Department

Consumer and Food Sciences

Degree

PhD Consumer Science

Perceptions and acceptance of grapefruit-like model beverages that vary in taste, colour and aroma sensory properties: effects of sensitivity to bitter taste and TAS2R38 and TAS2R19 bitter receptor genes

Grapefruit (Citrus paradise Macfadyen) varieties are white, pink and ruby red, and an excellent source of many nutrients and phytochemicals that contribute to a healthy diet. Consumption appears to be associated with a reduced risk of certain chronic diseases, such as obesity, diabetes, cancers and cardiovascular disease. Despite the health benefits, consumption of grapefruit in South Africa remains low. Dr Gustav Gous works in the citrus industry and supports juice processors with technical expertise.  His love of juice processing inspired him in his PhD study to study acceptance of the sensory properties of grapefruit.

Consumer choice decisions is a complex process. Sensory (e.g. colour, flavour and taste) and non-sensory characteristics (e.g. product information and prices) influence choice behaviour.  Gustav studied the perception of grapefruit flavour resulting from the integration of multisensory signals, consumer sensitivity and genotype.  The main objective of the study was to determine the effect of varying the bitterness, sweetness, colour and aroma intensity of a grapefruit-like model beverage on the perception and consumer liking with the aim of giving guidance to breeders on selection and improvement of grapefruit traits to optimize hedonic value. The second objective was to determine the effects of sensitivity to bitter taste [as determined through 6-propylthiouracil (PROP) taster classification] and genetic variation in TAS2R38 and TAS2R19 SNP genotypes on hedonic rating of the flavour of grapefruit-like beverages differing in bitter/sweet taste intensity.

This study showed that low bitterness, high sweetness, low grapefruit aroma levels and red colour increase consumer liking of grapefruit juice. It further found that genetic variation in TAS2R38 and TAS2R19 genotypes are partly responsible for the dislike of bitter grapefruit beverages.

Email

[email protected]

Supervisors

Primary supervisor Prof HL de Kock

Co-supervisor: Dr V Coetzee

Research Profiles

• LinkedIn – https://www.linkedin.com/in/gustav-gous-62b2767b/

Memberships

• SAAFoST (South African Association for Food Science & Technology

Publications

• Gous, A.G.S., Almli, V.L., Coetzee, V., De Kock, H.L. (2019). Effects of Varying the Color, Aroma, Bitter, and Sweet Levels of a Grapefruit-Like Model Beverages on the Sensory Properties and Liking of the Consumer. Nutrients, (11) 464-.

Conferences

• Gous, A.G.S., Almli, V.L., Coetzee, V., De Kock, H.L. (2015) Cross model interaction of sensory propertes of grapefruit-like beverages for optimization of consumer liking. AfroSense, 23- 26 November 2015, STIAS Conference Centre, Stellenbosch, South Africa.
• Gous, A.G.S., Almli, V.L., Coetzee, V., De Kock, H.L. 2015. Cross model interaction of sensory propertes of grapefruit-like beverages for optimization of consumer liking. SAAFost Congress, 06- 09 September 2015, Tsogo Sun Elangeni, Maharani Complex, Durban, South Africa.
• Gous, A.G.S., Almli, V.L., Coetzee, V., De Kock, H.L. (2015) Cross model interaction of sensory propertes of grapefruit-like beverages for optimization of consumer liking. 11th Pangborn Sensory Science Symposium, 23-27 August 2015, Gothenburg, Sweden.
• Gous, A.G.S., Kotze, K., Onyeoziri, I., Coetzee, V., De Kock, H.L. 2014. The effect of genetic variation in taste perception on consumer acceptance of green leafy vegetables and grapefruit. SenseAsia 11-13 May 2014, Singapore.