Chemical Characteristics and Thermal Oxidative Stability of Novel Cold-Pressed Oil Blends: GC, LF NMR, and DSC Studies.

Plant oils contain a high content of unsaturated fatty acids. Studies of food products have revealed a considerable disproportion in the ratio of ω6 to ω3. This article presents information on the healthful qualities of eight new oil blends that contain a beneficial proportion of ω6 to ω3 fatty acids (5:1), as well as their degradation during heating at 170 and 200 °C. The fatty acid profile was analyzed by gas chromatography (GC), content of polar compounds and polymers of triacylglycerols by liquid chromatography (LC), water content was measured by the Karl Fischer method, and oxidative stability was measured by differential scanning calorimetry (DSC) and low-field nuclear magnetic resonance (LF NMR) methods. The results showed that during heating, the polar fraction content increased in samples heated at both analyzed temperatures compared to unheated oils. This was mainly due to the polymerization of triacylglycerols forming dimers. In some samples that were heated, particularly those heated to 200 °C, trimers were detected, however, even with the changes that were observed, the polar fraction content of the blends did not go beyond the limit. Despite the high content of unsaturated fatty acids, the analyzed blends of oils are characterized by high oxidative stability, confirmed by thermoanalytical and nuclear magnetic resonance methods. The high nutritional value as well as the oxidative stability of the developed oil blends allow them to be used in the production of food, in particular products that ensure an adequate supply of ω3 fatty acids.

Effect of Heating Temperature of High-Quality Arbequina, Picual, Manzanilla and Cornicabra Olive Oils on Changes in Nutritional Indices of Lipid, Tocopherol Content and Triacylglycerol Polymerization Process.

The aim of the study was to determine the stability and heat resistance of extra premium olive oil. The study material consisted of six extra virgin olive oils (EVOO) obtained from Spain. Four samples were single-strain olive oils: Arbequina, Picual, Manzanilla, and Cornicabra. Two samples were a coupage of Arbequina and Picual varieties: Armonia (70% Arbequina and 30% Picual) and Sensation (70% Picual and 30% Arbequina). Olive oil samples were heated at 170 °C and 200 °C in a pan (thin layer model). In all samples, changes in indexes of lipid nutritional quality (PUFA/SFA, index of atherogenicity, index of thrombogenicity, and hypocholesterolemic/hypercholesterolemic ratio), changes in tocopherol, total polar compounds content, and triacylglycerol polymers were determined. Heating olive oil in a thin layer led to its degradation and depended on the temperature and the type of olive oil. Increasing the temperature from 170 to 200 °C resulted in significantly higher degradation of olive oil. At 200 °C, deterioration of lipid nutritional indices, total tocopherol degradation, and formation of triacylglycerol polymers were observed. A twofold increase in the polar fraction was also observed compared to samples heated at 170 °C. The most stable olive oils were Cornicabra and Picual.

Effect of the Bleaching Process on Changes in the Fatty Acid Profile of Raw Hemp Seed Oil (Cannabis sativa).

Many refined oils from soybean, rapeseed, and sunflower, among others, are available on the food market, except olive oil. Refining, on the small production scale of niche oils, is not used due to the high cost of the refining process. Unrefined oils are characterized by intense taste, odor, color, and undesirable nutrients. The problem to be solved is determining the effects of incomplete refining of niche oils on their composition. One process, which does not require the use of complex apparatus, is the bleaching process. The results presented in this article relate to the research stage, in which the aim is to evaluate the changes occurring in the oil due to the low-temperature bleaching process with different process parameters. The presented research results provide evidence of the absence of adverse changes in the fatty acid profile of hemp oil of the varieties 'Finola', 'Earlina 8FC', and 'Secuieni Jubileu'. Seven different types of bleaching earth were used to bleach the oil in amounts of 2.5 and 5 g/100 g of vegetable oil. The fatty acid profile was obtained by gas chromatography (GC-FID). The obtained chromatograms were subjected to statistical analysis and principal component analysis (PCA). The results show that there was no effect of the type of bleaching earth and its amount on the change in the fatty acid profile of bleached oils. Only real differences between the types of hemp oils were observed. However, an overall positive effect of the bleaching process on hemp oil was found. The amount of saturated fatty acid (SFA) was reduced by 17.1% compared with the initial value, resulting in an increase in the proportion of polyunsaturated fatty acids (PUFA) by 4.4%, resulting in an unsaturated fatty acid (UFA) proportion of 90%. There was a significant improvement in the SFA/PUFA ratio by 26% over the baseline, and the omega-6/omega-3 ratio by 8.9% to a value of 3.1:1. The new knowledge from this study is evidence of the positive effect of the low-temperature bleaching process on the fatty acid profile. In contrast, the parameters of the bleaching process itself are not significant.

Analysis of Changes in the Amount of Phytosterols after the Bleaching Process of Hemp Oils.

Unrefined vegetable oils from niche oilseeds are now sought after by consumers because of their unique nutritional properties and taste qualities. The color and flavor intensity of niche oils is a big problem, and their refining is not industrially feasible due to the small production scale. The study undertaken aimed analyze the effect of changing the amount of phytosterols (PSs) after the bleaching process of hemp oils of the 'Finola', 'Earlina 8FC' and 'Secuieni Jubileu' varieties. Cold-pressed (C) and hot-pressed (H) crude vegetable oils were bleached with selected bleaching earth (BE) at two concentrations. The post-process BE was extracted with methanol. The amount of PSs in the crude oils and the extract after washing the BE with methanol was analyzed by GC (gas chromatography). The study shows that the bleaching process did not significantly affect the depletion of PSs in the oils. Trace amounts of PSs remain on the BE and, due to methanol extraction, can be extracted from the oil. The conclusion of the performed research is that the bleaching of hemp oil does not cause depletion of the oil, and it significantly improves organoleptic properties. The oil bleaching process results in an oil loss of less than 2% by weight of the bleached oil, while the loss depends on the type of BE used. The study shows that the loss of phytosterols after the bleaching process averages 2.69 ± 0.69%, and depends on the type of BE used and the oil extracted from different varieties of hemp seeds.

Quality of Oil Pressed from Hemp Seed Varieties: 'Earlina 8FC', 'Secuieni Jubileu' and 'Finola'.

In the last decade, the demand for edible niche oils has increased. Therefore, the aim of this study was to characterize the seeds hemp (Cannabis sativa L.) varieties: 'Finola' (FIN-314)', 'Earlina 8FC', and 'Secuieni Jubileu', and cold and hot pressed oils were prepared from each seed. The seeds were examined for moisture content, granulometric distribution, bulk density, and fat content. Seeds were pressed without and with preconditioning (60 °C), and oil yield and pressing time were recorded. The oil was filtered through cellulose membranes. Oil-water content, oil color, fatty acid profile, and sterol content were studied. From the study conducted, there are significant differences in the parameters of oil recovery and its quality compared to 'Finola' seed oil, which is widely reported in the literature. 'Finola' oil yield was the lowest, with an average of 79% compared to 'Earlina' (82%) and 'S. Jubileu' (84%). All oil samples contained a comparable amount of sterols, with campesterol (0.32 mg/g), ß-sitosterol (1.3 mg/g) and Δ5-avenasterol (0.15 mg/g) predominating. From the organoleptic evaluation, it was evident that both varieties hemp oils and marc ('Earlina' and 'S. Jubileu') were not bitter like the "Finola" oil and marc. More detailed studies in this direction have to be undertaken.

The Stability of Refined Rapeseed Oil Fortified by Cold-Pressed and Essential Black Cumin Oils under a Heating Treatment.

Polar compounds and polymers are regarded as the most reliable indicators of oil degradation during heating, and it is desirable to find methods to reduce these undesirable changes. The aim of this study was (1) to determine the effect of enrichment with black cumin cold-pressed oil (CP) or essential oil obtained from black cumin cold-pressed oil in an equivalent amount (ES) on limiting the polar compounds and polymers content in blends based on refined rapeseed oil during high-temperature heating in a thin layer; (2) to determine tocochromanol losses and their effect on the change content of the polar compounds and polymers. Four fortified oils were made from refined rapeseed oil and one of the four additives (10% CP, 20% CP, 0.1% ES, and 0.2% ES). All fortified oils and refined rapeseed oil as a control sample were heated at 170 and 200 °C on the pan in a thin layer and evaluated regarding loss of individual tocochromanol homologs by HPLC-FL, polar compounds content, oxidized triacylglycerols (TAG), and polymers content by HPSEC-ELSD. Additionally, the fatty acid profile in nonheated oil was investigated. Tocochromanol analysis showed loss in all the samples. At 170 °C polymers were not detected; no difference was noted for polar compounds and oxidized TAG content; only the 20% CP sample showed a higher level. At 200 °C the 10% CP sample exhibited a significant protective effect with the lowest content of polar compounds, oxidized TAG, and dimers.

Nutritional Value and Biological Activity of Gluten-Free Bread Enriched with Cricket Powder.

Cricket powder, described in the literature as a source of nutrients, can be a valuable ingredient to supplement deficiencies in various food products. Work continues on the implementation of cricket powder in products that are widely consumed. The aim of this study was to obtain gluten-free bread with a superior nutritional profile by means of insect powder addition. Gluten-free breads enriched with 2%, 6%, and 10% of cricket (Acheta domesticus) powder were formulated and extensively characterized. The nutritional value, as well as antioxidant and ß-glucuronidase activities, were assessed after simulated in vitro digestion. Addition of cricket powder significantly increased the nutritional value, both in terms of the protein content (exceeding two-, four-, and seven-fold the reference bread (RB), respectively) and above all mineral compounds. The most significant changes were observed for Cu, P, and Zn. A significant increase in the content of polyphenolic compounds and antioxidant activity in the enriched bread was also demonstrated; moreover, both values additionally increased after the digestion process. The total polyphenolic compounds content increased about five-fold from RB to bread with 10% CP (BCP10), and respectively about three-fold after digestion. Similarly, the total antioxidant capacity before digestion increased about four-fold, and after digestion about six-fold. The use of CP also reduced the undesirable activity of ß-glucuronidase by 65.9% (RB vs. BCP10) in the small intestine, down to 78.9% in the large intestine. The influence of bread on the intestinal microflora was also evaluated, and no inhibitory effect on the growth of microflora was demonstrated, both beneficial (Bifidobacterium and Lactobacillus) and pathogenic (Enterococcus and Escherichia coli). Our results underscore the benefits of using cricket powder to increase the nutritional value and biological activity of gluten-free food products.

Degradation of Tocopherol Molecules and Its Impact on the Polymerization of Triacylglycerols during Heat Treatment of Oil.

The aim of the study was to analyze the influence of the surface area to volume ratio of pressed and refined rapeseed oils on the changes in tocopherol content and polymerization of triacylglycerols during heating. In the study the pressed and refined rapeseed oil was heated at 170 °C, during 6, 12, and 18 h with three different surface area to volume (s/v) ratios (0.378, 0.189, and 0.126 cm-1). During heating, a decrease in tocopherols and increases in dimers, trimers, and oligomers of triacylglycerols were observed. However, the changes were dependent on the surface area to volume ratio used, type of oil and time of heating. The biggest changes were observed in oil with the biggest s/v ratio (0.378 cm-1), and the lowest when the s/v ratio was 0.126 cm-1. The pressed oil was characterized by faster degradation of tocopherols and slower increase of triacylglycerol polymer levels compared to refined oil.

Cholinesterase inhibitory activity, antioxidative potential and microbial stability of innovative liver pâté fortified with rosemary extract (Rosmarinus officinalis)

Background: Rosemary (Rosmarinus officinalis) contains active substances that have desirable properties for industrial and herbal medicine applications, e.g., essential oils (1.5­2.5%), tannins, flavonoids, triterpenes, saponins, resins, phytosterols, rosmarinic acid and many others. The aim of this study was to determine the influence of rosemary extract and 20% rapeseed oil substitution for animal fat on storage changes and inhibition of cholinesterases in liver pâté. Results: Preliminary research showed that rosemary extract exhibited antioxidative activity in the system of accelerated Rancimat and Oxidograph tests. Then, rosemary extract was used as an ingredient in liver pâté. During the experiment, meat samples were refrigerated and tested on days 1, 5, 8, 12 and 15 after production. The study proved that the substitution of 20% of animal fat with rapeseed oil decreased the content of saturated acids and increased the content of monoenic fatty acids by approximately 5% and polyene fatty acids by 40%. Conclusions: In addition to antioxidative activity, the rosemary extract affected the health-promoting value of the samples, which inhibited cholinesterase activity during the entire storage period. The extract inhibited AChE more than BChE.

Composition and In Vitro Effects of Cultivars of Humulus lupulus L. Hops on Cholinesterase Activity and Microbial Growth.

Common hop (Humulus lupulus L.) has significant health-promoting properties. Hop cones contain resins, essential oils, proteins, polyphenols, lipids, waxes, and cellulose. Hop extracts include bioactive compounds such as polyphenolic compounds (phenolic acids, and flavonols), and chlorophylls. The aim of this study was to compare the pro-health potential of hop cone extracts obtained from three cultivars (Magnum, Lubelski, and Marynka). The results showed that the cones of Magnum cultivar demonstrated the highest biological activity. The sum of phenolic acids and flavonols in ethanol extract was the highest for this variety and was equal 4903.5 µg/g dw. Ethanol extracts of Magnum cultivars showed the highest degree of iron ion chelation (55.43-88.76%) as well as the activity against 1,1-diphenyl-2-picrylhydrazyl radical (4.75 mmol Tx/g dw). Hop cone extracts as cholinesterase inhibitors showed high potential for aqueous variants. In terms of antimicrobial activity, all investigated extracts demonstrated strong inhibition against Staphylococcus aureus and Staphylococcus epidermidis, with the Magnum cultivar showing the strongest inhibition. Owing to the biofunctional features of hop cone, it can be concluded that it is an attractive raw material with pro-health potential that can be used much more widely in food technology. However, it should be noted that toxicological tests and in vitro tests must be carried out before the raw material is used in food production.

Changes in oxidative stability and protein profile of flaxseeds resulting from thermal pre-treatment.

BACKGROUND: The oxidative stability of oilseeds is crucial for their technological/nutritional quality and shelf life. This research aimed to evaluate the effect of thermal pre-treatment (steaming and roasting under various time/temperature conditions) on flaxseed oil and protein stability. The monitoring of changes in oil oxidation in situ and protein profiles (SDS-PAGE) and analysis of the antiradical activity of ethanolic and aqueous fractions were included in the study. RESULTS: Flaxseed stability during storage was considerably affected by thermal pre-treatment conditions. Dynamics of oil oxidation was accelerated at 160 °C and 180 °C but slowed at 200 °C. Influence of pre-treatment conditions on the antiradical activity of the aqueous fraction was clearly observed and no effect concerning the ethanolic fraction was found. The most significant changes in protein profile of 200 °C-roasted flaxseed were found with the observed disappearance of 19 kDa protein. A treatment-dependent decrease in the 13 kDa protein was also detected. Based on the aqueous extract protein profiles, roasting conditions were found to be crucial for protein extractability. CONCLUSIONS: The study has broadened knowledge of the consequences of flaxseed thermal treatment. The deterioration of flaxseed oil oxidative stability is shown. The changes of 19 and 13 kDa proteins suggest their sensitivity to thermally induced aggregation and/or cross-link. © 2018 Society of Chemical Industry.

Anti-polymerization activity of tea and fruits extracts during rapeseed oil heating.

The aim of the study was to analyze the influence of natural antioxidants on polymerization of partially hydrogenated rapeseed oil heated in 170°C for 40h. In the research ethanolic extracts of green tea leaves (China Lung Ching), yellow tea leaves (China Kakecha), cranberry, blackberry, and lime were used. The yellow and green tea extracts were characterized by the highest content of total polyphenol and antioxidant activity. Polymers of triacylglycerols were found only in the polar fraction of heated oil. During heating, the increase of dimers, trimers, and oligomers was observed. However, it was dependent on the used additives and not directly related to the content of phenolic compounds and their antioxidant activity. The final content of polymers in oil samples increased in the fallowing order: green tea

Model studies on the formation of volatile compounds generated by a thermal treatment of steryl esters with different fatty acid moieties.

The consumption of plant sterols is reported to have a beneficial effects on human health, i.e. phytosterols are known for their cholesterol-lowering properties. Whereas, they are prone to oxidation and currently there is ongoing worldwide research aimed at the biological effect of phytosterol oxides. In this study volatile compounds formed during thermal degradation of stigmasteryl esters were identified. The research was conducted using standards of stigmasterol, fatty acids and stigmasteryl esters as well as fat enriched with stigmasteryl esters which were thermally treated at 60°C and 180°C for 12h. Volatile compounds were characterised by SPME-GC-MS. Among the volatiles formed during heating of stigmasteryl esters aldehydes, ketones, alcohols and hydrocarbons were found. The mechanism of the formation of volatile compounds from sterol esters was related to oxidation of steryl and fatty acid moieties. In particular, 2-methyl-3-pentanone and 5-ethyl-6-methyl-3-hepten-2-one were identified as unique degradation products formed from degradation of the steryl moiety specifically, and a mechanism of their formation was suggested. Both volatiles could be a good indicator of thermo-oxidative degradation of functional food products enriched in phytosterols and their esters.

The Effect of Buckwheat Hull Extract on Lipid Oxidation in Frozen-Stored Meat Products.

This study investigated the effect of antioxidants on lipid stability of frozen-stored meat products. Buckwheat hull extract was used to enrich fried meatballs made from ground pork. During 180-d storage of meat products, lipid oxidation (peroxide and 2-thiobarbituric acid reactive substances [TBARS] value) was periodically monitored. The results were compared with butylated hydroxytoluene (BHT). The addition of antioxidants decreased lipid oxidation in stored meatballs. The highest ability to control peroxide and TBARS values was demonstrated for buckwheat hull extract. Moreover, buckwheat hull extract showed a higher 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity as well as higher Fe(II) ion chelating ability, as compared with BHT. The total content of phenolic compounds are highly correlated to the individual polyphenols in extract of buckwheat hull, among which the following were assayed: 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, gallic acid, isovanillic acid and p-coumaric acid, and flavonoids: isoorientin, quercetin, quercetin 3-d-glucoside, rutin, and vitexin. These results indicate that plant extracts can be used to prolong shelf life of products by protecting them against lipid oxidation and deterioration of their nutritional quality.

Antioxidative potential, nutritional value and sensory profiles of confectionery fortified with green and yellow tea leaves (Camellia sinensis).

This paper presents a study on development of functional food products containing green and yellow tea leaves. The results indicated that green and yellow tea are significant tools in the creation of the nutritional value, antioxidative potential and stability of the lipid fraction of cookies. Tea-fortified cookies showed considerably higher contents of dietary fiber, especially hemicellulose and insoluble fractions, and were characterized by significantly higher antioxidant potential associated with their phenolics content. Results of ABTS, DPPH, ORACFL and PCL assay showed significantly higher antioxidant potential of tea cookies, highest for yellow tea. The antioxidative potential of applied teas was significant in terms of the inhibition of hydroperoxide content, while formation of secondary lipid oxidation products was less spectacular. It is concluded that tea leaves could be widely used as a source of polyphenols with high antioxidative potential, as well as fiber; thus introducing numerous health benefits for the consumer.

Antiradical capacity and polyphenol composition of asparagus spears varieties cultivated under different sunlight conditions.

BACKGROUND: Asparagus officinalis has a high nutritional value. Asparagus is rich in a number of bioactive compounds, mainly flavonoids (quercetin), glutathione, vitamin C, vitamin E, fructans (inulin and fructooligosaccharides) and phytosterols (b-sitosterol). These compounds may play an important role in human health. The purpose of this study was to examine the antioxidant potential and polyphenol composition of white, pale-colored and green asparagus spears of different cultivars. METHODS: Investigations were conducted on different asparagus spear extracts. The study included three colors of asparagus (white, pale-colored and green) from five different cultivars subjected to the ethanol extraction procedure. Total phenolic content was also determined by the Folin-Ciocalteu method. Polyphenol (phenolic acids and flavonols) composition was estimated using the HPLC method. The antioxidant properties of extracts were examined using DPPH, ABTS and metal ion chelating assays. RESULTS: The highest contents of phenolic and flavonoids were observed in green asparagus from Grolim and the lowest in pale-colored asparagus from Gyjmlin. It was found that both the color of asparagus and the cultivar had a significant effect on the composition of phenolic acid and flavonols. Radical scavenging activity toward DPPH• and ABTS was highest for green asparagus cv. Grolim and Eposs. The greatest number of Fe ions was chelated by samples of green asparagus cv. Grolim and Huchel's Alpha and pale-colored asparagus cv. Huchel's Alpha. CONCLUSIONS: It was shown that the antioxidant activity of asparagus spears measured by antiradical and chelating activity test depends on variety and color. The highest activity was found in green asparagus and the lowest was identified in white asparagus extracts. It has also been clarified that changes in flavonol and phenolic acid composition and increases in their diversity depends on growing with sunlight and variety. Asparagus can provide a valuable source of phenolic compounds in the human diet.

Antioxidant properties of extracts from Ginkgo biloba leaves in meatballs.

The aim was to determine the effect of Ginkgo leaf extracts on the stability of lipids and cholesterol in pork meatballs over 21days of refrigerated storage. The antioxidants used were characterized by their antioxidant activity towards lipids and cholesterol. Extracts were prepared from green and yellow leaves from Ginkgo biloba L. trees. Water, acetone and ethanol were used as extractants. The extracts showed stabilizing effects on both lipid and cholesterol oxidation processes. The lipid oxidation process of pork meatballs was mostly inhibited by the aqueous and ethanolic extracts of the yellow leaves. Their antioxidant activity was higher than that of BHT. All the extracts had a stabilizing effect on cholesterol and most of them inhibited the formation of oxidized derivatives. The acetone and ethanol extracts of green leaves and the ethanol extract of yellow leaves inhibited the formation of cholesterol oxidation products formation most effectively.