The flavor problem of soybean oil. VII. Effect of trace metals

Evans, C. D.; Schwab, A. W.; Moser, Helen A.; Hawley, J. E.; Melvin, Eugene H.

doi:10.1007/bf02612095

Cited by 54 publications

(13 citation statements)

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“…This is probably due to the action of the phosphoric acid in reacting with trace metal compounds, and also with the calcium and magnesium salts of phosphatidic acids, so modifying these compounds as to facilitate their removal (Swern, 1964;Hvolby, 1971;Gutfinger & Letan, 1978;List et al, 1978a;List, Mounts & Henkin, 1978b). However, the level of phosphorus, and especially iron, in phosphoric acid degummed and bleached physically refined soyabean oil at 240°C for 2 hr are lower than that of phosphoric degummed physically refined oil under similar conditions, as a result of the bleaching stage (Evans et al, 1951(Evans et al, , 1952List, Mount & Henkin, 1978~). The levels of phosphorus and trace metals determined in the phosphoric acid-degummed and bleached and then physically refined oil are roughly in line with the normal range of good quality finished oils (Pryde, 1980).…”

Section: Resultsmentioning

confidence: 90%

Quality characteristics of physically refined soyabean oil: effects of pre‐treatment and processing time and temperature

Jawad

Kochhar

Hudson

1983

Int J of Food Sci Tech

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Conventional alkali refining of edible oils is being replaced progressively by physical refining, which offers improved yields, reduced processing times and few by-product problems. The variables involved in physical refiningpre-treatment, processing time and processing temperature-have been studied on a laboratory scale for the refining of soyabean oil, and related to the quality characteristics of the refined products. The best results are obtained with phosphoric acid degummed, partially bleached oil processed at up to 250°C for not more than 2 hr. Higher temperatures and longer times lead to quality defects such as loss of stability, increased viscosity, darkening and chemical changes reflected in reduction of iodine value and increase in free fatty acids.

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Section: Resultsmentioning

confidence: 90%

Quality characteristics of physically refined soyabean oil: effects of pre‐treatment and processing time and temperature

Jawad

Kochhar

Hudson

1983

Int J of Food Sci Tech

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“…Investigations of the effects of trace metals and oxygen level on lipid oxidation in oil have previously been conducted separately (1,(8)(9)(10)(11). However, no investigations of the effect of copper in combination with various oxygen concentrations in pure oil have been reported.…”

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confidence: 95%

“…Karahadian and Lindsay (10) reported that 20 ppm of copper (II) ions had a strong pro-oxidative effect in fish oil. Evans et al (1) found that addition of 0.003 ppm copper to soybean oil did not give a lower flavor score after 4 d of storage at 60°C, compared to samples without added copper. However, addition of 0.03 ppm had a measurable pro-oxidative effect after the same storage time.…”

mentioning

confidence: 97%

“…One important factor to influence the rate of oxidation is the concentration of metals in the oil. Copper and iron are the most active metals for inducing oxidation in oils (1)(2)(3); however, copper is reported most pro-oxidative (1,3). To ensure oxidative stability, it is recommended that the copper content be kept below 0.02 ppm in refined, bleached, and deodorized soybean oil (4).…”

mentioning

confidence: 99%

“…Lipid oxidation is one of the major causes of quality losses in oils during storage (1). One important factor to influence the rate of oxidation is the concentration of metals in the oil.…”

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confidence: 99%

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Influence of oxygen and copper concentration on lipid oxidation in rapeseed oil

Andersson

Lingnert

1998

J Americ Oil Chem Soc

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The influence of oxygen concentration and copper on lipid oxidation in rapeseed oil during storage at 40°C was investigated. The oil was stored in air, or with 1.1%, 0.17%, or 0.04% oxygen in the headspace, and 70 or 0.07 ppm copper was added. Volatile oxidation products and oxygen consumption were monitored. Addition of 70 ppm copper to the sample in air resulted in a 70-fold higher hexanal concentration after 35 d of storage, compared to the sample without added copper. The addition of 0.07 ppm copper to the sample stored in air gave a doubled hexanal concentration, compared to the sample without copper, after 35 d of storage. For the samples with 70 ppm copper at 0.17% and 0.04% oxygen, all oxygen was consumed after 7 d of storage. The results show the importance of minimizing the oxygen available for oxidation, especially when pro-oxidants are present. In the sample with 70 ppm added copper, in air, the hexanal increase was 65 times larger than for the same sample in 0.04% oxygen. A comparison of the effect of oxygen or copper on oxidation shows that the addition of 70 ppm copper to the 0.04% oxygen sample gave the same increase in hexanal content as an oxygen increase to 0.17%. JAOCS 75, 1041-1046 (1998). FIG. 6. Hexanal concentration (ng/L HS) of the samples without copper in air and with 0.07 ppm copper in air, in 1.1% O 2 , in 0.17% O 2 , and in 0.04% O 2 . Error bars indicate standard deviations from three measurements. See Figure 5 for abbreviation. FIG. 7. 2-Hexenal concentration (ng/L HS) of the samples without and with 70 ppm copper at four oxygen levels as in Figure 5. Error bars indicate standard deviations from three measurements. See Figure 5 for abbreviation.

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Bleaching

Taylor¹

2005

Bailey's Industrial Oil and Fat Products

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Traditionally, bleaching refers to that process by which colored pigments are removed from fats and oils by adsorption onto bleaching earth. Of course, certain noncolored constituents are also removed as well. In fact, the removal of particular colored and noncolored constituents during bleaching is necessary if high‐quality oil is to be produced. In this chapter, the idea of bleaching as primarily an adsorptive purification process is developed. Four key aspects are addressed: (1) the use of adsorptive purification agents, (2) the adsorptive removal of targeted constituents, (3) practical means and methods for achieving optimal efficiency and efficacy from the bleaching process, and (4) approaches for dealing with spent adsorbents. The properties and preparation of the main adsorptive purification agents used in the bleaching process (activated carbon, bleaching earth, and silica hydrogel) are discussed; differences between acid‐activated and natural bleaching earths and the types of clays used in their manufacture are delineated. The effects of various trace constituents (and contaminants) on oil quality, and the nature and specificity of their interaction with surface‐active (adsorption) sites are described. In particular, the control that noncolored constituents (phospholipids, soaps, free fatty acids, peroxides) exert over the adsorption of colored pigments (carotenoids, chlorophyll, pheophytins) is elucidated. Optimal bleaching practices and filtration conditions (“press bleach effect”) as well as processes and equipment for achieving maximum efficiency from the bleaching process are described. Finally, various tactics regarding spent filter cake, including utilization/disposal, best methods to recover retained oils, and control over smoldering, are examined.

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The flavor problem of soybean oil. VII. Effect of trace metals

Cited by 54 publications

References 5 publications

Quality characteristics of physically refined soyabean oil: effects of pre‐treatment and processing time and temperature

Quality characteristics of physically refined soyabean oil: effects of pre‐treatment and processing time and temperature

Influence of oxygen and copper concentration on lipid oxidation in rapeseed oil

Bleaching

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