To clarify the mechanism of the browning reaction observed in fish products, the separation and identification of a few intermediate products were carried out in model browning systems.
Acetaldehyde and 2-hexenal, the main aldehydes in autoxidized oil, were incubated with ammonia ethanol solution at 37°C for 4 days.
From the reaction mixture containing acetaldehyde, carbonyl compounds were separated as their 2, 4-dinitrophenylhydrazones by T. L. C. (Fig. 2). As a result, crotonaldehyde and aldol were identified as the main products (Table 1), and the occur-rence of these aldehydes indicated that aldol condensation had occurred. As crotonaldehyde has a higher browning potential than acetaldehyde (Fig. 3), it is assumed to be polymerized without much accumulation.
From 2-hexenal, the formation of 2-(1-butenyl)-octa-2, 4-dienal as the first browning substance was proved by elementary analysis (Table 2), NMR spectrum (Fig. 5) and mass spectrum (Fig. 5). This substance was formed also by aldol condensation and the dehydration of two molecules of 2-hexenal.
Correlating these results with the facts that the browning of acetaldehyde was faster in DMSO than in ethanol (Fig. 4), and the selective reduction of carbonyl groups faded the browning substances almost completely (Fig. 7), the authors concluded that aldol condensation was the main reaction in the early stage of browning.

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It has previously been reported that the brown discoloration of fish products is mainly due to the reaction between carbonyl compounds derived from autoxidized oil and volatile bases such as ammonia, but the mechanism of this reaction has not been solved.
In this paper, in order to make clear the mechanism of the browning reaction, the browning substances derived from several model systems were fractionated and the nitrogen content and other properties were investigated.
Autoxidized methyl esters of cuttle-fish liver oil were incubated with ethanol solution of ammonia at 37°C. Yielded browning substances were fractionated by silicic acid column chromatography. For each fraction, the extent of browning, nitrogen content, mean molecular weight and IR absorption spectrum were measured.
With the progressive degree of polymerization, the nitrogen in the brown substance increased, but the amount of nitrogen was too low to be a product of the Maillard reaction. It also differed from the Maillard reaction in that the nitrogen content of the browning substances was not proportional to the initial amount of nitrogen com-pounds. Consequently, the browning reaction mechanism of the autoxidized oil-ammonia system differs from that of the Maillard reaction.
KOH also caused browning, but the extent of browning was far less than that with the same concentration of ammonia.
The browning substances extracted from defatted saury meat-autoxidized oil system and discolored boiled-dried anchovy closely resembled in nature those of the ammonia-autoxidized oil model system.

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グルコ二糖類の加酢分解及び硫酸分解を行なった結果,加酢分解に対しては1, 6-結合が他の結合糖より著しく分解をうけやすく,他方酸分解に対しては1, 6-結合(第1級アルコール基結合)は1, 4-, 1, 3-, 1, 2-結合(第2級アルコール基結合)より分解されにくく, 3種のトレハロースについてはα, α-トレハロースがグルコ二糖類中最も分解されにくいのに対してα, β-トレハロースは最も分解されやすかった.それらの結果から各種グルコ二糖類の分解について論議した.

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The oxidation and the browning reaction of pyrogallol were caused by the polyphenoloxidase (EC 1.10.3.1) preparation obtained from the immature fruit of satsuma mandarin. The effects of some factors such as pH, temperature and inhibitors on this reaction were investigated.
The optimum pH of this reaction was around 7.2-7.6, and no reaction was found below pH 6.0. This reaction was strongly inhibited by the compounds such as potassium cyanide and sodium diethyldithiocarbamate and also remarkably inhibited by L-ascorbic acid. The enzyme preparation was considerably stable at relatively high temperature.

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パチマンの加酢分解とギ酸分解及びラミナリンの加酢分解を行い分解の条件を検討した,その結果得られた最適条件を基にして,さらにパチマンの加酢分解を行い, Carbon C. C.により分別しラミナリビオースを調製した.これらの結果からパチマンはWarsi等のいうように, 1, 3-β結合から成るグルコ多糖類であることを再確認するとともにβ-結合においても1, 6-結合が1, 3-結合より加酢分解に対する抵抗性が小であろうと推定した.
ラミナリビオースの調製法としてはこの方法は好適であると思う.

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