Article

Umami Compounds Are a Determinant of the Flavor of Potato (Solanum tuberosum L.)

Quality, Health and Nutrition, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom.
Journal of Agricultural and Food Chemistry (Impact Factor: 2.91). 12/2007; 55(23):9627-33. DOI: 10.1021/jf0717900
Source: PubMed

ABSTRACT

Vegetable flavor is an important factor in consumer choice but a trait that is difficult to assess quantitatively. The purpose of this study was to assess the levels of the major umami compounds in boiled potato tubers, in cultivars previously assessed for sensory quality. The free levels of the major umami amino acids, glutamate and aspartate, and the 5'-nucleotides, GMP and AMP, were measured in potato samples during the cooking process. Tubers were sampled at several time points during the growing season. The levels of both glutamate and 5'-nucleotides were significantly higher in mature tubers of two Solanum phureja cultivars compared with two Solanum tuberosum cultivars. The equivalent umami concentration was calculated for five cultivars, and there were strong positive correlations with flavor attributes and acceptability scores from a trained evaluation panel, suggesting that umami is an important component of potato flavor.

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Available from: Laurence J M Ducreux, Jun 11, 2015
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    • "Analysis of 5 0 -nucleotides (AMP ? GMP) 5 0 -nucleotides were extracted with the modified methods described by Liu et al. (2006), Morris et al. (2007). Tuber tissue (0.5 g) from raw as well as microwave cooked tubers were rapidly frozen in liquid Nitrogen and homogenized into powder. "
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    ABSTRACT: Potato flavour depends on the level of umami compounds and volatiles. Major umami compounds present in potatoes are 5′-nucleotides (adenosine-5′-monophosphate: AMP and guanosine-5′-monophosphate: GMP) and amino acids (aspartic acid and glutamic acid). The level of these compounds in Indian potato cultivars has not been investigated. Therefore, a method was standardized for the detection of umami 5′-nucleotides from raw and microwave cooked tubers of forty four Indian potato cultivars using high performance liquid chromatography. In raw tubers, concentration of 5′-nucleotides ranged from 1.70 µg g−1 fr. wt. in Kufri Jawahar to 6.68 µg g−1 fr. wt. in Kufri Muthu. In microwave cooked potatoes concentration of 5′ nucleotides ranged from 2.97 µg g−1 fr. wt. in Kufri Jawahar to 9.54 µg g−1 fr. wt. in Kufri Himalini. Under microwave cooking, the concentration of 5′-nucleotides was found to increase manifolds ranging from the highest in Kufri Lalima (272 %) to the lowest in Kufri Kundan (0 %). A positive correlation existed between the level of 5′-nucleotides and organoleptic scores given by the panelists. A positive correlation was observed in the flavour of varieties having dry matter of <18 %. Further investigations on the concentration of umami compounds in Indian potato cultivars may lead to finding out better tasting cultivars for potato product development .
    Full-text · Article · Dec 2014 · Indian Journal of Plant Physiology
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    • "Previously, it was assumed that the accumulation of 5'-nucleotides in cooked tubers is due to the action of nucleases that breakdown RNA. But Morris et al. (2007) could not find any difference in the level of the enzyme activity in different cultivars showing different 5'-nucleotides concentrations. During microwave cooking, the tuber temperature increases relatively uniformly, with all parts reaching 100 °C within a few minutes of each other (Concha et al., 2002). "
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    ABSTRACT: Fresh potatoes are preferred for cooking over stored potatoes due to the superior taste of freshly harvested potatoes since with the increase in storage duration, quality as well as taste of potatoes are known to deteriorate. Therefore, the aim of the present study was to investigate the effect of storage (for 180 days at 4 °C and 12 °C) on concentration of flavouring compounds, particularly umami 5’ nucleotides viz. adenosine monophosphate (AMP) and guanosine monophosphate (GMP) along with changes in carbohydrates. AMP+GMP content ranged from 2.19 to 4.69 μg/g FW (fresh weight) in freshly harvested raw and microwaved tubers of 11 potato cultivars. The content of umami 5’ nucleotides increased to appreciable amounts during microwave cooking (3.52 to 8.92 μg/g FW). During storage at 4 and 12 °C, flavouring compounds ranged from 0.29 to 2.39 μg/g FW and 0.34 to 2.92 μg/g FW in raw tubers and from 0.91 to 5.64 μg/gFW and 2.00 to 4.28 μg/gFW in microwaved potatoes, respectively. On an average, there was 19% and 10% decrease in starch content whereas 112% and 69% increase in reducing sugars and 90% and 57% increase in sucrose content, at 4 °C and 12 °C storage, respectively. It is known that the quality and taste of potatoes deteriorates during storage due to starch hydrolysis leading to reducing sugar accumulation, but this study has revealed that it is not only the sugar accumulation but also the decrease in flavouring compounds viz. AMP+GMP which results in poor taste of stored potatoes. Hence, sugars accumulation and deterioration of flavouring compounds together leads to poor taste of stored potatoes.
    Full-text · Article · Jan 2014
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    • "Both are very polar molecules and are, therefore, difficult to analyze directly by conventional reversed-phase liquid chromatography (RPLC) without derivatization. Amino acids in complex matrices are usually analyzed by LC or gas chromatography (GC) using a derivatization step to make them less polar and more volatile for GC (Oruna-Concha and others 2007) or less polar to give better retention with RPLC (Morris and others 2007; "
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    ABSTRACT: An ion-pair LC-ESI-MS method was developed capable of analyzing various reported umami or umami-enhancing compounds, including glutamic acid and 5′-ribonucleotides. The method was validated using tomato and potato samples and showed overall good analytical performance with respect to selectivity, detection limit, linearity, and repeatability. The method was applied to various tomato samples resulting in concentrations of glutamic acid and 5′-ribonucleotides that were in good comparison with literature. The methodology might also be used for the discovery of new umami (enhancing) compounds in an untargeted mode. This was to a certain extent demonstrated for tomato samples by correlating all peaks observed with the ion-pair liquid chromatography-mass spectrometry (LC-MS) method to sensory properties using multivariate statistics. Practical Application: This study describes the development and application of a LC-MS method, which can be used to quantify several known umami (enhancing) compounds in various foods. Furthermore, the method might be useful for the discovery of new umami (enhancing) compounds.
    Full-text · Article · Aug 2011 · Journal of Food Science
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