DETERMINATION OF OLIGOSACCHARIDES IN PROTEIN-RICH FEEDSTUFFS BY GAS-LIQUID-CHROMATOGRAPHY AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Gas-Liquid chromatography (GLC) and high-performance liquid chromatography (HPLC) methods were developed for quantitative analysis of oligosaccharides in protein-rich feedstuffs. A total of 18 meal or cake samples derived from soybean, cotton, sunflower, and rapeseed and two samples of field peas were studied. the most suitable extraction media was determined by using water or 50% and 80% (v/v) of alcohol (methanol or ethanol) on meal samples of soybean and cottonseed and a feed mixture (soybean meal/barley, 1:1 w/w). Excellent agreement was found between the HPLC and GLC results for sucrose and raffinose content, while the average value for stachyose was 0.4% (absolute units) lower with GLC compared to HPLC. Sucrose was the main sugar found in the protein-rich feedstuffs (3.00-7.59% of dry weight) but only a minor sugar in cottonseed (0.96-1.14%). Among the raffinose oligosaccharides, stachyose was predominant in soybean (3.94-4.62%) and rapeseed (0.94-1.52%), verbascose in field peas (1.69-2.90%), and raffinose in cottonseed (3.10-4.52%) and sunflower (1.53-2.48%). On the basis of the overall precision and the consistently higher value of stachyose obtained, HPLC should be the method of choice for the type of feed materials described here.