21-3 |
Fructooligosaccharides in yogurt: Functional and microbiological properties |
R. W. HUTKINS, S. L. Cuppett, H. K. Voss, and H. Kaplan. Dept. of Food Science & Technology, Univ. of Nebraska, Lincoln, 338 Food Industry Complex, Lincoln, NE 68583-0919 Prebiotic oligosaccharides, especially fructooligosaccharides (FOS), have attracted much interest due to their ability to influence the bacterial populations in the gastrointestinal tract and to provide positive health benefits to the human or animal host. However, until recently, the metabolic basis for how FOS is metabolized and fermented by lactic acid bacteria has not been studied. In addition, incorporation of oligosaccharides in foods such as yogurt may be expected to influence various functional properties, but few studies have examined these effects. Research in our laboratory has focused on understanding the molecular basis for FOS metabolism and on how FOS and other prebiotics affect functional and sensory properties in yogurt. Biochemical and genetic studies have shown that in Lactobacillus paracasei 1195, a FOS-fermenting lactic acid bacterium, FOS metabolism requires the presence of a FOS-specific transport system. The transport system is ATP-dependent and is induced during growth on FOS or inulin. The FOS that accumulates inside the cell is hydrolyzed by an intracellular b-fructofuranosidase. Although this pathway of FOS metabolism occurs, in vitro, it is unlikely that FOS is utilized during yogurt manufacture, since most yogurt cultures are unable to ferment FOS. In other experiments, we have evaluated the effect of inulin and two different commercial FOS products on the physical, chemical, and sensory properties of nonfat yogurt. Yogurts made with varying levels of FOS or inulin had significantly less syneresis than control yogurt; the higher the FOS or inulin, the greater was the water-holding capacity. However, a reverse trend was observed for FOS and firmness. Sensory analysis revealed that FOS addition reduced the perception of sourness and increased sweetness. At high levels, yogurt containing FOS was smoother and more acceptable. These results revealed that the functionality of FOS and inulin in nonfat yogurt are similar and that both provide acceptable organoleptic properties.
Session 21, Health benefits and functionality of fructooligosaccharides
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