Abstract
Canola seeds are largely used for oil extraction, while the rest of the plant, particularly the leaves, remain an underutilized yet unexplored functional food ingredient. The aim of this study is to investigate the upcycling of canola leaves powder (CL) to develop wheat bread with an increased potential nutritional value. The impact of including 5 g/100 g CL in combination with 20 g/100 g freeze-dried sourdough (flour weight basis) was investigated on the technological and nutritional properties of wheat dough and bread. Furthermore, this study aimed to evaluate the effect of sourdough acidification on starch digestibility in CL-enriched bread. Incorporation of CL and/or sourdough prolonged dough development time and reduced dough stability during mixing. GlutoPeak analysis revealed a rapid gluten aggregation when CL was incorporated. From a nutritional perspective, breads enriched with CL exhibited higher dietary fiber and total phenolic content, while sourdough incorporation lowered bread pH. The harder crumb texture resulting from CL inclusion was counteracted by the softening effect of sourdough. Image analysis further showed a finer and more homogeneous crumb structure due to leaves incorporation, characterized by increased pore density and reduced mean pore area. Regarding starch digestibility, CL showed a tendency to reduce the in vitro starch hydrolysis rate (k) and combined with the sourdough, further slowed down starch hydrolysis. Results suggest that using CL in breadmaking can be a valuable strategy to valorize this by-product within a circular economy framework.
Supplementary Information
The online version contains supplementary material available at 10.1007/s11130-026-01485-1.
Keywords: Rapeseed, GlutoPeak, Crumb microstructure, RVA digestogram, Phenolic compounds, Starch digestibility
Abbreviations.
CL Canola leaves powder.
CTRL Control sample.
RVA Rapid Visco Analyzer.
SD Sourdough sample.
SDCL Sourdough and canola leaves powder sample.
TPC Total Phenolic Content.
TTA Total Titratable Acids.
Introduction
Annually, modern food systems generate about 1.3 billion tons of food waste and losses, leading to wasted resources, added disposal costs, and increased pollution [1]. In this context, circular economy strategies are increasingly focusing on the utilization of underused plant biomass in food products such as bakery goods as a functional ingredient.
Rapeseed, otherwise known as canola, is an important oilseed crop, ranking second in global production of oil-bearing seeds. Underutilized parts of the canola plant, namely stalks and leaves, generate a great amount of biomass, commonly used as a cover crop for soil protection [2]. It must be emphasized that after seedling emergence, a single canola plant can grow up to 30 green leaves, making up 15–25% of its total biomass [3]. In terms of resources and production efficiency, utilization of all plant parts, such as canola leaves into food products can be an effective waste-to-value strategy, opening new economic opportunities for the canola supply chain and improving resource efficiency by valorizing this by-product. Like other Brassica species, canola aerial parts are rich in bioactive compounds like vitamins, pigments, polyphenols, and glucosinolates, which have been widely associated with potential health-promoting effects [4, 5]. For instance, glucosinolates and their hydrolysis products (e.g., isothiocyanates) are well recognized for their involvement in anti-cancer, anti-inflammatory, and antioxidant mechanisms on human body [4]. Beyond their antioxidant properties, polyphenols have received increasing attention for their potential role in modulating postprandial glycemic response, partly through the inhibition of carbohydrate-digesting enzymes as α-amylase and α-glucosidase [6]. Although phenolic compounds have been more frequently associated with modulation of carbohydrate-digesting enzymes activity, the potential contribution of other Brassica-derived metabolites within complex food matrices cannot be excluded.
Brassica by-products, including leaves, have been upcycled into powders, flours or extracts and used as functional ingredients in nutraceutical formulations, as natural colorants in beverages and as additives in fermented foods, sauces and bakery products [7]. Regarding wheat bread, Lafarga et al. [8] reported a substantial increase in the content of total phenolic compounds and antioxidant activity when 2 g/100 g of broccoli co-products, namely stalks and leaves, were incorporated. However, from the technological point of view, replacing wheat flour with vegetables leads to gluten dilution and structure disruption due to increased fiber content, which affects the properties of doughs and bread. Specifically, Korus et al. [9] demonstrated that incorporating lyophilized kale powder at 5 and 10 g/100 g resulted in increased dough development time and mixing tolerance index. Furthermore, they reported a more compact bread crumb structure which resulted in higher hardness and lower specific volume.
Sourdough fermentation remains widely used today, with its impact on dough and bread quality largely attributed to matrix acidification by lactic acid bacteria [10]. The lowering effect on the pH of a matrix by sourdough fermentation could be exploited as a modulator of the efficacy of bioactive compounds in slowing down the digestibility of starch. For instance, Aleixandre and Rosell [11] evaluated the impact of pure phenolics on corn starch gel microstructure, texture, and in vitro digestibility, with or without controlling the pH. They found that, despite variations due to compound type, all phenolics consistently reduced the rate and extent of starch hydrolysis by at least 5% at controlled pH levels.
To date, no studies concerning the inclusion of canola leaves in bakery products have been conducted. Therefore, the aim of the research was to evaluate the effect of replacing wheat flour with canola leaves powder (CL) alone and the combined effect of CL and sourdough on the quality characteristics of dough and bread. Additionally, the study explored whether CL-derived bioactive compounds, as indicated by total phenolic content, could contribute to modifications in starch hydrolysis kinetics, and whether sourdough acidification might enhance this effect within the bread matrix.
Impact of canola leaf powder and sourdough on the wheat flour functionality
Mixing properties of the doughs containing CL and sourdough are summarized in Table 1. The inclusion of CL significantly (p < 0.05) increased the dough development time and decreased stability with respect to control. Similarly, Korus et al. [9] reported a 5% increase in dough development time upon 5 g/100 g substitution with lyophilized kale, although they did not observe changes in the stability. Likely, the fiber content of the CL might interfere in the gluten formation, leading to a weaker structure. However, the effect could not be attributed only to fibers but also to phenolic compounds that might interfere with gluten hydration. In fact, Ning et al. [12] found a longer development time when adding green tea powder (1–4 g/100 g flour) to whole-wheat dough, likely due to phenolic compounds interacting with gluten proteins and delaying network formation. Incorporating sourdough also led to higher (p < 0.05) development time and lower stability values than the control and the SD. This effect can be attributed to the proteolytic activity of lactic acid bacteria and the activation of endogenous flour proteases induced by the acidification of the matrix, which results in different degrees of gluten depolymerization consequent weakening [13]. Finally, the combination of the two treatments (SDCL) led to the lowest (p < 0.05) dough stability values, but it seems that sourdough counteracted the impact of the CL on the development time.
Table 1.
Mixing behavior, gluten aggregation, and pasting parameters of control (CTRL) and doughs formulated with canola leaf powder (CL), sourdough (SD), or their combination (SDCL)
| Parameters | CTRL | CL | SD | SDCL | p (Sourdough) |
p
(Canola leaves) |
||
|---|---|---|---|---|---|---|---|---|
| Mixing properties | ||||||||
| Development time (min) | 1.8 ± 0.2 d | 8.6 ± 0 a | 3.9 ± 0 c | 4.8 ± 0b | 0.0001 | 0.0000 | ||
| Stability (min) | 18.1 ± 0.1 a | 1.7 ± 0b | 1 ± 0c | 0.7 ± 0d | 0.0000 | 0.0000 | ||
| Weakening (Nm) | 0.098 ± 0.001b | 0.442 ± 0.004 ab | 0.49 ± 0.014 a | 0.508 ± 0.168 a | 0.0188 | 0.0404 | ||
| Gluten aggregation properties | ||||||||
| Peak Maximum Time (s) | 74 ± 2.8 ab | 59 ± 7.1 bc | 77.5 ± 0.7 a | 47.5 ± 0.7 c | 0.2148 | 0.0012 | ||
| Maximum Torque (Nm) | 74 ± 1.7 a | 77.3 ± 0.2 a | 66.9 ± 1 b | 74.4 ± 0.3 a | 0.0032 | 0.0022 | ||
| EnMT (AU) | 1508 ± 30 a | 1024 ± 35 b | 1074 ± 13 b | 613 ± 15 c | 0.0000 | 0.0000 | ||
| Pasting properties | ||||||||
| Peak viscosity (cP) | 2512 ± 18 a | 2529 ± 11 a | 2400 ± 11 b | 2383 ± 38 b | 0.0013 | 1.0000 | ||
| Trough (cP) | 1502 ± 62 a | 1345 ± 37 a | 1313 ± 91 a | 1290 ± 66 a | 0.0619 | 0.1309 | ||
| Breakdown (cP) | 1011 ± 43 a | 1184 ± 27a | 1087 ± 102 a | 1093 ± 28 a | 0.8697 | 0.0964 | ||
| Final Viscosity (cP) | 2471 ± 23 a | 2300 ± 5 ab | 2262 ± 3 b | 2193 ± 86 b | 0.0076 | 0.0193 | ||
| Setback (cP) | 969 ± 38 a | 955 ± 42 a | 950 ± 94 a | 903 ± 20 a | 0.4168 | 0.4857 | ||
Values are expressed as mean ± standard deviation. Different letters in the same row indicate significant differences (p < 0.05). p-values refer to main effects and interaction from two-way ANOVA (Canola leaves: yes/no; Sourdough: yes/no). EnMT: energy to Maximum Torque
To gain additional insight into the impact of CL on gluten, the gluten aggregation test, by using the GlutoPeak, was performed. SDCL sample exhibited significantly lower (p < 0.05) peak maximum time than control (Table 1). The shorter peak maximum time observed in CL-containing samples suggests an accelerated protein aggregation under GlutoPeak conditions. It seemed that CL incorporation was predominant in fostering gluten aggregation. It has been reported that phenolic compounds can modulate gluten aggregation by either cleaving disulfide bonds or forming rapid non-covalent cross-links [14]. Although GlutoPeak indicated faster aggregation in CL-containing samples, this does not necessarily translate into shorter dough development times measured by Mixolab, since GlutoPeak evaluates rapid protein aggregation in diluted systems under high shear, whereas Mixolab monitors progressive dough development under continuous mixing and hydration. This suggested that the delay in the dough development during mixing might be therefore attributed to the leaves’ impact in the hydration of the rest of the wheat flour constituent and less on gluten aggregation. The maximum torque recorded at the gluten peak decreased significantly (p < 0.05) upon the incorporation of sourdough alone. Again, this reduction may be attributed to the weakening of the protein matrix, likely due to proteolytic activity occurring during sourdough fermentation that results in a softer and less elastic network [13]. The comparative analysis of aggregation energy (EnMT) showed a marked decrease following the addition of either CL or sourdough. Notably, the combination of both treatments resulted in the lowest EnMT value observed in the SDCL sample (613 AU), suggesting an additive effect of leaves and sourdough on protein aggregation. EnMT parameter has been validated as a reliable indicator of dough strength, with lower values typically associated with weak gluten matrix [15].
No meaningful differences were observed in the shapes of RVA curves derived from CL incorporation. The results are in contrast with those found by Krupa Kozak et al. [16], who replaced corn and potato starches in gluten free sponge cake formulations with 5 g/100 g broccoli leaf powder. The authors associated the decrease in peak and breakdown viscosities and the increase in setback mainly with starch dilution, but also with the high protein content of broccoli leaf powder (28.99 g/100 g). Considering that the protein content of the CL is much lower (9.52 g/100 g) than the reported for broccoli, that may account for the divergence. Conversely, the statistical analysis showed a prominent effect of sourdough incorporation on peak viscosity, with SD and SDCL having lower (p < 0.05) values. These results are consistent with Fadda et al. [17] study, where 20 g/100 g sourdough addition reduced peak viscosity compared to control, likely due to acid hydrolysis of starch in the presence of sourdough, leading to lower molecular weight products.
Bread proximate composition
The CL significantly reduced the pH, and as expected, that reduction was more pronounced in the presence of sourdough (Table 2). Moreover, an increase in total titratable acids (TTA) was observed because of CL substitution. A similar result was found by Martirosyan et al. [18], who supplemented 4 g/100 g of broccoli powder in wheat bread. This can be attributed to the intrinsic composition of canola, which, as reported for other Brassica species, are rich in organic acids such as malic and citric acids [19]. The organic acids produced by the lactic acid bacteria during fermentation led to a further increase of bread TTA in SD and SDCL, which differed significantly (p < 0.05) to the control.
Table 2.
Physicochemical properties, total phenolic content, proximate composition, color parameters, and crumb image analysis of breads formulated with canola leaf powder (CL), sourdough (SD), or both (SDCL). Proximate composition is expressed on a wet basis, whereas total phenolic content is expressed on a dry matter basis
| Parameter | CTRL | CL | SD | SDCL | p (Sourdough) |
p
(Canola leaves) |
|---|---|---|---|---|---|---|
| pH | 5.87 ± 0 a | 5.63 ± 0.01 b | 5.21 ± 0.02 d | 5.25 ± 0.01 c | 0.0000 | 0.0000 |
| TTA (mL NaOH/g) | 0.55 ± 0.06 c | 0.93 ± 0.05 b | 1.05 ± 0.06 a | 1.08 ± 0.05 a | 0.0000 | 0.0000 |
| Total phenolic content (mg GAE/g) | 0.57 ± 0.02b | 1.62 ± 0.02a | 0.37 ± 0.02b | 0.87 ± 0.01b | 0.0047 | 0.0001 |
| Moisture (%) | 33.95 ± 0.65 a | 29.13 ± 1.13 b | 32.46 ± 1.17 a | 27.04 ± 0.23 b | 0.0039 | 0.0000 |
| Protein (g/100 g) | 14.33 ± 0.31 a | 13.81 ± 0.44 a | 14.18 ± 0.15 a | 14.07 ± 0.26 a | 0.7799 | 0.1461 |
| Fat (g/100 g) | 0.11 ± 0.01 b | 0.24 ± 0.07 a | 0.10 ± 0.02 b | 0.22 ± 0.07 a | 0.4386 | 0.0001 |
| Ash (g/100 g) | 1.47 ± 0.01 b | 1.9 ± 0.13 a | 1.47 ± 0.01 b | 1.81 ± 0.09 a | 0.3057 | 0.0000 |
| Insoluble fibers (g/100 g) | 1.58 ± 0.03 bc | 2.48 ± 0.25 a | 1.1 ± 0.18 c | 2.31 ± 0.26 ab | 0.1275 | 0.0011 |
| Soluble fibers (g/100 g) | 0.64 ± 0.38 b | 2.28 ± 0.55 a | 2.06 ± 0.02 ab | 1.87 ± 0.41 ab | 0.0672 | 0.0357 |
| Total dietary fibers (g/100 g) | 2.22 ± 0.35 c | 4.76 ± 0.3 a | 3.16 ± 0.17 b | 4.18 ± 0.15 ab | 0.1184 | 0.0011 |
| Textural properties | ||||||
| Hardness (g) | 745 ± 100 b | 1890 ± 63 a | 507 ± 53 c | 906 ± 193 b | 0.0000 | 0.0000 |
| Springiness | 3.9 ± 0.62 a | 1.21 ± 0.31 b | 3.89 ± 0.54 a | 1.11 ± 0.09 b | 0.7829 | 0.0000 |
| Cohesiveness | 0.86 ± 0.01 a | 0.8 ± 0.02 b | 0.86 ± 0.01 a | 0.82 ± 0.02 b | 0.1905 | 0.0000 |
| Chewiness (g) | 2520 ± 643 a | 1838 ± 507 ab | 1699 ± 307 b | 818 ± 108 c | 0.0001 | 0.0003 |
| Resilience | 0.54 ± 0.01 a | 0.49 ± 0.04 ab | 0.45 ± 0.03 c | 0.5 ± 0.02 bc | 0.0105 | 0.0003 |
| Color | ||||||
| L* | 83.92 ± 1.05 b | 58.82 ± 0.83 d | 88.07 ± 2.51 a | 62.68 ± 0.94c | 0.0000 | 0.0000 |
| a* | 0.38 ± 0.17 a | -5.31 ± 0.39 c | 0.22 ± 0.12 a | -4.32 ± 0.26b | 0.0000 | 0.0000 |
| b* | 24.21 ± 0.3 c | 37.85 ± 1.13 b | 23.83 ± 0.7 c | 40.5 ± 1.78a | 0.0029 | 0.0000 |
| Crumb analysis | ||||||
| Mean cell area (cm2) | 0.071 ± 0.004 b | 0.015 ± 0.002 c | 0.11 ± 0.01 a | 0.018 ± 0.001 c | 0.0009 | 0.0000 |
| Cell density (cells/cm2) | 53.33 ± 6.42 a | 253.98 ± 31.42 b | 37.52 ± 6.8 a | 225.48 ± 2.48 b | 0.0042 | 0.0000 |
| 2D Area (cm2) | 16.13 ± 0.12 a | 15.75 ± 0.36 a | 15.93 ± 0.10 a | 15.63 ± 0.57 a | 0.6293 | 0.4133 |
Values are expressed as mean ± standard deviation. Different letters within the same row indicate significant differences (p < 0.05). p-values refer to main effects and interaction from two-way ANOVA (Canola leaves: yes/no; Sourdough: yes/no)
Bread containing CL showed an increased (p < 0.05) fat and ash content. In a recent comparative study, Santamaria et al. [20] reported that the incorporation of 2 g/100 g of green leaf powders such as spinach and chard significantly increased the ash content of flatbread, whereas such effect was not observed with kale or pak choi powders. Conversely, the incorporation of kale powder increased the fat content. Similar findings were reported by Ranawana et al. [21] who observed an increase in fat content when 10 g/100 g of freeze-dried broccoli powder was added to an oil-free bread formulation. The total dietary fiber content was significantly increased in bread containing canola leaves powder (CL and SDCL), due to the increase in soluble and insoluble fibers provided by CL. This is consistent with previous evidence with other Brassica species [9]. In comparison with control, the total phenolic content (TPC) in CL bread increased significantly (p < 0.05). An increased TPC content was also observed in bread containing several leafy vegetable powders at flour substitution levels ranging from 1 g/100 g to 3 g/100 g [22].
Impact of canola leaf powder and sourdough on bread quality
The proofing time of the different dough formulations was optimized based on fermentation kinetics, as described in the Materials and Methods section. In the SDCL formulation, although sourdough tended to prolong fermentation time, this effect did not fully counteract the fermentation-accelerating impact of CL, and proofing time remained shorter than in the control dough. A similar reduction in proofing time has been reported in fiber-enriched systems, where structural modifications and partial weakening of the gluten network facilitate faster dough expansion to a given height [23].
The incorporation of CL significantly (p < 0.05) increased crumb hardness. It has been already assessed that adding Brassica species in bread formulation leads to higher hardness [8, 9, 21]. Phenolic compounds in canola leaf powder may interact with gluten via hydrogen bonding, hydrophobic interactions, and thiol-disulfide exchange, as results of gluten aggregation indicated, leading to harder crumb [24]. The sourdough significantly (p < 0.05) decreases the hardness, presumably due to the proteolytic enzymes acting on gluten. Remarkably, the softening effect exerted by sourdough effectively counteracted the hardening of CL, as the hardness values of SDCL were comparable (p < 0.05) to that of the control. In addition, CL resulted in a significant reduction of springiness and cohesiveness, that was not counteracted with the concomitant addition of freeze-dried sourdough. Therefore, CL breads were more brittle with the tendency to crumble. Similar findings were reported by Korus et al. [9].
Color is a critical quality attribute in baked products, as it strongly affects consumer perception and expectations. As expected, the incorporation of canola green leaves resulted in negative a* values, indicating pronounced greenness, along with a reduction (p < 0.05) in lightness (Fig. 1). A synergistic effect between the two treatments was also observed for the crumb yellowness, as SDCL showed the highest b* values. A similar effect on crumb color was found by Korus et al. [9] after inclusion of kale at concentrations of 5 and 10 g/100 g and by Lafarga et al. [8] who incorporated 2 g/100 g of broccoli co-products into wheat bread formulations. Conversely, sourdough bread exhibited the highest crumb lightness, and this effect partially offset the darkening caused by CL, as reflected by the higher (p < 0.05) L* values observed in SDCL compared to CL.
Fig. 1.
Digitalized cross-sections of baked bread samples: control wheat bread (CTRL) and breads with canola leaf powder (CL), sourdough (SD) or both (SDCL)
Crumb grain structure, defined by the size, shape, and distribution of cells as well as cell wall thickness is a key determinant of bread quality. In this study, CL incorporation significantly (p < 0.05) influenced crumb pore uniformity and cell distribution. Compared to CTRL and SD bread, all CL-containing samples exhibited a finer and more homogeneous crumb structure. This was evidenced by a significant decrease in the proportion of large pores (> 10 mm²), a simultaneous increase in small pores (> 0.99 mm²) and a balanced intermediate gas cell class (0.99–9.99 mm2) (Fig. 2). This is further supported by the significantly higher cell density observed in CL and SDCL samples (253.98 and 225.48 cells/cm², respectively), along with the corresponding decrease in mean pore area (0.015 and 0.018 cm², respectively). Korus et al. [9] found an increase in pores density with a simultaneous significant (p < 0.05) decrease in the number of large pores (> 5 mm2), while Ning et al. [12] observed an increase in mean pore diameter after green tea leaves substitutions ranging from 1 to 4 g/100 g. On the other hand, sourdough incorporation in bread led to the largest mean cell area (0.11 cm2). Moreover, SD bread had the highest percentage of area occupied by pores bigger than 10 mm2, indicating coarser, and more irregular crumb grain. Area of bread slices remained unaffected by either CL or sourdough substitution (Table 2). Nonetheless, the cross-sectional images of the experimental breads presented in Fig. 1 may provide preliminary visual indications of possible differences. The similar 2D area suggests that structural changes occurred mainly at the microscopic level, as variations in cell sizes and density compensated each other, maintaining comparable slice dimensions across treatments.
Fig. 2.
Cell area distribution of control (CTRL) and breads with canola leaf powder (CL), sourdough (SD), and their combination (SDCL), as percentage of the total area according to three pre-selected dimensional categories: ▓Class 1 (< 0.99 mm²), ▓ Class 2 (0.99–9.99 mm²), ░ Class 3 (> 10 mm²). Bars with the same letter within each class do not differ significantly (p < 0.05)
Starch hydrolysis kinetics
Leaves inclusion did not result in a significant reduction in starch hydrolysis (k) with respect to CTRL (Fig. 3, Table 3). The sourdough presence led to a reduction (p < 0.05) in the k values compared to the control. Notably, the SD and SDCL bread exhibited stabilized pH around 5.2, matching the conditions of Aleixandre and Rosell [11] who studied the inhibitory effect of phenolic compounds on starch hydrolysis under controlled pH. Results are also consistent with Guzar et al. [25] who demonstrated that the stabilization of the pH near 5.2 allows phenolic compounds to effectively reduce starch hydrolysis rate. The C∞ value, representing the residual starch at the end of hydrolysis and thus the extent of starch hydrolysis, was significantly (p < 0.05) lower in CL. Conversely, the inclusion of sourdough led to the highest C∞ value, indicating a reduced hydrolysis extent. Remarkably, sourdough counteracted the hydrolytic activity induced by CL powder addition, as reflected by the higher C∞ value of SDCL compared to CL. The chemical changes occurring during fermentation with sourdough limit starch gelatinization, partly explaining the reduced digestibility of cereals treated with sourdough [26]. These findings were supported by the correlation analysis between enzymatic starch hydrolysis kinetics and starch gelatinization, which revealed a strong positive relationship between k and final viscosity (r = 0.99), and a negative correlation between C∞ and peak viscosity (r = – 0.70). Although the phenolic fraction was assessed only through total phenolic content (TPC), thus providing a broad, non–compound-specific estimation, the observed correlation between TPC, sourdough addition, and the slowdown of starch digestion represents a meaningful and valuable finding. Nevertheless, the possible contribution of other bioactive compounds, including glucosinolates, to starch digestibility modulation [27] cannot be excluded and deserve further investigation.
Fig. 3.
Variation of apparent viscosity during enzymatic hydrolysis of control (CTRL) and breads containing canola leaf powder (CL), sourdough (SD), and their combination (SDCL) expressed as viscosity (cP) over time (min)
Table 3.
Starch hydrolysis kinetics in control (CTRL) bread and breads with canola leaf powder (CL), sourdough (SD), and their combination (SDCL). Kinetics were evaluated using the RVA digestograms
| Parameter | CTRL | CL | SD | SDCL | p (Sourdough) |
p
(Canola leaves) |
|---|---|---|---|---|---|---|
| k (min− 1) | 2.56 ± 0.23 a | 2.04 ± 0.01 ab | 1.9 ± 0.05 b | 1.5 ± 0.11 b | 0.0031 | 0.0080 |
| µ∞ | 1707.17 ± 38.94 b | 1256.67 ± 8.58 c | 2233.56 ± 5.89 a | 1712.44 ± 101.95 b | 0.0002 | 0.0002 |
| µ₀ | 6094 ± 45.255 a | 5352 ± 39.598 b | 6037 ± 28.284 a | 5355 ± 121.622 b | 0.6109 | 0.0001 |
Values are expressed as mean ± standard deviation. Different letters within the same row indicate significant differences (p < 0.05). p-values refer to main effects and interaction from two-way ANOVA (Canola leaves: yes/no; Sourdough: yes/no). Parameters: First-order hydrolysis rate constant (k); initial viscosity (µ₀); viscosity at the end of the digestogram (µ∞)
Conclusions
Using CL in breadmaking can represent a valuable tool for harnessing a by-product of an extensively cultivated Canadian crop within the circular economy framework. CL and freeze-dried sourdough significantly modified dough and bread properties. Replacing wheat flour with 5 g/100 g CL and/or 20 g/100 g sourdough, significantly changed the dough mixing behavior and gluten aggregation properties compared to control dough, with CL mainly acting on gluten development and aggregation, while sourdough had impact on gluten aggregation and starch gelatinization, lowering the peak and final viscosities. From a technological standpoint, the shorter proofing time observed in CL-containing formulations may represent an advantage by reducing fermentation duration while improving the nutritional profile of the final product. CL-enriched breads exhibited a finer and more uniform crumb structure, although the hardness was significantly higher than the control. However, the addition of sourdough counterbalanced the fiber-induced increase in bread firmness due to CL. The combination of sourdough and CL significantly reduced the rate of starch digestibility. This effect may be partly attributed to the acidic environment generated by sourdough fermentation, which could enhance the inhibitory activity of polyphenols on starch-digesting enzymes. Nevertheless, although an assessment of total phenolic content (TPC) was performed and revealed an association between increased TPC levels, sourdough incorporation, and reduced starch digestibility, a more advanced quantitative and qualitative profiling of individual phenolic compounds would be required to conclusively elucidate the underlying mechanisms. Moreover, Brassica species are known to contain other bioactive compounds, such as glucosinolates, which may also contribute to the nutritional and functional properties of the experimental bread. However, their quantification was not included among the targeted analyses of this preliminary study and warrants further investigation. Finally, it is important to acknowledge that the absence of sensory evaluation represents a limitation of this study, and future research will therefore include sensory testing to guide product optimization.
Supplementary Information
Below is the link to the electronic supplementary material.
Author contributions
Emanuele Tomassini : Writing – original draft, Investigation; Formal analysis; Data curation . Nicola Gasparre : Writing – review & editing; Supervision; Conceptualization; Funding acquisition. Robert Duncan: Writing – review & editing. Antonio Piga: Writing – review & editing; Supervision Cristina M. Rosell : Writing – review & editing; Conceptualization; Supervision; Investigation; Funding acquisition.
Funding
This work was financially supported by the NSERC Discovery Grant Program (RGPIN-2023-04289) and by the Canada Foundation for Innovation (44211) and Research Manitoba (6399).
Data Availability
Data will be available from authors upon request.
Declarations
Ethics Approval
Not applicable.
Consent for participation and publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
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Data will be available from authors upon request.