Interlaboratory study on lipid oxidation during accelerated storage trials with rapeseed and sunflower oil analyzed by conjugated dienes as primary oxidation products

11 Páginas.-- 5 Figuras.-- 2 Tablas.-- Material suplementarioAccelerated storage tests are frequently used to assess the oxidative stability of foods and related systems due to its reproducibility. Various methods and experimental conditions are used to measure lipid oxidation. Differences between laboratories make it necessary to determine the repeatability and reproducibility of oxidation tests performed under the same conditions. The objective of the present interlaboratory study was to evaluate the outcome of a storage test for two different bulk oils, sunflower oil (SFO) and rapeseed oil (RSO), during a period of 9 weeks at 20°C, 30°C, 40°C, and 60°C. Sixteen laboratories were provided with bottled oils and conducted the storage tests according to a detailed protocol. Lipid oxidation was monitored by the formation of conjugated dienes (CD) and the activation energy (Ea) was determined for comparative purposes and statistically evaluated. An increase in CD formation was observed for both oils when the storage temperature was increased in all laboratories. The Ea,1 ranged from 47.9 to 73.3 kJ mol−1 in RSO and from 27.8 to 62.6 kJ mol−1 in SFO, with average values of 58.2 and 46.8 kJ mol−1, respectively. The reproducibility coefficients were 10.9% and 18.2% for RSO and SFO, respectively. Practical applications: In order to compare results on oxidative stability of foods derived from different studies, the reproducibility of storage tests and methods employed to evaluate the oxidation level should be considered. This study provides fundamental data on the reproducibility of lipid oxidation under accelerated storage conditions and defines important parameters to be considered for the conduction of experiments.Open access funding enabled and organized by Projekt DEAL. We thank Brökelmann + Co – Oelmühle GmbH + Co for the donation of the vegetable oils. The authors gratefully acknowledge Lina Stuthmann from the Food Technology Division, Kiel University and Inge Holmberg from the National Food Institute, Technical University of Denmark for their skillful help.Peer reviewe

Amaranth Seeds and Products – The Source of Bioactive Compounds

In recent years, new products obtained from amaranth seeds have entered the food market including expanded “popping” seeds and flakes. Lipids and biologically-active substances dissolved in these products are susceptible to changes. Additionally, due to the fact that fat quality has high dietary importance, there is a need to conduct detailed quality and quantity studies on the lipid composition of Amaranthus cruentus

Comparison of Volatiles and Chemical Composition of Traditional and Non-Traditional Honey Available on the Polish Market

The purpose of the work was to compare the quality of selected honey available on the Polish market, including traditional (rape, lime and meadow and marsh honey) and non-traditional honey (lime, buckwheat, and honeydew honey from coniferous honeydew). Parameters such as electrical conductivity, color, pH, acidity, water, hydroxymethylfurfural, total phenols content, and ability to deactivate ABTS cation radicals were determined. The profile of aroma compounds was carried out by GC-MS technique, and determination of sugars was performed by HPLC. It was found that all tested honey met standards according to European law requirements. Semi-quantitative analysis of volatile compounds showed that all honey samples contain numerous volatiles (in buckwheat honey there were 67 compounds, and in honeydew honey from coniferous honeydew, only 40 compounds). Characteristic volatile compounds of each aroma profile were described e.g., benzaldehyde, acetone, 2-methyl-butanal, nonanal, benzyl alcohol were found in rape honey aroma, and furfural, isovaleric acid, ethanol, delta-valerolactone, isovaleraldehyde, 2-methyl-butanoic acid, and phenylacetaldehyde in buckwheat honey aroma. The total content of volatiles was the highest in buckwheat honey (199.62 µg/kg), and in traditional lime honey (195.17 µg/kg). The lowest total content of volatile substances was established in non-traditional lime honey (73.20 µg/kg) and in rape honey (39.52 µg/kg)

Comparison of the Spreadability of Butter and Butter Substitutes

There are many types of butter, soft margarine, and blends, e.g., a mixture of butter and vegetable fats, on the market as bread spreads. Among these, butter and blends of butter with vegetable fats are very popular. The consumer’s choice of product is often determined by functional properties, such as texture, and the physicochemical composition of butter and butter substitutes. The aim of this study was to compare sixteen market samples of butter and butter substitutes in terms of spreadability and other selected structural (spreadability, hardness, adhesive force, and adhesiveness) and physicochemical parameters (water content, water distribution, plasma pH, color, acid value, peroxide number, saponification number, and instrumentally measured fatty acid profile) to investigate their correlation with spreadability. The parameters determined here were correlated with factors such as the type of sample, measuring temperature, and physicochemical composition. The statistical analysis revealed a very strong positive correlation between hardness and spreadability for all samples tested at 4 °C, as well as between hardness and spreadability for all samples tested 30 min after removal from the refrigerator; however, the interpretation of the results was different if the butter and butter substitute samples were subjected to a multivariate analysis separately

Concept of Batch and Fed-Batch Cultures of <i>Yarrowia lipolytica</i> as a Valuable Source of Sterols with Simultaneous Valorization of Molasses and Post-Frying Rapeseed Oil

Food byproduct streams can potentially be transformed into value-added products such as microbial lipids in bioprocesses based on the non-conventional Yarrowia yeast. The effect of culture conditions of Y. lipolytica KKP 379 wild strain in waste media on the efficiency of lipid accumulation, fatty acid composition, presence of selected sterols, yield and elemental composition of biomass has been studied. Batch and fed-batch bioreactor cultures were carried out in media with molasses hydrolysate (MH) and post-frying rapeseed oil. It was determined that biomass grown in MH contained more minerals than in medium with rapeseed post-frying oil. Considering the PDSC study, the Tmax of oxidation induction ranged from 10.04–26.36 min for the analyzed samples. The biomass from fed-batch cultures with MH had the highest total sterol content (68.40 mg/goil), dominated by ergosterol at 60.16 mg/g. Feeding with post-frying rapeseed oil with new doses of mineral medium promoted maintaining the cellular lipid content at a high level (30.75–31.73%) for 50 h, with maximum yield at 37.50%. The results of the experiment showed that the cellular lipid accumulation efficiency of Y. lipolytica yeast and the content of sterols in the cell membrane can be manipulated by selecting waste substrates and culture mode

Chemical Composition, Physical Properties, and Aroma Profile of Ethanol Macerates of Mistletoe (Viscum album)

Maceration parameters such as alcohol and mistletoe content were studied to obtain high-quality macerates to produce biska, a traditional Istrian herbal spirit. An ethanol&ndash;water solution containing 25, 40, 55, and 70 v/v% ethanol and 20, 40, and 80 g/L mistletoe was macerated and pH, total acids, extract content, and color parameters were measured. Volatile compounds were determined by GC/MS. More than 150 different volatile compounds were detected. The composition of the ethanol&ndash;water solution and mistletoe content affects the values of total extract, total acids, and color. Samples with lower alcohol content have a higher number of different acids, aldehydes, alcohols, esters, and ketones, while macerates with higher alcohol content are rich in hydrocarbons and terpenes. Ethyl decanoate; ethyl hexynoate; ethyl octanoate; benzaldehyde; hexanal; octanal; and the terpene compounds limonene, cymene, menthone, humulene, eucalyptol, linalol, and borneol contribute significantly to the aroma of the macerates due to a low odor threshold. Ylangene and &alpha;- and &beta;-bourbonene are tentatively determined new terpene molecules that are not found in the mistletoe literature, as well as thujone, which was also detected. For the preparation of aromatic macerates, 40&ndash;50 v/v% ethanol and about 40 g/L mistletoe should be used

Chemical Composition, Physical Properties, and Aroma Profile of Ethanol Macerates of Mistletoe (<i>Viscum album</i>)

Maceration parameters such as alcohol and mistletoe content were studied to obtain high-quality macerates to produce biska, a traditional Istrian herbal spirit. An ethanol–water solution containing 25, 40, 55, and 70 v/v% ethanol and 20, 40, and 80 g/L mistletoe was macerated and pH, total acids, extract content, and color parameters were measured. Volatile compounds were determined by GC/MS. More than 150 different volatile compounds were detected. The composition of the ethanol–water solution and mistletoe content affects the values of total extract, total acids, and color. Samples with lower alcohol content have a higher number of different acids, aldehydes, alcohols, esters, and ketones, while macerates with higher alcohol content are rich in hydrocarbons and terpenes. Ethyl decanoate; ethyl hexynoate; ethyl octanoate; benzaldehyde; hexanal; octanal; and the terpene compounds limonene, cymene, menthone, humulene, eucalyptol, linalol, and borneol contribute significantly to the aroma of the macerates due to a low odor threshold. Ylangene and α- and β-bourbonene are tentatively determined new terpene molecules that are not found in the mistletoe literature, as well as thujone, which was also detected. For the preparation of aromatic macerates, 40–50 v/v% ethanol and about 40 g/L mistletoe should be used

Quality Assessment of Honey Powders Obtained by High- and Low-Temperature Spray Drying

The paper aimed to compare the quality of rapeseed and honeydew honey powders, obtained by two methods of spray drying&mdash;traditional at a high temperature (inlet air 180 &deg;C) and innovative low-temperature spray drying with the use of dehumidified air as a drying medium (inlet air 75 &deg;C). Total polyphenol content, antioxidant activity, and the content and types of aromatic compounds were determined. In addition, Fourier-transform infrared spectroscopy (FTIR) coupled with chemometrics analyses was done. Powders obtained by the low-temperature spray drying method (with dehumidified air) were characterized by a higher content of polyphenols, antioxidant activity, and aromatic compounds, compared to powders obtained by the traditional method. Honeydew honey compared to rapeseed honey was characterized by a higher content of polyphenols, antioxidant activity, and composition of aromatic compounds. The results proved that the production method had a higher impact on the final properties of powders than the type of honey

Verification of the Conditions for Determination of Antioxidant Activity by ABTS and DPPH Assays&mdash;A Practical Approach

The ABTS and DPPH methods are among the most popular assays of antioxidant activity determination. Attempts to adapt them to different analytes and the search for the highest values of antioxidant activity has resulted in a large variety of assay conditions to be presented in the literature, including the way the measurement is made. This makes it difficult to relate the results to real oxidation systems, and often makes it impossible to compare them. Such a comparison is limited in advance by the use of stable radicals that do not exist in nature and that react differently from those generated in food or in vivo. Therefore, it is important to introduce measures aimed at standardizing the conditions of the activity assay, including reaction time and several reaction environments suitable for testing different groups of compounds. In this study, we used natural antioxidants of various structures: phenolic acids, flavonoids, peptides and corresponding amino acids, ascorbic acid and &alpha;-tocopherol, and also synthetic analogues of selected compounds. The curves of dependence of the measured absorbance on the concentration of antioxidants were described, the ranges of linearity were determined, and the value of the error made when reading in various ranges of dependencies was estimated. We also determined and compared the activity values using two popular methods (IC50 and TEAC), taking into account different environments and reaction times. Based on the collected data, recommendations were formulated regarding the reaction conditions adapted to the studies of individual groups of antioxidants, and unified reaction times were proposed. Taking into account the state before reaching the equilibrium of antioxidants reacting in a complex manner, this approach may introduce a simplified reference to the competing reaction that occurs in reality