scholarly journals UTICAJ NAČINA PRESOVANJA NA PROMENE LEŠNIKOVOG ULJA TOKOM ČUVANJA I SENZORNA SVOJSTVA KEKSA

2021 ◽  
Author(s):  
Mirjana Radovanovic ◽  
◽  
Marko Petkovic ◽  
Vesna Đurovic ◽  
Nemanja Miletic ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Sensory Evaluation ◽  
Oxidation Products ◽  
Peroxide Number ◽  
Hazelnut Oil ◽  
Secondary Oxidation ◽  
Sensory Score

The changes in the spectrum, peroxide numbers and specific absorbances (at 232 nm and 270 nm) of fresh and storaged oils (4 months at 4 °C) obtained by different hazelnuts pressing were monitored. The results showed reduced viability of the oil obtained from the hazelnut exposed to elevated temperature during conditioning and pressing: changes in the spectrum about 290 nm, a peroxide number close to the legally allowed maximum (7.5 mmolkg-1) and possible presence of secondary oxidation products. Sensory evaluation of biscuits with hazelnut oil showed that the samples belonged to the categories of quality: very good and good. The overall sensory score was highest for biscuits with hazelnut oil pressed in an electric press.

scholarly journals Impact of Tetrapeptide-FSEY on Oxidative and Physical Stability of Hazelnut Oil-In-Water Emulsion

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1400
Author(s):  
Chenshan Shi ◽  
Miaomiao Liu ◽  
Qinghua Ma ◽  
Tiantian Zhao ◽  
Lisong Liang ◽  
...  
Keyword(s):  
Particle Size ◽  
Physical Stability ◽  
Test System ◽  
Oxidation Products ◽  
Hazelnut Oil ◽  
Secondary Oxidation ◽  
Antioxidant Additive ◽  
Water Emulsion ◽  
Oil In Water ◽  
Oil In Water Emulsion

This study investigates the antioxidant behaviors of a hazelnut tetrapeptide, FSEY (Phe-Ser-Glu-Tyr), in an oil-in-water emulsion. The emulsion was prepared with stripped hazelnut oil at a ratio of 10%. O/W emulsions, both with and without antioxidants (FSEY and TBHQ), were incubated at 37 °C. The chemical stabilities, including those of free radicals and primary and secondary oxidation productions, along with the physical stabilities, which include particle size, zeta-potential, color, pH, and ΔBS, were analyzed. Consequently, FSEY displayed excellent antioxidant behaviors in the test system by scavenging free lipid radicals. Both primary and secondary oxidation products were significantly lower in the FSEY groups. Furthermore, FSEY assisted in stabilizing the physical structure of the emulsion. This antioxidant could inhibit the increase in particle size, prevent the formation of creaming, and stabilize the original color and pH of the emulsion. Consequently, FSEY may be an effective antioxidant additive to use in emulsion systems.

scholarly journals Investigation of the oxidative stability of cold pressed sunflower oil of high-oleic type subjected to elevated temperature

2017 ◽  
Vol 71 (2) ◽  
pp. 175-182
Author(s):  
Ranko Romanic ◽  
Snezana Kravic
Keyword(s):  
Elevated Temperature ◽  
Oxidative Stability ◽  
Sunflower Oil ◽  
Oxidation Products ◽  
Coefficient Of Determination ◽  
Secondary Oxidation ◽  
High Oleic ◽  
Conjugated Trienes ◽  
Cold Pressed ◽  
Very High

In this paper the oxidative stability of cold pressed sunflower oil of high-oleic type was investigated, using Schaal?Oven test at elevated temperature (63?2?C). At the same time samples of linoleic type oils, cold pressed and refined, were tested. The extent of oxidative changes was analyzed regarding the content of primary and secondary oxidation products during the period of 14 days. To especially expressed increase in oxidative values, with very high values of the coefficient of determination occurred in samples of linoleic type of oils, cold pressed and refined, whereas these changes were much less observed in the sample of cold pressed sunflower oil of high-oleic type (R2 ? 0.99). The cold pressed oils of high-oleic and linoleic type, as well of refined sunflower oil of linoleic type were measured and the content of conjugated dienes and conjugated trienes. In the period of 14 days, the lowest increase in oxidative value and the lowest degree of conjugation into the conjugated diene and triene were determined in cold pressed sunflower oil of high-oleic type, indicating a significantly better oxidative stability of this type of oil compared to linoleic types.

Chemical lonization-mass spectrometry of secondary oxidation products from methyl linoleate and linolenate

Lipids ◽  
1986 ◽  
Vol 21 (5) ◽  
pp. 333-337 ◽  
Author(s):  
E. N. Frankel ◽  
W. E. Neff ◽  
R. D. Plattner
Keyword(s):  
Mass Spectrometry ◽  
Methyl Linoleate ◽  
Oxidation Products ◽  
Secondary Oxidation

scholarly journals Effect of heating on the oxidative stability of corn oil and soybean oil

2019 ◽  
Vol 70 (2) ◽  
pp. 303 ◽  
Author(s):  
R. Saeed ◽  
S. Naz
Keyword(s):  
Soybean Oil ◽  
Microwave Heating ◽  
Corn Oil ◽  
Acid Value ◽  
Oxidation Products ◽  
Chemical Degradation ◽  
Conventional Heating ◽  
Secondary Oxidation ◽  
Total Oxidation ◽  
Ft Ir

The effects of conventional and microwave heating on the oxidative properties of corn and soybean oil were evaluated. The results showed that acid value, peroxide value, oxidative indices, total oxidation value, and p-anisidine values changed significantly with the rise in temperature (p < 0.05). The peroxide and p-anisidine values for corn oil (PV: 50.670 meqO2/kg, p-AV: 8.248) were greater than soybean oil (PV: 41.694 meqO2/kg, p-AV: 7.566) for conventional heating. The peroxide and p-anisidine values for soybean oil (PV: 6.545 meqO2/kg, p-AV: 76.539) were greater compared to corn oil (PV: 5.074 meqO2/kg, p-AV: 65.360) for microwave heating. The results concluded that microwave heating had a greater impact on the chemical degradation of the fatty acids of the oil. The FT-IR spectra showed peak changes at 3743 cm-1 and 1739 cm-1 and confirmed the rancidity of the oils from microwave heating due to the formation of secondary oxidation products. It was concluded that corn oil showed more oxidative changes compared to soybean oil.

scholarly journals Effects of various antioxidants on oxidative stability of anchovy (Engraulis encrasicolus) oil

2019 ◽  
Vol 36 (4) ◽  
pp. 367-372 ◽  
Author(s):  
Mehmet Gökhan Soydan ◽  
Fatime Erdoğan
Keyword(s):  
Fish Oil ◽  
Storage Period ◽  
The Other ◽  
Oxidation Products ◽  
Butylated Hydroxytoluene ◽  
Rosemary Extract ◽  
Control Group ◽  
Secondary Oxidation ◽  
Total Oxidation ◽  
Oil Storage

The aim of study was to investigate four commercial available antioxidants (groups A (300 mg propyl gallate (PG)+10 mg rosemary extract (RE)/1000 mg), B (240 mg butylated hydroxy anisole (BHA)+80 mg PG+80 mg citric acid (CA)/1000 mg), C (120 mg BHA+120 mg PG+50 mg CA)/1000 mg), D (150 mg butylated hydroxytoluene (BHT)+100 mg BHA+10 mg PG)/1000 mg) used to evaluate oxidation during the storage in fish oil. Antioxidants were added to the fish oil to determine which ones were most effective in preventing oxidation, and fish oil was stored in the amber bottles at room temperature (20 °C) for 90 days. The control group samples were stored under the same conditions and antioxidant was not added. To determine the effect of antioxidants, the recommended by the manufacturer dose of commercial antioxidant (1000 mg kg-1 fish oil) was used in the experimental groups. The formation of the primary and secondary oxidation products in fish oil storage trial was examined by conducting the peroxide value (PV) and p-anisidine value (AV) analyses. The total oxidation value (TOTOX) was calculated based on the PV and AV measurements. Minor changes were observed in the PV of the fish oil during the first 30 days. In the study, antioxidant added samples (groups B, C, D > 5 meq kg-1) were oxidized on the 45th day; on the other hand both control and group A oxidized on the 75th day. A possible prooxidative effect was seen for some of the antioxidants. There was a very little change secondary oxidation of fish oil and no significant effects of all four antioxidant groups on the changes of AV (<20) during the storage period (P>0.05). In addition TOTOX was calculated under GOED (<26) limit during the storage for 90 days. At the end of the study, control samples were not significantly different from the other samples with antioxidant-added. Due to the results obtained at the end of the 90-day study, it was found that none of the antioxidants were used efficiently in this study.

scholarly journals Thiamine in Lipid Systems vs. the Antioxidant Activity of Epigallocatechin Gallate and Caffeine

2021 ◽  
Vol 13 (9) ◽  
pp. 4644
Author(s):  
Justyna Piechocka ◽  
Krystyna Szymandera-Buszka
Keyword(s):  
Antioxidant Activity ◽  
Epigallocatechin Gallate ◽  
Oxidation Products ◽  
Model Systems ◽  
Thiamine Pyrophosphate ◽  
Thiamine Hydrochloride ◽  
Secondary Oxidation ◽  
Oxidation Degree ◽  
Thiamine Content ◽  
The Stability

The aim of this study was to determine correlations between the concentration of thiamine hydrochloride or thiamine pyrophosphate and the antioxidant activity of epigallocatechin gallate (EGCG) and caffeine, as well as thiamine stability. The study was conducted in model systems. Oxidation degree indices of soybean oil (peroxide value and anisidine value LAN) and concentrations of total thiamine were determined. To compare the dynamics of the changes in thiamine content during storage, half-life T1/2 was determined. There was a strong correlation between the stability of thiamine and the stability of the oil. Thiamine was particularly sensitive to secondary oxidation products. Higher losses of thiamine introduced in the form of thiamine pyrophosphate were found (4–6%). The addition of tea components increased fat stability and thus reduced thiamine losses. The dynamics of thiamine loss were found to be lower with EGCG than caffeine. The antioxidant activity of these components was significantly reduced when the content of thiamine (1.0–20.0 mg/100 g) was higher than the natural level in foods. In order to maintain thiamine stability and the high activity of the active tea ingredients, it is necessary to consider their simultaneous addition to the systems in concentrations that limit their interactions.

The Oxidation Products of Rubber

1939 ◽  
Vol 12 (2) ◽  
pp. 225-234
Author(s):  
A. van Rossem ◽  
P. Dekker
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Tensile Properties ◽  
High Speed ◽  
Accelerated Aging ◽  
Direct Determination ◽  
Oxidation Products ◽  
Vulcanized Rubber

Abstract In their summary of the aging of vulcanized rubber, Porritt and Scott state that three factors are responsible for the changes in mechanical properties of vulcanized rubber during aging, viz.: (a) oxidation of the rubber; (b) after-vulcanization; (c) some colloidal change of the rubber, sometimes termed aggregation. Of these factors, oxidation is by far the most important because it is responsible for the decrease in mechanical properties, which leads to the general deterioration of rubber from a technical standpoint. It was Marzetti who proved that the decrease of mechanical properties in accelerated aging is due to oxidation. Later, Kohman confirmed this in a more concise way and showed that even such small amounts as 0.5% of oxygen absorbed by vulcanized rubber are sufficient to decrease tensile properties to 50% of their original value. When studying aging, three ways of tackling this problem are possible, viz.: (1) Investigations of the mechanical properties, either under normal conditions, or under special conditions such as elevated temperature or high speed. (2) Determination of oxidation products, which are formed during oxidation of the rubber. (3) Direct determination of the amount of oxygen which is absorbed by the rubber. It is clear that any of these methods may be combined with accelerated aging tests.

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