kibble size (diameter) and its effect on canine palatability...large kibble small kibble 0.68 2.0a...

Kibble Size (Diameter) and Its Effect on Canine Palatability

Ella(<20#)

Kristopher Figge

AFB International

Technical Sales & Service

Why Kibble Size (diameter)?

Research Highlights

• Data could help prove / disprove the notion that small dogs prefer smaller kibbles.

• Manufacturers may be able to reduce the number of SKUs they have to produce.

• Retailers may be able to carry more brands on their shelves, attracting a larger customer base.

• Data could help manufacturers make that next big PAL performance improvement.

Introduction• General discussion about canines

• Factors affecting canine palatability (PAL)

• Kibble size discussion– Hypothesis

– Experimental design, measurements

– Definitions & results

• Summary / conclusions

• Other literature

General Items About Canines• Dogs are omnivores. They tend to respond to a wider

variety of flavors, including sugar. They prefer stronger, roasted aromas.

• Like humans, they have molars and can move their jaw laterally.

• They tend to choose diets based on aroma. PAL testing shows a strong link between first choice and total consumption (r2 = 88).

• In PAL testing, more likely to go to one bowl and stay there.

Factors Affecting Canine PAL (The PAL Triangle)

Raw Materials(Fats, oils, meals, palatants, etc.)

Texture, Size, Shape Processing (sME, etc.)

Age, Dental Health, Physical Environment, Overall Health

Hypothesis

Kibble size (diameter) will affect the PAL of a dry dog diet.

➢ Smaller kibble size will be preferred by all (3) dog sizes.

➢ Specific Surface Area (sSA) will be the driver for this preference.

➢ The sSA will affect flavor / aroma release.

Experimental Design

• Standard / fixed reference points:

➢A finely ground (#3) 25/10 diet - corn & chicken meal-based diet

➢ Same lot of meal used for all (3) diets

➢All variables coated with the same components:Fat: 5.0% poultry fat

Palatant: 1.5% liquid dog palatant

➢Moisture: 8.3% (S), 7.8% (M), 7.9% (L)

➢ Bulk density: 22 lbs./ft3 (all variables)

Experimental Design - Variables

1. Kibble Diameter 2. Dog size

SMALL (7mm – 8mm)

MEDIUM (11mm – 12mm)

LARGE (15mm – 16mm)

Fergie (<30.0#) Casino (30.1 – 54.0#)

TJ & DeDe (>54.1#)

Equipment & Processing Parameters

Equipment

Open Area / Ton

Open Area / Ton =

Area =

Small Kibble Medium Kibble Large Kibble

Die Size (inches) 0.20 0.28 0.38

# of dies 6 6 3

Area (inches2) 0.1884 0.3693 0.3401

Feed Rate (lbs / hr) 696 1354 1247

Open Area / Ton 0.5414 0.5454 0.5454

# of diesπD2

4

Area(Feed Rate / 2000)

SMALL

MEDIUM

LARGE

Specific Mechanical Energy (sME)

sME =

% Load =

Small Kibble Medium Kibble Large Kibble

Extruder Amps (Watts) 52 58 55

Feed Rate (lbs/hr) 696 1354 1247

Extruder Frequency (Hz) 50 60 60

sME (kW hrs / ton) 99.62 68.54 70.57

Actual Amp LoadsFull Load Amps

(Motor size – kW)(% load)(Actual Speed / Base Speed

Rate – tons / hr

Open Area/Ton & sME• The open area / ton was controlled to maintain consistency

between kibble sizes (diameters).

• sME was indirectly varied so as to control bulk density and obtain the required size (diameter).

• This, most likely, led to the differences in starch gelatinization

sME (kW hrs. / ton) Starch Gelatinization

Small Kibble 99.62 87.5%

Medium Kibble 68.54 81.7%

Large Kibble 70.57 79.2%

Specific Surface Area (sSA)

• When we weighed up 50g of each kibble size, we saw,– Small kibble = 523 pieces

– Medium kibble = 243 pieces

– Large kibble = 128 pieces

• sSA = [2 * (πr2 / 4) + πDL] * (# of pieces)– Small kibble = 107,771mm2

– Medium kibble = 94, 328mm2

– Large kibble = 79, 429mm2

• The small kibble had more than 10% more surface area than the medium kibble and ~25% more surface area than the large kibble.

Texture Analysis

Texture Overview

• TA.XT Plus Texture Analyzer – 20 samples– TA-94 probe – flat disc – 45mm

– TA-52 probe – 2mm rod

– TA-43 probe – 3mm thick “chisel”

• Mean Force (g) = average force needed to crush the kibble during the test.

• Peak Force (g) = maximum amount of force needed to continue crushing the kibble.

• Area (Work)(gsec) = indicates how much effort was required to crush the kibble.

Probe Selection• The TA-94 was selected to evaluate how

the kibble would react if the kibble was “crushed” by the entire molar.

• The TA-52 was selected to evaluate how the kibble would react if split by the canine(s).

• The TA-43 was selected to evaluate how the kibble would react if split by the edge of the molar(s).

Texture Results

TA-94 “Disc / Plate” Probe Mean Force (g) Peak Force (g) Area (Work)(g•sec)

Small Kibble 4560.87 6122.56 4992.76

Medium Kibble 8694.69 11778.02 12735.24

Large Kibble 17491.45 21095.09 34040.15

TA-52 Probe Mean Force (g) Peak Force (g) Area (Work)(g•sec)

Small Kibble 2628.48 3799.43 1001.35

Medium Kibble 4388.86 12808.43 2444.09

Large Kibble 5095.26 15950.21 2752.56

TA-43 “Chisel” Probe Mean Force (g) Peak Force (g) Area (Work)(g•sec)

Small Kibble 3366.26 5303.54 1785.63

Medium Kibble 5818.46 9427.94 2974.76

Large Kibble 7875.89 12066.61 4588.99

Texture Discussion• The LARGE kibble had the highest texture scores on all (3) TA.XT

probes used.

• Texture affects PAL (Peachey and Harper, 2002) and is one of the ways most pet dogs select the food given to them (Bradshaw, 2006).

• According to Watson (1994), hard diets are more preferable for dogs than soft diets.

• Miller et al. (1975) found that hard and brittle dry dog foods are less appealing to dogs compared to meat-like textured foods.

E-Nose & E-Tongue (ENET) Analysis

Kronos E-NOSE Astree E-TONGUE

ENET Overview

• The E-Nose (EN) provides information about the headspace (aroma) composition of a sample(s).

• The E-Tongue (ET) uses 12 proprietary sensors to determine the taste of a sample(s).

• Samples are tested in triplicate. The raw data is combined, and undergoes multi-variate statistical analysis. Lines are drawn on the graph connecting the same sample data points, forming a triangle.

• This tool is used to determine similarities and degree of difference between samples, not good & bad.

ENET – Uncoated Kibbles

Large Kibble

Medium Kibble

Small Kibble

PC1 = 69%

PC2 = 27%

ENET – Coated Kibbles

Large Kibble

Medium Kibble

Small Kibble

PC1 = 71%

PC

2 =

27

%

ENET Summary

• For the uncoated kibbles, the PCA plot shows that the large kibble is different from the medium and small kibbles.

• Similarly, the plot also shows that there is little difference between the medium & small kibbles.

• For the coated kibbles, the PCA plot shows that the large kibble is different from the medium and small kibbles.

• The plot also shows that there is little difference between the medium & small kibbles.

PAL Data / Results

PAL Testing Protocol

• Test diets were the sole source of food.

• Each [size] panel consisted of 40 dogs, over a two-day period.

• Two bowls are presented, each containing 2x daily food requirement.

• Bowls are switched from day 1 to day 2, to avoid handedness.

• Both bowls are removed when one is emptied.

• Data is reviewed for appropriate consumption, intake & choice.

PAL Data Interpretation

• Consumption Ratio (CR): Consumed A / Consumed B

• Intake Ratio (IR-A): Consumed A

(Consumed A + Consumed B)

• First Choice (FC-A): % eating out of Bowl A first

• Preference: Outside the range of 0.45 - 0.55 IR

• p-Value (p): Probability that A is significantly different from B (want < 0.05 = 95% confidence level)

PAL Data – Small Dogs(<30.0 lbs.)

Ration A Ration B IR-A CR FC-A PREF p-Value

Large Kibble Small Kibble 0.62 1.5A 0.63 22A : 7B 0.003

Large Kibble Medium Kibble 0.70 2.3A 0.65 29A : 4B 0.000

Medium Kibble Small Kibble 0.44 1.4B 0.45 6A : 18B 0.073

➢ Large > Medium & Small

➢ Small = Medium

*** Tests were conducted using 40 dogs less than 30 pounds, over 2 days.

I loved the large kibble!

PAL Data – Medium Dogs(<30.1 lbs. – 54.0 lbs.)

Ration A Ration B IR-A CR FC-A PREF p-Value

Large Kibble Small Kibble 0.68 2.0A 0.79 24A : 6B 0.000

Large Kibble Medium Kibble 0.76 3.1A 0.75 27A : 1B 0.000

Medium Kibble Small Kibble 0.46 1.3B 0.56 11A : 16B 0.178

➢ Large > Medium & Small

➢ Small = Medium

***Tests were conducted using 40 dogs between 30.1–54.0 pounds, over 2 days.

I loved the large kibble!

PAL Data – Large Dogs(>54.1 lbs.)

Ration A Ration B IR-A CR FC-A PREF p-Value

Large Kibble Small Kibble 0.75 2.7A 0.77 27A : 5B 0.000

Large Kibble Medium Kibble 0.68 1.9A 0.70 24A : 7B 0.000

Medium Kibble Small Kibble 0.51 1.1A 0.64 13A : 12B 0.374

➢ Large > Medium & Small

➢ Small = Medium

***Tests were conducted using 40 dogs weighing more than 54.1 pounds, over 2 days.

Me too!!!

PAL Summary

• Each panel (size) of dogs preferred the larger kibble size over the medium and small kibble sizes.

• This difference in consumption (CR) and intake (IR-A) was significant (p<0.05).

• The most intriguing part of the PAL data that stood out was the First Choice (FC).

• Based on this data, further analytical tests were conducted the determine what may have driven the FC.

GC-MS Results

Uncoated Kibbles

Summary – Uncoated Kibbles• Total ppb:

– The Large kibbles have about 23% more total ppb* than the Small kibbles and about 13% more total ppb* than the Medium kibbles.

• The Large kibbles have the highest total ppb* of all classes except Hydrocarbons and Sulfurs.

• The Large kibbles have at least 2X less trans-2-Nonenal, 1-Methyl-2-pyrrolidinone and 2-Piperidinone.

GC-MS – Coated Kibbles

Summary – Coated Kibbles

• The Large kibble showed more flavor compounds generated from initial and latter stages of flavor reaction(s):

– Early phase products of the Maillard reaction and Strecker degradation (e.g. Furfural, 2-Methylpropanal and 2-Methylbutanal) were detected at comparable levels in the products.

– Other volatile compounds generated in the latter stages of the Maillardreaction (e.g. alkylbenzaldehydes, benzaldehydes & pyrazines) were higher in the large kibble.

– The large kibble has more higher molecular weight acids, aldehydes, hydrocarbons and ketones (especially di-carbonyl ketones which are important intermediates for generating other reaction products).

Hypothesis Review

Hypothesis

Kibble size (diameter) will affect the PAL of a dry dog diet.

➢ Smaller kibble sizes will be preferred by all (3) dog sizes.[Disproved. All 3 dog sizes actually preferred the large kibble over the small & medium kibbles]

➢ Specific Surface Area (sSA) will be the driver for this preference. [More sSA did not equate to greater PAL]

➢ The sSA will affect flavor / aroma release. [The large kibble had

a more robust flavor /aroma profile]

Benefits

• Stores / Distributors – fewer individual brand SKUs = more products/choices for pet owners

• Manufacturers – fewer SKUs = increased production efficiency

• Possible PAL increases with little to no costs

• Data provides a scientific look into dogs and their preference for the size of kibble they eat

Summary / Conclusions

• In this study, kibble size (diameter) did affect PAL.

• The sSA was not the driver of preference.

• However, the concentration of certain flavor components on the larger kibbles appear to have driven the preference.

• Texture may have also contributed to the overall PAL, as the larger kibble was most preferred and had the highest scores for texture profile.

Future Research

• Would we see the same results in a high-meat formula? No-grain diet? Semi-moist products?

• Further understanding around sME / cook and its impact on canine PAL.

• Investigate how sSA can further optimize how the fat / palatant(s) adhere to the kibble and drive preference.

• Texture and sSA - how unique coating systems may optimize the interaction.

Questions?

Kristopher FiggeTech. Sales & Service

AFB International

Tel: (636) 634-4142

Email: kfigge@afbinternational.com

Other Contributors:Gordon Stirling