Folate fortification of rice through parboiling: optimisation, rice quality, consumer acceptance and in-vitro relative bioaccessibility & absorption using Caco-2 cells

Parboiling has been examined in this thesis as the means to fortify rice with folic acid. The development of the fortification method was governed by four major aspects, namely, optimisation based on nutrient retention, rice quality, consumer acceptance and nutrient bioaccessibility and absorption. Multifactorial models were developed to describe folate retention. The optimal parboiling condition for the fortification purpose was soaking brown rice at 70 ◦C for 2 h. Fortified rice produced at 70 ◦C was further investigated for the rice quality examination, focussing on Head Rice Yield, kernel dimensions and colour. No significant change in Head Rice Yield and grain dimension was observed between raw and fortified rice, suggesting that the economic value of rice will not be compromised with the fortification process and rice uniformity may likely be achieved after mixing with the untreated rice. Despite the inherent yellow colour of folic acid, compared to parboiled rice, significant difference in yellowness was exhibited only in rice fortified at 1.2 gfolic acid/ 300 gbrown rice, but not among that fortified at lower concentrations. Visual and organoleptic acceptance of the fortified rice by consumers was examined. The appearance of uncooked rice (fortified at 1.2 gfolic acid/ 300 gbrown rice) prepared at 70 ◦C and soaked for 1 h resembled the commercial parboiled rice. An informed health claim on the fortified rice increased the consumers purchase intent which suggested that they welcomed the fortified product. Food familiarity (i.e. familiarity with parboiled rice) improved consumers purchase intent suggesting a higher chance of acceptance in the parboiled rice-consuming countries. The sensory acceptability of three cooked rice samples (rice soaked in 0.15 gfolic acid/ 300 gbrown rice at 70 ◦C for 1, 2 and 3 h and then mixed in with commercial white rice) was compared to the commercial white rice (ControlWhite). No significant difference was noted in liking attributes between the samples and ControlWhite. More than 50 % of the consumers were willing to purchase the samples. Their purchase intent increased after they were notified of the additional health benefits from the rice, they especially inclined to purchase the rice soaked for 2 and 3 h. Lastly, the bioaccessibility and absorption of folic acid in the fortified rice was assessed using in-vitro Caco-2 cell model. Fortified rice was more bioaccessible (91 %) than the aqueous folic acid control (81 %). As for the extent of absorption, no significant difference was observed between the transport results of fortified rice and folic acid control, suggesting that the added folic acid in the fortified rice could be absorbed as well as the control

Influence of evoked contexts on hedonic product discrimination and sensory characterizations using CATA questions

This research contributes new understanding of the role of consumption context. 12 studies involving 1727 consumers were conducted as central location tests (CLT). Using between-subjects experimental designs, the influence of evoked contexts relative to control condition for hedonic responses and sensory product characterization using check-all-that-apply (CATA) questions was evaluated. Contexts were evoked by asking consumers to think of the last time they ate/drank the focal product category or by imagining a specific consumption situation where product consumption would take place (e.g., breakfast on a weekend morning). In half of the studies, consumers were asked to provide a description of the consumption context they imagined. There was no consistent trend in the results regarding the influence of evoked context of hedonic responses. Effects were seen in a minority of studies, but not consistently showing differences in mean scores or changes in sample discrimination. The type of context that was evoked (last time ate/drank vs. specific situation) did not systematically influence the results, although the use of a description phase during context evocation was detrimental to hedonic sample discrimination. In all the studies where participants were asked to describe the context they imagined, hedonic discrimination was inferior to that achieved under no evoked context. Sensory responses to CATA questions were highly similar under evoked and no evoked context and suggested that product characterisations generated by consumers in a typical CLT provide a good proxy for sensory product experience in contextualised consumption situations.Financial support was obtained from The New Zealand Ministry for Business, Innovation & Employment and Plant & Food Research, Comisión Sectorial de Investigación Científica (Universidad de la República, Uruguay), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil), Spanish Ministry of the Economy and Competitiveness (AGL2012-36753-C01) and EU FEDER funds. Staff at The New Zealand Institute for Plant and Food Research Ltd. are thanked for help in planning and collection of data

Comparison of check-all-that-apply and forced-choice Yes/No question formats for sensory characterisation

The application of check-all-that-apply (CATA) questions for sensory product characterisation is gaining acceptance and popularity. This question format has been reported to be a quick and reliable means of gathering sensory profiles from consumers, concurrently with hedonic assessment. However, a limitation of CATA questions is that they do not encourage deep processing by respondents. Forced-choice questions, where respondents answer ‘‘yes’’ or ‘‘no’’ for each term, may encourage systematic processing and be useful when consumers undertake sensory profiling tasks. This research compared sensory profiles elicited by consumers using CATA questions or forced-choice Yes/No questions and contribute to ongoing investigations of CATA questions and related question formats with a view to developing guidelines for best practise. Across seven consumer studies with 600+ consumers and multiple product categories, consistent evidence was obtained that forced-choice Yes/No questions are associated with higher term citation frequencies. However, this did not consistently translate into greater product discrimination. Conclusions regarding similarities and differences amongst samples and the stability of sample and term configurations were generally independent of question format (i.e., whether the sensory data were elicited by CATA or forced-choice Yes/No questions). Overall, the comparison of CATA and forcedchoice Yes/No questions for sensory characterisation suggested parity of the two question formats. This extended to consumers’ perceived difficulty and tediousness for completing the test. Regardless of question format, consumers, on average, perceived the tests as easy and not tedious