Analysis of furanoid esters in soybean oil and the effect of variety and environment on furanoid ester content

Abstract

An improved method was developed to analyze the major furanoid esters in soybean oil. The method is based on urea fractionation of the methyl esters, silver ion chromatography, and gas chromatography of the furanoid concentrate. Activation of the soybean lipoxygenase decreased the amount of furanoid ester recovered from the oil, but the degumming of crude soybean oil and the choice of solvent used to extract soybean lipids caused no change in furanoid ester content. Fifty-six soybean varieties, representing a wide range in maturity group and geographical origin, were grown in Puerto Rico and used to determine the range of furanoid ester contents. Furanoid ester II ranged from 0.033-0.29 mg/g, and ester III ranged from 0.058-0.27 mg/g. The two major furanoid esters were positively correlated with each other and with maturity group. Growth environment as well as variety caused significant differences in furanoid content. JAOCS 74, 1099-1103 (1997). KEY WORDS:Analysis, effect of growth environment, effect of variety, furanoid fatty acids.Fatty acids containing a furan ring, or furanoid fatty acids, were first discovered by Morris et al. (1) in the seed oil of Exocarpus cupressiformis. More than 30 furanoid acids have been reported in a variety of animal and plant sources.The physiological role of these acids remains a matter of speculation. They may be involved in animal reproductive rhythms (2) and embryo development (3). Batna and Spitellar (4) suggest that they may act as antioxidants in plants. Furanoid acids inhibit lysyl oxidase and may be useful in the treatment of diseases that entail excess collagen and elastin deposition (5). Their biosynthetic pathway is not clear.Besides the seed oil of E. cupressiformis, furanoid esters have been found in algae (Chlorophyta sp.), mushroom (Agaricus bisporus), and yeast (Saccharomyces cerevisiae); they are also found in the roots and shoots of grasses (Poaceae sp.), clover (Trifolium pratense), dandelion (Taraxacum officinale), chive (Allium sativum), wheat (Triticum aestivum), rice (Oryza sativa), potato (Solanum tuberosum), cabbage (Brassica oleracea), orange (Citrus sinensis osbeck), lemon (Citrus limon), strawberries (Fragaria sp.), and birch leaves (Betula pendula) (6) as well as the latex of Hevea brasiliensis (7). Furanoid esters occur in greater amounts in the green parts of plants than in the stems, roots, and seeds.Three furanoid acids were identified in soybean oil by Guth and Grosch (8) and are shown in Figure 1. Guth and Grosch (8) reported that the three furanoid esters totaled 250-390 mg/kg in soybean oil, 70-120 mg/kg in wheat germ oil, 13-36 mg/kg in rapeseed oil, and 17-24 mg/kg in corn oil. Furanoid esters were absent in olive and sunflower oils. Analyses of the soybean cultivar Century and five soybean genotypes that lacked one or two of the three lipoxygenase isoenzymes revealed that their seed oils contained 190-225 mg/kg of furanoid ester II and 91-132 of ester III (9). The concentrations of furanoid esters were not correlated with lipoxygenase ...

Valuable furan fatty acids in soybeans and soy products

“…These amounts were low, but comparable with those of other lipophilic antioxidants like vitamin E [20]. Comparably high FuFA concentrations of 16-65 mg/100 g FAMEs were detected in soybeans [19,21]. Wu et al reported FuFA contents of 16-49 mg/100 g FAMEs (9D5 and 11D5) in soybeans harvested in autumn [19].…”

“…For instance, soybeans harvested in springtime were richer in FuFAs than soybeans harvested in autumn (e.g. 17 vs. 27 mg/100 g FAMEs for the same variety and growing site) [19]. Guth and Grosch found comparable values of 26-42 mg/100 g FAMEs in soybean oil extracted from soybeans in their laboratory [22].…”

“…Frequently, FuFA concentrations were determined after transesterification and expressed as contribution to 1 Institute of Food Chemistry (170b), University of Hohenheim, Garbenstr. 28, 70599 Stuttgart, Germany the total fatty acid methyl esters (FAMEs) [15,19]. These amounts were low, but comparable with those of other lipophilic antioxidants like vitamin E [20].…”

“…Comparably high FuFA concentrations of 16-65 mg/100 g FAMEs were detected in soybeans [19,21]. Wu et al reported FuFA contents of 16-49 mg/100 g FAMEs (9D5 and 11D5) in soybeans harvested in autumn [19]. By analysis of 56 soybean varieties grown in Puerto Rico, Wu et al outlined that the content of D-FuFAs was strongly affected by variety, environment, season and maturity [19].…”

“…Wu et al reported FuFA contents of 16-49 mg/100 g FAMEs (9D5 and 11D5) in soybeans harvested in autumn [19]. By analysis of 56 soybean varieties grown in Puerto Rico, Wu et al outlined that the content of D-FuFAs was strongly affected by variety, environment, season and maturity [19]. For instance, soybeans harvested in springtime were richer in FuFAs than soybeans harvested in autumn (e.g.…”