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Background and Objectives:
Pollution of the environment has become one of the very serious problems in the world.
Factors contributing to these problems are both natural causes and man created activities.
As livestock production intensifies, air, water and soil pollution becomes a problem.
Utilization of feedstuffs especially by young pigs is influenced by the presence of
anti-nutritional factors and fiber. An ideal thermal treatment procedure should
sufficiently inactivate anti-nutritional factors and increase the bioavailability of
nutrients, especially the essential amino acids.
Micronizing or infra-red processing has been developed commercially for the heat
treatment of bulk feeds to improve their nutritional worth.
The long term goal of this proposal was to establish infra-red processing as a viable
technology for increasing the value of a variety of pulses and cereals as they would
become more attractive to both domestic and export markets for human and livestock use.
The study was divided into two parts.
- Processing of Pulses with Infra-Red Lamps –
Mathematical Modelling and Equipment Developments
- Enhancement of the Nutritive Value of Pulses
and Cereals for Early Weaned Pigs
Procedure and Project Activities:
Processing of Pulses with Infra-Red Lamps - Mathematical Modelling and Equipment
Developments
Dehulled yellow peas, grown and harvested in 1998 in southwestern Manitoba, were
provided by Roy Legumex of St. Jean, MB. The average initial moisture content (mc) was
approximately 7±1% weight basis (wb) and initial protein content was approximately 21%.
The micronizer components were a high-density infrared (IR) pyropanel strip heater. The
heat source comprised four tungsten filament lamps, 500W each. Before micronization, pea
samples were tempered to two moisture contents (26 and 28% wb) for 16 to 18 h. A 20 g
sample of split peas was evenly distributed on wire mesh. Thermocouples attached to a data
acquisition system were placed within kernels at three locations under the infrared lamps
to determine the temperature change in the kernels. The infrared lamp provided heat
intensity of 12.3, 16.8, and 23.2 kW/m2 at the kernel surface and the trials
were conducted in triplicate. After micronization, the kernels were cooled then sealed in
a plastic bag and refrigerated at 5ºC for further testing. Table 1 displays the treatment
of samples. After the peas were tempered to 26 and 28% wb mc, the changes in mass of peas
were measured during micronization using an electronic balance. The intensity of the IR
lamp was set to the same levels as when temperature of peas was monitored. The temperature
and moisture measurements over time allowed for the verification of a mathematical model
developed based on basic laws of heat and mass transfer.
The functional properties of the micronized peas were determined using differential
scanning calorimetry (DSC) technique and simulated digestibility tests. The DSC tests were
performed on micronized and non-micronized peas to ensure the IR treatment did, in fact,
gelatinize the starch found in peas while maintaining other nutritional components, such
as protein. In these tests, the peas were micronized until kernels’ temperature
reached 130° - 140ºC.
Three 20 g samples were micronized at optimum intensity of 16.8 kW/m2
(optimum in terms of gelatinization of starch and maintaining the protein and lipid
contents). The three micronized samples were ground together. The DSC trials were then
conducted immediately, 24 h, and 14 days after micronization to determine the
retrogradation of starch.
To ensure that micronization does not detrimentally affect protein content for
digestion in vitro digestibility tests were performed. Tests consisted of a
reference sample (non micronized, non moisturized 7% mc wb) and two micronized samples.
This allowed for a comparison of the effect of varying intensities when performed on the
same material.
Enhancement of the Nutritive Value of Pulses and Cereals for Early Weaned Pigs
Oats and peas were either processed (extruded or micronized) and/or supplemented with
enzymes to increase nutrient digestibility, whereas barley was only micronized. Extrusion
was carried out first by moving product through an auger and conditioner where steam was
injected to raise the temperature and moisture content to 62.8ºC and 20%, respectively.
The product was then passed through the extruder screen and carried through the cylinder
in 30 - 40 sec, at a cylinder T of 137.8º - 162.8ºC. Following extrusion through two 2.4
mm X 76.2 mm openings in the die plate the product was cooled and dried to 11% moisture.
Micronizing of cereals and peas was carried out in a commercial micronizer (Precision
Feed, Winnipeg). Micronization was done with gas fired infra-red ceramic heaters. The
cereals and peas were preconditioned to 20% moisture and micronized at 140ºC for 45 sec.
The turgid ruptured product was then rolled flaked and cooled.
Five experiments were conducted: the first three investigated oats and barley and the
last two investigated peas. In Experiment One, 264 Cotswold early weaned (16±2d) pigs
randomly allocated to eight experimental treatments containing 35%: (1. oat groats; 2.
rolled oats; 3. extruded oats @ 130ºC; 4. extruded oats @ 140ºC; 5. extruded oats @
150ºC; 6. micronized oats @ 140ºC; 7. micronized barley @ 140ºC with 10% whey powder;
8. 40% micronized barley @ 140ºC with 5% whey powder) and a commercial control (3275kcal
ME, 1.39% and 0.80% for phase 1 and 3285kcal ME, 1.20% and 0.70% digestible lysine and
methionine plus cystine, respectively for phase 2) were fed from 5 to 20 kg weight. In
Experiment Two, apparent digestibility of dry matter, energy, nitrogen, ß-glucan and
amino acids was determined for six dietary treatments (containing 75% oats: 1. oat groats;
2. rolled oats; 3. extruded oats (130ºC); 4. extruded oats (140ºC); 5. extruded oats
(150ºC); 6. micronized oats (140ºC) using twelve 16 day old piglets fitted with ileal
T-cannulas (3 periods x 2 piglets x 6 diets).
Experiment Three was designed to determine the effect of enzyme supplementation
(ß-glucanase, xylanase and protease) on the nutritional value of oat groats and extruded
(140ºC) oats. The experimental diets were comprised of 75% oats, 20% canola meal and 5%
premix (1. oat groats; 2. oat groats + enzyme; 3. extruded oats (140ºC); 4. extruded oats
(140ºC) plus enzyme). Experiment Four investigated the effect of enzyme addition to raw,
extruded and micronized peas (75% inclusion) on nutrient digestibility. A nitrogen free
diet was used to correct for endogenous losses.
The final experiment was a growth study involving 70 crossbred pigs (4 kg) at 16 days
of age. The dietary treatments were a soybean meal control (1), raw peas (2), raw peas
plus enzymes (3), extruded peas (4), extruded peas plus enzymes (5), micronized peas (6),
and micronized peas plus enzymes (7). Peas were included at 30 and 35% in the phase 1+2
diets, respectively.
Results and Discussion:
Processing of Pulses with Infra-Red Lamps –
Mathematical Modelling and Equipment Developments
The experimental results of temperature and moisture changes of peas exposed to IR
radiation show similar heating and drying patterns. Table 1 summarizes the maximum
temperature reached within the kernel and the corresponding micronization time. The total
time required to fully micronize the samples increased with decreased intensity. For the
IR intensity of 12.3 to 23.2 kW/m2, the total processing time was from 104 to
42 s, respectively. A power function was used to express the moisture change and utilized
in the mathematical model derived. Predicted temperature and moisture changes of peas
during micronization fairly accurately followed the measured results.
Table 1. Treatments
of micronized dehulled yellow peas.
|
Sample Name |
Intensity ±S.D.
(kW/m2) |
Moisture Content
(% wb) |
Final Temperature ±S.D.
(°C) |
Length of
Processing
Time Required ±S.D.
(s) |
|
A1 |
12.31 ± 1.2 |
28 |
138.32 ± 7.4 |
1042 ± 16 |
|
A2 |
12.3 ± 1.2 |
26 |
137.0 ± 2.4 |
88 ± 13 |
|
B1 |
16.8 ± 0.1 |
28 |
147.9 ± 3.5 |
93 ± 9 |
|
B2 |
16.8 ± 0.1 |
26 |
135.8 ± 2.2 |
79 ± 8 |
|
C1 |
23.2 ± 0.6 |
28 |
129.5 ± 4.7 |
42 ± 6 |
|
C2 |
23.2 ± 0.6 |
26 |
142.0 ± 3.7 |
58 ± 12 |
1 n = 5
2
n = 3
Table 2 was produced to determine the amount of energy required to gelatinize the
remaining starch in the processed and unprocessed kernels. The onset temperature was used
in further analysis rather than the peak temperature. The reference pea flour had an onset
temperature of 63.4ºC, within 3.2% of the pure waxy maize. As a result of micronization,
the onset temperatures of the samples were lower than the reference samples. This was due
to the reorganization of the starch during the heat treatment, making it available for
gelatinization at a lower temperature. The lower the heat intensity resulted in a lower
onset temperature. This was the reverse of what was expected since the reference sample
had the highest onset temperature.
Table 2. Amount of
energy required to gelatinize starch and the melting onset temperature.
|
Treatment |
Energy ±S.D. (J/g) |
Onset
Temperature ±S.D.
(°C) |
|
Reference |
5.081 ± 0.45 |
63.4 ± 2.4 |
|
A1 |
0.25 ± 0.16 |
51.1 ± 5.8 |
|
A2 |
0.37 ± 0.28 |
49.2 ± 3.6 |
|
B1 |
0.19 ± 0.14 |
51.3 ± 4.6 |
|
B2 |
0.24 ± 0.17 |
51.0 ± 3.5 |
|
C1 |
0.07 ± 0.06 |
54.6 ± 0.2 |
|
C2 |
0.11 ± 0.06 |
53.4 ± 6.3 |
1n =
5
This could be a result of high standard deviations, but could also be an effect of heat
treatments. Had an even lower intensity been tried, the onset temperature might have
started to increase. In general, the results show the higher the intensity of the infrared
heat source, in conjunction with a high moisture content, the less energy was required to
melt the starch, indicating more starch was gelatinized. Depending on the treatment, the
micronized peas required 92 to 98% less energy to melt the available starch in comparison
to non-treated peas. The moisture content had a greater effect with the lower intensities,
though the standard deviations also increased.
The effect of retrogradation, or the reforming of starch after time, is illustrated in
Table 3. The sample that was tested in the DSC immediately after micronization needed 0.25
J/g to melt the starch and 0.31 J/g and 0.39 J/g was required for the samples tested 24 h
and 14 days after micronization, respectively, indicating the reforming of starch is most
prominent within the first 24 h (approximately 25% of starch was reformed). Storing
micronized peas for a period of two weeks affected the product’s digestibility by
additional 30%.
Table 3. Effect of
retrogradation of starch on the energy required to gelatinize starch and
the melting onset temperature.
|
Treatment |
Energy (J/g) |
Onset Temperature (°C) |
|
B2 (immediately) |
0.25 |
54.3ª |
|
B2 (24 h) |
0.31 |
58.2 |
|
B2 (14 days) |
0.39ª |
50.5 |
ª
indicates only
one peak on graph (metastability) refer to Wray (1999)
The in vitro dry matter and protein digestibilities for the 26% mc wb treated samples
and a reference sample are given in Table 4. The different heat treatments were not
statistically significant for increasing dry matter digestibility. Overall, the heat
treatment increased dry matter digestibility of the dehulled yellow peas by an average of
approximately 38%. The different heat treatments were not statistically different for the
amount of protein available for digestion, though there was an overall improvement for the
treated samples compared with the non-treated sample of approximately 6%.
Table 4. Dry matter
and protease digestibilities.
|
Sample |
Digested Dry
Matter (%) |
Digested protein
(%) |
|
Reference 1 |
45.32 |
82.44 |
|
Reference 2 |
-a |
-a |
|
B1 |
70.59 |
86.76 |
|
B2 |
72.12 |
89.78 |
|
C1 |
71.17 |
86.83 |
|
C2 |
74.14 |
88.49 |
a
Tube broke during dialysis/digestion
Researchers have varying opinions whether the nutritive value of feedstuffs improve
with micronization. This could be due to the differences in micronizing techniques, such
as the final temperature of the product and the length of processing time.
Enhancement of the Nutritive Value of Pulses and Cereals for Early Weaned Pigs
The results of the first study showed that there was no real advantage to processing
oats (extrude, micronize, roll); piglets performed equal (p<0.05) to the standard
commercial diet on all treatments. Similar to the growth
performance of piglets in the first trial, no improvement in digestibility of dry matter,
energy, crude protein, amino acids and ß-glucan were achieved by extrusion or
micronization of oats. Enzyme addition to oat groats or extruded oats also showed
no beneficial effect on nutrient ileal digestibilities. The apparent and true ileal
digestibilities of raw peas, extruded peas and micronized peas supplemented with and
without enzymes are shown in Tables 5 and 6. Due to the fact that each processed pea plus
or minus enzymes was studied independently, it is difficult to compare the results due to
confounding of experiments. However, there was a trend for improved apparent and true
ileal digestibilities upon extrusion and micronizing with additional slight improvements
upon enzyme addition. Results of the growth trial are shown in Table 7. The only treatment
effect was detected in the starter phase for feed/gain ratio. The raw pea diet resulted in
poorer feed/gain relative to the soybean control, the extruded peas plus enzyme and the
micronized pea diets. However, overall, the pigs fed the micronized pea diet supplemented
with enzymes performed equal to the SBM-control fed pigs, with a trend towards poorer
performance of all other diet combinations.
Table 5. Mean
apparent and True ileal digestibility (%) irrespective of Enzymes of
processed peas.
|
|
RAW |
Extruded |
Micronized |
|
Apparent |
True |
Apparent |
True |
Apparent |
True |
|
Energy |
78.9 |
80.3 |
81.6 |
85.3 |
83.3 |
86.2 |
|
Crude Protein |
80.9 |
86.1 |
82.2 |
88.4 |
86.8 |
88.7 |
|
Indispensable AA |
79.2 |
85.9 |
83.5 |
89.2 |
84.3 |
91.0 |
|
Dispensable AA |
74.8 |
84.8 |
79.5 |
88.2 |
81.5 |
89.1 |
Table 6. Mean ileal
digestibility (%) of processed peas supplemented with (+) or without (-)
Enzymes.
|
|
PROCESSING |
|
Raw |
Extruded |
Micronized |
|
Enzyme |
(-) |
(+) |
(-) |
(+) |
(-) |
(+) |
|
|
APPARENT |
|
Energy |
78.3 |
79.1 |
80.2 |
82.0 |
82.0 |
83.7 |
|
Crude Protein |
75.4 |
82.7 |
79.8 |
83.0 |
83.7 |
87.9 |
|
Indispensable AA |
76.2 |
80.2 |
80.9 |
84.4 |
80.2 |
85.7 |
|
Dispensable AA |
71.9 |
75.7 |
76.1 |
80.7 |
79.9 |
82 |
|
|
TRUE |
|
Energy |
79.9 |
80.4 |
83.6 |
85.9 |
84.5 |
86.8 |
|
Crude Protein |
84.5 |
86.7 |
85.7 |
89.3 |
85.6 |
89.7 |
|
Indispensable AA |
84.4 |
86.4 |
86.9 |
90.0 |
88.0 |
90.0 |
|
Dispensable AA |
83.3 |
85.3 |
84.4 |
89.4 |
84.7 |
90.6 |
Table 7. Effect of
processing method and enzyme supplementation on average daily feed
intake (ADI), average daily gain (ADG) and average feed conversion
efficiency (FCE) or early (16d) weaned.
|
Parameters |
SBM – C |
Raw |
Extruded |
Micronized |
S.E.M.1 |
|
Enzyme |
- |
- |
+ |
– |
+ |
- |
+ |
|
|
STARTER 1 |
|
ADI (g/d) |
341 |
365 |
346 |
394 |
343 |
406 |
317 |
28.5 |
|
ADG (g/d) |
316 |
247 |
289 |
272 |
291 |
323 |
370 |
36.1 |
|
FCE (feed/gain) |
1.17a |
1.34b |
1.20ab |
1.29ab |
1.18a |
1.18a |
1.02a |
0.069 |
|
STARTER 2 |
|
ADI (g/d) |
699 |
867 |
795 |
802 |
809 |
867 |
747 |
45.6 |
|
ADG (g/d) |
575 |
532 |
519 |
502 |
539 |
581 |
553 |
32.8 |
|
FCE (feed/gain) |
1.27 |
1.63 |
1.52 |
1.54 |
1.52 |
1.46 |
1.35 |
0.09 |
|
OVERALL |
|
ADI (g/d) |
529 |
576 |
556 |
549 |
559 |
595 |
514 |
20 |
|
ADG (g/d) |
429 |
404 |
397 |
416 |
408 |
437 |
408 |
18 |
|
FCE (feed/gain) |
1.26 |
1.43 |
1.40 |
1.37 |
1.38 |
1.36 |
1.26 |
0.05 |
ab means within a row followed by different postscripts are significantly
different (p<0.05)
1S.E.M. - standard error of the mean
A design multilamp IR micronizer was capable of producing heat intensities of 12.3 to
23.2 kW/m2. Micronization of peas at the 16.8 kW/m2 heat intensity
elucidated this intensity as optimum in terms of gelatinization of starch and maintaining
the protein and lipid contents. Micronization with an electrical IR lamp increased the dry
matter digestibility approximately by 38%, increased the amount of available protein by 6%
and gelatinized the starch in peas, therefore, requiring 92 to 98% less energy to melt the
available starch. In general, increased initial moisture contents resulted in increased
gelatinization of the available starch. Retrogradation of starch was most prominent during
the first 24 h after micronization (25% starch reformed). Storage of micronized products
for two weeks increased the starch retrogradation by additional 30%.
The following conclusions can be derived from the in vivo studies:
- There was a trend towards poorer performance of piglets fed processed oats or barley
(p<0.05).
- Extrusion or micronizing of oats did not improve the nutritional worth.
- Addition of enzymes to oat groats and extruded oats eliminated all ß-glucan content
and reduced extract viscosity of the feed but had no beneficial effect on digestibility of
nutrients.
- Extrusion or micronizing did not alter the nutrient composition of peas.
- Extrusion and micronizing peas tended to improve the overall apparent and true ileal
digestibilities.
- Piglets fed pea diets with or without enzymes supplementation performed similar to the
soybean meal control fed piglets with a trend in favor of the micronized diets.
Acknowledgements:
The authors gratefully acknowledge that this project was made possible due to funding
from the following organizations: Government of Manitoba and Canada through
Canada-Manitoba Agri-Food Research and Development Initiative (ARDI), Emerson Milling
Inc., Manitoba Hydro, and Manitoba Pork.
Appendices:
Several additional studies were conducted with Raw, Extruded and Micronized peas with
and without µ-amylase; µamylase
plus xylanase; µ-amylase, protease plus xylanase. Table A1 for
Apparent and True ileal digestibility is below.
Table A1. Summary
of total ileal digestibility (%) of amino acids of peas in early weaned
pigs.
|
Processing |
Enzymes |
|
|
None |
µ-A
A+Xy |
µA+Xy+PRO |
Average |
|
APPARENT |
|
Raw |
76.8 |
77.5 |
76.4 |
75.8 |
76.6 |
|
Extruded |
78.6 |
82.8 |
85.0 |
80.2 |
81.7 |
|
Micronized |
81.6 |
83.5 |
86.9 |
81.3 |
83.3 |
|
Mean |
79.0 |
81.3 |
82.5 |
79.1 |
80.5 |
|
SEM |
1.52 |
2.97 |
1.66 |
2.50 |
|
|
TRUE |
|
Raw |
84.0 |
85.6 |
85.9 |
85.6 |
85.3 |
|
Extruded |
86.0 |
89.3 |
89.7 |
90.2 |
88.8 |
|
Micronized |
87.6 |
92.1 |
90.7 |
91.3 |
90.4 |
|
Mean |
85.9 |
89.0 |
88.8 |
89.0 |
88.2 |
|
SEM |
1.54 |
1.44 |
1.14 |
1.21 |
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Conclusions from Table A1:
- Overall extrusion and micronizing of peas (only trends can be identified) irrespective
of enzyme supplementation improved total apparent ileal amino acid digestibility by 6.7%
and 8.7%, respectively. Overall enzyme supplementation irrespective of processing improved
apparent ileal amino acid digestibility by 2.5%. It appears that xylanase and protease did
not have any benefit.
- Overall extrusion and micronizing of peas irrespective of enzyme addition improved true
ileal amino acid availability by 4.1% and 6%, respectively. µAmylase
on average improved digestibility by 3.6% with no further benefits from xylanase and
protease.
NOTE: Digestibility of individual amino acids are available in Tables A2 to A9 of Final
Report.
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