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Validation of Loss on Drying Methods in Pet Foods
Dr. Jane M. Caldwell 2018 AAFCO Annual Meeting
Fort Lauderdale, FL July 31, 2018
Pet Food Categories
• Dry pet food (15%) • Wet pet food (>30%) • Freeze-dried pet treats (
MoistureinDryPetFoodDeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods(Study1)
MethodNumber OfficialName Temp(⁰C) Time(hr) Equipment/Procedure N MeanMoisture
(%)
RelativeRecovery
(%)
AOAC930.15 LODforFeeds 135 2 ConvectionOven 33 8.03a* 112
AOAC935.29/945.15 LODinMalt 104 3 ConvectionOven 33 7.73a 108
AOAC950.46 LODinMeat 125 4 ConvectionOven 24 7.63a 106
AOAC2001.12(I) MoistureinFeed,Grain&Forage(MEOH/Formamide)
50 n/a Titration(KarlFischer) 24 7.18ab 100
ASTMD6869-03 MoistureinPlastics 130 var Titration(KarlFischer) 24 7.06ab 98
AOAC2001.12(II) MoistureinFeed,Grain&Forage(boilingMEOH)
66 n/a Titration(KarlFischer) 8 6.80ab 95
AOAC969.35/925.45A LODinSugars(Mod.) 70 4 VacuumOven 33 6.25b 87
*Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
MoistureinDryPetFoodDeterminedByTitration(KarlFischer)andLoss-on-DryingOven(LOD)OvenMethods(Study2)
Moisture(%)
Sample AOAC2001.12(I) ASTMD6869-03 AOAC950.45B(b) AOAC945.15 AOAC969.35N=3 KarlFischer(Feed) KarlFischer(Plastic) Convection(125⁰C,4h) Convection(105⁰C,3h) Vacuum(70⁰C,4h)
1 6.57a 6.79a 6.46a 7.03 5.55
2 6.97a 7.31a 7.14a 7.60 5.79
3 7.50a 7.93 7.69a 8.41 7.18a
4 7.63a 8.19a 7.70a 8.99 7.67a
5 6.17a 5.78 6.07a 6.23a 4.49
6 6.03a 5.31 5.70 6.03a 3.79
7 7.80 6.86 7.53 7.46 5.80
8 7.20a 6.31 7.30a 7.06a 5.50
9 4.66a 3.93 4.28a 4.09 2.58
10 9.47a 9.16a 10.00 9.97 8.45
11 7.20a 6.73a 7.16a 7.07a 5.6112 7.33a 7.23 7.34a 7.48a 6.19
aMeanswithinarowwiththesameletterarenotstatisticallydifferent(p>0.05)fromKarlFischerAOAC2001.12(I)mean.
Observations for LODs in Dry Pet Food
• KF (AOAC 2001.12) is LOD validation standard
• Convection • 135⁰C too hot (118%) • 125⁰C okay • 104⁰C okay
• Vacuum: too low at 4 h
MoistureinDryPetFood(Grain-free)DeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods*
Method Lab Temp(⁰C) Time(hr) Equipment/Procedure MeanMoisture
(%)
RelativeRecovery
(%)
AOAC930.15 X 135 2 ConvectionOven 8.72a** 110
AOAC930.15/925.10 Y 133 2 ConvectionOven 8.42ab 106
AOAC930.15 Z 135 2 ConvectionOven 8.18ab 103
AOAC991.02 Y n/a n/a Titration/Methanolextraction(KarlFischer)
7.93bc 100
AOCSCa2e-84 X n/a n/a Titration(KarlFischer) 7.79bcd 98
AOAC935.29 X 104 3 ConvectionOven 7.78bcd 98
NFTA2.2.2.5 Z 105 3 ConvectionOven 7.76c 98
AOAC934.06/925.45 Y 70 Overnight VacuumOven 7.48cd 94
ASTMD6869-03 Z 130 n/a Titration(KarlFischer) 7.24de 91
AOAC925.09 X 100 5 VacuumOven 6.75ef 85
AOAC969.35 Z 70 4 VacuumOven 6.24f 79
*TotalN=34;LabX&Yhad2N/method;LabZhad5N/method
**Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
MoistureinDryPetFood(HighProtein/Meat)DeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods*
Method Lab Temp(⁰C) Time(hr) Equipment/Procedure MeanMoisture
(%)
RelativeRecovery
(%)
AOAC930.15 Z 135 2 ConvectionOven 6.10a** 111
AOAC930.15 X 135 2 ConvectionOven 5.98ab 109
AOAC930.15/925.10 Y 133 2 ConvectionOven 5.82abc 106
NFTA2.2.2.5 Z 105 3 ConvectionOven 5.74bc 105
ASTMD6869-03 Z 130 n/a Titration(KarlFischer) 5.52cd 101
AOAC991.02 Y n/a n/a Titration(KarlFischer) 5.48cd 100
AOCSCa2e-84 X n/a n/a Titration(KarlFischer) 5.44cd 99
AOAC935.29 X 104 3 ConvectionOven 5.17de 94
AOAC934.06/925.45 Y 70 Overnight VacuumOven 4.98ef 91
AOAC925.09 X 100 5 VacuumOven 4.70fg 86
AOAC969.35 Z 70 4 VacuumOven 4.40g 80
*TotalN=34;LabX&Yhad2N/method;LabZhad5N/method
**Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
MoistureinDryPetFood(Potato)DeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods*
Method Lab Temp(⁰C) Time(hr) Equipment/Procedure MeanMoisture
(%)
RelativeRecovery
(%)
AOAC930.15 Z 135 2 ConvectionOven 9.21a** 126
AOAC930.15 X 135 2 ConvectionOven 9.12ab 125
AOAC930.15/925.10 Y 133 2 ConvectionOven 8.90ab 122
NFTA2.2.2.5 Z 105 3 ConvectionOven 8.52bc 116
AOAC935.29 X 104 3 ConvectionOven 7.96cd 109
ASTMD6869-03 Z 130 n/a Titration(KarlFischer) 7.63d 104
AOAC934.06/925.45 Y 70 Overnight VacuumOven 7.56d 103
AOAC991.02 Y n/a n/a Titration(KarlFischer) 7.32de 100
AOCSCa2e-84 X n/a n/a Titration(KarlFischer) 7.24de 99
AOAC925.09 X 100 5 VacuumOven 6.60ef 90
AOAC969.35 Z 70 4 VacuumOven 6.44f 88
*TotalN=34;LabX&Yhad2N/method;LabZhad5N/method
**Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
MoistureinDryPetFood(Economy)DeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods*
Method Lab Temp(⁰C) Time(hr) Equipment/Procedure MeanMoisture
(%)
RelativeRecovery
(%)
AOAC930.15 Z 135 2 ConvectionOven 8.45a** 109
AOAC930.15 X 135 2 ConvectionOven 8.20abc 106
NFTA2.2.2.5 Z 105 3 ConvectionOven 8.08ac 105
AOAC930.15/925.10 Y 133 2 ConvectionOven 7.76abcd 101
AOAC991.02 Y n/a n/a Titration(KarlFischer) 7.72abcd 100
ASTMD6869-03 Z 130 n/a Titration(KarlFischer) 7.50bd 97
AOCSCa2e-84 X n/a n/a Titration(KarlFischer) 7.37bcd 95
AOAC935.29 X 104 3 ConvectionOven 7.28de 94
AOAC934.06/925.45 Y 70 Overnight VacuumOven 6.99def 91
AOAC969.35 Z 70 4 VacuumOven 6.51f 84
AOAC925.09 X 100 5 VacuumOven 6.45ef 84
*TotalN=34;LabX&Yrunduplicatereps/method;LabZranquintuplicatereps/method
**Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
Observations for LODs in Dry Pet Food; part 2
Did NOT use KF standard for animal feed (1-15%) It depends…LAB and INGREDIENT variation
• Grain-Free • 135⁰C might work (103-110%) • 104⁰C good (98%) • Vacuum OVERNIGHT (94%)
• High Protein • KFs all close (99-101%) • 104⁰C good (94 & 105%) • DID NOT RUN 125⁰C
Observations for LODs in Dry Pet Food; part 2
It depends… • Potato
• 135⁰ too hot (122-126%) • 104⁰C hot (109-116%) • Vacuum ON (103%)
• Economy • 133⁰C great (101%) • DID NOT RUN 125⁰C • 104 & 105⁰C okay (94 & 105%)
Validate with AOAC 2001.12
MoistureinSemi-MoistPetTreatsDeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods
MethodNumber OfficialName Temp(⁰C)
Time(hr)
Equipment/Procedure N MeanMoisture
(%)
RelativeRecovery
(%)
AOAC930.15 LODforFeeds 135 2 ConvectionOven 34 24.61a* 120
AOAC935.29 LODinMalt 104 3 ConvectionOven 34 24.08a 118
ASTMD6869-03 MoistureinPlastics 130 var Titration(KarlFischer) 34 21.12b 103
AOAC969.35/925.45A LODinSugars 70 4 VacuumOven 34 20.75b 102
AOAC991.02 MoistureinSemi-MoistPetTreats
n/a n/a MethanolExtractionTitration(KarlFischer)
25 20.43b 100
*Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
Glycerinandotherhumectantsintreats.
AOAC991.02titratesformoistureinsoft-moistandsemi-moistpetfoodscontaining20-30moistureandothervolatilematerials.
Goldstandardforthismatrix.
Samplesrangefrom17to26%moisture.
Observations for LODs in Semi-Moist Pet Treats
• LOD in Sugars (102%): How sweet it is! • Vacuum oven • 70⁰C • 4 hours
MoistureinWetPetFoodDeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods
MethodNumber OfficialName Temp(⁰C) Time(hr) Equipment/Procedure N MeanMoisture
(%)
RelativeRecovery
(%)
NFTA2.2.1.1/2.1.4 LODforForages,Silage,WetFeeds(Two-stepmethod)
55(105)
ON(3)
ConvectionOvens 20 76.64a 100
AOAC991.02 MoistureinSemi-MoistPetTreats(Two-stepmethod)
55(n/a) ON(n/a) ConvectionOvenMethanolExtractionTitration(KarlFischer)
20 76.54a 100
AOAC935.29 LODinMalt 104 3 ConvectionOven 20 75.39a 98
AOAC950.46B(b) LODinMeat 125 4 ConvectionOven 20 75.37a 98
AOAC930.15 LODforFeeds 135 2 ConvectionOven 20 75.35a 98
AOAC991.02 MoistureinSemi-MoistPetTreats n/a n/a MethanolExtractionTitration(KarlFischer)
20 71.76b 94
*Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
AOAC991.02titratesformoistureinsoft-moistandsemi-moistpetfoodscontaining20-30moistureandothervolatilematerials.
Observations for LODs in Wet Pet Food
• Two-step methods for KF and LOD • 104, 125 & 135⁰C also 98% • KF for semi-moist low (94%) • More data needed.
MoistureinFreeze-DriedPetFoodTreatsDeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods
MethodNumber OfficialName Temp(⁰C) Time(hr) Equipment/Procedure N MeanMoisture
(%)
RelativeRecovery
(%)
AOAC2001.12(I) MoistureinFeed,Grain&Forage(MEOH/Formamide)
50 n/a Titration(KarlFischer) 7 3.31a* 100
ASTMD6869-03 MoistureinPlastics 130 var Titration(KarlFischer) 7 2.86a 86
AOAC935.29 LODinMalt 104 3 ConvectionOven 7 2.55a 77
AOAC969.35/925.45A
LODinSugars 70 4 VacuumOven 7 0.77b 23
AOAC969.35/925.45D**
LODinSugars 60 18 VacuumOven 7 0.77b 23
*Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
**NodigestquartzsandusedinDmethod.
MoistureinFreeze-DriedPetFoodTreatsDeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods–Study2
MethodNumber OfficialName Temp(⁰C) Time(hr) Equipment/Procedure N MeanMoisture
(%)
RelativeRecovery
(%)
AOAC930.15 LODforFeeds 135 2 ConvectionOven 7 5.95a* 138
AOAC950.46B(b) LODinMeat 125 4 ConvectionOven 7 5.17a 120
AOAC2001.12(I) MoistureinFeed,Grain&Forage(MEOH/Formamide)
50 n/a Titration(KarlFischer) 7 4.30a 100
*Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
Observations for LODs in Freeze-Dried Pet Food Treats
• Chewy.com •
MoistureinDriedBeefSticksDeterminedbyTitration(KarlFischer)andLoss-on-Drying(LOD)OvenMethods
MethodNumber OfficialName Temp(⁰C)
Time(hr) Equipment/Procedure N MeanMoisture
(%)
RelativeRecovery
(%)
AOAC2001.12(I) MoistureinFeed,Grain&Forage(MEOH/Formamide)
50 n/a Titration(KarlFischer) 7 13.66a* 100
AOAC930.15 LODforFeeds 135 2 ConvectionOven 7 13.37a 98
AOAC950.46B(b) LODinMeat 125 4 ConvectionOven 7 11.54a 84
*Levelsnotconnectedbythesameletteraresignificantlydifferent(p>0.05)
Discussion of Pet Food LOD Results
• Review data • Commentary period for labs/stakeholders • Suggestions for further studies • Can we make some conclusions/give guidance?
Dr. Jane Caldwell402-829-9858
jcaldwell@midwestlabs.com
Dr. Jane M. Caldwell402-979-1411
jcaldwell@midwestlabs.com
Karl Fischer (Moisture by Titration)
GOLD STANDARD: Reaction of iodine with water. Used for TRUE MOISTURE & NIR calibration
Not free of procedural issues……..
• AOAC 2001.12 (I & II) (2005) – Moisture in Animal Feed, Grain and Forage (1-15%) • AOAC 991.02 (1995) – Moisture in Soft-Moist & Semi-Moist Pet Treats (20-30%) • ASTM D6869-03 (2011) - Moisture in Plastics (0.005-100%) • AOCS Ca 2e-84 (1997) Moisture in Fats & Oils
AOAC 2001.12 (I) Moisture in Animal Feed, Grain and Forage (1-15%)
• High-speed homogenization in vessel? • Pre-homogenization outside vessel
• MEOH/Formamide extraction (50⁰C)
• Time in titration vessel not a factor
• Run in triplicate • Comparable to ASTM D6869-03
AOAC 2001.12 (II) Moisture in Animal Feed, Grain and Forage (1-15%)
• Boiling MEOH (66⁰C) • No obvious advantages over (I).
• Small volume of water easy to release? • Vapor pressure issues • Never used
AOAC 991.02 – Moisture in Soft-Moist & Semi-Moist Pet Treats (20-30%)
• MEOH extraction with titration
• Shake 15 min @ room temperature
• 10 g
• Results always low
• Limited by time
ASTM D6869-03 - Moisture in Plastics (0.005-100%)
• Used by global pet food giants
• 0.10 to 1.0 g (
AOCS Ca 2e-84 (1997) Moisture in Fats & Oils
• 5-25 g sample of fat or oil
• Chloroform/methanol extraction
• Electrometric end point
• No time restrictions
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