Articles in accredited journals:

Career:            32

Number – past 5 years:          14

Number – past 3 years:          8

Cactus pear antioxidants: a comparison between fruit pulp, fruit peel, fruit seeds and cladodes of eight different cactus pear cultivars (Opuntia ficus-indica and Opuntia robusta)

May 2019. Journal of Food Measurement and Characterization (Impact factor: 1.181)

M. de Wit, A. Du Toit, G. Osthoff, A. Hugo

Vol 7(3) DOI 10.1007/s11694-019-00154-z

Mucilage powder from cactus pears as functional ingredient: influence of cultivar and harvest month on the physicochemical and technological properties

Alba Du Toit, Maryna De Wit, Hermanus J. Fouché, Marli Taljaard, Sonja L. Venter & Arno Hugo

2019 Journal of Food Science and Technology (IF 1.797)

DOI 10.1007/s13197-019-03706-9

Antioxidant properties of fresh and processed cactus pear cladodes from selected Opuntia ficus-indica and O. robusta cultivars     

du Toit, A., de Wit, M., Osthoff, G., Hugo, A.

2018 South African Journal of Botany (IF 1.340)

118, pp. 44-51

Relationship and correlation between antioxidant content and capacity, processing method and fruit colour of cactus pear fruit  

du Toit, A., de Wit, M., Osthoff, G., Hugo, A.

2018 Food and Bioprocess Technology pp. 1-9 (IF 2.998)

South African Cactus Pear Seed Oil: A Comprehensive Study on 42 Spineless Burbank Opuntia ficus-indica and Opuntia robusta Cultivars       

de Wit, M., Hugo, A., Shongwe, N.

2018 European Journal of Lipid Science and Technology

120(3),1700343 (IF 2.145)

Cultivar and harvest month influence the nutrient content of Opuntia spp. Cactus pear cladode mucilage extracts

Du Toit, A., De Wit, M., Hugo, A.

2018 Molecules 23(4),916 (IF 3.098)

Relationship and correlation between antioxidant content and capacity, processing method and fruit colour of cactus pear fruit

Du Toit, A., De Wit, M., Osthoff, G., Hugo, A.

2018 Food and Bioprocess Technology (2.998)

11(8), pp. 1527-1535

Quality Assessment of Seed Oil from Selected Cactus Pear Cultivars (Opuntia ficus-indica and Opuntia robusta)

De Wit, M., Hugo, A., Shongwe, N.   

2017 Journal of Food Processing and Preservation

41(3),e12898 (IF 1.51)

Effect of cultivar, season and locality on lipid content and fatty acid composition of cactus pear seed oil       

de Wit, M., Hugo, A., Shongwe, N., van der Merwe, R.

2016 South African Journal of Plant and Soil

33(4), pp. 279-288 (IF 0.55)

Replacement of gelatin with Opuntia ficus-indica mucilage in flavored pink and unflavored white marshmallows. Part 2: Consumer liking   

Du Toit, L., Bothma, C., De Wit, M., Hugo, A.

2016 Journal of the Professional Association for Cactus Development 18, pp. 40-51 (IF 0.3)

Replacement of gelatin with liquid Opuntia ficus-indica mucilage in marshmallows. Part 1: Physical parameters

Du Toit, L., Bothma, C., De Wit, M., Hugo, A.          

2016 Journal of the Professional Association for Cactus Development 18, pp. 25-39 (IF 0.3)

Physico-chemical and sensory evaluation of cactus pear (Opuntia ficus-indica l. Mill and opuntia robusta wendl) cladode flour in different baked products

de Wit, M., Bothma, C., Hugo, A., Absalom, C., van den Berg, C.  

2015 Journal of the Professional Association for Cactus Development 17, pp. 89-106 (IF 0.3)

The effect of genotype, location and season on the lipid content and lipid composition of cactus pear (Opuntia ficus-indica) seed

De Wit, M., Shongwe, N.C., Hugo, A.           

2015 Acta Horticulturae 1067, pp. 173-179

Antioxidant content and capacity of fruit from different colour cactus pear (O. ficus-indica and O. robusta) cultivars    

Du Toit, A., De Wit, M., Osthoff, G., Hugo, A.           

2015 Acta Horticulturae 1067, pp. 187-192 (IF 0.223)

Acceleration of yoghurt fermentation time by yeast extract and partial characterisation of the active components

Smith, E.-A., Myburgh, J., Osthoff, G., De Wit, M.

2014 Journal of Dairy Research 81(4), pp. 417-423 (IF 1.598)

Thermal treatment, Jelly processing and sensory evaluation of cactus pear fruit juice        

de Wit, M., Bothma, C., Swart, P., Frey, M., Hugo, A.

2014 Journal of the Professional Association for Cactus Development 16, pp. 1-14 (IF 0.3)

The influence of location, cultivar and season on cactus pear fruit quality    

Shongwe, N., De Wit, M., Osthoff, G., Nel, P., Labuschagne, M.

2013 Acta Horticulturae 995, pp. 165-180 (IF 0.223)

The influence of cultivar and season on cactus pear fruit quality        

Rothman, M., De Wit, M., Hugo, A., Fouché, H.J.

2013 Acta Horticulturae 995, pp. 201-212 (IF 0.223)

Comparison of the milk composition of free-ranging indigenous African cattle breeds

Myburgh, J., Osthoff, G., Hugo, A., Nel, K., Fourie, D.

2012 South African Journal of Animal Sciences

42(1), pp. 1-14 (IF 0.412)

Determination of seasonal influences on sensory attributes of South African cactus pear cultivars

Rothman, M., de Wit, M., Bothma, C., Hugo, A.       

2011 Journal of the Professional Association for Cactus Development 14, pp. 41-52 (0.3)

The effect of variety and location on cactus pear (Opuntia ficus-indica) fruit quality

de Wit, M., Nel, P., Osthoff, G., Labuschagne, M.T.

2010 Plant Foods for Human Nutrition 65(2), pp. 136-145

(IF 2.465)

Characterization of a spray-dried soymilk powder and changes observed during storage  

Osthoff, G., Hugo, A., Van Wyk, P., De Wit, M., Meyer, S.

2010 Food Science and Technology International

16(2), pp. 169-178 (IF 1.081)

Comparison of the milk composition of free-ranging blesbok, black wildebeest and blue wildebeest of the subfamily Alcelaphinae (family: Bovidae)     

Osthoff, G., Hugo, A., de Wit, M.      

2009 Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology 154(1), pp. 48-54 (IF 1.607)

Milk composition of captive vervet monkey (Chlorocebus pygerythrus) and rhesus macaque (Macaca mulatta) with observations on gorilla (Gorilla gorilla gorilla) and white handed gibbon (Hylobates lar)           

Osthoff, G., Hugo, A., de Wit, M., Nguyen, T.P.M., Seier, J.

2009 Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology

152(4), pp. 332-338 (IF 1.067)

The chemical composition of milk from free-ranging African buffalo (Syncerus caffer)       

Osthoff, G., Hugo, A., De Wit, M., Mai Nguyen, T.P.

2009 African Journal of Wildlife Research 39(1), pp. 87-102 (IF 0.6)

Milk composition of a free-ranging white rhinoceros (Ceratotherium simum) during late lactation

Osthoff, G., Hugo, A., de Wit, M.      

2008 Mammalian Biology 73(3), pp. 245-248 (IF 1.159)

Milk composition of three free-ranging African elephant (Loxodonta africana africana) cows during mid lactation

Osthoff, G., de Wit, M., Hugo, A., Kamara, B.I.        

2007 Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology 148(1), pp. 1-5 (IF 1.607)

The composition of serval (Felis serval) milk during mid-lactation      

Osthoff, G., Hugo, A., de Wit, M.      

2007 Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology 147(2), pp. 237-241 (IF 1.607)

Milk composition of free-ranging sable antelope (Hippotragus niger) 

Osthoff, G., Hugo, A., de Wit, M.      

2007 Mammalian Biology 72(2), pp. 116-122 (IF 1.159)

Milk composition of free-ranging springbok (Antidorcas marsupialis)

Osthoff, G., Hugo, A., de Wit, M.      

2007 Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology 146(3), pp. 421-426 (IF 1.607)

The composition of cheetah (Acinonyx jubatus) milk

Osthoff, G., Hugo, A., de Wit, M.      

2006 Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology 145(3-4), pp. 265-269

(IF 1.607)

A comparative study of lipolysis and proteolysis in Cheddar cheese and yeast-inoculated Cheddar cheeses during ripening     

De Wit, M., Osthoff, G., Viljoen, B.C., Hugo, A.        

2005 Enzyme and Microbial Technology 37(6), pp. 606-616 (IF 2.638)

Milk composition of a free-ranging African elephant (Loxodonta africana) cow during early lactation

Osthoff, G., De Waal, H.O., Hugo, A., De Wit, M., Botes, P.

2005 Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology 141(2), pp. 223-229 (IF 2.196)

Accepted publications in press:

Du Toit, A., De Wit, M., Fouché, H.J., Hugo, A., Venter, S.L. 2019. Rheological characterization of cactus pear mucilage for application in nutraceutical food products.

Acta Horticulturae

Du Toit, A., De Wit, M., Fouché, H.J., Hugo, A., Venter, S.L. 2019. Determination of the functional properties of freeze-dried cactus pear mucilage powder from cladodes of four South African cultivars.

Acta Horticulturae

Venter, S.L., Fouché, H.J., De Wit, M., Mavengahama, S., Coetzer, G.M., Swart, W.J., Amonsou, E. March 2019. The effect of fostering partnerships on broadening the food base: the role of cactus pear, an underutilised crop with unlimited potential, the South African perspective.

Acta Horticulturae

De Wit, M., Fouché, H.J., De Waal, H.O., Coetzer, G.M., Venter, S.L. 2019. Promoting the potential of spineless cactus pear (Opuntia ficus-indica) as a multi-use crop at the Oppermansgronde community in the Free State Province of South Africa.

Acta Horticulturae

De Wit, M., Coetzer, G.M., Fouché, H.J., Venter, S.L. 2019. Climatic influences on fruit quality and sensory traits of cactus pear (O. ficus-indica): a five-year evaluation.

Acta Horticulturae

De Wit, M., Du Toit, A., Fouché, H.J., Hugo, A., Venter, S.L. 2019. Screening of cladodes from 42 South African spineless cactus pear cultivars for morphology, mucilage yield and mucilage viscosity.

Acta Horticulturae

M.Sc. and Ph.D. done in Dairy chemistry and -biochemistry (1997-2003)
Fruit- and vegetable processing and -biochemistry (2004-)

Project leader of plant food processing (fruit and vegetables),
Team member of Dairy chemistry and -biochemistry group
 

I regard my research on cactus pears as being valuable, since increased droughts necessitates exploration of under-utilized crops that can withstand harsh
environmental conditions as is increasingly being observed in South Africa. SA is the only country in the world where 42 different cultivars of spineless cactus pears,
originally from the American Burbank collection, are found and propagated. The importance of this plant to humans and animals is immense. In many parts of the world it
is the only food available for humans and animals and it provides water, nutritional and functional ingredients. My current research aim is to explore the utility of cactus
pears as part of mainstream human nutrition in arid and impoverished regions. This includes using the plant as both fruit and vegetable, utilizing waste products and byproducts
as well as its application as functional ingredients.

The spineless Opuntia ficus-induca and Opuntia robusta cactus pear species, imported into South Africa in 1914 mainly for fodder, necessitated its valuation for human
food. It is a so-called new crop with immense potential for use in the food, nutraceutical, pharmaceutical and cosmetic industries. Research on cactus pears for human
food uses in SA was almost non-existent and its application as human food source needed investigation. The ARC is investigating 42 cultivars for fruit and cladode
(fodder) production in Bloemfontein. South Africa is the only country in the world propagating the original spineless Burbank cultivars which were imported from Florida in
1914. Even countries where cactus pear originated from such as Mexico and Chile, cultivate only a few spiny cultivars. One of the first questions to be answered was if
the fruit of all 42 cultivars being evaluated were suitable for human consumption, in other words, fruit quality was determined physico-chemically as well as sensorically.
Data for Bloemfontein was compared to data from other secondary orchards established by the ARC and the Department of Agriculture at other agro-ecological regions
namely Oudtshoorn (16 cultivars) and Cradock (14 cultivars). The influence of season and locality on cactus pear fruit quality was established. Fruit quality, especially
in terms of sensory quality, was further evaluated and reported.

From fruit quality, my focus shifted to alternative food uses of cactus pears. To establish cactus pears as a multi-use crop, other parts of the plant such as the cladodes
and waste products e.g. seeds were investigated.
A study was launced into the oil composition and fatty acid analysis of the seeds from the cactus pear fruit. This oil is currently one of the most expensive oils to be
used in culinary and cosmetic industries. Oils from the 42 cultivars from Bloemfontein, 16 cultivars from Cradock and 14 cultivars from Oudtshoorn were evaluated and
compared over two seasons. Oil quality and stability was also determined.

Functional ingredients in cactus pears include the soluble fibre mucilage. Mucilage is a hydrocolloid with interesting functional properties. Although it is generally
recognised as a negative aspect in cladode processing, I wanted to explore its unique properties as functional ingredient in food products.
A patent was registered in 2011 by the UFS (Du Toit and De Wit, 2011) on the extraction of mucilage from cactus pear cladodes. A Masters project on mucilage as gelling agent in marshmallows was completed. 

Other functional ingredients include antioxidants. Antioxidant content and potential of cactus pear fruit (pulp, peel and seeds) and cladodes from fresh and processed
products were evaluated. These included ascorbic acid, betalains, phenolic constituents and carotenes. Fruit and cladodes were juiced, dried, heat processed and
pickled. 
Further functional applications of cladodes for human consumption was also investigated. The influence of cladode flour addition to different baked products was
investigated. This was done to increase fibre content and replace wheat flour (gluten) to which allergies are known for. 

Food chemistry, specifically the chemical changes in foods during processing, with a special interest in fruits, vegetables and dairy products.

Undergraduate courses:

VWS 224 (Food Systems from 2006-2010),

FSCC 2612 (VWS 232), (Food Chemistry from 2011-),

FSCC 2622 (VWS 222), (Food Chemistry from 2011-),

FSCP 3724 (VWS 324), (Fruit and vegetable Processing),

FSCP 4814 (VWS 414), (Fruit and vegetable Processing Advanced),

SAFA 7926 (MVL 740), (Masters in Sustainable Agriculture)

FSCL 4814 (VWS 693), (Literature)

FSCR 4814 (VWS 695) (Project)

Postgraduate courses:

VWS 605 (General Food Science),

VWS 606 (Fruit and vegetable Processing),

VWS 607 (2 modules: Fruit and vegetable Processing),

MVL 740 (2 modules: Preservation of Food and Processing of fruit and vegetables),

AGB 704 (2 modules: Preservation of Food and Processing of fruit and vegetables).

VWS 600 (M.Sc.)

VWS 900 (Ph.D.)

1. Presentation of 1-day and 3-day Short courses in value-added dairy products.  A total of 13 1-day and 9 3-day courses had been presented since 1999.

2. Participation in Information days regarding cactus pears organised by the ARC and UFS.