A chemometric study on the identification of 5-methylfurfural and 2-acetylfuran as particular volatile compounds of oxidized fish oil based on SHS-GC-IMS.

Fish oil develops particular off-odors, mainly fishy odor, from the oxidation of its characteristic fatty acids, docosahexaenoic (DHA) and eicosapentaenoic (EPA). Anchovy oil (AO) was taken as representative of fish oils. This was compared to three vegetable oils with different fatty acid compositions, i.e. camellia, sunflower and linseed oil, and differential volatile compounds were identified by static-headspace gas-chromatography ion-mobility-spectrometry (SHS-GC-IMS) and orthogonal partial-least-squares discriminant analysis (OPLS-DA) during oxidation at 60 °C. Three groups of differential volatile compounds detected at higher concentrations in the AO were screened out and two compounds, identified as 5-methylfurfural and 2-acetylfuran, were characteristic to the AO and not found in the vegetable oils. They were formed from both EPA and DHA, only present in the AO, and their formation mechanisms were proposed. The contents of 5-methylfurfural and 2-acetylfuran increased linearly with the oxidation time and consequently they could be used as oxidative markers of fish oils.

Effect of Stored Humidity and Initial Moisture Content on the Qualities and Mycotoxin Levels of Maize Germ and Its Processing Products.

With high fat and protein content, maize germ is easily infected with fungus and mycotoxins during its storage. The qualities and safety of germ and its processing products may be affected by the storage. However, studies on the effect of storage on quality and polluted mycotoxin level of maize germ are limited. In this study, maize germ was stored with different initial moisture contents (5.03, 9.07, 11.82 and 17.97%) or at different relative humidity (75, 85 and 95%) for 30 days. The quality indices of germ (moisture content and crude fat content) and their produced germ oils (color, acid value and peroxide value) as well as the zearalenone (ZEN) and deoxynivalenol (DON) levels of germ, oils and meals were analyzed. Results showed that maize germ with high initial moisture contents (11.82, 17.97%) or kept at high humidity (95%) became badly moldy at the end of storage. Meanwhile, the qualities of these germ and oils showed great changes. However, the ZEN and DON contents of this maize germ, oils and meals stayed at similar levels (p < 0.05). Therefore, the storage could produce influence on the qualities of germ and oils, but showed limited effect on the DON and ZEN levels of germ and their processing products. According to this study, the storage condition of germ with no more than 9% moisture content and no higher than 75% humidity was recommended. This study would be benefit for the control of germ qualities and safety during its storage.

Occurrence of deoxynivalenol in maize germs from North China Plain and the distribution of deoxynivalenol in the processed products of maize germs.

69 maize germ samples from North China Plain, 40 processed products of maize germs obtained in lab, 30 crude corn oils from factories and 40 refined corn oils from supermarkets in China were analyzed of deoxynivalenol (DON) by HPLC combined with ultraviolet detection and immunoaffinity column. 95.7% of maize germs were contaminated by DON. The average content was 449.0 µg/kg. The average of DON in processed products of maize germs including solvent extracted oil, cold-press oil, meal and cake was 163.7, 113.1, 1111.5 and 1175.2 µg/kg, respectively. Only 20% of crude corn oil and 12.5% of refined corn oil were contaminated by DON with the range of 67.5-340.5 µg/kg and 57.1-207.5 µg/kg, respectively. During the production of corn oil, solvent extraction oil had a larger amount of DON than pressing oil. The contamination of DON in corn oil was not serious or widespread, which indicated a low risk of health.