Wax analysis of vegetable oils using liquid chromatography on a double‐adsorbent layer of silica gel and silver nitrate‐impregnated silica gel

Abstract

A chromatographic method is described to measure the crystallizable wax content of crude and refined sunflower oil. It can also be applied to any other vegetable oil. The preparative liquid chromatography step on a glass column containing a silica gel adsorbent superimposed upon a silver nitrate-impregnated silica gel support is used to isolate a wax fraction which is then analyzed by gas chromatography. The recovered wax fraction contains, in addition to the crystallizable waxes, hydrocarbons and other compounds with gas chromatographic retention times corresponding to waxes with chain lengths C 34 -C 42 . These compounds are short-chain saturated waxes in fruit oils, such as grapeseed and pomace. In seed oils such as sunflower, soybean or peanut, the compounds initially referred to as "soluble esters" are identified as monounsaturated waxes, esters of long-chain saturated fatty acids, and a monounsaturated alcohol, mainly eicosenoic alcohol. Such waxes are absent from corn or rice bran oils.Paper no. J9705 in JAOCS 78, 401-410 (April 2001). FIG. 3.Chromatogram from GC-MSD5972 of the silylated methyl esters of the c. waxes (A) and the soluble esters (B) of sunflower oil. See Figure 1 for abbreviation. In Ansil notation, A = alcohol, n = chain length, and sil = silylation.

A process for the preparation of food‐grade rice bran wax and the determination of its composition

“…The percentage compositions of WE in purified RBW samples are shown in Table 3. The results in Table 3 are similar to the reported WE composition of crude RBO (24), which is a mixture of C 44 -C 62 WE, with C 52 WE being the predominant one. The finding of a high yield of C 48 -C 64 esters (>93%) in RBW is significant and has not been reported in other vegetable oils.…”

“…However, results on the composition of RBW have been controversial. Iwama and Maruta (6) fractionated RBW into hard wax (38.5%) and soft wax (11.2%) and found the composition of hard wax to be a mixture of esters of C 22 , C 24 , and C 34 FA and C 18 to C 34 fatty alcohols (FAL). Yoon and Rhee (7) reported the presence of a substantial amount of dark brown resin-like matter in both soft and hard wax and only C 22 to C 30 FAL and C 16 to C 26 FA.…”

Peanut oil: Compositional data

“…These soluble esters are monounsaturated waxes with the same fragment 278 in their mass spectrum as in sunflower and soybean oils [56].…”

Lack of Effect of Sugar Cane and Sunflower Seed Policosanols on Plasma Cholesterol in Rabbits

“…Octacosanol (C28) is reportedly the main active compound and differs in concentration between sources. For example sugar cane varieties, wheat germ and potato pulp contain 50 -80% [2][3][4]33], while sunflower wax contains ϳ13% [34] octacosanol. The lack of change in TC and non-HDL cholesterol (LDL) with SFP treatment in the present study may be explained by the low level of octacosanol in SFP, if this fatty alcohol is the mediator of the purported hypocholesterolemic effect however, this does not explain the lack of effect seen in the present study with SCP which contains 65% octacosanol, nor does it provide an explanation for the lack of change or difference between varieties in other studies using wheat germ or other varieties of SCP [2,24,28].…”