- 背景資料
乳果糖(Lactulose)又稱乳酮糖，其組成是由果糖和半乳糖以β-1,4醣苷鍵鍵結而成，為一種人體不可吸收的糖類。因乳果糖在人體不可被吸收、且可促使腸道水分增加、及刺激腸道蠕動之特性，現今已被當作瀉劑(藥品)使用。
此外，乳果糖經研究證實，屬於益生元(prebiotic)物質的一種。因可做為部分乳酸菌的增殖因子，並可使<奶粉哺餵的嬰兒腸道菌>與<母乳哺餵的嬰兒腸道菌>相近，故衛生福利部於107年1月9日公告修正食品添加物「乳酮糖」之使用食品範圍及限量:
1️⃣本品可於特殊營養食品中視實際需要適量使用
2️⃣本品可用於標示有每日食用限量之食品，每日食用量，其乳酮糖總含量不得高於10g
3️⃣使用限制➡️限於補充食品中不足之營養素時使用
乳果糖普遍被認為是非自然生合成之糖類，其主要存在於牛乳或乳製品...等食品當中，牛乳中的糖類以乳糖為主，大多數的牛乳在包裝成產品之前，因食品安全或延長保存期限..等目的，皆會先經過殺菌或滅菌的步驟(例如:高溫短時間殺菌HTST、超高溫瞬間滅菌UHT)。乳糖在加熱的過程中，較容易發生異構化(isomerization)作用，進而轉變成乳果糖<異構物質isomer>。此外，隨著牛乳熱處理的程度增加，乳糖異構化後所形成的乳果糖，其生成量也會隨之增加，因此在近年來的研究當中，乳果糖也被當作牛乳受熱程度的指標物質之一。
- STANDARD ASSAY PROCEDURE (Rapid Method):
A. SAMPLE PREPARATION (Liquid Milk):
1. To a 1.5 mL polypropylene microfuge tube, add the following with mixing after each addition:
2. To a 1.5 mL polypropylene screw cap microfuge tube, add:
* These components should be prepared as described on page 6.
B. ENZYMATIC DETERMINATION REACTION:
- CONSIDERATIONS: (Rapid Method)
A. MODIFIED SAMPLE PREPARATION:
Milk Powder:
Accurately weigh 5 g of milk powder into a 100 mL beaker. Add 40 mL of distilled water and stir on a magnetic stirrer until fully dissolved. Transfer to a 50 mL volumetric flask, make to volume with distilled water and mix thoroughly. Continue from step 1 of Sample Preparation (Liquid Milk) (section A, page 7).
Evaporated Milk:
Pipette 2 mL of evaporated milk into a 50 mL volumetric flask, make to volume (50 mL) with distilled water and mix thoroughly. Continue from step 1 of Sample Preparation (Liquid Milk) (section A, page 7). In this instance an additional dilution factor (F) of 25 should be used for the calculation of lactulose content (see Calculation, page 9).
B. TROUBLESHOOTING:
Samples with (A2-A1) above 0.300 or (A3-A2) above 1.500:
Recommendations for re-processing samples that have generated absorbance differences (A2-A1) above 0.300 or (A3-A2) above 1.500 when processed using the Standard Assay Procedure (section A and B, pages 7 and 8) are given in the table below. The suggested recommendations are dependent upon the combination of the two absorbance values generated:
商品特色
商品規格
- 商品規格 50 檢測反應
Bottle 1:
β-Galactosidase suspension (3 mL).
Stable for > 2 years at 4°C.
Bottle 2:
Glucose oxidase and catalase, lyophilised powder.
Stable for > 2 years below -10°C.
Bottle 3:
Buffer (6 mL, pH 7.6) plus sodium azide (0.02% w/v) as a preservative.
Stable for > 2 years at 4°C.
Bottle 4:
NADP+ plus ATP.
Stable for > 2 years at 4°C.
Bottle 5:
Hexokinase plus glucose-6-phosphate dehydrogenase suspension, 2.2 mL.
Stable for > 2 years at 4°C.
Bottle 6:
6-Phosphogluconate dehydrogenase suspension (2.2 mL).
Stable for > 2 years at 4°C.
Bottle 7:
Phosphoglucose isomerase suspension (2.2 mL).
Stable for > 2 years at 4°C.
Bottle 8:
Lactulose (0.1 mg/mL) plus D-fructose (0.05 mg/mL) standard solution (5 mL).
Stable for > 2 years; store sealed at 4°C.
