The color of beer, which is a typical example of the Maillard or browning reaction, is mainly attributed to melanoidins. However, as melanoidins are heterogeneous polymers formed by the Maillard reaction, there is little data on the chemical structure of the components responsible for the color of beer. To obtain chemical information on the color components of beer, we here isolated a low-molecular-weight yellow pigment from black beer and identified it using instrumental analyses and an authentic sample. As a result, the pigment was identified as perlolyrine, which is a Maillard reaction product from tryptophan; however, its contribution to the total color of beer was very low. This pigment was present in various kinds of beer at the level of 3.2-14.0 μg/100 mL.
Objective: Questionnaires assessing the consumption frequencies of "grain dishes," "fish and meat dishes," and "vegetable dishes" are often used to evaluate whether a participant's diet is nutritionally balanced.This study examined how accurately such questionnaires reflect actual consumption frequencies.Methods: A self-administered questionnaire assessing the typical consumption frequency of "grain dishes," "fish and meat dishes," and "vegetable dishes" were administered to 4th year female university students (n = 33), studying to become registered dietitians. Self-taken photographs of meals and snacks consumed during a seven-day period were also obtained from participants. Actual consumption frequencies of "grain dishes," "fish and meat dishes," and "vegetable dishes" were determined by examining dietary photographs. The correlation between self-reported food consumption and actual food consumption as measured by dietary photographs was examined, as were tendencies in under-and over-reporting of food consumption. Subsequently, participants were individually interviewed regarding any discrepancies between self-reported and actual food consumption frequencies during the seven-day period.Results: Participants showed a tendency to over-report rather than under-report consumption frequency in their questionnaire responses. This was especially true for "grain dishes." Over-reporting was observed in 36.4% of participants. The reasons given by participants for this inconsistency were grouped into three categories: (1) difficulties in answering the questionnaire or in paying attention to what was eaten, (2) over-or under-estimation of what was eaten, and (3) inaccurate answers to the questionnaire.
Conclusions:Participants tended to over-report food consumption in their questionnaire responses.Results of this study suggest that self-report measures do not accurately reflect actual consumption frequencies of "grain dishes," "fish and meat dishes," and "vegetable dishes." Jpn. J. Nutr. Diet., 74 (6) 182~190 (2016)
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