Nutritional value and acceptability of lactic acid fermented sweetpotato leaves utilized as vegetables

Transcription

1 Nutritional value and acceptability of lactic acid fermented sweetpotato leaves utilized as vegetables The Markets, Processing, and Utilization Community of Practice Meeting Dar Es Salam, Tanzania th March 2016

2 Authors George Ooko Abong *, Mercy Chepkoech, Grace Oguya *Dept. Food Science, Nutrition and Technology, University of Nairobi, Box 29053, Nairobi, Kenya.

3 Introduction Sweetpotatoes play important food security role. Mainly roots are utilized in East Africa while leaves and vines utilized as animal feed. Leaves are highly perishable and only acceptable to a few users in Kenya unlike other countries where they are generally consumed. Sweetpotato leaves are good sources of vitamins A and C, protein, iron and zinc.

4 Introduction Recent introduction and promotion of orange-fleshed sweetpotatoes in EA, Kenya included. Increased utilization of leaves in addition to roots would enhance the nutritional contribution of the crop to the human diet significantly-complete!!!! Especially in terms of increased vitamin C and protein intake.

5 Introduction Traditional preparation methods can be in order, but other value addition methods may be necessary. Lactic acid fermentation known to enhance nutrient availability provides an alternative process of producing a value added product from the leaves. Nutritional value and acceptability of lactic acid fermented sp leaves in Kenyan context remains unknown. Preliminary partial results of trials from Transmara East presented.

6 Methodology Current presentation part of ongoing researchonly a section is presented. Three varieties commonly grown in Transmara, Narok County harvested from farmers-purple leaves, purple vines and green leaves. Leaves analysed for protein, moisture, oxalates, vitamin A & C- Analysis on raw and cooked (traditional boiling)- sensory evaluation carried out. Lactic acid fermentation, minerals on-going

7 %MC Results-MC High moisture foods as other vegetables; sig differ with variety Raw Cooked Raw Cooked Raw Cooked Green leaves Purple leaves Purple vines

8 beta carotene (µg/100g) Results-Beta carotene Sig. (p<0.05) high in purple vines; retention 53-69% Cooked Raw Cooked Raw Cooked Raw Green leaves Purple leaves Purple vines

9 vitamin C (mg/100g) Results-Vitamin C No sig. with variety; high vit C; retention of 32 and 42% Cooked Raw Cooked Raw Cooked Raw Green leaves Purple leaves Purple vines

10 protein content (%) Results-Protein No sig. difference with variety or reduction on boiling Cooked Raw Cooked Raw Cooked Raw Green leaves Purple leaves Purple vines Axis Title

11 Crude fibre (%) Results-Protein High fibre; some reduction?? Cooked Raw Cooked Raw Cooked Raw Green leaves Purple leaves Purple vines

12 oxalates (mg/100g) Results-Oxalates No sig difference with variety; Sig. reduction in purple varieties Cooked Raw Cooked Raw Cooked Raw Green leaves Purple leaves Purple vines

13 Percent respondents Sensory-Taste Liked moderately like moderately like very much dislike slightly Neither Purple vine Purple leaves Green leaves

14 Percent respondents Liked moderately Sensory-Flavor like moderately like very much dislike slightly neither like nor dislike Purple vine Purple leaves Green leaves Dislike very much

15 Percet respondents Liked moderately Sensory-Appearance like moderately like very much dislike slightly dislike very much Purple vine Purple leaves Green leaves

16 percent respondents Liked moderately Sensory-Texture like moderately like very much dislike moderately neither like nor dislike Purple vine Purple leaves Green leaves

17 Percent respondents Sensory-overall acceptability All acceptable-liked moderately Purple vine Purple leaves Green leaves like moderately like very much dislike slightly

18 Conclusions and way forward Sweetpotato leaves have high levels of vit. A&C and good amount of protein. Leaves acceptable as boiled vegetables. Normal boiling reduces vitamins and oxalates sign, Oxalate reduction by fermentation to be established. Mineral evaluation and lactic acid fermentation ongoing.

19 UON Acknowledgements SASHA

20 THANK YOU