoids of homogenized sample were analysised by HPLC technique at 21°C.

Data were expressed as mean value ± standard deviation of which all experiments were repeated three times.

ResultsTable 1: Lutein content of vegetables and its retention after cooking

Vegetables (100g) TreatmentLutein (μg/ 100gedible Concentration

True Retention

     portion)   change (%CC)of lutein (%)

Swamp Cabbage Raw 53 ±0.5    (Ipomoea aquatica) SF4 61 ±0.2 15.7 94.5  SF8 26 ±0.0 -51.8 34.5  B4 31 ±1.5 - 40.7 78.8  B8 90 ±1.3 68.9 241.5

Spinach (Spinacia Raw495 ±1.4    

oleracea) SF4 15 ±2.8 -68.9 28

  SF8124 ±1.9 -74.9 20

  B4428 ±0.5 -13.5 99.4

  B8140 ±2.4 -71.8 35.3

Tapioca Shoots Raw134 ±1.9    

(Manihot utilissima) SF4 26 ±0.1 -80.8 34.9  SF8 99 ±0.0 -26.4 44.2

  B4230 ±0.7 71 213.8

  B8388 ±0.4 188.8 418.8

White Spinach Raw 59 ±1.3    

(Amaranthus viridis) SF4125 ±19.4 111.4 153.5

  SF8 28 ±0.5 -52.8 18.8

  B4110 ±0.0 86.8 242.8

  B8235 ±21.5 297.9 417.9

Table 2: β-carotene content of vegetables and its retention after cooking

Vegetables (100g) Treatment

β-carotene (μg/100gedible portion)

Concentration change (%CC)

True Retention (%TR} of β-carotene

Swamp Cabbage Raw 138.4 ±5.8    (Ipomoea aquatica) SF4

309.3 ±2.3 123.5 178.8

  SF8 619 ±1.4 347.2 313  B4 336.35 ±6.2 143 315.9

  B8376.35 ±12.9 171.9 380.7

Spinach (Spinacia Raw 6176.5 ±65.8    

oleracea) SF42206.5 ±28.9 -64.3 32

  SF8 1448 ±1.4 -76.5 18.8  B4 3123 ±1.4 -49.4 58.2  B8 6193 ±349.3 0.27 125.3

Tapioca Shoots Raw 3265.5 ±0.7    (Manihot SF4 602.8 ±20.9 -81.54 14.8utilissima) SF8 10521 ±2.8 222.2 193.3  B4 1386.8 ±8.1 -57.53 53  B8 2705 ±21.9 -17.2 120

White Spinach Raw 4994 ±14.7    

(Amaranthus SF41260.2 ±12.9 152.3 176.6

viridis) SF8 583.9 ±1.6 16.92 46.8  B4 781 ±35.4 56.4 187.7

  B81163.5 ±91.2 132.98 244.6

Discussion Table 1 and 2 show, the lutein and β-carotene contents

of the selected vegetables after boiling and stir-frying for 4 and 8 minutes respectively.

Results obtained show that the stir-frying had reduced lutein content for all vegetables ranging from 8-89%.

The effect of boiling for lutein varied (0-428%) with different vegetables at both cooking durations of 4 and 8 minutes.

Boiling for 8 minutes increased retention of β-carotene in all vegetables ranging from 18-380%.

While stir-frying generally increased the retention of β-carotene for all vegetables 2-3 times except for spinach.

β-carotene was in the order of spinach > tapioca shoots > Ceylon spinach > red spinach > Chinese cabbage > white spinach > swamp cabbage.

So, the lutein content was in the order of spinach > Ceylon spinach > red spinach > Chinese cabbage > swamp cabbage > white spinach > tapioca shoots.

Both lutein and β-carotene were negatively affected by frying while boiling resulted increase of β-carotene but 11% losses of lutein.

Limitation of The Study Vegetables from different places may have different

composition of minerals and vitamins affected by the usage of fertilizers and herbicides.

Difficulties in analysis are due to qualitative and quantitative variations in composition and wide concentration range of the carotenoids in a given food.

It would be necessary to carry out a greater number of analysis for each vegetable from different geographical sources at different times.

Conclusion The present study exhibits β-carotene retention

in the vegetables studied with cooking methods and type of vegetables. Cooked vegetables have variations in carotenoids composition brought by varying cooking conditions (time and temperature), types of vegetables and the interaction between cooking methods and types of vegetables.

References Aman, R., Schieber, A. and Carle, R. 2005. Effects of Heating and

Illumination on Trans-Cis Isomerization and Degradation of β-Carotene and Lutein in Isolated Spinach Chloroplasts. Journal of Agricultural and Food Chemistry 53: 9512-9518.

Aman, R., Biehl, J., Carle, R., Conrad, J., Beifuss, U., Schieber, A. 2005. Application of HPLC coupled with DAD, APcI-MS and NMR to the analysis of lutein and zeaxanthin stereoisomers in thermally processed vegetables. Food Chemistry 92: 753-763.

Amin, I. and Cheah, S.F. 2003. Determination of Vitamin C, β-carotene and Riboflavin contents in Five Green Vegetables Organically and Conventionally Grown. Malaysian Journal of Nutrition 9(1): 31-39.

AOAC. 1984. Official Methods of Analysis, 18th edition. Bernhardt, S. and Schlich, E. 2006. Impact of different cooking

methods on food quality: Retention of lipophilic vitamins in fresh and frozen vegetables. Journal of Food Engineering 77: 327-333.

Chen, B.H. and Tang, Y.C. 1998. Processing and stability of carotenoid powder from carrot pulp waste. Journal of Agricultural and Food Chemistry 46: 2312-2318.

Wen, T. N., Prasad, K.N., Bao, Y. and Amin, I. 2010. Bioactive substance contents and antioxidant activity of blanched and raw vegetables. Innovative Food Science and Emerging Technologies 11: 464-469.