Dried Kelp (Kombu), Scallop, and Dried Bonito (Katsuobushi)
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Aqua-BioScience Monographs, Vol. 10, No. 1, pp. 1–22 (2017) www.terrapub.co.jp/onlinemonographs/absm/ Flavor Constituents in Savory Seafood: Dried Kelp (Kombu), Scallop, and Dried Bonito (Katsuobushi) Yoichi Ueda1* and Kenji Fukami2 1Japan Food Additives Association Kodenma-cho Shin Nihonbashi Building, 4-9, Nihonbashi-Kodenma-cho, Chuo-ku, Tokyo 103-0001, Japan 2Ajinomoto Co., Inc., 1-15, Kyobashi 1-chome, Chuo-ku, Tokyo 104-8315, Japan *e-mail: [email protected] Abstract Received on Omission tests of the synthetic water extract of dried kelp (Kombu-dashi) revealed that November 10, 2015 the water solution prepared by mannitol, monosodium glutamate (MSG), potassium chlo- Accepted on April 13, 2016 Online published on ride (KCl), and sodium chloride (NaCl) represented the whole taste characters of the March 10, 2017 synthetic extract. Succeeding study suggested that the characteristic Kombu-dashi like kokumi flavors (continuity, mouthfulness, and thickness) were generated by flavor inter- Keywords action among mannitol, MSG, and KCl. Some studies of taste interactions among NaCl, • dried kelp KCl, sweet amino acids, and 5¢-inosinate (IMP) showed that NaCl strengthened umami • garlic and sweetness of some amino acids and also suggested that IMP enhanced umami of Gly, • onion • scallop L-Ser, and L-Ala synergistically. The sulfur-containing compounds in garlic and onion, • dried bonito such as alliin, S-propenyl-L-cysteinesulfoxide and reduced glutathione (GSH), had no • mannitol tastes by themselves but they gave rise to kokumi flavors in umami solution or soups. • glutamate Scallop and beef contained a high amount of GSH and the peptide strengthened kokumi • sweet amino acid flavors of synthetic extracts of these foods. The examination of volatile compounds in • sulfur compound dried bonito by using GC-MS and GC-sniffing methods revealed that acetol and 2,3- • glutathione pentandione reacted with amino acids or protein in boiled bonito meat, generated pyrazines. • pyrazin Straight-chain aldehydes might be involved in the deterioration of crushed dried bonito. • hydrogen sulfide • umami Hydrogen sulfide, one of the key flavor components, decreased during preservation of • flavor interaction 3+ crushed dried bonito catalytically by the complex of Fe and histidine. This study, in- • kokumi cluding new findings, would lead to improve the quality of processed foods and contrib- • deterioration odor ute to future studies of taste phisiology and flavor chemistry. 1. Introduction modalities are called “kokumi flavors” in Japan. Aroma or odors of foods are generated by volatile compounds. Various kinds of food flavoring materials are used In the case of several foods, such as fruits, the whole for traditional dishes or cuisine in the world. Many aroma character can be reconstructed by a few kinds studies on flavors of foodstuffs have been done. Many of volatile compounds. In many cases a lot of volatile of their subjects were volatile odor components or non- components, however, comprise whole flavor charac- volatile taste active compounds which have basic tastes teristics of foods. For the components easily disappear (sweetness, sourness, saltiness, bitterness, or umami). or change to other compounds by the reactions among On the other hand many foods have flavor characters them, it has been a big issue how to control unstable expressed by terms such as complexity, body, continu- volatile compounds generated after enzymatic or ther- ity, mouthfulness, thickness, etc. It is difficult to de- mal reaction. fine these terms clearly, but these flavors sometimes Consumers request various kinds of high quality govern palatability of the foods. These flavor charac- processed foods which are convenient, have attractive teristics are presumed to be generated by the results of tastes or flavors, natural feeling, etc. To reply to those interactions among components in foods. These flavor demands from industry, basic studies are inevitable to © 2017 TERRAPUB, Tokyo. All rights reserved. doi:10.5047/absm.2017.01001.0001 2Y. Ueda and K. Fukami / Aqua-BioSci. Monogr. 10: 1–22, 2017 Table 1. Role of each component on the flavor of synthetic seafood extracts. Cited from Trends in Food Science & Technol- ogy, December 1996 (Vol. 7), Fuke S and Ueda Y, Interactions between umami and other flavor characteristics, 407–411, Table 1, „ 1996, with permission from Elsevier. Component removed Effect on the synthetic extract Sea urchin Snow crab Scallop Short-necked clam Dried skipjack Glutamate Umami Ø Umami Ø Umami Ø Umami Ø Umami Ø Sweetness ≠ Sweetness Ø Sweetness Ø Sweetness Ø Sweetness Ø Character Ø Palatability Ø Palatability Ø AMP No effect Umami Ø Umami Ø Umami Ø No effect Sweetness Ø Sweetness Ø Palatability Ø Palatability Ø IMP Umami Ø No effect No effect No effect Umami Ø Aftertaste Ø Sweetness Ø Palatability Ø Glycine Sweetness Ø Umami Ø Sweetness Ø Sweetness Ø No effect Character Ø Sweetness Ø Palatability Ø Bitterness ≠ Alanine Sweetness Ø Sweetness Ø Sweetness Ø No effect No effect Bitterness ≠ Arginine Umami ≠ Character Ø Character Ø Character Ø No effect Sweetness ≠ Palatability Ø + Na NA Sweetness Ø Umami Ø Sweetness Ø Sourness Ø Umami Ø Character Ø Umami Ø Character Ø Character Ø Palatability Ø Sourness Ø Palatability Ø Cl- NA Palatability Ø Sweetness Ø Sweetness Ø Sourness Ø Umami Ø Umami Ø Character Ø Palatability Ø Palatability Ø Palatability Ø “Character” refers to the specific characteristic flavor of the seafood. The descriptions used were: umami, bitterness, specific flavor, aftertaste, sourness, saltiness, palatability, no effect. Effects on saltiness are not shown. ≠ indicates flavor characteris- tic increased when component removed. Ø indicates flavor characteristic decreased when components removed. NA, Not analyzed. develop new ingredients and technology. We have en- tion will deal with the flavor characteristics of glutath- gaged in the research to get basic new knowledge on ione contained in scallop and other food materials, fo- kokumi flavors and to control unstable volatile com- cusing on the flavor interaction with umami substances pounds for quality improvement of processed foods, or other components extractive from some foods. The by the combination of instrumental analyses and sen- thermal degradation mechanism of glutathione will also sory evaluation. In this monograph, we will show three be mentioned. The third section will give an overview categories of our studies on the flavor constituents in of the mechanisms of increase or decrease in key vola- seafood and other foodstuffs. First of all, we will de- tile flavor components of dried bonito. scribe the studies on the key non-volatile components of “Kombu-dashi”, popular Japanese soup stock pre- 2. Flavor interaction among active components pared from dried kelp (Laminariaceae). The taste or in seafood flavor interaction between amino acids and other taste active compounds will also be shown. The next sec- L-Glutamic acid was found in 1908 as the key taste doi:10.5047/absm.2017.01001.0001 © 2017 TERRAPUB, Tokyo. All rights reserved. Y. Ueda and K. Fukami / Aqua-BioSci. Monogr. 10: 1–22, 2017 3 Table 2. Synthetic extract of Kombu-dashi. Unpublished data. Compound Conc. (mg/100 ml) Glu◊Na (MSG) 37 Asp◊Na 16 Lactic acid◊Na 0.4 Formic acid 0.3 Malic acid 0.3 Citric acid 1.1 Succinic acid◊Na 0.2 Acetic acid 0.3 Pyroglutamic acid 0.9 Fig. 1. Concept of flavor. KCl 255 KI 1 2 NaCl 135 CaCl2 5 MgCl2 16 NaH2PO4 19 Mannitol 1200 Alginic acid◊Na 7 Prepared by mixing commercial chemical compounds to match the compositional profile as determined analytically. pH 6.3. taste amino acid enhanced urchin-like taste and whole flavors. Taste active components in snow crab were investigated by using omission tests from synthetic extract made of commercial chemical compounds and Fig. 2. Dried kelp (kombu). Provided from UMAMI Infor- arginine was determined to enhance flavors under the mation Center, „ 2016. condition of coexisting with glutamic acid, inosinic acid, adenyric acid and glycine (Hayashi et al. 1981). Glycogen was found to constitute characteristic flavors constituent of “Kombu-dashi”, Japanese common soup of scallop (Watanabe et al. 1990). stock, prepared from dried kelp (Ikeda 1912). After industrialization of its salt, monosodium glutamate 2-1. Determination of non-volatile key flavor com- (MSG), this taste active crystal has been used for many ponents in Kombu-dashi cuisines as an inevitable seasoning worldwide. Many studies have been done on the flavor characteristics of As mentioned above, Kombu-dashi is used widely MSG. Especially the findings of synergistic effect be- for Japanese cuisines. This common soup stock itself tween glutamate and 5¢-ribonucleotides on umami taste has characteristic aroma and complex tastes. Although was a big event worthy of special mention (Kuninaka the key taste component was revealed to be monoso- 1964; Yamaguchi 1967). Glutamate does not only add dium glutamate, other constituents are necessary to umami to food but also enhances kokumi flavors such reconstruct whole Kombu-dashi characters. We inves- as continuity, mouthfulness, and thickness of many tigated the other flavor active non-volatile components foods (Yamaguchi and Kimizuka 1979; Yamaguchi in Kombu-dashi. There are some kinds of dried kelp in 1979, 1987). This phenomenon suggested that the Japan and it is believed that the quality of Kombu-dashi flavor interaction between glutamate and other com- depends on cultivation location or rating (size, shape, ponents would be developed in various foods. etc.) of kelp. Several studies about taste active components in At the beginning of our study we determined the savory seafood revealed that taste active compounds, authentic extraction condition for preparation of stand- such as amino acids, interact with other components ard Kombu-dashi. We investigated the preparation con- and strengthen the whole taste and character (Fuke and dition, focusing on temperature, resources of water, and Ueda 1996). Methionine was identified as a key flavor flavor characters, and we finally determined that the component of sea urchin (Komata 1964).