Update on Food and Feed Mary Beth Hall Research Animal Scientist U. S. Dairy Forage Research Center USDA-Agricultural Research Service Madison, WI ACS 7/16/13
The sugars, starches, and insoluble carbohydrates, demand study. Goals: improved methods for estimation more correct methods of estimating nutritive values. -- Report of the Committee on Ways and Means for Securing More Thorough Chemical Study of Foods and Feeding Stuffs --Assoc. of fficial Agricultural Chemists, August, 1890
Where we started: Crude fiber Crude protein Crude fat Ash Calories Active Ingredients Microbes Amino acids Starch Fats Fructans Calories Protein Sugars Vitamins Fiber Fatty acids Minerals Antioxidants
Purpose of Food & Feed Analysis Adulterants Active Ingredients / Guarantees Nutritional Value Widely varying matrices Possess chemical & physical effects Influence nutrition & health
Purpose of Food & Feed Analysis Used in: Food and feed labeling Quality control Diet and ration formulation Used by: Companies / Trade Regulators Nutritionists Consumers
Costs, Turn-around, Accuracy Food and feed labeling Diet and ration formulation Effect of error
35 30 25 Milk / day, kg 20 15 10-220 lb milk 5 0 5/14/99 5/16/99 5/18/99 5/20/99 5/22/99 5/24/99 5/26/99 5/28/99 5/30/99 6/1/99 6/3/99 6/5/99 6/7/99 6/13/99 6/15/99 6/17/99 6/19/99 6/21/99 6/23/99 6/25/99 6/27/99 6/29/99 7/1/99 6/9/99 6/11/99 Date 7/3/99 Averhoff and Hall, 2000
35 30 25-563 lb milk Average Milk Loss: 744 lb/cow/episode Milk / day, kg 20 15 10 5 0 5/14/99 5/16/99 5/18/99 5/20/99 5/22/99 5/24/99 5/26/99 5/28/99 5/30/99 6/1/99 6/3/99 6/5/99 6/7/99 6/9/99 6/11/99 6/13/99 6/15/99 6/17/99 6/19/99 6/21/99 6/23/99 6/25/99 6/27/99 6/29/99 7/1/99 7/3/99 Averhoff and Hall, 2000
Carbohydrates That Matter Plant Carbohydrates Cell Contents Cell Wall ---------Digestible------- ------------------------------Indigestible---------------------------- rganic Mono- & Acids Disaccha -rides Sugars Starch ligosaccha -rides Dietary Starch Fructans Pectic Hemicelluloses Cellulose Substances Mixed linkage -glucans Fructans Soluble Fiber Detergent Fibers Acid Neutral
Plant Cell Structure Cell contents rganic acids Sugars Starch ligosaccharides Fructans Middle lamella Pectic substances b-glucans Cell wall Hemicellulose Cellulose Lignin
Carbohydrates: Animal Feeds AAFC pressured to allow labeling of carbohydrates in animal feeds Must / will cover all animal species Nutritionally relevant & defined / predicts nutrient supply & animal performance Verifiable by AAC / other recognized method AAC starch method for animal feeds no longer valid Questions on appropriate labeling for fiber
The Ideal Fiber Analysis Nutritionally relevant Chemical & physical effects Across species Robust, simple, repeatable, inexpensive AAC approved
Fiber Analyses Crude Fiber Acid Detergent Fiber Neutral Detergent Fiber Total Dietary Fiber
Crude Fiber - circa 1840 s Ether extraction Dry & weigh Reflux with 1.25% sulfuric acid 30 min. Reflux with 1.25% sodium hydroxide 30 min Gravimetric measure of organic residue. Does not measure soluble fiber. Weende / Proximate Analysis System
The crude fiber method solubilizes hemicelluloses, cellulose and lignin to varying degrees. From Van Soest, 1994
Crude Fiber Not nutritionally relevant. Fails to accurately recover insoluble fiber. AAC Method 962.09. Used / required for regulatory purposes. 1 6 10
Acid Detergent Fiber - 1967 Fat extraction (if necessary). Reflux 1 hour with acid detergent (0.5 M H 2 S 4 and CTAB). Gravimetric measure of organic residue. Recovers cellulose, lignin, protein, traces of other carbohydrates. Does not measure soluble fiber.
Acid Detergent Fiber Somewhat nutritionally relevant (species? state?). Simple, inexpensive, robust assay. AAC Method 973.18. 5 8 10
Neutral Detergent Fiber Fat extraction (if necessary). Reflux 1 hour with neutral detergent, heat-stable, a-amylase, and/or sulfite. Gravimetric measure of organic residue. Recovers hemicellulose, cellulose, lignin, traces of protein. Does not measure soluble fiber.
Neutral Detergent Fiber Nutritionally relevant (species?). Simple, inexpensive, robust assay. NDF = Insoluble Dietary Fiber AAC Method 2002.04. 7 8 10
Dietary Fiber AAC 985.29: Enzymatic - gravimetric AAC 2009.01: Enzymatic - gravimetric liquid chromatographic HPLC Includes soluble & insoluble dietary fiber and oligosaccharides
Dietary Fiber Analysis Nutritionally relevant (species?). New inclusion of oligosaccharides. Multifaceted, expensive assay. AAC Method 2009.01. 9 4 10
Method Comparison Crude Fiber (AAC, 1980) NDF (Robertson and Van Soest, 1977) TDF (Prosky et al., 1985) Feedstuff CF NDF TDF Corn 1.7 9.5 9.2 Wheat 3.2 13.4 17.9 Citrus pomace 12.5 26.2 66.8 Beet pulp 19.0 60.1 76.8 Wheat bran 9.6 45.7 45.1 Courtesy of G. Fahey, 2002
Thoughts Dietary and neutral detergent fibers are nutritionally relevant. Which is most appropriate depends on species and feeds. Crude fiber is not useful for nutritional applications.
Why Dietary Starch? Starch: A non-structural polysaccharide of plants composed of glucose with a-(1-4) and a-(1-6) linkages (well established def.). Dietary: Classifies the fraction as being related to nutrition, not to other applications (as was done with dietary fiber ). Dietary Starch: Relates the nutritional fraction of a-linked carbohydrates to starch. Bottom Line Informal Definition: Any carbohydrate that digests like starch.
Dietary Starch Why not call it starch? Assays don t and never have measured just plant starch, unless many types of samples were excluded. Liver Starch from plants Glycogen in animals & microbes Breakdown products of these (maltooligosaccharides)
Starch: Polarimetry Analysis fficial EU method of analysis Change in optical rotation of solubilized pure starch minus substances soluble in 40% Et [a] D 20 for pure starches: Rice: +185.9, potato: 185.4, corn: +184.6 Repeatability: + 0.4% if starch < 40%, + 1.1% if starch > 40% Interference: CaC 3, lactose, citrus pulp, sugar beet, linseed, copra, & rapeseed products, yeast, inulin, greaves (sugars, fructans, other?), optically active substances Third Commission Directive, CNSLEG 1972L0199, 1999
Starch: Enzymatic Analysis Gelatinization Disrupting the hydrogen bonding/ crystalline structure of starch chains Hydrolysis a-amylase, amyloglucosidase CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 H 2 H 2 H 2 End product detection Glucose, reducing sugars CH 2
Sources of Error Multiple transfers Inaccurate standard curve Glucose standard purity Incomplete hydrolysis Microbial predation Chemical alteration Volumetric accuracy Interfering substances: Nonspecific enzymes & run conditions Affected past starch assays Starch % DM Starch % DM 100 90 80 70 60 50 40 30 20 10 0 25 20 15 10 5 Corn Starch 0 Confectioner s Sugar Hall et al., 1999
Starch: Low Recovery Isomerization of reducing end glucose Neutral to alkaline ph + heat: reducing end glucose isomerizes to fructose. An issue with hydrolysis with gelatinization at neutral ph? CH 2 CH 2 HCH 2 CH 2 H CH 2 Maltose Maltulose Autoclave ph 4.5 7.0 Glucose 96.7 93.2 Maltulose 0 4.6 Maltose/ 2.6 1.7 isomaltose Dias and Panchal, 1987
Glucose Detection % of no ascorbic acid 102 100 98 96 94 92 90 0 10 20 30 40 50 60 Ascorbic acid, umoles <10 mmol hydrophilic antioxidant / 0.1 g sample DM Different detection method Identification of matrices? Hall and Keuler, 2009, JAACI 92:50
Glucose Detection Standard curve deviation in prediction 1.5 1.0 0.5 0.0-0.5-1.0 2 pt linear 5 pt linear 0 200 400 600 800 1000 5 pt quadratic Standard curve nearly, but not quite linear Apparently inherent in the chemistry 3 to 5 points similar, but 3 is overfit Hall and Keuler, 2009, JAACI 92:50
Dietary Starch Completing pre-study trial 16 labs (5 industry, 9 state, 2 research) 1250 Glucose Standard Curve 1000 y = 10.776x 2 + 871.21x + 0.2204 R² = 1 Glucose, ug/ml 750 500 250 0 0.000 0.200 0.400 0.600 0.800 1.000 1.200 Absorbance, 505 nm
Sugars & Fructans Definitions in place Investigating methods Fructan Sugars CH 2 H CH 2 CH 2 CH 2 H CH 2 H CH 2 H HCH 2 H CH 2 H2 C CH 2
Questions?