Chubak is a plant belonging to the family Caryophyllaceae and the genus Acanthophyllum (Figure 15.1a). Chubak has wooden pillow‐shaped shrubs with biting spurs (their leaves deform to spurs). Some shrubs and some with thick root and mostly grown in Iran are Acanthophyllum, and a number of others, which are annual and perennial but herbaceous, are of the Saponaria genus, which is mostly grown in Europe, but a few are also seen in Iran. A total of 61 species of this genus are found worldwide, and of these, 33 species are capable of growing in Iran, and 23 species are native to this region . On the basis of available sources, most of these species have been identified in the eastern parts of Iran (Khorasan Province) and its adjacent regions (Afghanistan and Turkmenistan) . The root of Chubak (Figure 15.1b) is a valuable source of saponin, which is one of the most important active compounds in it, and many previous works have focused on identifying its structure, physicochemical properties, and biological activity [3–6]. In addition to saponin, polysaccharides and water‐soluble gum (hydrocolloids) are also other important compounds whose presence in the roots of the various species of the plant has been reported [7,8]. The lower parts of the plant are completely wooden, the flowers are white, the length of the plant is 20–25 cm, the length of the leaf is 1–2 cm, it has five petals, the tip is wide and white, and the bottom is red . In general, they are called Saponaria in French and soapwort in English . A species of this genus, called Acanthophyllum squarrosum, has long been known as “Chubak” or “bayk” for people, who have been using the thick root for washing and cleaning clothes due to its saponin substance, which is similar to soap, and for making a sweet dessert (known as Halvah in Iran). The Acanthophyllum genus of the Acanthophyllum mucronatum species was named for the first time in 1831 by Mayer. Since then, 14 species have been introduced in five classes by the Bowsia in the eastern flora. The oldest list of Acanthophyllum species in Iran has been presented by Professor Rahmat Parsa [ 1,11]. It has been demonstrated that the purified Chubak extract contains 84.3% carbohydrate, and that this amount of sugar is higher than that of guar gum and a little less than that of xanthan gum and gum arabic. Analysis of monosaccharides by HPLC also showed that the water‐soluble polysaccharides extracted from this extract are a type of glucoarabinogalactan polysaccharide [ 7, 8]. In this chapter, the characteristics of Chubak root hydrocolloidal extract and its application in different food products based on its functional properties such as emulsifying, aerating, and stabilizing agents are reviewed.
The extraction process is an important primary step in the purification of active compounds in different plant organs. Conventional extraction methods such as Soxhlet extraction method, which has been used for many decades, are very time consuming. In addition, these methods require the use of high levels of solvents . That is why there is a lot of demand for new extraction methods with shorter time, less solvent consumption, greater efficiency, and environmentally safe .
The production of the CRE with high saponin content in a shorter time and using less solvent for its use in food formulations was evaluated by Keyhani et al. . The extraction process was performed with the Soxhlet method as well as the ultrasound technique, and the extraction efficiency was evaluated by determining the emulsification index (E24) and foaming ability (Fh) [15,16]. In order to optimize the extraction conditions, the effects of sonication time, temperature, ultrasonic wave intensity, particle size, solvent‐to‐sample ratio, and solvent concentration on the extraction yield were determined.
It was shown that the saponins extracted by the ultrasonic method has a higher emulsifying and foaming ability (P < 0.05) compared to those extracted by the conventional (Soxhlet) method. The maximum amounts of E24 and Fh were achieved by the conventional method after 480 min of extraction, which was close to the E24 and Fh values after 40 min of extraction with ultrasound, as there was no significant difference between them (P > 0.05). On the basis of this, it can be stated that the extraction time with ultrasonic waves decreases by about a factor of 12 compared with the conventional method of producing Chubak extract with high saponin content, but with the same emulsification and foaming characteristics. The capability of the ultrasonic technique to increase the speed of extraction of saponins from the roots of Chubak plant and as a consequence, shortening the extraction process time, is also evident in the results of other researchers [17–22]. Increasing the sonication time from 10 to 40 min increased the E24 and Fh values significantly (P < 0.05); however, in the range of 40–60 min, this increase was much slower and not significant (P < 0.05). In addition, it can be concluded that during extraction of CRE with ultrasonic waves, the major part of saponin compounds are extracted from the Chubak root in the first 40 min of sonication. As a result, it will be possible to achieve extra efficiency in the early stages of extraction. With the continuation of the extraction process and as the phenomenon of diffusion to the more inward parts of the plant tissue continues, the diffusion rate decreases with prolongation and hardening of the diffusion pathway, because of the lower diffusion level and also the decreased concentration gradient in the perimeter of the specimen. Finally, there is no apparent change in the amount of extraction [19, 22]. With increasing temperature, the E24 and Fh values exhibit a significant upward trend (P < 0.05), so that it can be concluded that the extraction efficiency of saponins increased with increasing temperature in a constant time range. Increasing the temperature can also cause the cell walls to open, which makes target compounds available. Moreover, at high temperature, the viscosity of the solvent decreases and the diffusion rate increases; therefore, the extraction efficiency increases . The E24 and Fh values significantly (P < 0.05) increased as the intensity of ultrasound waves was increased by 80%, but by increasing this factor from 80% to 100%, not only was this increase was not observed but a small decrease was observed instead. Then, in the extraction with ultrasonic waves, the amount of energy transferred from the sonicator to the environment is directly related to the sound intensity of the device. Therefore, by increasing the intensity, more energy is introduced into the environment, which increases the extraction efficiency. However, if this output power is too high, it will result in an excessive increase in the number of bubbles in the outer solvent during cavitation, which can reduce the amount of energy generated by the sonication applied, and thus the extraction efficiency will not increase . With a decrease in the particle size of the sample to 0.1–0.4 mm, the values of E24 and Fh increased significantly (P < 0.05), but with a further reduction to <0.1 mm, no increase was observed. It can be stated that, in general, in the case of constant weight of solids as the particle size decreases, the surface area increases and the diffusion phenomenon is effective in increasing the extraction efficiency, but when the sample size is too small, the use of ultrasound waves causes severe cell failure, which is not a good result of the diffusion phenomenon and ultimately does not significantly increase the extraction efficiency .
Increasing the ratio of solvent to sample from 10 to 25 ml g−1 caused a significant increase in the E24 and Fh values (P < 0.05), but increasing it to 55 ml g−1 did not only increase these amounts but also reduce them. This means that at a low ratio of solvent to sample, solvent saturation occurs faster, and as a result the extraction efficiency decreases. When this ratio is increased, a greater concentration between the plant cells and the external solvent is produced, and the extraction of the target compounds is improved, but if the use of the solvent is excessive and the solution becomes very dilute, this additional solvent does not increase the concentration difference significantly, and it is even possible to limit the extraction efficiency . Increase in the solvent concentration from 20% to 60% increased E24 and Fh amounts significantly (P < 0.05). However, its increase by up to 80% caused a decrease in these values. As a result, at a solvent concentration of 60%, a higher amount of saponin is extracted. In this connection, it may be noted that saponins are compounds that are soluble in pure alcohol or in dilute alcohol . It seems that the saponins in CRE are better dissolved in a slightly diluted alcohol, as a result of which extraction is improved. While during conventional extraction the highest E24 and Fh values were 0.581 and 4.467 cm, respectively, the creation of optimal conditions for factors affecting ultrasound extraction caused the increase of E24 to 0.764 and Fh to 7.033 cm. The use of the ultrasonic technique to extract saponins from the ginseng plant also increased the extraction efficiency by 30% compared with the classical method . This improvement in extraction efficiency due to the use of the ultrasound waves compared to the conventional method during extraction of saponins was also reported from mangrove leaves , root of Radix Bupleuri , and root of different species of the ginseng plant . The extraction temperature, ultrasonic wave intensity, particle size, the solvent‐to‐sample ratio, and solvent concentration increased the extraction efficiency of saponin from CRE. Another important point is that extraction with ultrasound waves, by making it feasible to provide CRE faster and at a lower temperature, prevents the heat damage of saponins and elimination of their functional characteristics, in particular, the emulsification and foaming properties that are required in the processing of certain foods.
CRE is rich in saponins, which have antioxidant and antimicrobial properties and prolonged shelf life in bakery and fried products. The effect of CRE on the physicochemical and microbial properties of doughnut was investigated at the levels of 0.1, 0.2, and 0.3 g/100 g of doughnut dough . The antioxidant activity of doughnut containing CRE was evaluated using the percentage of free radical scavenging , total phenolic compounds , and peroxide value .
The results showed that the effect of CRE on the antioxidant activity of doughnut was significant (P < 0.01). The highest percentage of free radical inhibitory was observed in the doughnut sample containing 0.3% of CRE and on the first day of storage. When the CRE level was increased, the antioxidant activity increased. Pourhaji et al.  evaluated the antioxidant properties of green tea and ascorbic acid in the formulation of fried doughnuts and also concluded that natural antioxidants have more free radical scavenging activity than the control sample containing synthetic antioxidants. These results are also consistent with the report of Tsong et al. . The maximum total phenolic compounds were observed for the sample containing 0.3% CRE and on the first day (P < 0.01). The phenolic compounds extracted from the plants do not disappear during baking, which is why phenolic compounds are also effective at high temperatures. High temperature during cooking eliminates some of the ingredients in foods, as a result of which the phenolic compounds of the extract increase. This result was consistent with the results of Holtekjolen et al. . The highest peroxide value was observed for the control sample, but it was decreased by adding CRE to the doughnuts. The saponin in CRE is responsible for the antioxidant activity which absorbs the radicals produced during oxidation reaction, forms a p‐quinone complex, and prevents the formation of rancid flavors . Izzreen and Noriham  investigated the antioxidant effect of Malaysian herbs on the cake, and they reported that the peroxide value was still acceptable after 15 days of storage. Also, they stated that ascorbic acid, along with other antioxidants such as vitamin E, citric acid, and so on, reduces the oxidation rate.
From the results obtained in relation to the moisture content analysis during storage time, it can concluded that the moisture content of all samples decreased during storage time, but compared to the control sample, CRE added to doughnuts has been more effective in slowing down the rate of this reduction after several storage periods. Maintaining moisture is one of the properties of saponin contained in CRE; the results obtained were consistent with the research conducted by Alberice and coworkers . This moisture‐retaining effect on the softening of the doughnut crumb is quite impressive.
The results of the textural attributes of doughnuts showed that the control sample had the highest hardness, and an increase in the percentage of CRE reduced the harness of doughnut (Figure 15.2). Also, during storage until the third day, the hardness of the samples increased.
With the addition of CRE to doughnuts, the number of microorganisms decreased, which is due to the antimicrobial properties of saponins. Li et al.  concluded that saponins, as a natural biochemical agent, are effective in reducing microorganisms and inactivating foodborne viruses. Alberice et al.  in a study on preventing the growth of spoilage agents in orange juice concluded that saponin extract of Sapindus saponaria with thermal treatment is completely effective in disabling Alicyclobacillus acidoterrestris, which is a spoilage agent in orange juice.
In general, the results of the research done by Entezari et al.  showed that the increase of CRE in doughnut formulation increased the amount of moisture content, and doughnut texture remained fresh and soft until the last storage day. Also, adding Chubak extract to the doughnut formulation significantly increased antioxidant properties and phenolic compounds, and decreased peroxide value and total count.
The effect of CRE addition (at the levels of 0.1%, 0.2%, 0.3%, and 0.4%) and storage time on the physical, chemical, rheological, and textural properties of yogurt was investigated [38–40]. With addition of CRE, the syneresis of yogurt samples decreased significantly compared to control treatment (yogurt sample without CRE). Syneresis in yogurt is due to the shrinkage of the 3D structure of the protein network, which leads to a reduction in the binding power of whey proteins and its exclusion from yogurt. In addition, with increasing CRE concentration in yogurt samples, the syneresis exhibited a decreasing because of the denser gel network formed due to the water absorption properties of this gum. The results of this research are consistent with the results reported by Violeta et al.  and Ghorbani et al. . Staffolo et al.  showed that yogurt containing apple fiber and wheat fiber had less syneresis than non‐fiber samples.
The viscosity of yogurt is an important feature that affects its quality. According to Table 15.1, yogurt containing CRE had the highest apparent viscosity (222.29 mPa s) at 0.4% concentration and after 21 days storage, whereas the lowest apparent viscosity (153.85 mPa s) was observed for the control sample on the first day. During the storage period, the apparent viscosity increased in all samples. This increase in viscosity during storage can be due to (1) changes in the protein–protein binding in the three‐dimensional protein network of yogurt  and (2) the increased binding capacity of water to CRE, which reduces the flowability and increases the resistance to flowing, or the apparent viscosity . At higher CRE concentrations, intermolecular entanglement and internal droplets will increase viscosity and increase the limitation of molecular drift due to the entanglements between polymeric chains. Investigations have shown that increasing the inulin concentration in low‐fat yogurt increases the apparent viscosity . Also, increasing the beta‐glucan concentration had a positive effect on the viscosity of non‐fat yogurt , while concentrations higher than 0.02% of locust bean gum reduced the apparent viscosity of low‐fat yogurt . The increased apparent viscosity of yogurt has been reported during the storage period by Abu‐Jdayil and Mohameed .
Table 15.1 Effect of Chubak root extract (CRE) and storage time on the apparent viscosity (mPas at shear rate 50 s1) of yogurt samples.
Source: Safari et al. .
|CRE concentration (%)||1st day||7th day||14th day||21st day|
As shown in Table 15.2, all samples produced at different CRE concentrations and storage times exhibited a flow index behavior (n) value less than unity, confirming shear‐thinning or pseudoplastic behavior. In this research, the flow behavior index of the samples decreased with increasing CRE concentration, indicating greater pseudoplasticity (or viscosity changes with shear) at higher CRE concentrations. According to the Herschel– Bulkley model, increasing the CRE concentration increased the consistency coefficient (k) and yield stress (τ0) of yogurts. On the first day after production, the highest value of yield stress (24.56 Pa) was related to the sample containing 0.4% CRE, whereas the lowest yield stress (16.26 Pa) was related to the control sample. The effect of storage time on the flow behavior index confirms that more interactions in yogurt structure occur during the storage period, which leads to further development of the yogurt gel structure and more protein‐polysaccharide stabilization. It seems that a rearrangement of the protein structure is responsible for increasing the viscosity of the samples. Such a rearrangement in the protein structure is very similar to that of acid casein gels , and the decrease in the flow behavior index (a greater deviation than in Newtonian behavior) during the storage period is strong evidence that new interactions occur during the storage period.
Table 15.2 Herschel–Bulkley model parameters determined for yogurt samples as influenced by the Chubak root extract (CRE) concentration and storage time.
Source: Safari et al. .
|CRE concentration (%)||Storage (day)||σ0 (Pa)||k (Pa sn)||n (−)||R2|
σ0, Yield stress; k, consistency coefficient; n, flow behavior index.
Texture is one of the important factors in the quality evaluation of semi‐solid foods like yogurt, which influence their acceptance and satisfaction by consumers. Adding different concentrations of CRE to low‐fat yogurt produced a significant difference compared to the control sample. The highest (4.69 g) and lowest (2.87 g) hardness values were observed in the sample containing 0.4% CRE on the 21st day and the control sample on the first day, respectively (Table 15.3). These results are probably due to the increased viscosity of samples containing high levels of CRE. The viscosity of the samples can, in part and not completely, reflect the parameters of the texture analysis . Over time, the hardness of the samples increased, which is due to changes in the arrangement and interconnection of proteins . The adhesiveness of the control sample increases when CRE is added to the low‐fat yogurt. In this regard, it can be stated that considering the adhesive force – which is the force required to overcome the surface weight between particles – if the gel structure and protein network of the yogurt samples have more stiffness, the adhesive force is also higher, which confirms the results of the texture hardness parameters. Increasing the concentration of hydrocolloids increased the adhesiveness of the samples, which could be due to the creation of a stronger 3D network in these samples. The addition of a polysaccharide may increase the elasticity of the product by forming a strong quasi‐gel structure, resulting in a more cohesive and rigid structure . In sum, increasing the CRE concentration in yogurt formulations significantly increased the rheological properties and decreased the syneresis content [ 38– 40]. The results also show that CRE has good potential as a stabilizing agent in yogurt formulations.
Table 15.3 Textural properties of yogurt samples as a function of Chubak root extract (CRE) concentration and storage time.
Source: Safari et al. .
|CRE concentration (%)||Storage (day)||Hardness (g)||Adhesiveness (g·s)|
Ketchup or tomato sauce is a heterogeneous suspension product of tomato paste or fresh tomato and is produced by the combination of additives such as spices and thermal processing; for this reason, phase separation control is very important. Ketchup consistency or viscosity is the most important feature from the engineering and consumer perspectives .
CRE was used in ketchup formulation , and the rheological properties of samples containing CRE (0.5%, 1%, and 1.5%) and the control sample were investigated using the method described in  and a rotational Brookfield viscometer (with a shear rate of 0–100 s−1). The flow curves of the samples were successfully fitted by the Bingham model. The results presented in Table 0 show that the Bingham plastic viscosity (ηB) increased as the concentration of CRE increased. The highest ηB (11.13 mPa s) is related to the sample with the maximum CRE concentration, and the least amount (10.16 mPa s) is for the control sample. The addition of CRE increased the Bingham yield stress (τ0B). This data is consistent with the results of Correia and Mittal . The Bingham rheological parameters of all samples were increased after 60 days of storage, which could be due to the increased water‐binding capacity of CRE (high water absorption of hydrocolloids), which reduces the flowability and increases the resistivity of the sample against flow (Table 0). These results are consistent with the research conducted by others [ 53 57–59]. The consistency of the ketchup samples (Brix 21) measured by a Bostwick consistency meter (at 25 °C for 30 s of flow) showed a similar trend as the Bingham rheological parameters (Table 0). Sahin and Ozdemir  investigated the effect of some hydrocolloids and concluded that by increasing the concentration of hydrocolloids, the consistency coefficient and apparent viscosity increase and the amount of Bostwick flow decreases. In summary, it can be said that ketchup sauce can be prepared with proper consistency and viscosity using CRE as a thickener. The addition of CRE in moderate concentrations improves texture quality in ketchup and is recommended as a suitable herbal source for use in the sauce industry. The highest viscosity and yield stress were reported for the sample containing 1.5% CRE. So adding hydrocolloids to ketchup, in addition to increasing its viscosity, reduces serum separation.
Table 0 Effect of Chubak root extract (CRE) and storage time on the rheological properties of ketchup.
Source: Hosseini Tabatabaie et al. .
|0 (day)||60 (days)||Bostwick consistency (mm)|
|CRE (%)||η B (mPas)||τ0B (Pa)||R2||η B (mPas)||τ0B (Pa)||R2||0 (day)||60 (days)|
a Data are the mean of three replications.
The effects of CRE, quillaia extract, and propylene glycol alginate on the foaming, physicochemical, and sensory properties of non‐alcoholic flavored (lemon) and simple (black) beers were investigated [61–64]. Turbidity, color, total soluble solids, carbon dioxide, pH, bitterness, taste, and odor were the most important qualitative characteristics measured for the samples (Tables 15.5 and 15.6). According to the analysis of sensory evaluation of non‐alcoholic lemon‐flavored beer sample, the bitterness was relatively tangible, but the taste of bitterness and astringency was quite obvious for the simple (black) beer sample.
Table 15.5 Some physicochemical and sensory properties of non‐alcoholic lemon‐flavored and black beers.
|Non‐alcoholic beer type||TS (oBrix)||pH||Taste and odor||Turbidity (EBC)||Color (EBC)||CO2 (g per 100 ml)|
Table 15.6 Foaming properties of non‐alcoholic lemon‐flavored and non‐flavored beers as affected by quillaia extract, Chubak root extract (CRE), and propylene glycol alginate.
|Lemon‐flavored beer||Simple (black) beer|
|Concentration (g l−1)||Time (s)||QE||CRE||PGA||QE||CRE||PGA|
QE, Quillaia extract; CRE, Chubak root extract; PGA, propylene glycol alginate.
To increase the stability of emulsion–foam systems, the surface tension between two immiscible fluids must be decreased; in the food industry, a series of surface‐active agents called emulsifiers are used for this purpose. The results showed that there were significant differences between the lemon‐flavored beer samples containing CRE, quillaia extract and propylene glycol alginate in terms of foaming capacity and stability at concentration levels of 0.1%, 0.2%, and 0.3%, in addition, they were able to form foam and maintain foam at low concentrations; however, the foaming capacity of quillaia extract was greater than that of CRE and propylene glycol alginate at all levels (Table 15.6). It should be noted that in general the foaming capacity and stability of the foam in the beer samples containing quillaia extract has shown the highest increase compared to CRE and propylene glycol alginate (Table 15.6). According to this assessment, the best levels of application of the selected emulsifiers are 0.05 and 0.1.
The effect of CRE alone and in combination with mono‐ and diglyceride emulsifiers (E471) at three levels (0%, 0.5%, and 1%) on the physicochemical properties (pH, specific gravity, color parameters, rheological properties, specific volume, porosity, and textural attributes) of muffin cake was investigated .
The addition of CRE and E471 alone led to a decrease in the pH of the muffin dough; however, this decrease was not significant (P < 0.05). Their simultaneous application intensified the decreasing trend (Table 15.7). The greater role of CRE in decreasing pH can be attributed to the presence of terpenoid‐type saponins in CRE. In some sources, they are also referred to as acid saponins . The specific gravity of muffin cake dough can be used to determine the number of air bubbles entering the dough and the amount of air holding during mixing of the dough, and usually, its lower content in the dough represents a higher volume in the cake . As seen in Table 15.7, the addition of CRE, as well as E471 alone, significantly reduced the specific gravity of the dough (P < 0.05). Their simultaneous use also led to a smaller value for this index. That demonstrates the strong capability of CRE to enter more and smaller air bubbles into the dough texture and actually improves its aeration activity.
Table 15.7 Influence of Chubak root extract (CRE) and E471 emulsifier on some physicochemical properties of muffin dough.
Source: Keyhani et al. .
|CRE (%)||E471 (%)||pH||L*||a*||b*||S.G. (g cm−3)||n (−)||k (Pa sn)|
S.G.: specific gravity.
a–f: Different letters in each column represent existence of a significant difference at a 5% probability level.
Adding CRE and E471 alone increased the L* index of dough. Their simultaneous use intensified this incremental trend. The reverse results were obtained for the a* and b* indices (Table 15.7). The greater the L* index of dough, the greater the capability of CRE to bleach the dough. As shown in Table 15.7, the flow behavior index (n) for the dough of all muffin samples was less than 1, indicating non‐Newtonian shear‐thinning flow behavior. The addition of CRE and E471 alone significantly decreased n and significantly increased the consistency coefficient (k) values (P < 0.05); however, CRE was more effective than E471 in the development of these changes. In the case of the apparent viscosity, as shown in Figure 15.3, the viscosity of dough decreased with increasing shear rate in all samples. Another noteworthy result was that samples containing larger amounts of CRE and E471 had a higher viscosity (Figure 15.3). The very low viscosity of the dough causes the air bubbles to easily reach the surface, and they might get lost when it is broken; also, trapped air bubbles in dough during its mixing may not be retained in the cake while baking, which leads to the destruction of the structure of the cake in the oven . Now, if the distribution of air particles in the dough is favorable, the viscosity increases, leading to a better volume and texture in the final product . Similar results showed the ability of emulsifiers to increase the viscosity of cake dough and improved the quality of the final product [ 67–70].
The addition of CRE and E471 alone significantly increased the cake specific volume (P < 0.05). The superiority of CRE compared to E471 was significant in the increase of this index. With their simultaneous application, the specific volumes were further increased. The correlation between these results with the results obtained for specific gravity and viscosity was expected, because usually the increase in the volume of the cake occurs as a result of a reduction in the specific gravity of the dough ; on the other hand, it is obviously dependent on changes in viscosity . The addition of CRE and E471 alone was accompanied by a significant increase in the cake porosity (P < 0.05); however, the CRE effect was more potent than E471's. In justifying this result, it can be stated that using emulsifiers, air bubbles are finely and homogeneously distributed in all parts of the dough, and over the baking time, the air removal of these bubbles is uniform. As a result, the cake will produce a porous texture, while the probability of the tunneling phenomenon will be lower [71,72]. In this connection, Del Vecchio  showed that emulsifiers, by affecting the size of air cells in the dough, can reduce the number of tunnels in the cake and observed that the use of SSL emulsifiers at both 0.4 and 1 g levels reduced tunneling compared to the control sample. Zeleznak and Hoseney  and Rogers et al.  also reported similar results.
The addition of CRE and also E471 alone significantly decreased the hardness of the muffin samples (P < 0.05). Their simultaneous use also exacerbated this downward trend. During the storage time, the hardness of all samples increased, but the important observation was that compared to the control sample, both additives were effective in slowing down the rate of this increase, and of course, in this regard, E471 showed better performance than CRE (Table 15.8). In fact, emulsifiers, by creating complexes with starch and being absorbed on its surface by decreasing the water output of gelatinized starch, delay the staling process. In addition to the above, the advantages of reducing firmness and delaying staling in the muffin cake that CRE and E471 have shown in this section can be attributed to the moisture characteristic. On the other hand, the occurrence of staleness in bakery products such as bread and cake is related to the amount of moisture and the rate of water loss in the crumb of these products , so that there is a correlation between the moisture content of the bread and the degree of its staleness . In fact, water can be effective in reducing the firmness of the brain by playing a plasticizing role. In addition, because increasing the amount of available water for starch increases the chances of crystallization, the considerable tendency of emulsifiers to absorb water and their high water retention capacity make less water available to starch. As a result, less starch is swollen, gelatinized, and during storage is crystallized again, which eventually reduces firmness and delays staling of the product [75,76]. This mechanism has also been reported in cake by many researchers for other emulsifiers [69, 70 77–79].
Table 15.8 Influence of Chubak root extract (CRE) and E471 emulsifier on the moisture content and hardness of muffin cake during storage.
Source: Keyhani et al. .
|Moisture content (%)||Hardness (g)|
|CRE (%)||E471 (%)||1 day||2 day||10 day||1 day||2 day||10 day|
a–h: Different letters in every column represent existence of a significant difference at a 5% probability level.
In summary, the use of CRE in the formulation of muffin cake decreased the specific gravity, increased the L* index and viscosity in the case of dough, and increased the specific volume, porosity, moisture, and softness in the case of cake. These findings clearly highlight the possibility of introducing this new extract as a natural, inexpensive, and affordable emulsifier.
In regard to egg white problems, much research has been done to replace whole or partial egg whites in the formulation of various cakes using different ingredients (mainly those with the ability to create a stable foam) [ 65, 70 80–92]. Levels of 25%, 50%, and 75% by weight of egg whites in the formulation of sponge cake were replaced with CRE .
The partial replacement of egg white with CRE and also with water reduced the pH of the dough (Table 15.9). The process of pH reduction during replacement with CRE showed a more severe condition, as the minimum value for this attribute was found at 75% substitution level. In justifying this finding, it should be noted that egg white pH was about 8.7, and the pH value of the CRE was about 5.4; hence, a reduction in the pH of the dough was expected during the partial replacement of egg whites (a relatively alkaline mixture) with CRE (a relatively acid compound). The partial replacement of egg whites with CRE caused a significant increase in the L* index and a significant reduction in a* and b* indices (P < 0.05). The higher L* index of dough for CRE samples compared to the other samples is due to the bleaching ability of CRE (Table 15.9). Increasing the level of egg white replacement with CRE resulted in higher values for specific gravity, but this incremental trend was not significant. Unlike CRE, during the partial replacement of egg whites with water, the increase in specific gravity was significant (P < 0.05). The results obtained in this section clearly showed that CRE with its extraordinary foaming ability introduces a large quantity of air into the dough by increasing the number of air bubbles and also reducing their size, and has the same function as egg whites. Celik et al.  also concluded that the partial replacement of egg whites with saponin extract of soapwort plant does not significantly increase the specific gravity of the dough.
Table 15.9 Egg white substitution effect with Chubak root extract (CRE) and water (W) on physicochemical properties of dough.
Source: Karazhiyan and Keyhani .
|Treatment||pH||L*||a*||b*||S.G. (kg m−3)||n (−)||k (Pa sn)|
S.G., Specific gravity; n, flow behavior index; k, consistency coefficient.
a–e: Different letters in each column represent existence of a significant difference at a 5% probability level.
All sponge cake samples showed non‐Newtonian shear‐thinning behavior (n < 1, Table 15.9). The partial replacement of egg white with CRE increased the n value and reduced the consistency coefficient (k). The results of this research established that CRE can be effective in maintaining the coherence and stability of the cake dough in the absence of part of the egg whites. This finding can be explained by the presence of polar and non‐polar groups in the structure of saponins in the CRE, which enables this extract to facilitate proper aeration and the formation of emulsions. The emulsification effect of CRE on the viscosity of the dough as established by the accuracy of the results obtained by others [ 66, 67, 69, 70] has become more important. The researchers argued that emulsifiers are able to increase the viscosity of the cake by enabling proper distribution of air in the cake dough, thereby improving the quality of the final product. The use of similar saponin extracts such as soapwort extract in Halva  and quillaia extract (E999) in baked products  as an emulsifier confirms this role of CRE.
The effect of the partial replacement of egg white with CRE as well as with water on the L*, a*, and b* parameters of crust and crumb was similar to the effect on the same parameters of dough. At the end of the baking process, CRE samples were compared to the control sample, and in particular, the samples replaced with water had a more pronounced appearance; these observations were consistent with the values recorded for the L* index of the samples. Removal of egg white reduced protein levels, thus reducing the intensity of the Millard reaction, and eventually a lighter color is observed in the cake crust. The results for specific volume and porosity indicated the effective role of CRE in retention of air bubbles in the structure of cake during baking and also in the creation of texture with fine and uniform cavities in the final product. Specific gravity, viscosity, specific volume, and porosity are characteristics which are particularly affected by the process of aeration in the cake dough before baking, and the stability and expansion of air bubbles in the cake structure during cooking. The general comparison of the values of these characteristics in samples in which a portion of egg whites was replaced by a CRE with a control sample and also with the amounts of samples in which a part of the egg white was replaced with water demonstrated the strong performance of CRE, which was evident in the improvement of the aeration process. The possibility has arisen of replacing some of the egg white used in the production of sponge cake with this herbal natural native extract.
The incorporation of hydrocolloids is an alternative means of stabilizing o/w emulsions against creaming. Mayonnaise is a kind of semi‐solid oil‐in‐water emulsion containing 70%–80% fat. Among mayonnaise ingredients, egg yolk, the most common emulsifying agent in this foodstuff, is most critical for the stability of the product [96,97]. Nevertheless, a major problem with egg yolk is its high cholesterol content, so many attempts have been carried out to develop low‐cholesterol sauces with characteristics that are similar to real mayonnaise . The effect of CRE substitution level with egg yolk on the rheological properties and stability of a mayonnaise was studied . The rheological measurements were carried out using a rotational viscometer in the shear rate range 0–60 S−1 at 25 °C. Mayonnaise texture was also evaluated by the back extrusion test to a depth of 40 mm (about 80% deformation) and at a constant crosshead velocity of 1 mm s−1.
The flow behavior of the mayonnaise samples formulated showed that the relationship between the shear stress and shear rate was nonlinear. The power‐law and Herschel–Bulkley models were well fitted to the experimental data with high determination coefficients (Table 15.10). The flow behavior indices, n p and n H , of the samples were in the range 0.13–0.37 and 0.21–0.45, respectively, and they decreased with increasing CRE substitution level in the formulation, indicating stronger shear‐thinning behavior in the presence of CRE. The consistency coefficients, k n and k H , of the samples increased from 150.4 to 7265.5 and from 106.7 to 2843.9 Pa sn, respectively. It could be stated that the use of CRE in mayonnaise as an alternative to egg yolk substitution increased the viscosity of the final product. An increase in the consistency coefficient with an increase in gum concentration has been reported by researchers [100–102]. An explanation for this trend is that higher gum concentration could favor specific chain–chain associations and/or entanglements between polymer chains that enhance the density of cross‐links, and it seems that resistance to the shearing force increases as the macromolecular entanglements increase, due to the higher polymers' concentration in the emulsion. Different content levels of white lupin protein, xanthan gum, and oil optimized the composition of emulsions, which showed similar behavior . As a result, all emulsions showed shear‐thinning behavior, and the viscosity of the oil‐in‐water emulsion samples significantly increased with addition of xanthan gum. In addition, all investigated mayonnaise samples with modified rice starch and xanthan gum showed a shear‐thinning response .
Source: Ghahremani and Karazhiyan .
|Power‐law model||Herschel–Bulkley model|
|Sample||k p||n p||R 2||σ 0H||k H||n H||R 2|
a k P k P is the power‐law consistency coefficient (Pa sn), and n p is the power‐law flow behavior index (dimensionless). k H is the Herschel–Bulkley consistency coefficient (Pa sn), n H is the Herschel–Bulkley flow behavior index (dimensionless), and τ 0H is the Herschel–Bulkley yield stress (Pa).
The Herschel–Bulkley yield stress for the mayonnaise ranged from 40.38 to 3278.74 Pa, and its value increased with the CRE concentration (Table 15.10). When used as a salad dressing, the yield stress is an important characteristic for assessing mayonnaise quality because it must keep non‐fluid on the salad surface and retain its ability to adhere to the salad surfaces . Besides, the yield stress value is of great importance also for product acceptance among consumers . In general, Ghahremani and Karazhyian  anticipated that the yield stress value would increase proportionally with the increase in the disperse‐phase volume fraction and the strength of the attractive forces between the oil droplets.
As shown in Table 15.11, the highest values of all textural characteristics were observed in the samples with 100% CRE substitution level, followed by samples containing 75% and 50% CRE; however, the lowest values were recorded in the control, for example, with only egg yolk. One of the most important factors in consumer acceptability for mayonnaise is its firmness, which was increased by CRE. These results are in agreement with the results of Goankar et al.  and Maneini et al. . The positive surface area in the force‐deformation texture profile is an index of consistency of the sample and may be related to the consistency coefficients from rheological modeling. Increasing the gum level increased consistency, which indicates a logical correlation with rheological parameters (Tables 15.10 and 15.11). The viscosity of the samples can partially, but not wholly, reflect the texture analysis parameters . Addition of gum may increase the elasticity of the emulsion by itself as a result of the formation of a strong gel‐like structure in the continuous phase, imparting a more firm and adhesive structure and also producing smaller oil droplet diameters because of a reduced coalescence process during emulsification . Similar results were reported in the literature in which the composition of low‐fat oil‐in‐water emulsions (stabilized by white lupin protein) was optimized. Firmness and adhesiveness increased with an increase in protein, xanthan gum, and oil concentrations . An increase in CRE concentration improved the stability, consistency coefficient, and viscosity, and decreased the flow behavior index in mayonnaise. By using the desirable levels of CRE, producing low‐cholesterol low‐fat mayonnaise with properties closely similar to those of commercial products is possible .
Table 15.11 Texture profile analysis parameters for different mayonnaise samples containing Chubak extract substitutions.
Source: Ghahremani and Karazhiyan .
|Sample||Firmness (kg)||Adhesiveness (kg·s)||Adhesive force (kg)||Consistency (g·s)|
A study was performed to achieve a grape juice with suitable physical properties through evaporation and mixing. CRE and egg white, as a recognized aerating agent, were added to a grape juice at the concentration of 3% . The operation of evaporation, that is, aerating with a rotary evaporator, was done at 80 °C, 270 rpm and for durations of 0, 30, 60, and 90 min. Rheological measurements demonstrated that the flow behavior index decreased in all three treatments for longer process times. The decreasing trend of n in the CRE and EW samples was more dramatic than that of the control. Also, observations demonstrated that the k value increased in each of the three treatments under longer processing. The increasing trend of k was also more dramatic in the CRE and EW samples compared to that of the control. It can be stated that shear‐thinning behavior was evident at all stages of evaporation. A number of researchers have reported this behavior for various kinds of grape juice [109–111]. The decrease in n and increase in k following longer evaporation and stirring time was explained by reviewing the changes made in °Brix. Overall, the rheological behavior of the fruit juice products was influenced by the amount and characteristics of the constituent components. It was also dependent on the type of processing treatment . In this regard, the concentration factor (oBrix) had an influence on n and k values [113–115]. Since, during the evaporation and stirring process, the ascending trend of Brix was more dramatic in CRE and EW samples in comparison with that of the control, thus intensification of shear‐thinning behavior was more evident in these samples. Numerous published reports have been investigated the relationship between oBrix and the mentioned rheological parameters [ 112–121]. As well as grape juice aeration, CRE's performance was similar to that of EW . This suggests that it has good potential for producing stable foam. Considering the remarkable functional properties of CRE such as its foaming, emulsifying, and humectant qualities, as well as its pharmaceutical and therapeutic properties, it can be claimed that the use of a mixture of grape juice and CRE as an alternative to sugar in food formulations can prevent emergence of unfavorable qualitative changes in the product caused by sugar removal and add to its nutritional value, making it a potentially great functional product.
The root of Chubak is a source of saponin as the latter is one of the most important and active compounds in it, and on this basis, many of the studies have focused on determining the physicochemical and functional characteristics relating to saponins. In addition to saponin, polysaccharides and water‐soluble gum compounds are also other important compounds in the Chubak root. Extracts from the Chubak, root due to the presence of saponin and hydrocolloid compounds, has superficial and inter‐surface activity, and it is thus known as a natural emulsifier. It is also able to play the role of a proper foaming agent. The production of a kind of Chubak extract with high saponin content in a shorter time and using less solvent for the processing of food products was evaluated using the ultrasound method. Antioxidants and natural antimicrobial agents present in saponin of the Chubak extract can replace synthetic antioxidants in the doughnut and increase the doughnut's shelf life. CRE has good potential as a stabilizing agent in yogurt formulations, and increasing CRE in yogurt formulations significantly improved the rheological properties and decreased syneresis content. The use of CRE in ketchup sauce formulations facilitates proper consistency and viscosity with improved texture quality, viscosity, and reduced serum separation. Foam forming capability in non‐alcoholic beer showed the excellent potency of CRE in the formulation. The possibility of introducing CRE as a natural, inexpensive, and affordable emulsifier in muffin cake was studied, and it is also possible to replace a part of egg white in the preparation of sponge cake with CRE. Producing low‐cholesterol low‐fat mayonnaise with properties closely similar to those of commercial products is possible using CRE. The Chubak extract exhibited performance similar to that of egg white, which suggests that it has good potential for producing stable foam in grape juices. The accepted functional properties of CRE enable it to be used in many food formulations as an aerating agent, such as aerated confectionary products (meringue, mousses, nougats, etc.) and as a substituting for egg white and sugar in many formulations.