Assessment of Physicochemical, Functional, Rheological and end-use properties of Tribulus terrestris

ABSTRACT

Plants are excellent food and medicinal resources because of their unique composition. Researchers have discovered that thousands of plants can help in achieving the desired health status through advanced research. This research article reveals the nutritional composition and significance of Tribulus terrestris. In addition, it also analyzed the physio-chemical evolution of nutraceutical products from Tribulus terrestris. From the proximate analysis, it was found that T. terrestris is rich in fiber and fat 24.28 ± 0.93% and 14.49 ± 1.42%, respectively. The rheological properties of the product were observed. The results reveal that water activity, stability of product, and dough development time increased 59.0 ± 0.06%, 15.0 ± 0.06 min, and 4.3 ± 0.07 min, respectively, by increasing the powder percentage. The functional behavior of the samples was examined, and significant results were depicted. Bulk density and oil absorption increased by increasing the percentage of powder 83.86 ± 1.36% and 69.16 ± 3.61%. The results of emulsifying stability were recorded as non-significant. Results regarding color analysis showed non-significant behavior of supplemented biscuits. The textural behavior of the product increased from 1.47 Nm⁻² to 2.27 Nm⁻². Results regarding the spread factor increased from 3.01 ± 0.04 to 3.83 ± 0.01 from T₁ to T₄. The sensory results indicated that T1 (2% Tribulus powder), T2 (3% Tribulus powder), T3 (4% Tribulus powder), and T4 (5% Tribulus powder) were acceptable after the control group. Thus, Tribulus terrestris can be used as a nutraceutical and functional ingredient in baked goods.

KEYWORDS:

• Tribulus terrestris
• Functional properties
• Rheological behavior
• Spread factor
• Sensorial properties

Introduction

The nexus of food and nutrition in the century is old and human vitality is dependent on their effectiveness. The last two centuries witnessed dreadful (withdrawal) from traditional complementary medicines. The resulting diet-health linkages get much more attention in the 21^st century^[1]. Thus, expanding the global market to the next highest of around 200 billion US Dollars. Globally, researcher exploits thousands of plants for their potential to improve human health. The traditional knowledge held by rural communities played a pivotal role in helping the researchers achieve some golden mild stones.^[2]

Plants have a diverse and rich bioactive constituents, which exert numerous bioactivities having propitious health effects on the body of humans. Usually, plant-derived food consumption is said to be linked with refined health status as there is a reduction in the likelihood of chronic non-communicable diseases, like type II DM, cardiovascular diseases, neurodegenerative diseases, and various types of cancers.^[3] Henceforth, plant-based nutraceutical consumption is invigorated to ascertain human health for peerless management of disease and its prevention.^[4]

The “nutraceutical” concept was coined to make products with health-protective value readily available that do not need medical consultation. The “nutraceutical” term was ushered by combining “nutrition” and “pharmaceutics” components^[5] and is characterized as “more than the food but less than the pharmaceuticals” [3]. Principle reasons for this kind of interest encompass the increasing trend of these bioactive components usage that are plant-derived in pharmacological and therapeutic health aspects, concepts of emerging health promotion, and growing occurrences of nutritional therapy and phytotherapy implementation.^[6]

Tribulus terrestris plant is dicotyledonous and comes under the Zygophyllaceae family, which is known commonly as the small caltrops, land caltrops, or puncture vine. T. terrestris is a self-grown plant that is adapted to survive in harsh and dry climates.^[7] It abundantly grows in the continents of Asia, Africa, Europe, and Australia, and it is also found in sandy soil regions and with arid climate conditions.^[8] T. terrestris has been utilized since ancient times in the conventional medicinal practices of different cultures; Indian Ayurvedic medicine, conventional European medicine, and conventional Chinese medicine have all taken benefit from T. terrestris use.^[7,9] In conventional Chinese medicine, Tribulus terrestris is considered an exceptional medicine, with its fruits and roots having been utilized for more than a hundred years to treat a variety of ailments. Moreover, T. terrestris fruits and roots are effective in a wide range of disease treatments delineated in countries like Pakistan, India and Sudan.^[4] T. terrestris in Sudan is also used to protect or prevent kidney glomeruli (nephritis) inflammation and other inflammatory complications. It is also being utilized in Pakistan as an uricosuric and diuretic.^[8]

The current study was done to shed light on the nutritional perspective concerning its inclusion in various novel food products to ameliorate the potential health debilitation. Due to the availability and immense potential advantages, T. terrestris was used in this study as it is mostly wasted every year in large quantities without proper utilization. In this current study, T. terrestris was utilized in product development, i.e. biscuit which is consumed in large quantity all over the globe. These studies can further enhance the justification of the usage of T. terrestris in different food products. T. terrestris is a nutraceutical plant that is not grown on a simple daily use basis but rather used in capsules or likewise coating. It has multiple beneficial health impacts which impart positive changes on human health, it is also effective in ameliorating diseases like male fertility issues.

Material and methodology

Sample preparation

The current research project is designed to incorporate the Tribulus to explore its nutritional significance in novel food products. For this purpose, Tribulus samples were collected from urban pretties of district Layyah, and samples were dried and packed in air-tight containers for further utilization.

Proximate analysis

Moisture was determined by using a hot air oven model no (53 LTR NSL – UN55 MEMMERT (GERMANY)). To determine the ash content in the product, the weighted powder was kept on the stove to remove the carbon black after it was placed in a muffle furnace at 550 ± 5°C. Fiber contents were measured by using the heating mental. To perform fiber analysis, take the sample in a digestion conical flask with sulfuric Acid (0.255 N) for acid washing. Placed the flask on heating mental and boiled for 30 min. After passing from the filter the residues stick with a linen cloth. Wash the residue with distilled water and again transfer it into the digestion flask and add Sodium Hydroxide (base) (0.313 N) for base washing. Again, repeat the process for 30 min, and filtration is done. After completing the base washing process, place the residues in the muffle furnace. Weight the ignite content as fiber.

Crude fat contents in the powder were determined by using n-hexane on the soxhlet apparatus at 80°C. Crude Protein content was measured by the Kjeldahl method by using digestion tablets or a digestion mixture (copper sulfate, potassium sulfate, and ferrous Sulphate with 5:94:1), concentrated sulfuric acid, boric acid, and methyl red. Carbohydrate is a calculated method that was determined by subtracting the moisture, ash, fat, and protein contents from 100.

Functional properties

Functional properties of the flour blend like bulk density, water absorption, oil absorption, foaming ability and capacity, emulsification stability, and activity are determined by following the procedure.

Bulk density

The ratio between sample mass and volume occupied is called bulk density and is expressed as kg/m³. Take a 5 g sample in a 50 ml cylinder and record the net volume of the measuring cylinder Khan & Saini.^[10] Bulk density was calculated by following the formula.

$\mathrm{B}\mathrm{u}\mathrm{l}\mathrm{k}\mathrm{D}\mathrm{e}\mathrm{n}\mathrm{s}\mathrm{i}\mathrm{t}\mathrm{y}=\frac{wtofsample}{volofsample}$

Water absorption capacity

The water absorption capacity of flour was measured by the centrifugation method. Take 3 g sample with 25 ml distilled water in pre-weighted falcon tubes. After mixing, centrifuge at 3000 rpm for 30 min. After it, again gave the stay time for 5 min. Again, placed in centrifuged for 30 min at 3000 rpm. Collect the supernatant, pour it into a petri dish, and dry it in a hot air oven at 55°C for 20-min.^[11] Water absorption capacities were expressed as a gram of water bound per gram of the sample on a dry basis

$\mathrm{W}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{a}\mathrm{b}\mathrm{s}\mathrm{o}\mathrm{r}\mathrm{p}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{C}\mathrm{a}\mathrm{p}\mathrm{a}\mathrm{c}\mathrm{i}\mathrm{t}\mathrm{y}=\frac{\left(wtoftubewithsampleafterdryingsamplewt-wtoftube\right)-Samplewt}{wtofsample}$

Oil absorption capacity

By using the method of Lin et al. (1974) oil absorption capacity was determined. Took 5 g sample and mixed with 6 ml coconut oil. Stir for 1 min and give stay time. After it, place the sample in a centrifuge at 3000 rpm for 30 min. After that, the extra oil was decanted, and the contents of the tube were weighed. The OAC was determined as a gram of oil bound per gram of sample.^[12]

$\mathrm{O}\mathrm{i}\mathrm{l}\mathrm{A}\mathrm{b}\mathrm{s}\mathrm{o}\mathrm{r}\mathrm{p}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{C}\mathrm{a}\mathrm{p}\mathrm{a}\mathrm{c}\mathrm{i}\mathrm{t}\mathrm{y}=\frac{wtoftubewithsampleafterremovingoil-\left(tubewt+samplewt\right)}{Samplewt}$

Foaming activity, stability, and ability

Foaming is termed as the bubble formation in a continuous manner with enough surface tension to retain the bubbles. Foaming ability is termed as the capability of foam to survive after giving stay time, while foaming capacity is the ability of any ingredient to produce and stabilize the foam. Foaming activity and stability were determined by the method of Kaur and Singh.^[13] Took 1.5 gm sample with 50 ml distilled water in measuring cylinder. Shake the sample vigorously by using a home blender for 2 min. The volume of the foam formed was then recorded as the foam capacity (%). A final observation was made after 10 min for recording the foam stability (%).

$\mathrm{F}\mathrm{o}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{C}\mathrm{a}\mathrm{p}\mathrm{a}\mathrm{c}\mathrm{i}\mathrm{t}\mathrm{y}\left(\mathrm{\%}\right)=\frac{Volumeafterwhipping-volumebeforewhipping}{volumebeforewhipping}$

$\mathrm{F}\mathrm{o}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{S}\mathrm{t}\mathrm{a}\mathrm{b}\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{t}\mathrm{y}\left(\mathrm{\%}\right)=\frac{Volumeoffoamafter30mint}{initialfoamvolume}\hspace{0.17em}\times \hspace{0.17em}100$

Emulsification activity and stability

Emulsification activity is termed as the surface molecules’ capacity or oil’s maximum amount which can be emulsified using a fixed protein amount. Emulsification stability is termed as the phase separation rate in oil and water during the emulsion storage. Emulsification activity and stability were determined by using the method of Siddiq et al..^[14] Took 0.5 g sample with 5 ml distilled water and 5 ml refined coconut oil in a falcon tube. The contents were mixed for 5 min with vigorous shaking. The resulting emulsion was transferred into a centrifuge machine and centrifuged at 2000 rpm for 30 min. The ratio of the height of the emulsion layer to the height of the liquid layer was calculated, and the emulsion activity was expressed as a percentage. The emulsion stability was determined after heating the emulsion in a water bath at 80°C for 30 min, cooling it to 23 ± 1°C, and centrifuging it at 2000 rpm for 30 min. The emulsion stability expressed as a percentage was calculated as the ratio of the height of the emulsified layer to the height of the liquid layer.

Rheology of the Tribulus Terrestris blend

It is defined as the flow of matter and deformation is called rheology. Dough rheology plays an important role in the quality of products, baking of products, and information about the mechanical behavior of the products Iuga & Mironeasa.^[15] Take a sample on a 14% moisture base with the different percentages of Tribulus powder and place it into a farinograph bowl. Add the water and mix to form a dough. Farinograph determines dough and gluten properties in the sample by measuring the resistance against the mixing action of blades. Farinographic study about water absorption, dough development time, the moisture level of the flour, weakening of dough, dough stability, and maximum consistency during kneading. Rheology was determined by using a Brabander model 8124 farinograph (Brabander OHG, Germany) based on the AACC Method at the Rehmat wheat product mill at Ravi Road, Lahore.

Product development

The product was prepared by using the supplementation of Tribulus Powder with different concentrations to determine the nutritional composition of Tribulus terrestris powder. The Tribulus powder was added 0%, 2%, 3%, 4% and 5% in T₀, T₁, T₂, T_3, and T_4, respectively. First oil, butter, and grind sugar mix properly. Add flour, eggs, and cumin powder to the mixture, after adding baking powder and mixing vigorously. Made the four groups according to a treatment plan. In the end, Tribulus powder was added according to the recipe in each group. The composition of the ingredients as they were blended to form a product is as follows. To prepare 1 kg of the biscuits the following pattern was followed:

Table

Ingredients	Quantity
Butter	200g
Sugar	600g
Fine flour	1250g
Egg	2
Baking Powder	28g

Physical characterization of the product

The textural properties of the product were measured by using a Texture analyzer (TX-700). The hardness of the product was measured by cutting force, using a small three-point bending test rig with a sharp blade cutting probe. The force measured in Nm⁻² Klunklin & Savage.^[16]

Sensory evaluation

Sensory is an important parameter in the field of food science which deals with the effective response and human sensory perceptions of various kinds of food. The sensory analysis described both quantitative and qualitative characteristics like texture, flavor, color, taste, and aroma by trained panels. By this method of sensory, it is possible to pinpoint differences among products with different percentages of powder and examine relationships between sensory and chemical characteristics. The salty taste is produced by the presence of NaCl, the sweet taste is produced by the presence of carbohydrates, the bitter taste is produced by alkaloids, the sour taste is produced by acid, and the umami taste is produced by the salt of glutamic acid, i.e., MSG.^[17]

Statistical analysis

For the statistical analysis of the current study measure results “Statistic 8.1 software” was used. At the significance level of p ≤ .05% all the calculated results were analyzed by using the completely randomized design, and then the Latin square design was applied for obtaining the mean values. ^[18]

Results and discussion

In the first phase, the Tribulus terrestris seed was collected from a sandy area of Thall. The seeds were dried to reduce the moisture below 10% and stored in an air-locked plastic container. The seeds were analyzed for proximate composition, which showed that the plant is a rich source of fiber (24.28 ± 0.93%) and Carbohydrates (33.35 ± 1.03%). Whereas the protein contents were present in a lower amount 8.8 ± 0.30%, and fat content was recorded (14.49 ± 1.42%). Results are shown in Table 1.

Table 1. Proximate analysis of Tribulus terrestris powder.

Proximate	Moisture (%)	Ash (%)	Fat (%)	Fiber (%)	Protein (%)	NFE (%)
TT	9.65 ± 0.62	9.31 ± 0.37	14.49 ± 1.42	24.28 ± 0.93	8.8±.30	33.35 ± 1.03

The findings of Dastagir et al.^[19] reported higher fiber contents (37.1%) and Carbohydrate contents (33.35 ± 1.03%) in Tribulus terrestris powder which are not related to the current study but moisture, ash, fat, and protein contents are slightly related to this research work. Results of fiber content in the current study slightly agreed with Ghulam et al.^[20] who recorded (13.7%) fat content.

Rheology

Rheological properties of flour blend with different percentages of Tribulus powder show different behaviors during the processing of the product. All results are statistically highly significant and presented in Table 2. Moisture content decreased by increasing the percentage of Tribulus terrestris. Moisture contents in control white wheat flour were recorded at 14%, and the range of the moisture content % in the Tribulus terrestris powder blend was recorded from (10.1 ± 0.09 to 11.9 ± 0.05%). Water absorption is an effect of the moisture level of flour. Maximum water absorption (59.5 ± 0.05%) was recorded in 5% Tribulus terrestris powder, and minimum values were recorded in 2% Tribulus terrestris (57.9 ± 0.09%). It was shown that the higher the moisture level, the lower the water activity. Dough stability depends upon the water absorption in the flour blend. Dough stability directly increased with the percentage of water absorption. Water stability was recorded from 11.48 ± 0.17 to 17 ± 0.09 Min. Dough development time shows the same behavior as dough stability. If dough development time increases, it means it has higher dough stability and water absorption. Dough development time is inversely related to moisture percentage in the flour blend. The maximum development time recorded in 5% powder percentage 4.6 ± 0.09 Min., and minimum values recorded in 2% Tribulus powder 3.5 ± 0.06 Min. Maximum consistency during Kneading (CMAX) is described as the overall scenario during the test. It was recorded maximum in 2% Tribulus powder after control white wheat flour and minimum recorded in 5% powder.

Table 2. Rheological behavior of Tribulus terrestris. supplemented flour.

Tribulus	Moisture (%)	WA (%)	Stability (Min)	DT(Min)	Weakening (UF)	CMAX(UF)
T0	14.00 ± 0.20^a	59.3 ± 0.24^a	11.48 ± 0.17^e	2.9 ± 0.08^e	37.45 ± 1.4^a	493.09 ± 10.2^a
T1	11.9 ± 0.05^b	57.9 ± 0.09^d	12.5 ± 0.05^d	3.5 ± 0.06^d	23.0 ± 0.059^b	491.36 ± 0.05^b
T2	11.6 ± 0.06^c	58.4 ± 0.06^c	14. ± 0.06^c	4.0 ± 0.07^c	15.0 ± 0.066^c	484.09 ± 0.06^c
T3	10.4 ± 0.06^d	59.0 ± 0.06^b	15. ± 0.06^b	4.3 ± 0.07^b	13.0 ± 0.066^d	478.30 ± 0.06^d
T4	10.1 ± 0.09^e	59.5 ± 0.05^a	17. ± 0.09^a	4.6 ± 0.09^a	11.0 ± 0.099^e	472.40 ± 0.09^e
F Raito	423**	119**	264**	14990**	11417**	35591**

Functional properties of Tribulus Terrestris supplemented flour blend

Functional properties of the flour blend for the product describe the behavior of the ingredient during the baking and affect the finished product in terms of its taste, texture, and mouth feel. Bulk density is an important parameter in the functional property. Results were recorded as statistically significant. Maximum bulk density (83.86 ± 1.36%) was recorded in the T₄ treatment in which 5% Tribulus terrestris powder was added and minimum values (53.75 ± 0.04%) were recorded in the T₁ treatment in which the lowest percentage of Tribulus terrestris 2% added in a fine flour. Results regarding foaming ability were recorded as non-significant.

The results of foaming ability ranged from 39.89 ± 0.85 to 44.54 ± 0.24%. Similarly, the results of foaming stability were recorded as highly significant. Foaming stability for T₂ treatment was recorded the same as for T₃ treatment in which 4% Tribulus powder was added. Maximum values were recorded at 44.78 ± 0.77% in the T₃ treatment. Minimum values were recorded in the T₄ treatment in which 5% powder was added. Results for emulsifying ability were highly significant as shown in Table 3. The highest values recorded in treatment T₀ followed by T₁, T₂, T_3, and T₄ which were 45.89 ± 0.39, 45.44 ± 1.6, 44.55 ± 1.68, 44.33 ± 1.16, and 40.78 ± 0.77%, respectively. Results recorded for emulsifying stability were statistically non-significant. Maximum values recorded in T₄ treatment 31.91 ± 2.56% and minimum values recorded in T₀ 30.86 ± 2.25%. The results of water absorption capacity for flour blend with the addition of Tribulus terrestris were recorded as highly significant. Maximum values calculated in T₃ treatment followed by T₁, T₄, T_2, and T₀ 89.46 ± 0.23, 89.20 ± 12.50, 82.43 ± 2.21 and 45.01 ± 1.41%, respectively. The results of oil absorption capacity were recorded as non-significant. The range of OAC was recorded from 69.22 ± 1.38 to 64.00 ± 0.16%.

Table 3. Functional behavior of flour blend.

TT	Bulk density %	Foaming %		Emulsifying %		Absorption capacity%
		Stability	Ability	Stability	Ability	Oil	Water
T0	80.01 ± 0.33^b	43.67 ± 0.24^a	41.82 ± 3.87^ab	30.86 ± 2.25^ab	45.89 ± 0.39^a	67.62 ± 2.51^ab	45.01 ± 1.41^c
T1	53.75 ± 0.04^d	44.33 ± 1.34^a	44.54 ± 0.24^a	31.40 ± 0.06^ab	44.55 ± 1.68^a	64.00 ± 0.16^b	89.46 ± 0.23^b
T2	77.63 ± 0.54^c	44.78 ± 0.39^a	44.08 ± 0.29^a	32.40 ± 1.68^a	45.44 ± 1.6^a	66.46 ± 2.10^ab	82.43 ± 2.21^b
T3	80.90 ± 1.01^b	44.78 ± 0.77^a	41.75 ± 0.76^ab	27.76 ± 1.32^b	44.33 ± 1.16^a	69.22 ± 1.38^a	106.22 ± 1.15^a
T4	83.86 ± 1.36^a	42.33 ± 0.02^b	39.89 ± 0.85^b	31.91 ± 2.56^ab	40.78 ± 0.77^b	69.16 ± 3.61^a	89.20 ± 12.50^b
F Ratio	673**	6.12**	3.31^ns	1.71^ns	8.42**	2.77^ns	47.1**

Nutritional composition of Tribulus Terrestris product

The nutritional composition of food production is dependent on its nutritional components, moisture, ash, fat fiber protein, and CH₂O. Nutritional components of Tribulus powder supplemented biscuits showed variation in results. Maximum values of moisture content recorded in T₃ treatment were 4.91 ± 0.26 followed by T₄, T₂, T_1, and T₀ 4.84 ± 0.26, 4.80 ± 0.28, 4.78 ± 0.12, and 4.70 ± 0.34, respectively. The results of ash content were recorded as highly significant. The range of ash contents was calculated from 1.03 ± 0.04 to 1.44 ± 0.05. Maximum ash content noted in T₄ which has 5% Tribulus terrestris powder according to the standard recipe of products.

The ash content recorded in T₃, and T₂ were 1.36 ± 0.06 and 1.27 ± 0.02%, respectively. The control group had a minimum quantity of ash content which was 1.03 ± 0.04%. The results of fat contents in the product were recorded as statistically non-significant. Maximum fat was recorded in T₀ 30.04 ± 0.56%, and minimum fat content was recorded in T₄ which has 5% Tribulus powder 28.94 ± 1.60%. The results of fiber content in the product were recorded as highly significant. Maximum fiber content showed in T₄ 1.52 ± 0.05 followed by T₃, T₂, T_1, and T₀ 1.31 ± 0.03, 1.07 ± 0.02, 0.85 ± 0.02, and 0.36 ± 0.02%, respectively. Protein contents were recorded as non-significant in Tribulus terrestris supplemented product. The range of protein was estimated from 5.71 ± 0.30 to 5.91 ± 0.23%. Carbohydrate in the product was also calculated as statistically non-significant. Maximum carbohydrate calculated in T₀ (control) 59.31 ± 0.64% and minimum values calculated in T₄ treatment 58.58 ± 1.98%. All results are presented in Table 4.

Table 4. Nutritional composition of supplemented product.

TT	Moisture (%)	Ash (%)	Fat (%)	Fiber (%)	Protein (%)	CHO (%)
T0	4.70 ± 0.34^a	1.03 ± 0.04^e	30.04 ± 0.56^a	0.36 ± 0.02^e	5.71 ± 0.30a	59.31 ± 0.64^a
T1	4.78 ± 0.12^a	1.20 ± 0.05^d	29.94 ± 0.75a	0.85 ± 0.02^c	5.77 ± 0.28a	58.81 ± 0.97^a
T2	4.80 ± 0.28^a	1.27 ± 0.02^c	29.45 ± 0.98^a	1.07 ± 0.02^c	5.86 ± 0.17a	58.87 ± 0.99^a
T3	4.91 ± 0.26^a	1.36 ± 0.06^b	29.09 ± 0.79^a	1.31 ± 0.03^b	5.80 ± 0.09a	58.65 ± 0.73^a
T4	4.84 ± 0.26^a	1.44 ± 0.05^a	28.94 ± 1.60^a	1.52 ± 0.05^a	5.91 ± 0.23a	58.58 ± 1.98^a
F Ratio	0.68 ns	70.0**	0.64 ns	854**	0.37 ns	0.19 ns

Color analysis of Tribulus Terrestris supplemented the product

Color tonality of the product is an important parameter for the acceptance of the product. The chromatic characteristics of the biscuits were studied through the color space composed of L*, which measures the lightness of the samples from 0 (black) to 100 (white); a*, which measures the degree of redness (when positive) or greenness (when negative); and b*, which indicates the yellowness (when positive) or blueness (when negative) of the sample color.^[21] The lightness of the supplemented product decreased with the addition of greenish powder. Maximum light color was recorded in the control group, and the highest dark color was recorded in the T₄ treatment in which 5% Tribulus powder was added. The results were statistically highly significant which are shown in Table (5). Color recorded in T₀ was maximum followed by T₁, T₂, T₃, and T₄ 74.32 ± 1.23, 69.90 ± 1.22, 68.77 ± 0.72, and 65.08 ± 2.51, respectively. Results show that light color loss is caused by the addition of green powder. In color tonality, a* measures the (greenness). Maximum green color recorded in T₄ treatment 7.29 ± 2.54 and minimum green color recorded in T₀ followed by T₁ 14.84 ± 7.04 and 12.54 ± 2.05, respectively. In color tonality, b* shows (yellowness⁺) and (blueness⁻). The range of results regarded as b* starts at 30.21 ± 1.22 in T₄ and ends in T₀ (46.04 ± 3.24). The results were non-significant in b*. Chroma indicates the saturation of color in the product. In this research work, results of chroma were recorded as non-significant. Maximum saturation was observed in T₀ (control) 48.34 ± 5.33, and minimum values were recorded in T₄ treatment which was 30.95 ± 1.15. Hue represents the angle of color tone. The maximum color angle recorded in the T₁ treatment was 78.02 ± 2.69 and the minimum color angle (was 72.58 ± 2.78) recorded in the T₄ treatment in which 5% Tribulus terrestris powder was added. All results are shown in Table 5.

Table 5. Color analysis of product.

Treatments	L*	a*	b*	Chroma	Hue
T0	74.85 ± 7.63^a	14.84 ± 7.04^a	46.04 ± 3.24^a	48.34 ± 5.33^a	74.40 ± 6.63^a
T1	74.32 ± 1.23^b	12.54 ± 2.05^ab	35.52 ± 1.36^b	37.43 ± 1.71^b	78.02 ± 2.69^ab
T2	71.90 ± 1.22^b	10.39 ± 1.54^bc	34.02 ± 2.37^bc	35.37 ± 2.00^bc	75.03 ± 3.38^ab
T3	68.77 ± 0.72^c	8.13 ± 1.66^c	31.84 ± 2.96^bc	32.67 ± 3.05^cd	73.72 ± 2.04^ab
T4	65.08 ± 2.51^d	7.29 ± 2.54^c	30.21 ± 1.22^c	30.95 ± 1.15^d	72.58 ± 2.78^b
F Ratio	46.2**	0.55 ns	1.44 ns	0.82 ns	0.67 ns

Textural analysis of product

The force required to break the texture of the product is called the hardness of the product. It is measured in Nm⁻². It was observed that hardness increased by increasing the percentage of Tribulus powder. Maximum hardness recorded in T₄ (5% Tribulus powder) which was 2.28 Nm⁻² followed by TT 4%, TT 3%, TT 2%, and control 2.27 Nm⁻², 2.07 Nm⁻², 1.97 Nm⁻², and 1.47 Nm⁻², respectively. All data are represented in Figure 1.

Figure 1. Hardness of Product.

Thickness and spread factor of supplemented product

Thickness and spread factors are the physical parameters of the product. Thickness is measured by micrometer screw gauge measured in mm. The spread factor is the ratio of diameter to thickness of the product that has no units. The results are shown in Table 6. Maximum thickness recorded in T₀ (13.67 ± 0.03 mm) with (38.0 ± 0.04 mm). It was observed that by the addition of Tribulus powder thickness of the product decreased and the diameter of the product increased. The range of thickness recorded from 11.92 ± 0.04 to 9.9 ± 0.09 with the diameter 35.9 ± 0.03 to 38.0 ± 0.02 in Treatment T₂ to T₅ supplemented product. The spread factor depends on the thickness of the product. The spread factor in T₂ powder was recorded as 3.01 ± 0.04. It was gradually increased by increasing the percentage of Tribulus powder. In T₅ treatment, it was recorded at 3.83 ± 0.01. All the results were statistically significant as presented in Table 6.

Table 6. Physical parameter of product.

Treatment	Diameter (mm)	Thickness (mm)	Spread factor (D/T)
T0	38.0 ± 0.04^a	13.67 ± 0.03^a	2.77 ± 0.02a
T1	35.9 ± 0.03^d	11.92 ± 0.04^b	3.01 ± 0.04b
T2	37.0 ± 0.04^c	11.25 ± 0.06^c	3.28 ± 0.02c
T3	37.0 ± 0.04^c	11.23 ± 0.02^c	3.29 ± 0.02c
T4	38.0 ± 0.02^b	9.9 ± 0.09^d	3.83 ± 0.01d
F Ratio	18.1**	1824**	608**

Sensory analysis of Tribulus product

Sensory analysis of the product was performed by the expert sensorial panel. The product was prepared with different percentages of supplemented Tribulus terrestris powder ranging from 2%, 3%, 4%, and 5%. In sensory parameter, the panel differentiates color, taste, aroma, flavor, and texture w.r.t control product. The maximum acceptable level of color recorded in 2% and 3% Tribulus product. In 4% and 5% Tribulus products, the color was dark green which was not acceptable by the panel. The taste of the product was very bitter in 4% and 5% supplemented Tribulus terrestris biscuits. But the taste of 2% and 3% like to control product which was much accepted by the panel. The maximum aroma of the product was recorded in 3% supplemented biscuits. Five percent supplemented biscuits recorded muddy aroma which was least accepted by the sensorial panel. All groups recorded the same flavor except for the 5% supplemented Tribulus terrestris powder product. The texture of the product increased with an increasing percentage of powder products. Five percent supplemented Tribulus terrestris product had recorded maximum texture in the biscuits. The overall acceptability of the product was recorded by the expert sensorial panel. The panel concluded that after the control group, T₁(2% Tribulus powder), T₂ (3% Tribulus powder), T₃ (4% Tribulus powder), and T₄ (5% Tribulus powder) were recorded as acceptable, respectively. All results are represented in Figure 2.

Figure 2. Sensory Analysis of Product.

Discussion

The current research project was designed to incorporate the Tribulus to exploit its nutritional significance in novel food products. For this purpose, Tribulus samples were collected from urban pretties of district Layyah, and samples were dried and packed in air-tight containers for further utilization. In the first phase of research, the nutritional quality of Tribulus terrestris was measured, and results indicated that Tribulus terrestris contains a high amount of fiber content and a higher amount of mineral content as indicated in Table 1. In the second phase, flour blends were prepared and Tribulus terrestris was mixed with 2% to 5% and further evaluated for nutritional composition, functional properties, and rheological behavior.

The result regarding nutritional composition indicated that with an increment of Tribulus terrestris, there were significant tries in fiber and ash content and the rest of the parameters like protein, fat, and moisture content were affected non-significantly. The increase in dietary fiber and mineral content is a positive sign in current health indicators. Globally, people are consuming low amounts of fiber and minerals, and resultantly, there is a rise in nutritional and lifestyle disorders. Currently, if we look at the available list of current food products most of them are processed from white wheat flour having an extraction rate of 68% to 72% and which is quite deficient in dietary fiber and mineral contents. Their consumption is the result of the products prepared from them, lacking these ingredients. The addition of Tribulus terrestris can provide some pints of these essential nutrients.

In the same phase, the addition of Tribulus terrestris further assessed for the impacts on some functional properties. The results showed that the addition of these novel ingredients enhanced the water absorption capacity significantly having appreciable foaming capacity and emulsification capacity while there was a non-significant effect on bulk density and oil absorption capacity. The increase in water absorption was due to the presence of the fibrous compound, and normally, it is hypothesized that 1 gm of dietary fiber can absorb around 4–5 ml of water thus increasing the water absorption capacity by some appreciable amount of fiber contents. Foaming capacity and foaming stability are important parameters in sweet bakery products, for example, cupcakes, biscuits, and muffins. The addition of Tribulus terrestris improves the foaming capacity and stability and shows that it can be used as a functional ingredient in bakery products.

The rheological behavior was studied on Mixolab available at Rehmat Wheat Mill Lahore. Results indicated that the addition of Tribulus terrestris increased the water absorption capacity from 57.9% to 59.5%. However, dough development time and the addition of these novel ingredients result in increased dough development time from 3.5 to 4.6 min. However, the addition of powder was affecting the dough stability time, it increased the percentage of Tribulus terrestris powder. The maximum consistency of dough kneading decreased by increasing the powder percentage.

Conclusion

The current findings indicate that the Tribulus terrestris is rich in fiber and minerals, but that its proteins, fats, and moisture content are not significant. This is nutritionally significant due to having unique combinations, to being rich in dietary fibers and rich in minerals both are vital and current needs of humans. It helps to reduce gastrointestinal problems related to health and it has a good impact on digestion and absorption. The addition of Tribulus terrestris in the product increases the water absorption capacity of the product, it has extraordinary foaming capacity and emulsification capacity, however it has a very minimal effect on the oil absorption and bulk density. It has been observed that it increases the dough development time as well as it has also increased dough stability. The increased percentage of Tribulus terrestris powder affects the dough stability time. As a result of the properties listed above, Tribulus terrestris powder can be used as a functional and nutritional ingredient in a wide range of food products.

Acknowledgments

The researchers would like to acknowledge the Deanship of Scientific Research, Taif University, for funding this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).