- 背景資料
果糖的聚合物(Fructan)被定義為含有一個或多個fructosyl- fructose linkage，並以此鍵結為主體之物質，根據聚合物的大小和具體特徵(specifically characterised)可區分為低聚物(oligomer)和聚合物(polymer)。果糖的聚合物(Fructan)根據分子結構和分子量的不同，可分成三種:
1️⃣菊糖(inulin)類型:主要以β（2→1）糖苷鍵鍵結
2️⃣果聚糖(levan)類型:主要以β（2→6）糖苷鍵鍵結
3️⃣禾本科(graminan-type)(支鏈)類型:同時具有大量的β（2→1）和β（2→6）糖苷鍵鍵結
商業上果聚糖(levan)的量產，以細菌生產為主，利用蔗糖為碳原藉由細菌的分解酵素(levansucrase)產生果聚糖。果聚糖具有低熱量、低黏度和高水溶性的特性，在食品工業上可當作乳化劑、成型劑、穩定劑、增稠劑及風味攜帶劑等。此外，根據相關的動物研究數據顯示，果聚糖具有抗腫瘤的能力、降低血液中膽固醇的濃度，作為益生素(元)(Prebiotics)...等保健功效。 - A. Fructan Extraction
Samples containing 0-12% fructan
1. Accurately weigh 1.0 g of sample into a Pyrex screw cap culture tubes (25 x 150 mm) and add 25 mL of distilled water. Loosely cap the tube. Place the tube into a boiling water bath and heat for 5 min, tighten the tube cap and vigorously mix the contents. Heat the tube contents for a further 5 min and mix the contents.
2. Allow the solution to cool to room temperature and then quantitatively transfer it to a 50 mL volumetric flask and adjust to volume with distilled water. Mix the contents thoroughly.
3. If the sample contains significant quantities of D-glucose, D-fructose and/or sucrose (say 30-60% w/w), aliquots should be diluted a further 5-fold or 10-fold before assay. Mix the solution thoroughly and repeat the assay. For samples containing high levels of D-glucose, D-fructose, sucrose and/or maltose, the K-FRUC assay kit and protocol should by followed.
Samples containing 12-100% fructan (or fructan plus sugars)
1. Accurately weigh approx. 1.0 g of sample into a dry pyrex flask (500 mL capacity) and add 300 mL of hot distilled water. Place the flask in a boiling watrer bath and heat (at ~ 100°C) for 15 min (i.e. until the sample is completely dispersed).
2. Allow the solution to cool to room temperature and then quantitatively transfer it to a 500 mL volumetric flask and adjust the volume to the mark with distilled water. Mix the contents thoroughly.
- B. Further treatment of samples
1. Transfer ~ 2.0 mL of samples solutions into 2.0 mL microfuge tubes and centrifuge at 13,000 rpm for 5 min. Alternatively, filter an aliquot of the solution through a Whatman GF/A glass fibre filter paper. Analyse the sample soon after centrifugation or filtering. If this solution is stored for several hours at low temperature before analysis, the fructan may tend to precipitate from solution. In such cases, the solution should be reheated to ~ 80°C and allowed to cool to room temperature before samples are removed for centrifugation and analysis.
- C. Hydrolysis of Sucrose and low DP Maltosaccharides
1. Accurately dispense 0.2 mL aliquots of solutions to be analysed (containing approx. 0.1 to 2.0 mg/mL of fructan) into the bottom of glass test-tubes (16 x 100 mm).
2. Add 0.2 mL of solution 3 (sucrase/maltase mixture) to each tube and incubate the tubes at 30°C for 30 min.
3. Add 0.5 mL of buffer 2 (100 mM sodium acetate buffer, pH 4.5) to each tube with vigorous stirring on a vortex mixer. This is termed Solution A.
- D. Hydrolysis of Fructan
1. Accurately and carefully dispense 0.2 mL aliquots of Solution A (in duplicate) to the bottom of plastic spectrophotometer cuvettes (3 mL volume, 1 cm light path).
2. Add 0.1 mL of solution 4 (fructanase solution) to the bottom of one cuvette, and 0.1 mL of buffer 2 (100 mM sodium acetate buffer, pH 4.5) to the second cuvette. Mix the contents thoroughly and cover the cuvette with Parafilm®.
3. Incubate the covered cuvettes at 40°C for 30 min in a dry hotblock heater to effect complete hydrolysis of fructan to fructose and glucose (in the cuvettes containing the fructanase enzyme).
- E. Measurement of fructan
PROCEDURE:
商品特色
商品規格
- 商品規格(50個檢測反應)
Bottle 1:
Buffer (25 mL, pH 7.6) plus sodium azide (0.02% w/v) as a preservative.
Stable for > 2 years at 4°C.
Bottle 2:
NADP+ plus ATP.
Stable for > 5 years below -10°C.
Bottle 3:
Sucrase/maltase, lyophilised powder plus BSA.
Stable for > 5 years abelow -10°C.
Bottle 4:
Fructanase (recombinant, affinity purified exo-inulinase and endo-inulinase), lyophilised powder.
Stable for > 5 years below -10°C.
Bottle 5:
Hexokinase plus glucose-6-phosphate dehydrogenase and PGI suspension, 2.25 mL.
Stable for > 4 years at 4°C.
Bottle 6:
D-Fructose standard solution (0.5 mg/mL) in 0.2% (w/v) benzoic acid.
Stable for > 4 years; store sealed at room temperature.
Bottle 7:
Fructan control flour. Dahlia fructan freeze-dried in the presence of α-cellulose.
Stable for > 5 years; store sealed at room temperature.
