|JOHNSON, CASEY - North Dakota State University|
|THAVARAJAH, DIL - Clemson University|
|FENLASON, ABBY - North Dakota State University|
|THAVARAJAH, PUSHPARAJAH - North Dakota State University|
|AGRAWAL, SHIV KUMAR - International Center For Agricultural Research In The Dry Areas (ICARDA)|
Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2015
Publication Date: 8/17/2015
Citation: Johnson, C., Thavarajah, D., Fenlason, A., Thavarajah, P., Mcgee, R.J., Agrawal, S., Combs, G.F. 2015. A global survey of low-molecular weight carbohydrates in lentils. Journal of Food Composition and Analysis. 44:178-185.
Interpretive Summary: Lentil (Lens culinaris Medik.) is an ancient pulse crop, originating from the Mediterranean region and enduring as a staple food in Africa, Europe, South Asia, and Latin America. Varieties of lentil have been adapted for cultivation in diverse regions around the globe, including Asia, Africa, South America, North America, and Australia, enabling lentil production to meet the demands of a growing consumer base. Current world production is 4.4 Mt per annum, the majority of which comes from Canada, India, and Turkey (FAOSTAT, 2012). Lentil contains a wide array of low-molecular weight carbohydrates (LMWC), including mono- and di-saccharides, raffinose-family oligosaccharides (RFO), fructooligosaccharides (FOS), and sugar alcohols. Previous research has repeatedly shown that concentrations of these carbohydrates vary with genotype and growing environment. The unique profile of LMWC in lentil represents a repertoire of biochemical tools used by the plant for survival in diverse environments. For example, sucrose availability from the source tissues during water deficit decreases, acting as a signal to adjust seed development. In this way, the plant is able to distribute its resources to maximize its growth and reproduction in different environments. Moreover, many plant species produce RFO as a mechanism to enhance the desiccation and freezing tolerance of the seed. In addition to their roles in plant physiology, several LMWC, including FOS and RFO, have been extensively studied with respect to dietary interactions with the human gut microbiome and potential health benefits. These carbohydrates, often called ‘complex,’ ‘non-digestible,’ or ‘prebiotic’ carbohydrates, are not hydrolyzed by brush border enzymes in the small intestine. Microbes in the intestinal tract (especially colon) ferment the carbohydrates, producing short-chain fatty acids and profoundly affect the ecology of the large intestine and overall human health. These interactions are an important aspect of human health and nutrition, emphasizing the need to deepen our understanding of the expression of non-digestible carbohydrates in foods. Because LMWC concentrations in lentil can vary with growing environment, likely as a means of stress management and survival, it is conceivable that genotypes within a certain environment would use a similar strategy, or pattern, of carbohydrate expression relative to other environments. Recognizing such patterns would be useful in breeding lentils for new and existing environments. For example, lentil growers could target specific genetic material that is well-adapted to a particular environment (i.e., based on the average weather conditions of any locations). Identifying lentil cultivars and growing environments that result in relatively high concentrations of certain carbohydrates, such as prebiotics, could provide a niche for health-food marketing. Thus, the objectives in this study were to (1) determine the concentrations of LMWC in lentils grown in six different countries and (2) identify genotype and growing environments interactions with respect to LMWC concentrations.
Technical Abstract: Lentils contain a range of low-molecular weight carbohydrates (LMWC); however, they have not been well characterized. The objectives of this study were to (1) determine the concentrations of LMWC in lentils grown in different environments and (2) identify any genetic and environmental effects on those LMWC concentrations. We analyzed 335 samples from 10 locations throughout 6 countries using high performance liquid chromatography for sugar alcohols and various mono-, di-, and oligo-saccharides, including raffinose-family oligosaccharides (RFO) and fructooligosaccharides (FOS). Mean LMWC concentrations from each country varied widely: sorbitol, 1250-1824 mg/100 g; mannitol, 57-132 mg/100 g; galactinol, 46-89 mg/100 g; sucrose, 1750-2355 mg/100 g; raffinose + stachyose, 3314-4802 mg/100 g; verbascose, 1907-2453 mg/100 g; nystose, 8-450 mg/100 g; and kestose, from not detected to 244 mg/100 g. The concentrations of many of these LMWC varied with average temperature and precipitation of the region/country of origin. Significant genotype and genotype × location effects contributed to the variability in the concentrations of several LMWC, a feature that could prove useful in breeding lentils for novel agro-ecological environments and for consumer preference. The range of LMWC in lentil may contribute to its survival as a crop and its organoleptic and nutritional properties as a whole food.