Introduction and ObjectivesPulse flours are an excellent source of nutrients and when incorporated as ingredients in processed food products can improve the nutritional profile. Interest from food processors to use these ingredients in food products is high, however undesirable off flavours found in pulses are a major obstacle to the wide spread adoption of these ingredients by food processors. Pre-treating pulses using various thermal technologies can effectively de-activate or minimize their off flavours although the effects of these treatments on the end product quality of processed foods are unknown. The objective of this research is to measure the effects of two different thermal technologies (infra-red heating also known as micronization and roasting) of pulses prior to flour milling on the end product quality of extruded and baked foods.

Materials and MethodsExtruded Snacks

• Yellow peas, red and green lentils, chickpeas and navy beans were micronized using commercial parameters at InfraReady Foods (SK, Canada).• Untreated and micronized pulses were milled into flour using a Hosokawa Alpine 100 UPZ pin mill (Summit, NJ), blended with corn meal (75:25, pulse flour:corn meal) and extruded into directly expanded snacks using a Clextral EV25 co-rotating twin screw extruder (Firminy, France).• Quality of the snacks was determined using standard testing procedures for extruded foods including expansion ratio (ER), bulk density (BD) and texture characteristics. ER was reported as the ratio of the cross sectional diameter of the snack over die diameter. BD was determined by weighing the quantity of extruded pieces required to fill a 2 L container. Texture (crispiness) was measured using a TA.HD Plus texture analyzer (Texture Technologies, US) equipped with a Kramer shear cell.

Baked Products

• Yellow peas, faba and navy beans were micronized using commercial parameters at InfraReady Foods, (SK, Canada) or roasted (130oC, 30 min) in a Picard Electrical Revolving Tray Oven (QC, Canada).• Untreated and thermally treated pulses were milled into flour using a Ferkar multipurpose mill (Velenie, Slovenia) and baked into pan breads, pita breads and tortillas. Pulse flours were blended with wheat flour for pan breads (85:15, pulse flour: CWRS wheat flour) and pita breads and tortillas (30:70, pulse flour: CWRW wheat flour). Standardized baking methods developed at Cigi were used to bake all products.• Wheat flour reference samples were produced for all baked products.• Specific volume (SV) of pan breads was measured using a bread volume meter BVM L370, (Perten, Sweden). Brightness (L* ) values for bread and other products was determined using a Minolta CR400/410 colorimeter (Japan) and texture (firmness) of all baked products was determined using a TA.HD Plus texture analyzer (Texture Technologies, US).

Influence of Pre-milling Thermal Treatments of Pulses on End-Product Quality of Processed FoodsP. Frohlich, G. Young, Canadian International Grains Institute (Cigi), Winnipeg, Manitoba, Canada

@CigiWinnipeg cigi.caCigi

Table 3. Weight, diameter, thickness, brightness (L*) and firmness of tortillas made with pulse floursPulse Type Treatment Weight (g) Diameter (cm) Thickness(mm) L*¹ Firmness(g)

Wheat Reference 33.8 ± 1.8 16.4 ± 0.6 1.4 ± 0.7 80.5 ± 1.6 928.9 ± 93.9

Yellow pea Untreated 34.0 ± 0.3 a² 16.9 ± 0.3 a 0.7 ± 0.2 b 80.5 ± 0.4 a 660.7 ± 46.4 a

Micronized 33.4 ± 0.5 a 16.4 ± 0.6 ab 1.4 ± 0.5 a 80.2 ± 0.6 a 650.1 ± 89.8 a

Roasted 34.0 ± 0.3 a 16.0 ± 0.2 b 1.3 ± 0.4 ab 78.4 ± 0.8 b 647.4 ± 130.5 a

Navy bean Untreated 33.8 ± 0.2 a 16.3 ± 0.4 a 1.6 ± 0.2 a 80.4 ± 0.9 a 638.0 ± 99.0 a

Micronized 33.5 ± 0.9 a 16.3 ± 0.2 a 1.7 ± 0.2 a 80.8 ± 1.0 a 605.2 ± 31.7 a

Roasted 33.7 ± 0.4 a 15.9 ± 0.6 a 1.8 ± 0.1 a 78.5 ± 1.3 b 611.4 ± 100.6 a

Faba bean Untreated 33.4 ± 0.3 b 16.1 ± 0.3 a 1.7 ± 0.2 a 76.4 ± 1.2 ab 848.4 ± 75.0 a

Micronized 33.9 ± 0.3 ab 15.9 ± 0.4 a 1.8 ± 0.2 a 78.2 ± 2.6 a 834.8 ± 68.9 a

Roasted 34.1 ± 0.5 a 15.5 ± 0.5 a 1.8 ± 0.1 a 74.0 ± 0.5 b 880.0 ± 68.9 a

¹ L* indicates the value of brightness (0 – black, 100 – white) ² Values with the same letter in a pulse type in the same column are not significantly different (p<0.05)

Table 1. Expansion ratio (ER), bulk density (BD) and texture (crispiness) of micronized and untreated pulse extruded snacks

Treatment ER BD (g/cm³)Crispiness

(peak count)

Yellow pea Untreated 3.6 ± 0.1 a¹ 0.050 ± 0.0 a 263 ± 31.4 a

Yellow pea Micronized 3.8 ± 0.2 b 0.054 ± 0.0 a 262 ± 34.1 a

Green lentil Untreated 3.7 ± 0.1 a 0.060 ± 0.0 a 299 ± 25.5 a

Green lentil Micronized 3.7 ± 0.1 a 0.049 ± 0.0 b 263 ± 6.0 b

Red lentil Untreated 3.6± 0.1 a 0.05 ± 0.0 a 287 ± 8.4 a

Red lentil Micronized 3.7± 0.2 b 0.05 ± 0.0 a 248 ± 14.7 b

Chickpea Untreated 2.6 ± 0.1 a 0.135 ± 0.0 a 219 ± 15.6 a

Chickpea Micronized 2.5 ± 0.1 a 0.136 ± 0.0 a 213 ± 35.6 a

Navy bean Untreated 3.2 ± 0.1 a 0.091 ± 0.0 a 338 ± 16.9 a

Navy bean Micronized 3.3 ± 0.1 b 0.086 ± 0.0 a 328 ± 6.5 a

¹ Values within a pulse type with the same letter are not significantly different (p<0.05)

Table 4. Pocket height, diameter, brightness (L*) and firmness of pita breads made with pulse flours

TreatmentPocket Height

(mm) Diameter (cm) L*¹ Firmness²(g)

Wheat Reference 71.9 ± 8.1 17.9 ± 0.3 77.8 ± 0.5 1182.9 ± 475.8

Yellow pea Untreated 64.9 ± 5.6 b 17.1 ± 0.3 a 72.0 ± 0.7 a 884.7 ± 120.6 a

Micronized 62.3 ± 5.8 b 17.1 ± 0.4 a 70.4 ± 1.9 a 836.9 ± 301.9 a

Roasted 72.7 ± 2.1 a 17.4 ± 0.2 a 70.5 ± 0.6 a 994.6 ± 133.5a

Navy bean Untreated 66.0 ± 1.0 a 17.3 ± 0.2 b 74.3 ± 0.4 a 880.04 ± 87.4 a

Micronized 61.1 ± 4.2 a 17.8 ± 0.3 a 74.6 ± 0.9 a 955.2 ± 126.0 a

Roasted 64.8 ± 3.6 a 17.4 ± 0.2 ab 74.3 ± 0.4 b 852.0 ± 188.6 a

Faba bean Untreated 66.5 ± 5.4 a 17.0 ± 0.4 a 66.9 ± 1.1 a 942.7 ± 90.2 a

Micronized 68.6 ± 5.1 a 16.6 ± 0.7 a 66.6 ± 1.1 a 1052.9 ± 90.2a

Roasted 66.9 ± 2.8 a 17.2 ± 0.1 a 65.6 ± 2.1 a 911.3 ± 61.5a

¹ L* indicates the value of brightness of the interior top layer (0 – black, 100 – white)² Firmness of the internal top layer of the pita bread ³Values with the same letter in a pulse type in the same column are not significantly different (p<0.05)

• For pita breads, pocket height, diameter, L* and firmness were measured. • Weight, diameter, thickness, L* and firmness were used to measure the quality of tortillas.• Data for all products was analyzed using ANOVA. Differences between mean values were determined using the Tukey-Kramer Method (JMP, ver11).

Results and DiscussionExtruded Snacks

• ER values were higher for snacks made with micronized pulses with the exception of micronized green lentil and chickpea snacks (Figure 1 and Table 1).• Micronized green lentil snacks had lower BD values when compared to the untreated sample.• Micronized green and red lentil snacks had lower crispiness values when compared to the untreated samples. (In the extrusion system, generally higher ER, low BD and higher crispiness values are indicitive of good quality end-products).

Pan Bread

• Thermal treatments of pulses did not affect the SV of pan breads (Figure 2 and Table 2).• Thermal treatments decreased the L* values of all breads, indicating a darker crumb colour. Bread made with micronized faba beans was not significantly different from the bread made from roasted faba beans.• Thermal treatments had no effect on bread firmness.

Tortillas

• Tortilla weight was not affected by thermal treatments with the exception of roasted faba bean flours where higher weights were detected (Figure 3 and Table 3).• Tortillas made with roasted yellow peas exhibited lower diameters than the untreated samples.• Tortillas made from roasted yellow pea and navy bean were darker than the untreated or micronized samples. • Thermal treatments of pulses did not have an effect on tortilla firmness.

Pita Bread

• Pita bread made with roasted yellow peas exhibited higher pocket heights (Figure 4 and Table 4), while for other market classes thermal treatments did not have an effect on pocket height.• Increased diameters were observed for pita breads made with micronized navy beans compared to the untreated samples.• Thermal treatments of pulses did not have an effect on the firmness values of pita breads.

Yellow pea

Navy bean

Faba bean

Yellow pea

Navy bean

Faba bean

Conclusions• Micronization affected the expansion ratio and bulk density properties of snacks and decreased crispiness in some pulse types. This may be due to changes in starch and more specifically amylopectin structure as a result of infrared heating. Quality and magnitude of these changes were specific to a pulse type.• Dimensions of yellow pea tortillas and navy bean pita breads were affected by thermal treatments. However, the changes were small and specific to pulse type. Bread volume was not affected by thermal treatments.• Although results were not always statistically significant, thermal treatments lowered the brightness values for most baked products. Micronization had a smaller effect on these values when compared to roasting. During roasting, non-enzymatic browning is likely the cause for darker colours found in pulse flours and baked products. • Overall, thermally treated pulses can be successfully used as ingredients in food formulations as they exhibit improved flavour characteristics (shown through previous research) and have small to moderate effects on end product quality. • Efficacy of thermally treated pulses as ingredients in processed foods should be evaluated on a product by product basis while talking into account pulse type used.• Future research in this project will measure the sensory characteristics of the baked products assessed by a consumer panel.

Acknowledgements Funding for this project was provided by the Manitoba Pulse and Soybean Growers. The technical assistance of Cigi’s extrusion, baking and communication departments is greatly appreciated.

Table 2. Specific volume (SV), brightness (L*) and firmness values for pan bread made using pulse flours

Treatment SV (cm³/g) L*¹ Firmness (g)

Wheat Reference 6.5 ± 0.2 82.3 ± 0.3 116.2 ± 12.9

Yellow pea Untreated 6.1 ± 0.2 a² 81.0 ± 0.4 a 136.7 ± 7.0 a

Micronized 6.2 ± 0.1a 79.5 ± 0.5 b 130.5 ± 24.4 a

Roasted 5.9 ± 0.1 a 79.5 ± 0.2 b 121.0 ± 7.6 a

Navy bean Untreated 6.0 ± 0.2 a 81.2 ± 0.4 a 134.0 ± 10.2 a

Micronized 6.4 ± 0.2 a 80.1 ± 0.6 b 122.0 ± 8.9 a

Roasted 6.1 ± 0.2 a 79.8 ± 0.2 b 118.6 ± 14.9 a

Faba bean Untreated 6.3 ± 0.0 a 78.6 ± 0.3 a 136.2 ± 14.4 a

Micronized 6.6 ± 0.1 a 78.1 ± 0.4 a 122.9 ± 17.3 a

Roasted 6.4 ± 0.1 a 76.7 ± 0.7 b 131.4 ± 5.7 a

¹ L* indicates the value of brightness (0 – black, 100 – white)² Values with the same letter in a pulse type in the same column are not significantly different (p<0.05)

Figure 2. Pan bread, made with untreated and micronized pulses.

Figure 3. Tortillas, made with untreated and micronized pulses.

Figure 4. Pita bread, made with untreated and micronized pulses.

Order of baked products in Fig. 2-4: Untreated, Micronized, Roasted

Figure 1. Extruded snacks made with untreated (U) and micronized (M) yellow pea, red and green lentil, chickpea and navy bean flours.

U

M

Yellow pea

Navy bean

Faba bean