Development of a stock cube with functional food characteristics

Abstract

The chronic diseases of lifestyle, tuberculosis and Human immunodeficiency virus/Acquired immunodeficiency syndrome have a high prevalence in South Africa. These diseases are characterised by oxidative stress and a chronic inflammatory state that contribute to both the development and the acceleration of these diseases. Research into the phytochemical plant food components suggest that these substances could possibly play a vital role in the prevention of such disease. Corn steep liquor (CSL) is a waste product with an exceptionally high polyphenol content and total antioxidant capacity (TAC). This led to the suggestion that it could be utilised in the development of food products with functional food characteristics. Stock cubes, due to the widespread use among consumers of different socio-economic backgrounds, were identified as vehicle for the delivery of the CSL with its phytochemical content. This lead to the development of a stock cube utilising CSL as a source of phytochemical polyphenolic antioxidants with the micronutrients zinc, selenium and copper as added support to immunonutrition, along with iron due to the wide spread prevalence of iron deficiency in the South African population. The acceptability of the developed stock cube was tested by preparing savoury rice and pea soup and having blue collar (n = 50) and white collar (n = 49) participants rate the acceptability on a 9-point hedonic scale, ranging from “dislike extremely” to “like extremely”. The savoury rice received a 41% “like very much” rating followed by a 24% “like moderately” rating. The pea soup was rated even more positively as it received a 42% “like very much” rating and a 29% “like extremely” rating. In addition, among the blue collar participants, significant (p < 0.05 for each) findings occurred with a greater liking of the sample dishes prepared with the developed stock cube by participants of the ethnic Black grouping, with Xhosa as home language and being married, as well as those participants who habitually prepare the meals in the household. A significant (p < 0.05) finding with the white collar participants was a greater liking of the sample dishes prepared with the developed stock cube among those participants who would be willing to make use of a stock cube with health benefits. The developed stock cube was also subjected to six months accelerated shelf-life stability testing, reflecting twelve months real time storage. The parameters measured were microbial growth, oxidative rancidity, antioxidant status and organoleptic changes. All microbial growths tested remained within the acceptable specification ranges. Oxidative rancidity, measured as the peroxide value, was detected analytically at the fifth and sixth samplings, but was not detectable organoleptically. The antioxidant status, measured as the TAC and the total polyphenol content, remained relatively stable during the testing period. Though no noticeable organoleptic changes were observed during the stability testing, there was a darkening of

the colour by the second sampling. The results of the acceptance testing, as well as the shelf-life stability testing, support the conclusions that the study objectives of developing a stock cube with functional food characteristics and it being received positively by consumers were achieved. Keywords: stock cubes; corn steep liquor; phytochemicals; consumer acceptance; new product development