Oxidative stability of wax esters by thermogravimetric analysis

Hagemann, J. W.; Rothfus, J. A.

doi:10.1007/bf02679337

Cited by 12 publications

(7 citation statements)

References 6 publications

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“…It was concluded that the rate of oxygen diffusion across the air-oil interface is the limiting factor which determines the rate of oxidation (20,21). Although a high surface area-to-weight ratio was recommended for dynamic TGA oxidation studies (12), no details have been published on how the sample size affects the results in an isothermal TGA experiment. Table I illustrates the effect of the sample size on oxidation characteristics of an oil as measured isothermally at 150 C. Data shown here represent a single measurement for each sample weight.…”

Section: Resultsmentioning

confidence: 99%

“…The periodic determination of peroxide values (PV) in Wheeler's test (3), the active oxygen method (AOM) (4), automated AOM (5) and the ASTM oxygen bomb method (6,7) are stability tests widely accepted in the oil industry. Microanalytical methods such as gas chromatography (8), differential scanning calorimetry (9,10) and thermogravimetric analysis (10)(11)(12)(13)(14)(15) have gained popularity in recent years.…”

Section: Introductionmentioning

confidence: 99%

“…isothermally in a stream of flowing air or oxygen. A dynamic TGA was preferred for estimating the relative oxidative stabilities of the crambe oil ill), sperm whale oil and several wax esters (12). An isothermal as well as dynamic TGA were used to compare stabilities of several vegetable oils (10,(13)(14)(15).…”

Section: Introductionmentioning

confidence: 99%

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Reaction conditions for measuring oxidative stability of oils by thermogravimetric analysis

Mikula¹,

Khayat²

1985

J Americ Oil Chem Soc

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A method for evaluating the oxidative stability of otis based on heating the sample in an oven and periodically testing for weight gain has been known for over 100 years. Thermogravimetric analysis (TGA) with its highly sensitive recording electrobalance turns this simple method into a powerful technique for studying the relative thermooxidative stabilities of oils. This paper explores the potential of an isothermal TGA via evaluation of several freshly processed, unhydrogenated soybean oils. The objective was to define the parameters of the TGA experiment for fast routine measurement and to compare isothermal and dynamic experiments. The consideration of influence of temperature, specific surface area, air flow rate, sample volatilization and nature of the sample pan on the induction period (IP), which is a measure of the oil's resistance to oxidation, revealed that the temperature and specific surface area are the major parameters that affect the oxidation process. The Arrhenius plot in the range of 80-150 C has shown that the overall activation energy of the oxidation process for three freshly processed oils lies within the range of 21-22 kcal/mole. The rate of oxidation at 150 C is directly proportional to the specific surface area of an oil, suggesting that the rate of oxygen diffusion determines reaction rates at this temperature. A coefficient of variation of the IP better than 2% was found in a routine experiment (10 mg sample, 150 C, 60 ml/min air flow rate, aluminum pan) for typical oils which had an IP range of 25-31 rain.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reaction conditions for measuring oxidative stability of oils by thermogravimetric analysis

Mikula¹,

Khayat²

1985

J Americ Oil Chem Soc

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“…Generally, the cosmetic formulations containing jojoba oil have superior stability toward oxidation than other lipids used for this purpose. A comparative study of the relative oxidation stability of jojoba oil, sperm whale oil, carnauba wax esters, Limnanthes douglassi wax esters, and behenyl arachidate revealed that jojoba oil has high oxidative stability comparing all other oils [ 43 ]. Kampf conducted an in-depth study of the accelerated oxidation of crude jojoba oil and bleached and stripped oils.…”

Section: Chemical Properties Of the Oilmentioning

confidence: 99%

Jojoba Oil: An Updated Comprehensive Review on Chemistry, Pharmaceutical Uses, and Toxicity

Gad

Roberts²,

Hamzi³

et al. 2021

Polymers

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Jojoba is a widely used medicinal plant that is cultivated worldwide. Its seeds and oil have a long history of use in folklore to treat various ailments, such as skin and scalp disorders, superficial wounds, sore throat, obesity, and cancer; for improvement of liver functions, enhancement of immunity, and promotion of hair growth. Extensive studies on Jojoba oil showed a wide range of pharmacological applications, including antioxidant, anti-acne and antipsoriasis, anti-inflammatory, antifungal, antipyretic, analgesic, antimicrobial, and anti-hyperglycemia activities. In addition, Jojoba oil is widely used in the pharmaceutical industry, especially in cosmetics for topical, transdermal, and parenteral preparations. Jojoba oil also holds value in the industry as an anti-rodent, insecticides, lubricant, surfactant, and a source for the production of bioenergy. Jojoba oil is considered among the top-ranked oils due to its wax, which constitutes about 98% (mainly wax esters, few free fatty acids, alcohols, and hydrocarbons). In addition, sterols and vitamins with few triglyceride esters, flavonoids, phenolic and cyanogenic compounds are also present. The present review represents an updated literature survey about the chemical composition of jojoba oil, its physical properties, pharmacological activities, pharmaceutical and industrial applications, and toxicity.

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“…They are formed by the esterification of a fatty alcohol to a fatty acid (Patel et al, 2001). Dependent on the fatty acid and fatty alcohol moieties, WE have diverse physicochemical properties including melting temperature and oxidation stability (Hagemann & Rothfus, 1979;Patel et al, 2001). Given their diverse properties, WE occur in organisms distributed over the whole tree of life fulfilling different functions.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Acyltransferases in Neutral Lipid Synthesis

Vollheyde¹

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Wax ester (WE) are neutral lipids, which consist of a fatty acid and a fatty alcohol moiety connected by an ester bond. WE are synthesized via two reactions from acyl-coenzyme A (CoA)/acyl carrier protein (ACP) substrates. In a first step, fatty acyl reductases (FAR) reduce acyl-CoA/ACP to form fatty alcohols. In the second step, fatty alcohols are esterified to another acyl-CoA/ACP by wax synthases (WS) to yield WE. Reflecting the diversity of acyl-chain substrates, a huge variety of WE exist in nature. Dependent on the chain length and further modifications such as desaturation of the acid and alcohol moieties, WE have diverse physicochemical properties, supporting their various functions in nature. WE may be depositedIn the third project, the effect of cellular WE biosynthesis location was studied and a change in localization was established as a suitable tool to alter substrate availability in WE producing plants. Expression of different constructs consisting of FAR, WSD2 or WSD5 from Marinobacter aquaeolei with and without plastidial localization tag in A. thaliana seeds resulted in the formation of shorter and more saturated WE in plastids compared to cytosolic WE synthesis.

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Oxidative stability of wax esters by thermogravimetric analysis

Cited by 12 publications

References 6 publications

Reaction conditions for measuring oxidative stability of oils by thermogravimetric analysis

Reaction conditions for measuring oxidative stability of oils by thermogravimetric analysis

Jojoba Oil: An Updated Comprehensive Review on Chemistry, Pharmaceutical Uses, and Toxicity

Characterization of Acyltransferases in Neutral Lipid Synthesis

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