Measurement of inulin and inulin-degrading enzymes.
McCleary, B. V. (1998). “Proceedings of the Seventh Seminar on Inulin”, (A. Fuchs and A. Van Laere, Eds.), European Fructan Association, pp. 36-45.
A non-instrumental method for the measurement of fructan is described. The method simplifies fructan analysis, is easy to perform, uses standard laboratory equipment, and is accurate, reproducible and specific. The procedure employs highly purified and specific enzymes to hydrolyse sucrose, starch and fructans (inulins and graminan).
Fructans - Analytical approaches to a fibre that ferments.
Blakeney, A. B., McCleary, B. V. & Mugford, D. C. (1997). Chemistry in Australia, 17-19.
Fructans are defined as any compound where one or more fructosyl-fructose linkages constitute a majority of the linkages. This refers to polymeric material as well as oligomers as small as the diasaccharide inulobiose. Material included in this definition may or may not contain attached glucose. The terms oligomer and polymer are used by fructan researchers to distinguish between materials that can be specifically characterised and those that can not. Fructans are widely distributed in the plant kingdom. They are present in monocotyledons, dicotyledons and in green algae.
Measurement of inulin and oligofructan.
McCleary, B. V. & Blakeney, A. B. (1999). Cereal Foods World, 44(6), 398-406.
Fructans are defined as any compound in which one or more fructosyl-fructose linkages constitute a majority of the linkages (1). This refers to polymeric material as well as to oligomers as small as disaccharide inulobiose. Fructans are widely distributed in the plant kingdom. They are present in monocotyledons, dicotyledons, and green algae. Fructans differ in molecular structure and in molecular weight. They may be classified into three main types, the inulin type, the levan (previously called phlein) type, and the graminan type (2). The inulin group consists of material that has mostly of exclusively the (2→1) fructosly-fructose linkage. Levan is material that contains mostly or exclusively the (2→6) fructosyl-fructose linkage. The graminan (or branched) type has both (2→1) and (2→6) fructosly-fructose linkages in significant amounts (e.g. graminan from Gramineae). The distribution of fructans in nature, and the production of fructooligosaccharides, such as neosugar, using fructosyltransferase, has been reviewed in a monograph (3). In the context of this article and the analytical procedure described, the term fructan relates only to inulin and graminan. The current analytical procedure has not been evaluated on levan.
Measurement of total fructan in foods by enzymatic/spectrophotometric method: Collaborative study.
McCleary, B. V., Murphy, A. & Mugford, D. C. (2000). Journal of AOAC International, 83(2), 356-364.
An AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measuring oligofructans and fructan polysaccharide (inulins) in mixed materials and food products. The sample is extracted with hot water, and an aliquot is treated with a mixture of sucrase (a specific sucrose-degrading enzyme), α-amylase, pullulanase, and maltase to hydrolyze sucrose to glucose and fructose, and starch to glucose. These reducing sugars are then reduced to sugar alcohols by treatment with alkaline borohydride solution. The solution is neutralized, and excess borohydride is removed with dilute acetic acid. The fructan is hydrolyzed to fructose and glucose using a mixture of purified exo- and endo-inulinanases (fructanase mixture). The reducing sugars produced (fructose and glucose) are measured with a spectrophotometer after reaction with para-hydroxybenzoic acid hydrazide. The samples analyzed included pure fructan, chocolate, low-fat spread, milk powder, vitamin tablets, onion powder, Jerusalem artichoke flour, wheat stalks, and a sucrose/cellulose control flour. Repeatability relative standard deviations ranged from 2.3 to 7.3%; reproducibility relative standard deviations ranged from 5.0 to 10.8%.
Inhibition of Streptococcus mutans biofilm formation by Streptococcus salivarius FruA.
Ogawa, A., Furukawa, S., Fujita, S., Mitobe, J., Kawarai, T., Narisawa, N., Sekizuka, T., Kuroda, M., Ochiai, K., Ogihara, H., Kosono, S., Yoneda, S., Watanabe, H., Morinaga, Y., Uematsu, H. & Senpuku, H. (2011). Applied and Environmental Microbiology, 77(5), 1572-1580.
The oral microbial flora consists of many beneficial species of bacteria that are associated with a healthy condition and control the progression of oral disease. Cooperative interactions between oral streptococci and the pathogens play important roles in the development of dental biofilms in the oral cavity. To determine the roles of oral streptococci in multispecies biofilm development and the effects of the streptococci in biofilm formation, the active substances inhibiting Streptococcus mutans biofilm formation were purified from Streptococcus salivarius ATCC 9759 and HT9R culture supernatants using ion exchange and gel filtration chromatography. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry analysis was performed, and the results were compared to databases. The S. salivarius HT9R genome sequence was determined and used to indentify candidate proteins for inhibition. The candidates inhibiting biofilms were identified as S. salivarius fructosyltransferase (FTF) and exo-beta-D-fructosidase (FruA). The activity of the inhibitors was elevated in the presence of sucrose, and the inhibitory effects were dependent on the sucrose concentration in the biofilm formation assay medium. Purified and commercial FruA from Aspergillus niger (31.6% identity and 59.6% similarity to the amino acid sequence of FruA from S. salivarius HT9R) completely inhibited S. mutans GS-5 biofilm formation on saliva-coated polystyrene and hydroxyapatite surfaces. Inhibition was induced by decreasing polysaccharide production, which is dependent on sucrose digestion rather than fructan digestion. The data indicate that S. salivarius produces large quantities of FruA and that FruA alone may play an important role in multispecies microbial interactions for sucrose-dependent biofilm formation in the oral cavity.
Enzymatic Hydrolysis of Agavins to Generate Branched Fructooligosaccharides (a-FOS).
Huazano-García, A. & López, M. G. (2017). Applied Biochemistry and Biotechnology, 1-10.
Recently, agavins (branched neo-fructans) of short degree of polymerization have shown beneficial effects on the health of both healthy and overweight individuals. Therefore, the aim of the present work was to investigate the potential use of Agave angustifolia agavins on the generation of branched fructooligosacharides (a-FOS). A. angustifolia agavins were hydrolyzed using exo-, endo-inulinase, and a mixture of both (25 and 75%, respectively). Exo- and the inulinase mixture degraded quickly the agavins in relation to endo-inulinase treatment. Only endo-inulinase and the inulinase mixture generated a-FOS formation. Endo-inulinase degraded 31% of agavins, yielding approximately 20% of a-FOS after 48 h, whereas the inulinase mixture hydrolyzed 33% of agavins in just 90 min, but only yielded 10% of a-FOS. These results suggest that agave plants could be an abundant raw material for a-FOS production, which might have a huge prebiotic potential as new branched fructooligosaccharides with many applications in the alimentary and pharmaceutical industry.
Saccharomyces cerevisiae and Kluyveromyces marxianus cocultures allow reduction of fermentable oligo-, di-, and monosaccharides and polyols Levels in whole wheat bread.
Struyf, N., Laurent, J., Verspreet, J., Verstrepen, K. J. & Courtin, C. M. (2017). Journal of Agricultural and Food Chemistry, In Press.
Fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) are small molecules that are poorly absorbed in the small intestine and rapidly fermented in the large intestine. There is evidence that a diet low in FODMAPs reduces abdominal symptoms in approximately 70% of the patients suffering from irritable bowel syndrome. Wheat contains relatively high fructan levels and is therefore a major source of FODMAPs in our diet. In this study, a yeast-based strategy was developed to reduce FODMAP levels in (whole wheat) bread. Fermentation of dough with an inulinase-secreting Kluyveromyces marxianus strain allowed to reduce fructan levels in the final product by more than 90%, while only 56% reduction was achieved when a control Saccharomyces cerevisiae strain was used. To ensure sufficient CO2 production, cocultures of S. cerevisiae and K. marxianus were prepared. Bread prepared with a coculture of K. marxianus and S. cerevisiae had fructan levels ≤0.2% dm, and a loaf volume comparable with that of control bread. Therefore, this approach is suitable to effectively reduce FODMAP levels in bread.