Factors affecting the concentration of acrylamide during deep-fat frying of potatoesThe paper describes the effect of different factors influencing the concentration of acrylamide in deep-fat fried potato products. In French fries the amount of acrylamide increased with the temperature as well as the frying time, especially at temperatures higher than 175 7C. The increase of acrylamide with the time followed a linear function, whereas a non-linear relationship was given with the temperature of frying. As a result, a reduction of the processing temperature led to lower concentrations of acrylamide in the product.Both, oil type and silicon oil as antifoaming agents had no significant influence upon the acrylamide concentration in the food.The variety of potatoes had a strong effect on the acrylamide concentration in potato crisps and French fries. The investigation showed a significant correlation (r = 0.73) between the concentration of acrylamide and reducing sugars in raw potatoes, and no significant correlation with the asparagine concentration. The storage temperature of the raw material had an effect on the acrylamide concentration in the product. Lowering of the storage temperature from 8 to 4 7C resulted in an increase of the concentration of reducing sugars in the raw material, which led to a higher potential of acrylamide formation in the products.The experiments showed that the acrylamide concentration of French fries depended on the surface-to-volume ratio (SVR).

For the reduction of 3-monochloro-1,2-propanediol fatty acid esters (3-MCPD esters) and related compounds in edible fats and oils three different strategies are conceivable: removal of critical reactants from the raw material, changing of the refining process or removal of formed 3-MCPD esters and related compounds from the refined product. This paper discusses these possibilities and shows that different raw materials have different capabilities to form 3-MCPD esters and related compounds, whereas palm oil, but also corn oil or coconut oil possess the highest potential for the formation. Washing of the raw material before the refining process with water or ethanol (75%) reduced the capability for the formation of 3-MCPD esters and related compounds in palm oil for about 20 and 25%, respectively. The paper shows that chloride and DAGs seem to be important precursors for the formation of 3-MCPD esters and related compounds. A hypothesis was defined that a content of 4% DAGs could be a threshold for a higher potential of the raw material for the formation of the esters. Using acid solutions (formic acid) instead of water for the generation of strip steam during deodorization resulted in a reduction of the formation of glycidyl esters for about 35%.Practical application: In a first statement the German Federal Institute for Risk Assessment (BfR) but also others recommended to search for alternative techniques for the production of edible oils to ensure lower levels of 3-MCPD esters and related compound. Changing the selection criteria for the raw material, improving the raw material before refining or removal of 3-MCPD esters and related compounds after refining have the advantage that the refining process which has been optimized over the last 100 years regarding oil quality does not need to be changed.

The aim of the present study was to differentiate sensory good and bad virgin rapeseed oils based on the composition of the volatile compounds by means of linear discriminant analysis (LDA). A total number of 64 compounds were detected by dynamic headspace GC‐MS and combined olfactometry with potential for sensory quality assessment either as aroma‐active compound by substance concentration or flavor property or as a non‐aroma‐active compound by correlation with the panel assessment. From this initial set of substances, 13 volatile compounds showed significant differences in the concentration between sensory good and bad oils, whereas their concentration was higher in sensory bad oils. No significant differences were found for compounds characterizing sensory good virgin rapeseed oils. Based on these 13 volatile compounds, the present work shows for the first time that LDA was able to classify a training data set of 43 samples satisfactorily according to the sensory quality. As a proof for suitability, a discriminant function was calculated and successfully used to classify samples from an additional validation sample set. Practical applications: Virgin rapeseed oils are high‐quality products on the market, which are defined above all by their sensory quality. The sensory evaluation of virgin rapeseed oils by a trained sensory panel group is time and labor consuming and sometimes the results are not reliable. Therefore, the development of an analytical method for the discrimination of sensory good and bad virgin rapeseed oils based on the determination and statistical evaluation of volatile, aroma‐active compounds is a helpful tool to support the sensory evaluation. The repeatability of the analytical method is better than the sensory evaluation, which also helps to support the work of a panel group. Additionally, the amount of work for a panel group can be reduced due to a pre‐selection by the analytical tool. The present work shows a chemometric approach to differentiate sensory good and bad quality virgin rapeseed oils on basis of 13 volatile compounds. For the first time volatile compounds have been identified that can be correlated with sensory bad virgin rapeseed oils.

Seeds of 40 oilseed species from 23 different plant families (Brassicaceae, Cucurbitaceae, Fabaceae, Sapindaceae, Malvaceae, Gnetaceae, Clusiaceae, Bruseraceae, Ranunculaceae, Convolvulaceae, Amaranthaceae, Tiliaceae, Basellaceae, Solanaceae, Umbelliferae, Labiatae, Compositae, Theaceae, Euphorbiaceae, Caesalpiniaceae, Sapotaceae, Anacardiaceae, and Connaraceae) grown in Vietnam were analyzed for oilseed oil content, FA, and vitamin E. The seed oil content varied between 0.2 g/100 g for Mangifera indica and 75.7 g/100 g for Calophyllum inophyllum, whereas only nine seeds contained more than 40% oil. The tocopherol content ranged from 26 (Sapindus mukorossi) to 9361 mg/kg (Litchi chinensis). In nine seed oils unusual FA such as conjugated, cyclopropenoic, or epoxy FA were found.The oleochemical industry is increasingly interested in custommade and novel oils with specific FA compositions for applications in the oil and pharmaceutical industries (1). Such oils can be used for the synthesis of high-quality products without expensive purification of raw materials. In addition, oilseed breeders are searching for species to produce beneficial new genotypes (1). A recent example is rapeseed oil with 40 to 60% lauric acid, which normally contains little or none of this FA (2).Plant seeds contain tocopherols and tocotrienols, which are used as natural antioxidants and vitamin E (3-5). In nature four different derivatives of tocopherols and tocotrienols (α-, β-, γ-, and δ) can be found, which differ in the methylation of the chroman ring. The antioxidant activity increases for tocopherols and tocotrienols in the order α to δ, whereas the biological activity is inversely proportional to the antioxidant activity (6,7). Plastochromanol-8 (P-8) is a related compound that is more effective against oxidation than α-tocopherol (8).A large part of the genetic resources of the world is located in the southern hemisphere. These can be considered as potential sources of raw material for the development of future medicines and food, as well as renewable resources with interesting FA and associated enzyme systems. Unfortunately, very little information about this genetic potential is available and many species are disappearing. Therefore, identifying commercially valuable lipid-bearing plants is a timely issue.Vietnam is very rich in plants, most of which have not been investigated with respect to their FA and tocopherol compositions. Some information about the FA composition of oilseeds is available in the Seed Oil Fatty Acid (SOFA) database (9), but to our knowledge this database contains only very limited data about seed oils from plants grown in Vietnam. Therefore, the aim of this work was to determine the FA and tocopherol compositions of native North Vietnamese seeds. Correlations between the content of PUFA and the tocopherol/tocotrienol composition were objects of special interest. MATERIALS AND METHODSPlant material. Seeds from 40 plant species grown in Vietnam were obtained from a typical Vietnamese market and used for the in...

The bifunctional wax ester synthase/acyl coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT) from Acinetobacter sp. strain ADP1 (formerly Acinetobacter calcoaceticus ADP1) mediating the biosyntheses of wax esters and triacylglycerols was used for the in vivo and in vitro biosynthesis of thio wax esters and dithio wax esters. For in vitro biosynthesis, 5His 6 WS/DGAT comprising an N-terminal His 6 tag was purified from the soluble protein fraction of Escherichia coli Rosetta(DE3)pLysS (pET23a::5His 6 atf). By employing SP-Sepharose high-pressure and Ni-nitrilotriacetic acid fast-protein liquid chromatographies, a 19-fold enrichment with a final specific activity of 165.2 nmol mg of protein ؊1 min ؊1 was achieved by using 1-hexadecanol and palmitoyl-CoA as substrates. Incubation of purified 5His 6 WS/DGAT with 1-hexadecanethiol and palmitoylCoA as substrates resulted in the formation of palmitic acid hexadecyl thio ester (10.4% relative specific activity of a 1-hexadecanol control). Utilization of 1,8-octanedithiol and palmitoyl-CoA as substrates led to the formation of 1-S-monopalmitoyloctanedithiol and minor amounts of 1,8-S-dipalmitoyloctanedithiol (59.3% relative specific activity of a 1-hexadecanol control). The latter dithio wax ester was efficiently produced when 1-S-monopalmitoyloctanedithiol and palmitoyl-CoA were used as substrates (13.4% specific activity relative to that of a 1-hexadecanol control). For the in vivo biosynthesis of thio wax esters, the knockout mutant Acinetobacter sp. strain ADP1acr1⍀Km, which is unable to produce fatty alcohols, was used. Cultivation of Acinetobacter sp. strain ADP1acr1⍀Km in the presence of gluconate, 1-hexadecanethiol, and oleic acid in nitrogen-limited mineral salts medium resulted in the accumulation of unusual thio wax esters that accounted for around 1.19% (wt/wt) of the cellular dry weight and consisted mainly of oleic acid hexadecyl thioester as revealed by gas chromatography-mass spectrometry.Polyhydroxyalkanoic acids (PHA) in bacteria represent the most abundant group of neutral storage lipids, which serve as intracellular carbon and energy storage compounds (23). In addition, triacylglycerols (TAGs) and wax esters also occur as bacterial storage lipids, though at a much lower frequency than in eukaryotic microorganisms (22). Significant TAG accumulation was found, particularly in species belonging to the class Actinomycetes (1), as was reported for the genera Mycobacterium (3), Nocardia, and Streptomyces (2). TAGs are synthesized by the acyl coenzyme A (acyl-CoA):diacylglycerol acyltransferase (DGAT) (13), which catalyzes the esterification of diacylglycerol with long-chain acyl-CoA. Wax esters are oxoesters of primary long-chain fatty alcohols and long-chain fatty acids. Occurrence of wax esters has been frequently reported for various Acinetobacter species (6). Under growthlimiting conditions, Acinetobacter calcoaceticus accumulates wax esters intracellularly as insoluble inclusions. The chemical structure of the wax esters synthesized by A. ca...