Living and thriving cultures innovate, adapt and incorporate from other cultures. As the next topic in our series on chemistry and Inuit life and culture,1 we have chosen soy sauce. Though part of Chinese cuisine from way back in the mists of time, it is a relatively recent addition to the Inuit diet and in a unique context: Arctic char, both frozen (Kuak in Inuttut) and dried (called Pitsik) are dipped in soy sauce.
Arctic Char
The Arctic char, known as iKaluk in Inuttut, is closely related to both salmon and lake trout. It is native to Arctic and sub-Arctic waters. With bright red to pink flesh, Arctic char can weigh up to 9 kg, though about 5 kg is more typical (Fig. 1).
The flesh of Arctic char contains significant concentrations of carotenoids, hence the red colour (Fig. 2), which are known antioxidants and provide a variety of health benefits.
FIGURE 1
Chaim Andersen with Arctic char.
Credit: Paul McCarney
FIGURE 2
Arctic char, filleted and cut to hang and dry
Credit: C. Andersen
Even more importantly, Arctic char contain exceptionally high concentrations of omega-3 fatty acids which are vital to good health.2 Omega-3 fatty acids specifically contain a double carbon-carbon bond three carbon atoms away from the (end) methyl carbon atom. A space-filling representation of eicosapentaenoic acid, one of the omega-3 fatty acids in Arctic char, is shown in Fig. 3.
Soy Sauce
The Inuit have made soy sauce their condiment of choice for Arctic char and other marine food sources. Believed to have been first produced in China about 2,200 years ago, real soy sauce is made from a fermented paste of soybeans, roasted wheat grain, salt water and specific moulds (fungi).3 The fermentation or brewing process takes about three months. Soy sauce produced by the traditional method is usually identified on the label as having been ‘naturally brewed’ or ‘traditionally brewed’ (Fig. 4). The contents of such a sauce are typically: water, soy beans, salt, wheat flour.
Among many other healthy molecules, soy sauce is rich in niacin. Niacin (Fig. 5) is one of the B3 family of vitamins (insufficient niacin in the diet can cause nausea, skin and mouth lesions, anaemia, headaches and tiredness). As an added health bonus, fermentation of soy beans produces a number of antioxidants. In fact, real soy sauce is far richer in antioxidants than red wine.
FIGURE 3
Space-filling representation of the eicosapentaenoic acid molecule
Credit: https://commons.wikimedia.org/
wiki/File:Eicosapentaenoic_acid_
spacefill.png
FIGURE 4
The label of a bottle of traditionally brewed soy sauce
FIGURE 5
Ball-and-stick representation of niacin
Credit: https://en.wikipedia.org/wiki/
Niacin#/media/File:Niacin-3D-balls.png
Fake soy sauce is everywhere!
Before soy sauce users congratulate themselves on eating healthily, they should realize it is unlikely that they have been consuming brewed soy sauce but instead have been consuming chemically-hydrolyzed soy sauce. Soy-sauce-producing companies do not want to wait three months for each batch: instead, the soy beans are acid-processed as Joe Schwarcz has described:
“The cheaper ‘chemical’ version can be produced in a day simplyby adding hydrochloric acid to a defatted mash of soybeans, followed by neutralizing with sodium carbonate. But this is a brutal method that breaks proteins down to individual amino acids and the resulting flavour and aroma are quite different from fermented soy sauce. Undesirable compounds such as dimethyl sulphide and formic acid are also produced. Absent, though, is the brown colour produced by fermentation products, and this is solved by the addition of caramel colouring.4
In addition, chemically-hydrolyzed soy sauce is high in added sugars. A typical label will note the contents as: water, glucose-fructose, salt, caramel, hydrolyzed soy protein, corn syrup, citric acid and sodium benzoate. There are no health-beneficial compounds produced during chemical hydrolysis. Unfortunately, the only common brand of soy sauce in stores in Inuit communities is that of the chemically-hydrolyzed soy sauce.
An additional concern in consuming chemically-hydrolyzed soy sauce is that the glycerol by-product of soy chemical hydrolysis reacts with hydrochloric acid to produce 3-chloro-1,2-propanediol (3-MCPD)5 and 1,3-dichloropropane-2-ol. Some imported brands of chemically-hydrolyzed soy sauce contain excessive levels of these probable carcinogens and teratogens (Health Canada has established 1 ppm as the maximum ‘safe’ level of 3-MCPD in chemically-hydrolyzed soy sauce).
CH2(OH)CH(OH)CH2(OH)(aq) + HCl(aq) —› CH2(OH)CH(OH)CH2Cl(aq) + H2O(l)
CH2(OH)CH(OH)CH2Cl(aq) + HCl(aq) —› CH2ClCH(OH)CH2Cl(aq) + H2O(l)
Food for thought!
Our message is one of caution for all soy sauce consumers (always read the label – and know some consumer chemistry!). For Inuit, whose diet for thousands of years has enabled them to live healthy lives (a topic for a future article), it is regrettable that one of the condiments incorporated into their diet should commonly be one which is actually unhealthy. For Inuit, we contend, consumer activism is necessary to ensure that healthy foodstuffs are imported to the northern communities. Sadly, ‘imitation’ soy sauce is the least of Inuit health worries relating to chemical compounds, as we will describe in our next article.
References
- Andersen, C.; Rayner-Canham, G.W. Ramah Bay – 7,000 years of Aboriginal Culture – and Chemistry. Chem 13 News, September 2018. https://uwaterloo.ca/chem13-news-magazine/september-2018/ feature/ramah-bay-7000-years-aboriginal-culture-and-chemistry.
- Wikipedia. Fish Oil. https://en.wikipedia.org/wiki/Fish_oil.
- Wikipedia. Soy Sauce. https://en.wikipedia.org/wiki/Soy_sauce.
- Schwarcz, J. Saucey Sham. Canadian Chemical News 2010, 62 (7), 30.
- Wikipedia. 3-MCPD. https://en.wikipedia.org/wiki/3-MCPD.
Publisher's note: This article is a reprint from the October 2018 issue of Chem 13 News.
