Foods: Soy sauce

Hypertension in patients taking MAOIs who had eaten certain foods (soy sauce, chicken nu ets) has been attributed, in anecdotal reports, to an interaction with monosodium glutamate. However, a small controlled study found no evidence to support this idea, and the reaction was probably related to tyramine , (p.1153). 

Bound glutamates in proteins are very common in food. Human breast milk contains ten times as much as cows milk, and tomato juice contains four times as much as breast milk. However, free glutamate, as found in soy sauce or prepared foods, enters the bloodstream much faster than the glutamates bound in proteins, which are released slowly during digestion. 

Based on processing technology, the soybean foods that have been consumed in East Asia may be classified into two general types non-fermented and fermented (2-8) as shown in Table I. Names of these foods and the details of preparing and serving such foods may vary from country to country. Among them, soybean curd (tofu) and soy sauce have been the most widely consumed in the Orient. 

Because of the importance of soy sauce as a food flavorant, a new method for its production was developed. The importance of this novel processing procedure is that it significantly shortens the fermentation processing time by half or to about three months. Attempts at further modification of the process to prepare low-sodium-chloride-containing soy sauce are also described. 

An SPME unit consists of a piece of fused-silica fibre coated with a layer of a stationary phase such as non-polar poly(dimethylsiloxane) or polar polyacrylate or divinylbenzene/Carboxen/poly(dimethylsiloxane). The latter, for example, was suitable to trap the odorants (including sotolon) of soy sauce [19]. In the analytical procedure the fibre is exposed to the headspace of a food sample for 10-15 min. Then, the fibre is inserted into the injection port of a GC-mass spectrometry (MS) system. After desorption, the odorants are analysed. To improve the yields of the odorants, the fibre is placed in the effluent of a food sample purged with nitrogen [20]. 

Phenylethanol has a rose-like odour and makes the chemically produced compound the most used fragrance chemical in perfume and cosmetics, with a world market of about 7,000 t year [107, 108]. 2-Phenylethanol is also found in many foods as a characteristic flavour compound rounding off the overall aroma, especially in foods obtained by fermentation, such as wine, beer, cheese, tea leaves, cocoa, coffee, bread, cider and soy sauce [109]. In food applications, natural 2-phenylethanol is preferred rather than its nature-identical counterpart from chemical synthesis and it has a market volume of 0.5-11 year . This product is sold at market prices of up to US 1,000 per kiklogram and is mainly produced by yeast-based bioprocesses since its isolation from natural sources, e.g. rose oil, would be too costly [109]. 

Other daily products Ice cream (83). whole milk (50). sherbet (45). Miscellaneous foods Pretzels (7800), soy sauce (regular) (6082), dill pickles (4000-5000), soy sauce (mild) (3569), green olives (2400). soda crackers (1100), salted peanuts (groundnuts) (418), eggs (122). 

Various applications of PITC in analyses of acid hydrolysates of purified proteins and peptides (91) and of hydrolysates of feeds (92) have been described. Bidlingmeyer et al. (93) showed reversed-phase chromatographic analysis of free amino acids and hydrolysates of foods (soybean flour, mozzarella cheese, beer, and soy sauce) with formation of PITC derivatives to be a fast, reproducible method that presented a very good correlation with the results obtained by ion-exchange chromatography. 

Sample preparation for saccharin analysis by HPLC can be performed as indicated in Section I.C. Methods for extraction have also been described for desserts and sweets containing food thickeners (38) soy sauce, orange juice, and yogurt (60) chewing gum (17,39), and different food samples (42). Aminobenzoic acid, theophyllin, sodium fumarate, and adenine sulfate have been used as internal standards (17,31,39,44). 

E Kinoshita, Y Ozaw, T Aishima. Novel tartaric acid isoflavone derivatives that play key roles in differentiating Japanese soy sauce. J Agric Food Chem 45 3753-3759, 1997. 

Their presence has only been reported in a limited number of foods coffee, cocoa, meat products, barley and soy sauce. Very few sensory properties have been reported for oxazoles and oxazolines. 

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