Why o Dietary fibre includes cellulose hemicellulose pectin mucilidges gums

Why o dietary fibre includes cellulose hemicellulose

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Why? o Dietary fibre includes cellulose, hemicellulose, pectin, mucilidges, gums, lignin, etc. Soluble fibres are lost during the proximate analysis. Nitrogen Free Extract (NFE) = Digestible carbohydrate (CHO) - Esimates starch & sugar content % NFE = 100 ( % moisture + % Crude Fat + % ASH + % Crude Protein + % Crude Fibre ) - Potential sources of error / limitations: o NFE accumulates ALL of the ERRORS that exist for the other components 9
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General Comments on Proximate Analysis - No information is ‘digestability’ of food / feed o So we don’t know what wil actually be absorbed by an organism o No informmation of specific AA, minerals, lipids, or carbs o Still used as the basis for food labelling and animal feed analyses o Has prompted the development of more advance analytical assays to imporve food characterization Recall we are looking more for dry matter when looking at agriculture; - Numbers in red are made by proximate analysis - Percentages are different but in grams the amounts are the same Dietary Fibre - Non-digestible complex CHO - Structural part of plants More Accurate fibre analyses to complement the Proximate Analysis: (1) Van Soest Method - Differentiates between insoluble fibre o Cellulose & Hemicellulose o Lignin (poorly fermented, prevents fermentation of other fibres - Determines fermentable and non-fermentable CHO o Very important for agricultural applications! - Poorly differentiates sugars, starches, & soluble fibres 10
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(2) Southgate Method - Provides information about sugars, starch and various fibres - Useful for human nutrition and food labeling - Does not differentiate between various fibre components adequately, so this method is not used for agricultural applications Lecture 3: The Digestive System Different species, different needs, different systems, but common themes 1. Simple system (w/o caecum) 2. Simple system (w/ functional caecum) 3. Ruminant system 4. Avian system Gastrointestinal (GI) Tract - Mouth - Esophagus - Stomach - Small intestine - Large intestine - Caecum - Rectum GI Tract = Digestive Tract ≠ Digestive System Digestive System refers to the GI Tract & associated organs (liver, pancreas, gallbladder) General Terminology for Dietary Carbohydrates (CHO) & Digestion - DIGESTABILITY Does the host organism have the enzymes necessary to digest HO? o Digestible CHO versus non-digestible CHO (fibre) - SOLUBILITY is CHO soluble in the aqueous environment of the digestive tract? o Yes = soluble; No = insoluble - FERMENTABILITY Do gut bacteria have the enzymes necessary to break down CHO? o Yes = fermentable; No = non-fermentable 1. Simple System w/o caecum Ex. Human, pig, cat, dog Key Features: - Monogastric (single gastric system) - Non-functional caecum - Suited for a nutrient dense, low fibre diet Digestion - Oral cavity o Food is chewed o Food is mixed with saliva o Two enzymes released: α -amylase and lingual lipase - Stomach (cardia, fundus, body, antrum) 11
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o Empty = 50 mL, Filled = 1-1.5 L o Gastric emptying = 2-6 hrs o pH of stomach is acid ~2 o Food become “chyme” o Gastric glands secrete gastric juice H 2 O, electrolytes, HCL, enzymes -
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