Original Article
Ubiquinone contents in Korean fermented foods and average daily intakes

https://doi.org/10.1016/j.jfca.2011.03.018Get rights and content

Abstract

Coenzyme Q (CoQs, ubiquinones) in food may have antioxidative and other beneficial effects on human health. Data on the ubiquinones (CoQ10 and CoQ9) content of Korean fermented foods were determined, then the Korean daily intake of ubiquinones from those foods was estimated. The analytical method employed saponification before solvent extraction and quantification HPLC/MS equipped with diode array detection. Contents of CoQs in the fermented foods varied from 315.9 ± 12.6 μg/g (Jeotgal, a fermented fish) to below the detection limit (Soy sauce) on a dry basis. Doenjang (a fermented soy paste) was the richest sources of CoQ9 (110.1 μg/g), while CoQ10 was found highest contents in Jeotgal (291.0 μg/g). However, the major fermented food source of CoQs intake in the Korean population was Kimchi, representing 88.2% of the total CoQs (Q9 + Q10) intake. The estimated daily intake of total CoQs from the analyzed fermented foods was 11.6 mg/day/person, which was significantly higher than those of other populations reported (3–6 mg). It could be suggested that Korean fermented foods may have higher ubiquinone than unfermented foods due to their diverse microflora during the process of fermentation.

Introduction

Coenzyme Q10 (CoQ10) or ubiquinone-10 (UQ-10), an endogenous enzyme cofactor produced in all living cells in humans and distributed in cellular membranes, is an essential lipophilic component of the electron transport chain for oxidative phosphorylation, and it is known to be an energy booster and immune-system enhancer (Ernster and Dallner, 1995, Molyneux et al., 2005). Naturally occurring members are the coenzyme Q6–Q10, and the differences in their properties are due to the length of the side chain (Ernster and Dallner, 1995). CoQ10 is produced in the human body in variable amounts depending on the diet or diseases (Overvad et al., 1999). More than 90% of the CoQ10 content in human serum and biological tissues exists in the reduced form ubiquinol-10 (CoQ10H2) (Fig. 1), which is a powerful lipid-soluble antioxidant (Kaikkonen et al., 2002, Miles, 2007). Ubiquinol-10 protects low-density lipoproteins (LDL) from lipid peroxidation by scavenging peroxyl radicals and reducing α-tocopheryl radicals (Stocker et al., 1991, Mohr et al., 1992). The oxidized form (ubiquinone) may be reduced to ubiquinol enzymatically after absorption (Mohr et al., 1992). CoQ10 deficiency has been implicated in several clinical disorders, including chronic heart failure (Molyneux et al., 2008), hypertension (Kumar et al., 2009), Parkinson's disease (Beal, 2004) and malignancy (Portakal et al., 2000). Thus, exogenous CoQ10 may have beneficial effects on human health; i.e., CoQ10 present in food or taken as a dietary supplement appears to act primarily by elevating the coenzyme Q level in blood, where it may function as an antioxidant (Mohr et al., 1992). Despite the presumption that exogenous coenzyme Q may have beneficial effects on human health, only few studies have assessed contents of coenzyme Q in foods (Weber et al., 1997a, Mattila and Kumpulainen, 2001, Pravst et al., 2010). It has been reported that most foods contained ubiquinone and daily intake of CoQ10 was estimated to be 2–20 mg/day (Weber et al., 1997a, Mattila and Kumpulainen, 2001).

Traditionally, Koreans have consumed high quantities of fermented foods to overcome the protein deficiency risk resulting from a rice-based diet (Yoo, 1997). The main substrates used in the commercial or traditional production of the most familiar fermented products in Korea are vegetables (Kimchi), soybean (Doenjang, Cheonggukjang, Kochujang, Soy sauce), and fishes (Jeotgal). The Fermented foods have been placed as an important portion of the diet in Korea. The microflora responsible for this food fermentation is in many cases indigenous and includes strains of lactic acid bacteria (LAB), yeast, and fungi (Table 1) (Cheigh and Park, 1994, Yoo, 1997, Kim et al., 1998a, Ham et al., 2004, Cho and Seo, 2007, Guan et al., 2011).

Meanwhile, a number of microorganisms, including bacteria (e.g. Pseudomonas, Agrobacterium, Paracoccus), moulds (e.g. Aspergillus, Neurospora) and yeasts (e.g. Candida, Rhodotorula, Saitoella) have been reported as CoQ10 producers (Meganathan, 2001, Cluis et al., 2007). In particular, selection studies of wild-type strains showed that photosynthetic bacteria such as Rhodospirillum, Rhodobacter and Pseudomonas are excellent CoQ10 producers, with the highest specific CoQ10 content found in Rhodospirillum (Cluis et al., 2007). Therefore, it could be expected that Korean fermented foods may have higher CoQs, when compared to other foods without fermentation. Because the fermentation process by diverse microorganisms during manufacture might influence the production of CoQs and possibly the distribution of CoQs homologues. However, the contents of total and individual ubiquinone in fermented foods consumed in Korea have not been reported. Thus, the aim of this study is to determine CoQ9 and CoQ10 contents in some fermented food commonly consumed in Korea and estimates the average daily intake of these compounds using both the data generated and a recently published report.

Section snippets

Food samples

Fermented food samples used for analysis were selected considering the ordinary intake of the Korean population. They were obtained from different local markets and traditional shops, and prepared for analysis on the day of purchase or on the following day. Purchased samples were the brands commanding a high share of the domestic market and the best selling brands for fermented foods in Korea. The number of selected items in each food group for fermented foods from traditional and commercial

Ubiquinone contents in Korean fermented foods

There are several types of traditional fermented foods in Korea. The most common Korean fermented foods based on soybean (Doenjang, Kochujang, Cheonggukjang, and Soy sauce), vegetables (Kimchi), and fish (Jeotgal) as shown in Table 1. These fermented foods have an important role in the diet and nutrition of Koreans. The content of CoQ9, CoQ10, and total CoQs (Q9 + Q10) in Korean fermented food items are shown in Table 2. The ubiquinone content in these foods was significantly different between

Conclusions

The present study sought to determine CoQ9 and CoQ10 contents in Korean fermented food groups and estimate the average dietary intake of these compounds using both the data generated and a recently published dietary survey of Korean adults. The total CoQs (Q9 + Q10) content ranged from 5.5 ± 0.6 to 308.5 ± 18.9 μg/g in fermented soybean food group (Doenjang, Kochujang, Chonngukjang, Soy sauce), 110.2 ± 7.4 to 148.2 ± 12.3 μg/g in fermented vegetable food group (Kimchi), and 296.8 ± 11.9 to 315.9 ± 12.6 μg/g in

Acknowledgement

This work was supported by the Sungshin Women's University Research Grant 2009.

References (37)

  • M.F. Beal

    Mitochondrial dysfunction and oxidative damage in Alzheimer's and Parkinson's diseases and coenzyme Q10 as a potential treatment

    Journal of Bioenergetics and Biomembranes

    (2004)
  • H.S. Cheigh et al.

    Biochemical, microbiological and nutritional aspects of Kimchi (Korean fermented vegetable products)

    Clinical Review of Food Science and Nutrition

    (1994)
  • K.M. Cho et al.

    Bacterial diversity in a Korean traditional soybean fermented foods (doenjang and ganjang) by 16S rRNA gene sequence analysis

    Food Science and Biotechnology

    (2007)
  • L. Ernster et al.

    Biochemical, physiological, and medical aspects of ubiquinone function

    Biochimica et Biophysica Acta

    (1995)
  • P.H. Gale et al.

    Coenzyme Q: isolation and characterization of coenzyme Q10 (H-10)

    Biochemistry

    (1963)
  • S.S. Ham et al.

    Quality characteristics of soy sauce fermented by Bacillus licheniformis NH20 isolated from traditional meju and Aspergillus oryzae

    Food Science and Biotechnology

    (2004)
  • J.H. Hwang et al.

    Fermentation characteristics and antioxidative effect of red mustard leaf kimchi

    Journal of the Korean Society of Food Science and Nutrition

    (2000)
  • J. Kaikkonen et al.

    Coenzyme Q10: absorption, antioxidative properties, determinants, and plasma levels

    Free Radical Research

    (2002)
  • Cited by (0)

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