Oleic Acid Glycerides Content in the Oils of Maize Endospermic Mutants and Its Dependence on Temperature During Ripening

Identification of sources of increased content of oleic acid glycerides (oleates) and determination of the nature of its variability are prerequisites for improving oil quality. The purpose of this study was to establish the variability of the content of oleic acid glycerides (oleates) in maize oil depending on the genotype and ripening temperature. The experiments were carried out on a series of common maize inbreds and inbred-carriers of the su1, ae, and su2 mutations, which were grown for three years. The fatty acid composition of the oil was analysed by the Peisker gas chromatographic method. Genotype–environment interactions were assessed using the Eberhard– Russell algorithm. It was found that the carriers of the su1 and su2 mutations had the highest oleate content. The oleate content of maize oil generally increased with increasing ripening temperature. Unrelated inbreds based on one mutation significantly differed in the genetically determined level of oleate and showed non-identical responses to the ripening temperature. In inbreds of the first type, the content of oleates changed significantly with temperature fluctuation, while inbreds of the second type provided a fairly stable level of the trait under these conditions.

Development and certification of a reference material for zearalenone in maize germ oil

Zearalenone (ZEN), an estrogenic mycotoxin produced by several species of Fusarium fungi, is a common contaminant of cereal-based food worldwide. Due to frequent occurrences associated with high levels of ZEN, maize oil is a particular source of exposure. Although a European maximum level for ZEN in maize oil exists according to Commission Regulation (EC) No. 1126/2007 along with a newly developed international standard method for analysis, certified reference materials (CRM) are still not available. To overcome this lack, the first CRM for the determination of ZEN in contaminated maize germ oil (ERM®-BC715) was developed in the frame of a European Reference Materials (ERM®) project according to the requirements of ISO Guide 35. The whole process of CRM development including preparation, homogeneity and stability studies, and value assignment is presented. The assignment of the certified mass fraction was based upon an in-house study using high-performance liquid chromatography isotope dilution tandem mass spectrometry. Simultaneously, to support the in-house certification study, an interlaboratory comparison study was conducted with 13 expert laboratories using different analytical methods. The certified mass fraction and expanded uncertainty (k = 2) of ERM®-BC715 (362 ± 22) μg kg−1 ZEN are traceable to the SI. This reference material is intended for analytical quality control and contributes to the improvement of consumer protection and food safety. Graphical abstract

Protective effects of Lactobacillus plantarum strain P1 against toxicity of the environmental oestrogen di-n-butyl phthalate in rats

Phthalates are contaminants widely distributed in the food-chain, and they are considered as important environmental oestrogens in our lives. In the present study, eight strains of lactic acid bacteria were isolated for their ability to adsorb di-n-butyl-phthalate (DBP), and one of the strains, Lactobacillus plantarum strain P1, was selected for more detailed analyses of its phthalate adsorption capacity in vitro. This study also evaluated the in vivo protective effects of strain P1 against DBP toxicity in rats. Sixteen rats were divided into four groups, and animals received by oral gavage every other day for a period of one month saline with or without strain P1 at 2×1011 cfu/kg followed by maize oil with or without DBP (50 mg/kg). Strain P1 could adsorb more DBP than saline alone, and the concentration of mono-n-butyl phthalate in urine was decreased in animals receiving P1. Furthermore, oestrogenic effects of the different treatments were assessed through counting of sperm and observation of testis, and strain P1 could protect the sexual organs of male rats. Our results suggested that P1 is effective against phthalate toxicity due to its ability to adsorb DBP in vivo and could be considered as a new dietary therapeutic strategy against environmental phtalate toxicity.

Effect of microwave, deep frying and oven cooking on destruction of zearalenone in spiked maize oil

Mycotoxins are one of the most common types of chemical hazards related to edible oils. Although the refining process can remove such contaminations, they may still be present in the final oils due to defects during the refining steps. In addition, most oils produced in local manufactories are not refined and as such may be contaminated with mycotoxins. However, the effect of various cooking methods on the stability of mycotoxins in edible oils has rarely been studied. Hence, this study evaluated the impact of microwave, deep frying and oven cooking on the degradation of spiked zearalenone (50, 100 and 200 μg/l) in maize oil. Measurements were done by high performance liquid chromatography-fluorescence detection. The results showed that the majority of treatments, including time-temperature combinations of frying (130-190 °C for 2.5 and 5 min), oven cooking (110-230 °C for 2.5 and 5 min) and exposure time of microwave (2.5, 5 and 10 min) reduced zearalenone levels. Microwave cooking of samples containing 200 μg/l of zearalenone for 10 min showed the highest degradation of the toxin (~ 38%) following first order kinetics. The extent of destruction achieved by frying and oven cooking was also dependent on the initial concentration of zearalenone. These findings can be helpful to evaluate the chemical safety of edible oils or foods prepared by them.

Molecularly Imprinted Polymer as Selective Sorbent for the Extraction of Zearalenone in Edible Vegetable Oils

A method based on the selective extraction of zearalenone (ZON) from edible vegetable oils using molecularly imprinted polymer (MIP) has been developed and validated. Ultra-high-pressure liquid chromatography coupled with a fluorescence detection system was employed for the detection of zearalenone. The method was applied to the analysis of zearalenone in maize oil samples spiked at four concentration levels within the maximum permitted amount specified by the European Commission Regulation (EC) No. 1126/2007. As a result, the proposed methodology provided high recoveries (>72%) with good linearity (R2 > 0.999) in the range of 10–2000 μg/kg and a repeatability relative standard deviation below 1.8%. These findings meet the analytical performance criteria specified by the European Commission Regulation No. 401/2006 and reveal that the proposed methodology can be successfully applied for monitoring zearalenone at trace levels in different edible vegetable oils. A comparison of MIP behavior with the ones of QuEChERS and liquid–liquid extraction was also performed, showing higher extraction rates and precision of MIP. Finally, the evolution of ZON contamination during the maize oil refining process was also investigated, demonstrating how the process is unable to completely remove (60%) ZON from oil samples.

Fabrication and characterization of solvent evaporation-assisted sodium caseinate emulsion films

As plastic pollution increases, the development of degradable film has attracted much attention. Sodium caseinate was suitable to be a degradable film material for its mechanical performance and appearance. Maize oil was added to improve the properties of film material by microfluidization and solvent evaporation. Microfluidization could improve the droplet distribution of maize oil in the film building dispersions and the performance of film material. Solvent evaporation could further control the droplet distribution and the characteristics of film materials. The introduction of ethyl acetate could refine the droplet of maize oil distributing in the film building dispersions. The mechanical characteristics, water blocking properties and microscopic structure of solvent evaporation-assisted sodium caseinate emulsion films were improved.

Interactive effects of dietary fibre and lipid types modulate gastrointestinal flows and apparent digestibility of fatty acids in growing pigs

A total of eight ileal and caecal cannulated Yorkshire barrows were used to determine the interactions of dietary fibre (DF) and lipid types on apparent digestibility of DM and fatty acids (FA) and FA flows in gastrointestinal segments. Pigs were offered four diets that contained either pectin or cellulose with or without beef tallow or maize oil in two Youden square designs (n 6). Each period lasted 15 d. Faeces, ileal and caecal contents were collected to determine apparent ileal digestibility (AID), apparent caecal digestibility and apparent total tract digestibility (ATTD) of dietary components. The interactions between DF and lipid types influenced (P <0·05) the digestibility of DM and FA flows. The addition of maize oil decreased (P <0·05) AID of DM in pectin diets, and the addition of beef tallow depressed (P <0·001) ATTD of DM in cellulose diets. Dietary supplementation with beef tallow decreased (P <0·05) the AID of FA in pectin-containing diets but had no effects in cellulose-containing diets. Dietary supplementation with beef tallow increased (P <0·05) AID of SFA and PUFA and the flow of ileal oleic, vaccenic, linolenic and eicosadienoic acids and reduced the flow of faecal lauric, docosatetraenoic and docosapentaenoic acids in pectin- and cellulose-containing diets. In conclusion, the interaction between DF type and lipid saturation modulates digestibility of DM and lipids and FA flows but differs for soluble and insoluble fibre sources, SFA and unsaturated fatty acids and varies in different gastrointestinal segments.