Trends in Food Science & Technology 61 (2017) 103e115 Contents lists available at ScienceDirect Trends in Food Science & Technology journal homepage: http://www.journals.elsevier.com/trends-in-food-science- and-technology Review Metabolomics for empirical delineation of the traditional Korean fermented foods and beverages * Digar Singh 1, Sunmin Lee 1, Choong Hwan Lee Department of Bioscience and Biotechnology, Konkuk University, 05029, Seoul, South Korea article info abstract Article history: Background: The umpteen varieties of traditional Korean fermented foods, condiments, seasonings, and Received 12 August 2016 beverages deliver a wallop of savor, aroma, nutrients, probiotics, and functional bioactives. However, our Received in revised form surprisingly limited comprehensions of the associated metabolomes, related phenotypes, and health 21 October 2016 effects maneuvered through the perplexing interplay of fermentative microflora turns their empirical Accepted 3 January 2017 analyses a non-trivial undertaking. Available online 5 January 2017 Scope and approach: The economy data indicates that the shipment values for traditional Korean fer- mented foods per se stood a miraculous 4 billion USD in 2013 with burgeoning 71% increase in domestic Keywords: Metabolomes food industries in last decade (statistical yearbook, Korea Food and Drug Administration, 2014). Quin- Fermented soy-foods tessentially, the consumers now expect the highest possible standards of food manufacturing with in- Vegetables sights of their molecular contents and associated health effects. A range of analytical platforms, based on Seafood chromatographic separation coupled with spectrometric or spectroscopic detection, enables the Bioprocesses metabolomic snapshots for fermentative bioprocesses and underlying biotransformation mechanisms. However, a technological void still exist which restrict the generic use of analytical methodologies owing to the complexity of diverse metabolomes. Key findings and conclusions: This review outlines the metabolomic perspectives for the traditional Korean fermented foods and beverages. We discuss the current trends towards the application of metabolomics and related methodologies to probe their metabolite contents and functionality. Moreover, the crucial bottlenecks associated with fermentative bioprocess and microbial transformations are also addressed in the context of artisanal and industrial manufacturing processes. Further, the article pro- poses a rational metabolomic approach towards the discernment of palatability and insalubrities asso- ciated with fermented foods. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction studies have suggested the cultural trends of intentional fermen- tation practices by the early Neolithic civilizations in East Asia, The prehistoric civilizations of the Korean peninsula instru- ascertaining its traditional hegemony in pre-historic times mented the artisanal fermentative practices to gain the nutritive (McGovern et al., 2004). However, the earliest text reference to and functional diets, besides surviving the meagerness. Unwit- fermented soybeans was found in a Chinese dictionary “Shuo-wen tingly, our ancestors became the first biotechnologists to harness Chiehtzu” by Hsu Shen (121 AD) during the Kokan dynasty (25e220 beneficial microbes and their metabolites to enhance the palat- CE), which describes “Shi (soybean nuggets) as the bean products ability, shelf life, and savory of foods. Immediately henceforth, the made by placing the beans in the dark room for natural fermen- Far East civilizations excelled the art of turning every piece of na- tation to occur” (Steinkraus, 1983). Another important compilation ture's bounty into fermented stuffs, including grains, soybeans, from the medieval Korean history “Dongui Bogam” (1613 CE), by the vegetables, and seafood. Modern mass spectrometry (MS)-based royal physician, Heo Jun, during the rule of the Joseon (synonym: Chosun) dynasty of Korea, described the curative applications of doenjang. In recent times, the scientific reports with empirical de- * Corresponding author. lineations for the perplexing metabolomes for traditional fer- E-mail address: [email protected] (C.H. Lee). 1 These authors contributed equally to this work. mented foods and beverages are soaring high, both, in academia as http://dx.doi.org/10.1016/j.tifs.2017.01.001 0924-2244/© 2017 Elsevier Ltd. All rights reserved. 104 D. Singh et al. / Trends in Food Science & Technology 61 (2017) 103e115 well as industry. Translational metabolomics has incontrovertibly analytical platforms with case selective targeted or untargeted unfolded the functional aspects of a variety of fermented foods viz., approaches become indispensable to standardize the quality con- fermented soy, cereal, milk products, vegetables and herbs, sau- trol for promoting the widespread consumer acceptance of arti- sages, fish-based products, and health beverages, among others (Hu sanal or commercial fermented products. & Xu, 2013). Yet another perplexing, but intriguing, aspect of fermentative bioprocess includes a correlative assessment of the 3. Metabolomics: trends and neoteric approaches microbial consortia and their plethora of associated metabolites influencing the overall functional or deleterious aspects of desired Among the various 'omics' cascades, only metabolomics repre- end products. The aforementioned correlations are vital for sents the generic harbinger of genomic expressions carried by ensuring the desired health effects and nutrition, as well as the transcriptome as well as proteome together, and hence offers a characteristic taste, aroma, and consumption safety of fermented more tractable option for metabolome studies (Kell et al., 2005). foods produced using artisanal or industrial methods (Jung, Cho, Metabolomics is inconsistently defined as the analysis of the et al., 2015; Ray, Ghosh, Singh, & Chandra Mondal, 2016). Hence, quantitative complements of low molecular weight metabolites the neoteric metabolomic approaches, in conjunction with other (<1800 Da) present in a cell, tissue, or organism under a given set of 'omics' cascades (transcriptomics, proteomics, or genomics), can physiological conditions (Zhou, Xiao, Tuli, & Ressom, 2012). Bio- potentially transmogrify our classical perspectives towards fer- chemically, metabolites are the metabolic pathway intermediates mented foods and beverages. or the end products driving essential cellular functions i.e., bio- energetics and cell signaling. Besides their endogenous production 2. Socioeconomic trends, globalization, and metabolomics in the host, metabolites are also obtained exogenously through the critique of technological hurdles diet (Johnson, Ivanisevic, & Siuzdak, 2016). Hence, the food metabolomics typically encompasses the assessment of untargeted Fermented foods and condiments are often considered as the metabolite profiles coupled with statistical analyses as well as the primary components of the most prominent traditional cuisines in targeted identification of functional metabolites or the food safety Far-East Asian countries including China, Japan, and Korea. Aside biomarkers associated with metabolite toxins or contaminants from its role in food storage alone, the artisanal fermentation (Fig. 1). methods might have also been adapted to achieve the desired fla- vors, aroma, and health effects in diet. In the modern age, an esti- 3.1. Sampling, extraction, and instrumentations: methodologies mated one-third of the human diet comes from fermented foods and beverages (Borresen, Henderson, Kumar, Weir, & Ryan, 2012). A range of analytical platforms viz., nuclear magnetic resonance The rapid industrialization and consumer demands have bolstered (NMR), gas chromatography-mass spectrometry (GCÀMS), liquid the large scale production of traditional fermented foods and chromatography-mass spectrometry (LCÀMS), capillary beverages across the world. The data from the 'Ministry of Agri- electrophoresis-mass spectrometry (CEÀMS), 2D-NMR, and matrix culture, Food and Rural Affairs, the Republic of Korea, indicate that assisted laser desorption ionization - time of flight - mass spec- the national food export stood a miraculous 59 billion USD in the trometry (MALDI-TOF-MS) has recently been applied to probe the year 2014, with over 71% increase in the domestic food industries in functional metabolomes of traditional Korean fermented foods a decade. Additionally, the traditional fermented foods including (Kim, Cho, et al., 2012; Lee, Lee et al., 2016; Lee, Kim et al., 2012). Jang, Kimchi, and Jeotgal production witnessed a record figure of The present technologies allow the study of tens to hundreds of approximately 3.72 million tons in 2013 with a shipment value of metabolites in complex biological samples (Patti, Yanes, & Siuzdak, about 4 billion USD (statistical yearbook, Korea Food and Drug 2012). However, the complex fermentation matrix rich in dynamic Administration, 2014). A recent surge in the number of patents and microbial assortments makes their unbiased metabolomic evalua- literature describing the functional metabolites and health effects tion a non trivial undertaking. The first important step towards an associated with traditional fermented foods and beverages further unbiased metabolomic study involves temporal design based indicates their growing vogue among consumers (Table 1). sampling. In foodomics, the temporal fermentation dynamics, mi- The quality and safe consumption standards for fermented foods crobial successions,