Dr Ismari Van der Merwe
Senior Lecturer
Sustainable Food Systems and Development
LG 9.107
Sustainable Food Systems and Development
IB 71

Short CV

Qualification Summary




Year completed


University of the Free State


BSc Magister Scientiae

University of the North West


BSc Honours

University of the North West



University of the Free State


BSc Home Economics (Food)

University of the Free State


Grade 12

Hoërskool Sentraal


Tertiary Education

Philosophiae Doctor (UFS)

Degumming Gonometa postica cocoons using environmentally conscious methods (2015).

Supervisors: Prof H J H Steyn and Prof C Hugo


BSc Magister Scientiae (NWU)

Developing a micro-technique of canning small white beans and determining the influence of cultivar and locality on the canning quality of dry beans (Cum laude - 1992).

Supervisors: Prof C Venter and Dr A Liebenberg


BSc Home Economics Honours (NWU)

(Cum laude – 1990)


B Ed (UFS)



BSc Home Economics (UFS)

1983 – 1986


Work History Summary

Name of Company

Last position held

Dates of employment

UFS: Department of Consumer Science, Extension and Sustainable Agriculture

Program Director

Lecturer: Undergraduate and Postgraduate

2020 -

2005 -




UFS: Department of Consumer Science






Motheo College


Engineering Mathematics



1994 - 2005




Agricultural Research Council: Potchefstroom


Dry bean processing

1989 - 1994




Hoërskool Phillippolis


Consumer Science

Grade 8 – 12

1988 - 1989




Program Director


Co-ordinator of Community Service projects of the Department of Consumer Science


Open days


Safety Committee


Teaching and Learning Committee

Motheo FET College

Acting Head of examinations (2005)


Responsible for time-table and programs


Running marking centre for Mathematics: 1993 – 2010.


Academic and professional experience

MODERATOR (External):

North West University, Potchefstroom



MODERATOR (External):

MTech Tourism and Hospitality – TUT



MODERATOR (External):

  • University of Nambia – Nutritional Management; Home Ecology Education 2; Home Ecology 2.
  • Walter Sisulu University – Food Science 2 PO; Consumer Science food and nutrition.
  • North-West University – Honours (VVOO671).

2015 - currently

MODERATOR (External):

University of North West – Potchefstroom MSc.



Journal of Applied Science





PREVIEWER – Journal of Family Ecology and Consumer Science.





2008 - currently


1993 – 2010



Silk fibres from Gonometa postica were degummed with different, not yet considered, environmentally-conscious methods to conserve energy. The agents used were vermicompost, distilled water, catholyte, and Eucalyptus oil. The results were compared to a control, Orvus paste, which is currently in use as a chemical degumming agent. The physical properties of the silk fibres that were evaluated in this study included weight loss determination, degumming efficiency and scanning electron microscopy. The results indicated that the weight loss of G. postica fibres ranged from 27 to 41% over a time period of 10 days for the different methods evaluated. Orvus paste and Eucalyptus oil, catholyte and Orvus paste caused the greatest weight loss indicating the best sericin removal. Distilled water and Eucalyptus oil were the least successful in sericin removal, delivering a weight loss of less than 30%. The SEM micrographs indicated some sericin remnant still present on the fibres. Catholyte set a better standard for performance. It was concluded that catholyte, vermicompost and distilled water can be recommended as alternatives to the chemical Orvus paste as degumming method for G. postica wild silk.


To increase children`s preference for and consumption of vegetables, potato based vegetable chips were developed, using a basic choux paste. Hundred children, in the age range four to six years, participated in the study. A specially adapted five-point hedonic Smiley face scale was used. Children preferred pictures of potato chips to pictures of beetroot, green beans and carrots. For colour choice, carrot chips were significantly (p < 0.001) liked more than green bean and beetroot chips. For brown-type vegetables, sweet potato, butternut, butternut + sweet potato and sweet corn chips were significantly (p < 0.001) liked more than cauliflower and cabbage chips. The sweet potato had the highest numerical score of 4.16. Further tests performed with this chip found no significant differences in the liking of cooking method. The oven baked option was subsequently chosen for further tests, because it was the healthiest option. There were no significant differences in the liking of different oils, coatings and replacement of potato flour with chickpea flour. Population group had a significant effect on green bean (p=0.0189), butternut (p=0.0018) and cauliflower (p=0.0218) chip liking, while gender had a significant effect on beetroot (p=0.0158), butternut (p=0.0307) and cauliflower (p=0.0371) chip liking. Age had a significant effect on the liking of green bean (p=0.0338) and sweet potato (p=0.0445) chips. The interaction between gender and age had a significant effect on the liking of 50% replacement with chickpea flour in oven baked sweet potato chips (p=0.0378).


Food waste relates to three major world problems: food security, greenhouse gas emissions in the food supply chain, and waste disposal. One of the key ways to achieving sustainable food security globally, is to reduce food waste. In a country such as South Africa where between 12 to 14 million people are food insecure, the reduction of the R61.5 billion worth of food waste, could play a major role in this. In order to minimise household food waste, or consumer-related food waste, it is imperative to have an understanding of the factors influencing waste-related behaviour. The study focused mainly on the reasons for and behaviour when discarding food, consequently causing food waste. Subsequent to this, the researchers also determined what type of food was wasted most. This paper reports on the results of a survey conducted in Kimberley, in the Northern Cape of South Africa. A total of 100 questionnaires were distributed and completed, from which data were analysed. Although consumers indicated that they do not waste much food (the majority wasting approximately 5%), a significant proportion indicated that excess leftover food was discarded. A lack of planning for meals was found to be prevalent. Purchasing in bulk and purchasing the incorrect products were also found to contribute significantly to food waste. In this study it has been found that bananas and apples are the fruit that were most often wasted, and tomatoes and potatoes were the most wasted vegetables. Furthermore, leftover food was identified as one of the main sources of discarded food. Alternatives for the re-use of leftover food could aid consumer reduction of food waste. Alternative practices need to be developed to educate consumers about what to do with this food. A more thorough knowledge of factors influencing behaviour and attitudes towards food waste needs to be established. Thus, culture-specific and localised interventions should be synthesised, implemented and evaluated.

Publications (Short List)

 Van der Merwe, I., Steyn, H.J.H., Hugo, C. and Schall, R. (2017). The physical fibre properties of Gonometa postica after degumming the cocoons with different methods.  Journal of Consumer Sciences, Vol 45,pp. 1 - 11.

Swart, P., Bothma, C., van der Merwe, I. & Hugo, A. Acceptability of potato-based vegetable chips for children. International Journal of Home Economics, 9 (2), pp. 159-174.

Cronje, N., van der Merwe, I. & Muller, I-M. (2018). Household food waste: A case study in Kimberley, South Africa. Journal of Consumer Science, 46, pp. 1 - 9.


Finding alternative protein sources - the contribution of Insects to Food Security, Livelihoods and the Environment.

Trends towards 2050 predict a steady population increase to 9 billion people, forcing an increased food/feed output from available agro-ecosystems resulting in an even greater pressure on the environment. Scarcities of agricultural land, water, forest, fishery and biodiversity resources, as well as nutrients and non-renewable energy are foreseen.

Edible insects contain high quality protein, vitamins and amino acids for humans. Insects have a high food conversion rate, e.g. crickets need six times less feed than cattle, four times less than sheep, and twice less than pigs and broiler chickens to produce the same amount of protein. Besides, they emit less greenhouse gases and ammonia than conventional livestock. Insects can be grown on organic waste. Therefore, insects are a potential source for conventional production (mini-livestock) of protein, either for direct human consumption, or indirectly in recomposed foods (with extracted protein from insects); and as a protein source into feed stock mixtures.

The development of consumer acceptable products is currently the main focus area of our research content.

Area(s) of Interest

Textile Science -  research done on the wild silk of Southern Africa.

Food - busy with research on alternative protein sources.

Food waste - research done in South Africa, Lesotho and Swaziland.


Courses Presented

CNSF 2614

CNSF 2624

CNCS 6814

CNCS 6824

CNFD 6808

CNCS 6809

CNCS 8900

CNCS 9100





Community Service

Service Learning

Co-ordinator of Community Service projects of the Department of Consumer Science, Extension and Sustainable Agriculture.


Elfrieda van den Berg (Marketing Manager)
T: +27 51 401 2531


Dilahlwane Mohono (Faculty Officer)
T: +27 58 718 5284

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