Digestibility of resistant starch containing preparations using two in vitro models

BACKGROUND: Resistant starch (RS) is known for potential health benefits in the human colon. To investigate these positive effects it is important to be able to predict the amount, and the structure of starch reaching the large intestine. AIM OF THE STUDY: The aim of this study was to compare two different in vitro models simulating the digestibility of two RS containing preparations. METHODS: The substrates, high amylose maize (HAM) containing RS type 2, and retrograded long chain tapioca maltodextrins (RTmd) containing RS type 3 were in vitro digested using a batch and a dynamic model, respectively. Both preparations were characterized before and after digestion by using X-Ray and DSC, and by measuring their total starch, RS and protein contents. RESULTS: Using both digestion models, 60-61 g/100 g of RTmd turned out to be indigestible, which is very well in accordance with 59 g/100 g found in vivo after feeding RTmd to ileostomy patients. In contrast, dynamic and batch in vitro digestion experiments using HAM as a substrate led to 58 g/100 g and 66 g/100 g RS recovery. The degradability of HAM is more affected by differences in experimental parameters compared to RTmd. The main variations between the two in vitro digestion methods are the enzyme preparations used, incubation times and mechanical stress exerted on the substrate. However, for both preparations dynamically digested fractions led to lower amounts of analytically RS and a lower crystallinity. CONCLUSIONS: The two in vitro digestion methods used attacked the starch molecules differently, which influenced starch digestibility of HAM but not of RTmd

Validity of willingness to pay measures under preference uncertainty

This paper is part of the project ACCEPT, which is funded by the German Federal Ministry for Education and Research (grant number 01LA1112A). The publication of this article was funded by the Open Access fund of the Leibniz Association. All data is available on the project homepage (https://www.ifw-kiel.de/forschung/umwelt/projekte/accept) and from Figshare (https://dx.doi.org/10.6084/m9.figshare.3113050.v1).Recent studies in the marketing literature developed a new method for eliciting willingness to pay (WTP) with an open-ended elicitation format: the Range-WTP method. In contrast to the traditional approach of eliciting WTP as a single value (Point-WTP), Range-WTP explicitly allows for preference uncertainty in responses. The aim of this paper is to apply Range-WTP to the domain of contingent valuation and to test for its theoretical validity and robustness in comparison to the Point-WTP. Using data from two novel large-scale surveys on the perception of solar radiation management (SRM), a little-known technique for counteracting climate change, we compare the performance of both methods in the field. In addition to the theoretical validity (i.e. the degree to which WTP values are consistent with theoretical expectations), we analyse the test-retest reliability and stability of our results over time. Our evidence suggests that the Range-WTP method clearly outperforms the Point-WTP method.Publisher PDFPeer reviewe

Developing the Questionnaire

AbstractThis chapter outlines the essential topics for developing and testing a questionnaire for a discrete choice experiment survey. It addresses issues such as the description of the environmental good, pretesting of the survey, incentive compatibility, consequentiality or mitigation of hypothetical bias. For the latter, cheap talk scripts, opt-out reminders or an oath script are discussed. Moreover, the use of instructional choice sets, the identification of protest responses and strategic bidders are considered. Finally, issues related to the payment vehicle and the cost vector design are the subject of this section

A Comparison of Induced Value and Home-Grown Value Experiments to Test for Hypothetical Bias in Contingent Valuation

Contingent valuation, Hypothetical bias, Experiments, Induced values, Home-grown values, C91, H41, Q26, Q28,

Willingness to pay for a reduction in mortality risk after a myocardial infarction: an application of the contingent valuation method to the case of eplerenone

Contingent valuation, Myocardial infarction, Mortality, Cost-benefit,

Mitigating hypothetical bias in willingness to pay studies: post-estimation uncertainty and anchoring on irrelevant information

One possible source of hypothetical bias in willingness to pay (WTP) estimates is response uncertainty, referring to subject’s uncertainty about the value of the good under assessment. It has been argued that uncertainty can be measured using the post-valuation ‘certainty question’ that asks: ‘How certain are you about your stated WTP?’ and marks the degree of certainty on a quantitative or a qualitative scale. Research has shown that the self- reported certainty evaluations can help mitigate hypothetical bias and obtain increasingly accurate WTP estimates. These study reports present a simple test of reliability of post-valuation certainty assessment and then looks at the empirical evidence for clues regarding the general usefulness of certainty adjustment in mitigating hypothetical bias in WTP studies. We find that the post-estimation uncertainty scores are malleable, i.e., significantly correlated with entirely irrelevant information. We conclude that more robust evidence could justify the routine inclusion of certainty evaluation in WTP studies although in the meantime the interpretation of certainty- adjusted WTP values should be approached cautiously