Lipids and minerals in spelt (Triticum aestivum ssp. spelta) and common wheat (T. aestivum ssp. vulgare) : chemical and nutritional distinction between both cereals
(2004)
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- Spelt (Triticum aestivum ssp. spelta) and common wheat (Triticum aestivum ssp. vulgare) are closely related cereals that share their breadmaking character and the same ploidy level. Despite these similarities, both cereals are morphologically different, in particular, spelt kernels are hulled and wheat's are free-threshing, allowing their distinction before milling. Moreover, spelt is regarded as bringing a higher health benefit than wheat since Saint Hildegarde's treaty of medicine (12th century). However, health claims attributed to spelt are not substantiated by scientific evidence, as described in the literature review of this study. Adulteration of spelt products is another issue related to this cereal. Indeed, spelt's low yield, together with losses due to dehulling, partly account for its products being more expensive and prone to adulteration. Authentication of spelt is therefore compulsory. The above observations were the starting point of this research project, which aimed at two major objectives: first, to elucidate the basis of spelt's so-called nutritional benefit; second, to propose chemical tools in an attempt to authenticate spelt flours. Preliminary infrared spectroscopy results revealed that the study of lipids would be worthwhile. Therefore, lipid content and fatty acid profile of spelt and wheat wholemeal were determined. Spelt differs from wheat by a higher free lipid, total lipid and unsaturated fatty acid contents and spelt's higher oleate/palmitate ratio allows a classification of both cereals in two distinct, non-overlapping groups. In addition, the oleate/palmitate ratio may bring a substantial contribution in the setting of authentication procedures. In contrast, phytosterol analysis does not show any qualitative or quantitative difference between both cereals, thus supporting the fact that sterols are not implicated in spelt's nutritional benefit and that they cannot contribute to authenticate spelt products. Regarding minerals, Fe, Zn, Cu and Mg contents are higher in spelt than wheat. Although P content is also higher in spelt, phytic acid level is lower after 4-week storage. This may be due to a more intense endogenous phytase activity in spelt, in parallel with a possibly higher lipase activity, already suggested by infrared spectroscopy measurements. When these observations on lipids, minerals, and proteins (spelt has a higher protein content than wheat, but a similar gluten quality) are put together, they suggest that aleurone layer is a specific source of these nutrients in spelt. Such a view is also supported by the fact that tocopherol (a marker of germ) level is similar in spelt and wheat. In conclusion, this research indicates that spelt nutritional benefit over wheat could be related to minerals and, to a lesser extent, to unsaturated fatty acids. According to our results, the structure and/or metabolism of spelt's aleurone layer could be a major differentiating factor between spelt and wheat. On this basis, new chemical tools are proposed to distinguish both cereals after milling.
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Ruibal-Mendieta, N. L. (2004). Lipids and minerals in spelt (Triticum aestivum ssp. spelta) and common wheat (T. aestivum ssp. vulgare) : chemical and nutritional distinction between both cereals. https://hdl.handle.net/2078.5/97993