10-fiber Flashcards
what is AACC
American Association of Cereal Chemist (AACC) International,
what is dietary fiber according to AACC?
edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine.
what does dietary fiber include?
polysaccharides, oligosaccharides, lignin and associated plant substances.
what does dietary fiber promote?
beneficial physiological effects, such as, laxation, reduction of blood cholesterol and blood glucose.
Fiber is very important in foods from a
______ standpoint.
nutritional
Fiber reduces ______ levels, normalizes ______levels and maintains the _____ of the _____
Fiber reduces cholesterol levels, normalizes sugar levels and maintains the integrity of the colon:
how can fiber benefits people?
- -lower blood cholesterol and reduce obesity risk
- -lower blood glucose and reduce diabete risk
- -reduce intestinal ulcer 溃疡risk
- -reduce colon cancer risk
give an ex high in fiber
flaxseed
what does dietary fiber refer to?
the components in the food that are not digested by (resistant to) the human digestive enzymes in the intestinal tract.
what are the major dietary fiber component?
–Cellulose
–Hemicelluloses
–Pectins
–Hydrocolloids and Food Gums (e.g. glucan, alginates, guar
gum, xanthan, inulin, carrageenans).
–Resistant starch
–Lignin, waxes, cutin, tannin etc (minor components)
Classification of Dietary Fiber based on?
1- Function in the plant
2- The type of polysaccharide,
3- Digestion and physiological classification.
The most widely accepted classification for dietary fiber is based on?
its solubility in a buffer
what is SDF?
Soluble Dietary Fiber
what is IDF?
Insoluble Dietary Fiber
ex of SDF
pectin,
gums e.g. guar gum, xanthan, carrageenan, gellan
mucilages
ex of IDF
cellulose
hemicellulose
lignin
what are the 6 methods of determine fiber content?
- Crude Fiber Method
- Total Dietary Fiber Method
- Insoluble Dietary Fiber (IDF) Method
- Soluble Dietary Fiber (SDF) Method
- Neutral Detergent Fiber (NDF) method
- Acid Detergent Fiber (ADF) method
how is crude fiber calculated?
Crude fiber is calculated as the weight of residue retained after treating the defatted specimen脱脂样本 with acid (1.25% H2SO4) and alkali (1.25% NaOH), from
which the weight of ash is subtracted.
describe the steps of determination of crude fiber
- dried defatted sample+H2SO4, heating for 1h, filtration, get filtrate(cho)removed + residue
- residue washing with hot water, add NaOH, heat for 1h, filtration, get filtrate(protein) removed+ residue
- residue wash with hot water, drying, dried residue is W1, ashing at 550oC, get ash W2
- calculate crude fiber%= w1-w2/ wt. of sample x100
why add H2SO4?
remove CHO
why add NaOH?
remove protein
how to calculate crude fiber?
calculate crude fiber%= w1-w2/ wt. of sample x100
The original crude fiber method was replaced by ____ method, which is an ______ method.
dietary fiber method, enzymatic method.
describe the steps of determine total dietary fiber
- sample-dry defatted in buffer solution
- a-amylase, incubate 30min at 95oC to gelatinize starch
- cool to 60oC
- +protease, incubate 30min at 60oC
5.adjust ph 4.1-4.8 - amyloglucosidase, incubate 30min at 60oC
7.precipitate with 95% ethanol, filter, dry, weigh W1, protein W2, ash W3
Total Dietary Fiber (TDF)%= (W1- (W2+W3)/ Wt. of sample X 100
(some oligosaccharides such as derived from inulin, certain maltodextrin may not precipitated) - filtration, determination of IDF and SDF
describe the steps of IDF and SDF
- amyloglucosidase incubate 30min at 60oC, filtration and washing
- filtrate contains soluble dietary fiber SDF, precipitate with ethanol, filter, dry, weigh W1, protein W2, ash W3
- residue contain IDF, dry and weigh W1, protein W2, ash W3
what is NDF?
Neutral Detergent Fiber (NDF) is The residue after extraction with boiling neutral detergent , consist mainly of lignin, cellulose and hemicellulose .
what does NDF involves?
the use of boiling neutral solution of sodium dodecyl sulfate and EDTA.
what is ADF?
Acid Detergent Fiber (ADF) is the residue after extraction with boiling acid detergent , consist mainly of lignin, cellulose .
what does ADF based on?
the use of an aqueous solution of 1N H2SO4 and 2% acetyl trimethyl ammonium bromide. It does not determine hemicellulose which is a part of crude fiber and dietary fiber.
hemicellulose is not determine by? why?
ADF, it’s a part of crude fiber and dietary fiber
EDTA and sodium dodecyl sulfate is used in ?
NDF
1N H2SO4 and 2% acetyl trimethyl ammonium bromide is used in ?
ADF
