Food Taste Chemistry

10 Concluding Remarks MITSUO NAMIKI

Downloaded by FUDAN UNIV on April 19, 2017 | http://pubs.acs.org Publication Date: December 14, 1979 | doi: 10.1021/bk-1979-0115.ch010

Department of Food Science and Technology, Nagoya University, Chikusa-ku, Nagoya, Japan

Dear friends, we are very happy to have completed this really unique Symposium with such a success. As one of the organizers of this symposium, I would like to say a few words to close this session on taste. Since this symposium is held in the Joint Chemical Congress of ACS and CSJ, I hope you will allow me to talk a little while about my rather mixed up ideas on taste by using Japanese language. Figure I shows how we write "Symposium on the Taste of Foods" in Japanese. The first example is simply the phonetic translitera tion of the word Symposium written in "Katakana", a kind of Japanese traditional script. The next two Chinese characters are pronounced "shokuhin" and mean "food", the last character is "aji" which means "taste" or "flavor", our common interest. The character between them is "no" in "Hiragana", another kind of Japanese traditional script, and means "of". As you see, the Japanese language uses three kinds of s c r i p t s w i t h the words completely reversed from the arrangement found i n European languages. So I hope you might have some sympathetic f e e l i n g s f o r our Japanese s c i e n t i s t s here, i n c l u d i n g myself. Anyway, l e t me t e l l you how I d i d my l i t t l e a n a l y t i c a l work on these words. Since Chinese i s p i c t u r e w r i t i n g , the c h a r a c t e r f o r " a j i " can be separated i n t o two components. The l e f t one i s simply a square, meaning mouth. The other h a l f i s considered t o be p h o n e t i c a l l y e q u i v a l e n t t o "mi" o r " b i " which means "beauty" or "goodness". Therefore the composition of the c h a r a c t e r f o r " a j i " i n d i c a t e s t h a t t a s t e i s p r i m a r i l y "good to mouth", namely, p a l a t a b l e , d e l i c i o u s , and t a s t y . I n t h i s sense, I h e a r t i l y agree w i t h Dr. Boudreau who w i s e l y p o i n t e d out t h a t "umami" should be counted as a b a s i c t a s t e . The Chinese c h a r a c t e r f o r "umami", as shown i n t h i s f i g u r e , has i t s o r i g i n i n "a spoon and mouth", namely a good t a s t e e l i c i t e d by e a t i n g a d e l i c i o u s soup. As Dr. Yamaguchi s t a t e d , t h i s t a s t e "umami" i s known to be a t t r i b u t e d to mainly two f a c t o r s , MSG and n u c l e o t i d e s . I t happens t h a t the use of both of these f a c t o r s as f l a v o r i n g agents was o r i g i n a t e d by Japanese s c i e n t i s t s ;

Boudreau; Food Taste Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1979.

FOOD TASTE CHEMISTRY

248

Symposium

The Taste of.Foods


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Taste

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a

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s

*

Sweet

Bitter

Sour

Salty

Umami

Pungent

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A

π Flavor

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JJ: ^ ^ Tj- ^

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η ·» (bi) Beauty Good Grace

^ or spoon *~ X7 mouth

Figure 1.


10.

ΝΑΜίκι

Concluding Remarks

MSG by Dr. Kikunae Ikeda>who was once the president of the Chemical S o c i e t y of Japan, and n u c l e o t i d e s by Dr. Kodama, Dr. Kuninaka and o t h e r s . Dr. Kuninaka s f i n d i n g that a s m a l l amount of n u c l e o t i d e enhanced remarkably the "umami" of MSG has been of i n t e r e s t to the w o r l d , e s p e c i a l l y to the food i n d u s t r y . Here i t i s i n t e r e s t i n g to note t h a t i n the Japanese language the word "umami" sometimes means "unexpected p r o f i t " which j u s t f i t s t h i s case. I might add t h a t manufacture of these f l a v o r i n g agents has developed i n t o a b i g fermentation i n d u s t r y , which was developed mainly by the e f f o r t s of the a g r i c u l t u r a l chemists of Japan. The umami t a s t e , however, i s not always caused by j u s t these two agents, r a t h e r i t i s e l i c i t e d by a w e l l harmonized mixture of v a r i o u s food c o n s t i t u e n t s , such as amino a c i d s , p e p t i d e s , nucleo t i d e s , organic a c i d s , and i n o r g a n i c i o n s . This f a c t i s c l e a r l y demonstrated by the s t u d i e s of Dr. Konosu on the t y p i c a l umami of seafoods, and by Dr. M o r i on the t a s t e of soy sauce. Speaking of the mixture of these f l a v o r i n g agents, I t h i n k Japanese people have a good background to develop "umami". As you have seen i n the Japanese l e t t e r s , the Japanese people are them s e l v e s a w e l l homogenized mixture both i n c u l t u r a l and e t h n i c aspects. Their food h a b i t s are t y p i c a l l y omnivorous. Moreover, owing to the v a r y i n g c l i m a t e and a marine i s l a n d country, the food i s abundant i n k i n d , v a r y i n g from raw f i s h to v a r i o u s d e l i c i o u s fermentation products as shoyu, miso and, e s p e c i a l l y , sake. Here, I must c a l l a t t e n t i o n to the r e p o r t s by Dr. Solms and Dr. Mabrouk who informed us that the umami substances were developed and i n c r e a s e d by cooking and pr ocessing of foods. It is these types of s t u d i e s combined w i t h a s o p h i s t i c a t e d psycophysics which w i l l help us b e t t e r understand food f l a v o r . Now, I f e e l I have dwelt too long on the s u b j e c t of "umami", but the word "umami" i n Japanese language sometimes means "sweet ness". As to the sweeteners, i t i s no wonder that such a great d e a l of work has been done on new sweeteners of n a t u r a l and a r t i f i c i a l o r i g i n . U n t i l now, such work has been a k i n d of h i t and miss business. Therefore, the l a s t h a l f of the day was devoted to understanding some of the s t r u c t u r a l f e a t u r e s of molecules that determine t h e i r t a s t e p r o p e r t i e s . Based on the advanced stereo-chemical s t u d i e s on a l a r g e number of sweet and b i t t e r compounds by Dr. A r i y o s h i , Dr. B e l i t z and Dr. Ney, our understanding of the molecular p r o p e r t i e s of c e r t a i n t a s t e compounds has advanced markedly. N o t i c e a b l e a l s o i s an i n c r e a s e i n our understanding of the chemical p r o p e r t i e s of amino a c i d s , peptides and s i m i l a r n i t r o g e n compounds, s i n c e as we saw i n the f i r s t h a l f of the symposium, they are primary f l a v o r components i n many foods. At t h i s p o i n t , I would l i k e to i n d i c a t e t h a t t a s t e chemistry i s e s s e n t i a l l y s o l u t i o n chemistry. I t i s therefore e s p e c i a l l y s i g n i f i c a n t t h a t the b i t t e r n e s s of many compounds can be d i r e c t l y r e l a t e d to the hydrophobic p r o p e r t i e s of the molecules. The sour s e n s a t i o n has a l s o been shown to be r e l a t e d to the Br^nsted a c i d 1


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FOOD TASTE CHEMISTRY

p r o p e r t i e s o f the molecules. Thus, both sour and b i t t e r t a s t e s can be shown t o be r e l a t e d t o the s o l u t i o n p r o p e r t i e s o f the molecules. I n the f i n a l a n a l y s i s , t h a t which s t i m u l a t e s i s a molecular complex of the a c t i v e molecule and water. S o l u t i o n chemistry i s i n as p r i m i t i v e a s t a t e as i s t a s t e chemistry and they must develop together. On another important t a s t e , pungency, Dr. Govindarajan s a i d i n h i s paper t h a t t h i s s e n s a t i o n must be measured t o a c c u r a t e l y d e s c r i b e the f l a v o r o f c e r t a i n foods. He has a l s o suggested a r e l a t i o n s h i p between t a s t e and chemical s t r u c t u r e as has a l r e a d y been done i n the cases o f other t a s t e s . L a r g e l y untouched by t h i s symposium, but p o s s i b l y present i n the minds of many, i s the n u t r i t i o n a l s i g n i f i c a n c e o f t a s t e . What i s the exact r e l a t i o n s h i p between t a s t e and n u t r i t i o n ? I f we cook foods to produce f l a v o r f u l compounds, what i s the n u t r i t i o n a l s i g n i f i c a n c e o f these compounds? These and many other questions await answers. In ending these f i n a l remarks, I must s t a t e t h a t I f e e l so happy t o l e a r n d i r e c t l y t h a t the e f f o r t s o f s c i e n t i s t s a l l over the world a r e r e s u l t i n g i n a steady progress i n t h i s d i f f i c u l t f i e l d , and a r e c o n t r i b u t i n g to the w e l f a r e o f men by appealing t o t h e i r most fundamental and p e a c e f u l d e s i r e s o f e a t i n g good t h i n g s . I b e l i e v e t h i s o c c a s i o n w i l l be an important m i l e s t o n e i n the development o f t h i s r e s e a r c h . F i n a l l y , I would l i k e t o extend my hearty thanks t o the speakers f o r performing so w e l l , the audience f o r being so a t t e n t i v e and to Dr. Boudreau f o r h i s great e f f o r t s i n o r g a n i z i n g t h i s symposium. Thank you. RECEIVED August 16,

1979.


Food Taste Chemistry

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