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research article | DOI: https://doi.org/10.31579/2637-8914/100
1 Department of Food Science and Technology, Federal University of Technology Akure, Nigeria.
2 Department of Food Technology, The Federal Polythecnic, Ado Ekiti, Nigeria.
*Corresponding Author: Ifesan, BOT, Department of Food Science and Technology, Federal University of Technology Akure, Nigeria
Citation: Akosu I.N, Ifesan B.O.T, Ifesan B.T and Alabi A.O1. (2022). Nutritional and anti-diabetic properties of cookies supplemented with processed Vitex doniana leaf. J. Nutrition and Food Processing.5 (4); DOI:10.31579/2637-8914/100
Copyright: © 2022 Ifesan B.O.T this is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Received: 07 June 2022 | Accepted: 23 June 2022 | Published: 04 July 2022
Keywords: glycemic index; α-amylase; α-glucosidase; functional foods; antioxidant
This study investigated the potential of supplementing wheat flour with processed Vitex doniana leaf flour in the production of cookies and the prospect of utilizing the cookies as functional food. Cookies were formulated using dried and fermented Vitex doniana leaf in the ratio of 1:1. This include; the control, cookies with 100 g of wheat flour and no Vitex doniana leaf flour (WLC1), cookies with 95 g of wheat flour + 5 g Vitex doniana leaf flour (WLC2), cookies made with 90 g of wheat flour +10 g Vitex doniana leaf flour (WLC3), and cookies formulated with 85 g of wheat flour +15 g Vitex doniana leaf flour (WLC4). The physical and chemical properties, α-amylase and α-glucosidase inhibitory activities along with the glycemic index of the Vitex doniana leaf flour and wheat-Vitex doniana cookies produced were investigated. The cookies produced with 85 g of wheat flour +15 g Vitex doniana leaf flour had the highest protein (23.03%), fibre (6.46%), ash (33.3%) and fat content (29.80%) compared to the other formulated cookies. The cookies also demonstrated a strong inhibitory effect against α-amylase (19.8%-38.0%) and α-glucosidase (42.0%-76.0%) enzymes both of which are linked to type 2 diabetes mellitus. In addition, the incorporation of the processed Vitex doniana leaf flour in the cookies brought about a significant reduction in the glycemic index of the formulated cookies. In conclusion the results obtained in this study suggests that the supplementation of wheat flour with Vitex doniana leaf flour in the production of cookies could be contemplated as a functional food.
Functional foods can be defined as any food confirmed to have a health promoting or disease preventing property beyond the basic functions of supplying nutrient to the body (Martirosyan and Singh, 2015). Functional foods are known to contain high amounts of health promoting bioactive compounds and they are found in both plants and animals, but plants are more highly valued because they have the ability to synthesize phytochemicals which are beneficial to human health. The plant-based functional foods include fruits and vegetables, whole grains, fortified or enhanced foods, beverages, and dietary supplements (Jones and Varady, 2008; Schwager et al., 2008).
Diabetes mellitus (DM) is a metabolic disorder with a significantly high morbidity and mortality rate. It is caused either by deficiency in insulin secretion or degradation of secreted insulin (Cao et al., 2012), which is the result of cell alterations caused by many internal and external factors, such as obesity, sedentary lifestyle, and oxidative stress (Mamun et al., 2014; Ullah et al., 2016). It is characterized by hyperglycemia in postprandial and/or fasting state, and its severe form is accompanied by ketosis and protein wasting along with a number of complications such as retinopathy, neuropathy and peripheral vascular insufficiencies (Chehade and Mooradian, 2000).
There are number of natural products available that are helpful in controlling the progression of diabetes mellitus. Some of which include hundreds of plants which are being used as herbal remedies (Abo et al., 2008). The anti-diabetic potential of these plants are often attributed to the functional ingredients in them such as the dietary fiber (Onwulata et al., 2010; Trinidad et al., 2010). Another anti-diabetic potential of these plants is the ability to inhibit the enzymes associated with carbohydrate metabolism which in turn helps to modulate glucose and insulin response in human body (Tundis et al., 2010).
Vitex doniana of the genus Vitex which belongs to the family of Verbenaceae approximately includes 270 known species of trees and perennial shrub which are widely distributed in tropical West Africa and some East African countries. It is also present in some parts of Nigeria such as, Kogi, Benue, and parts of the savannah regions of Kaduna, Sokoto and Kano states (Yakubu et al., 2014). It is commonly called Vitex (English), Dinya (Hausa), Dinchi (Gbagyi), Uchakoro (Igbo), Oriri (Yoruba) Ejiji (Igala), Olih (Etsako) and Hulugh (Tiv) (Burkill, 2000). Mohammed et al. (2016) reported that the aqueous leaf extract of V. doniana was a strong inhibitor of α-amylase and α-glucosidase which are the key enzymes in carbohydrate digestion. Another study by Nwogo et al. (2013) reported a lowering of the fasting blood glucose in diabetic rat after the administration of V. doniana leaf extract at a dose of 250-750 mg/kg for five days. This is an indication that the extract contains bioactive compounds with potent antidiabetic property.
The essence of this study is to investigate the nutritional and anti-diabetic potential of cookies made from blends of processed V. doniana leaf flour and wheat flour.
The young leaves of Vitex doniana were purchased from Gboko main market, Benue State, Nigeria in January, 2020. The leaves were identified and authenticated in the Department of Crop Science and Pest Management, Federal University of Technology Akure, Nigeria. All the chemical reagents used were of analytical grade.
Methods
Dry leaf sample preparation
Fresh Vitex doniana leaves were air dried at 28 ± 2 °C on a cleaned laboratory table for one week in the Food Science and Technology food processing laboratory of the Federal University of Technology Akure. After which the leaves were milled into powder with a laboratory blender (model: binatone) and sieved using a 2.0 mm stainless steel fine-mesh kitchen sieve.
Fermented leaf sample preparation
Fresh leaves of Vitex doniana were fermented according to the method described by Ifesan et al. (2014). Salt was separately added to the sample (2 g of salt to 100 g of vegetable) and mixed thoroughly before packing it into a plastic bucket which was covered tightly to serve as a fermentation jar. Fermentation was allowed to proceed at room temperature for three days, after which the leaves were air dried at 28 ± 2 °C on a cleaned laboratory table for two weeks in the Food Science and Technology food processing laboratory of the Federal University of Technology Akure. It was then milled with a laboratory blender (model: binatone) and sieved using a 2.0 mm stainless steel fine-mesh kitchen sieve.
Production of cookies
Four samples of cookies were formulated as presented in Table 1, where varying percentage of wheat flour was replaced with the leaf flour comprising of 50% dry Vitex doniana and 50
Proximate composition of blends of dried and fermented Vitex doniana leaf flour and formulated cookies
The proximate composition of Vitex doniana leaf and formulated cookies in Table 2 shows that the V. doniana leaf flour (CVD) had the highest moisture content of 11.92% followed by the control cookies with 100 g of wheat flour and no leaf flour WLC1 (3.96%), cookies with 85 g of wheat flour and 15 g of leaf flour WLC4 (3.87%), cookies with 90 g of wheat flour and 10 g of leaf flour (WLC3) 3.60% and cookies with 95 g of wheat flour and 5 g of leaf flour WLC2 (3.14%). The moisture content of the cookies is dependent on the time and temperature used for the baking process and the moisture content obtained in this study was found to be within the acceptable limit for baked goods with respect to storage stability and microbial contamination. The ash content (9.74%) was highest in the V. doniana leaf flour CVD and lowest (1.31%) in the control cookies WLC1, however there was no significant difference (p > 0.05) between samples WLC2 (2.83%), WLC3 (3.11%) and WLC4 (3.33%) which were formulated with 5 g, 10 g and 15 g of V. doniana leaf flour respectively. The V. doniana leaf flour (CVD) had the lowest fat content of 3.60% while the cookies with 85 g of wheat flour and 15 g of leaf flour (WLC4) had the highest fat content of 29.80% but there were also no significant differences (p > 0.05) between the cookies formulated with 5 g, 10 g and 15 g V. doniana flour WLC2 (28.44%), WLC3 (28.81%) and WLC4 (29.80%) respectively. It was observed that the fibre content in the formulated cookies increased with increase in the amount of V. doniana leaf flour (5 g, 10 g and 15 g) used in samples WLC2 (3.30%) WLC3 (4.57%) and WLC4 (6.46%). However, the fibre content was highest in the V. doniana leaf flour (CVD) 16.24% and lowest in the control cookies (WLC1) 2.73%. The high fibre content of the formulated cookies obtained in this study may be beneficial for consumers struggling with diabetes mellitus as well as those that are obese since fibre is not completely broken down by the body and can help to control the deposition of glucose in the blood and also prevent constipation. A progressive increase in the protein content of WLC2 (8.13%), WLC3 (15.92%) and WLC4 (23.03%) was observed with increase in the amount of V. doniana leaf flour (5 g, 10 g and 15 g) added to the formulated cookies. The protein content recorded in this study was highest in the V. doniana leaf flour (CVD) 28.73% and lowest in the control cookies (WLC1) 4.46%. There was significant decrease in the carbohydrate content with increase in the amount of V. doniana leaf flour (5 g, 10 g and 15 g) added into sample WLC2 (52.82%), WLC3 (44.37%) and WLC4 (33.51%) respectively. However, the carbohydrate content was found to be highest in the control cookies (WLC1) 63.46% and lowest in the V. doniana leaf flour (CVD) 29.77%. The energy value of the V. doniana leaf flour (CVD) was 266.40 Kcal/100g while that of the control cookies (WLC1) was 488.49 Kcal/100g. However, the energy values of the formulated cookies ranged from 494.36 Kcal/100g to 500.45 Kcal/100g and was found to be higher than the FAO daily recommended energy values for adults which is 344 kcal /day.
Proximate | WLC1 | WLC2 | WLC3 | WLC4 | CVD |
Moisture | 3.96b±0.06 | 3.14d±0.02 | 3.60c±0.01 | 3.87b±0.00 | 11.92a±0.06 |
Crude Ash | 1.31c±0.34 | 2.83b±0.05 | 3.11b±0.01 | 3.33b±0.00 | 9.74a±0.60 |
Crude Fat | 24.09b±0.72 | 28.44a±1.06 | 28.81a±0.42 | 29.80a±1.51 | 3.60c±0.30 |
Crude Fibre | 2.73d±0.06 | 3.30d±0.00 | 4.57c±0.05 | 6.46b±0.13 | 16.24a±0.48 |
Protein | 4.46e±0.10 | 8.13d±0.18 | 15.92c±0.62 | 23.03b±1.01 | 28.73a±0.39 |
Carbohydrate | 63.46a±0.17 | 52.82b±1.30 | 44.37c±0.42 | 33.51d±0.73 | 29.77e±0.93 |
Energy | 488.49d±0.33 | 499.76b±0.85 | 500.45a±0.49 | 494.36c±1.08 | 266.40e±0.54 |
Means (±SEM) with different alphabetical superscripts in the same row are significantly different at p<0>
WLC1: cookies with 100 g of wheat flour and no leaf flour (control); WLC2: cookies with 95 g of wheat flour and 5 g leaf flour; WLC3: cookies with 90 g of wheat flour and 10 g leaf flour; WLC4: cookies with 85 g of wheat flour and 15 g leaf flour; CVD: Vitex doniana leaf flour.
Table 2: Proximate (%) and energy (Kcal/100g) composition of mixture of dried and fermented Vitex doniana leaf flour and formulated cookies
Physical assessments of wheat-Vitex doniana cookies
The mean values of the weight, diameter, height and spread ratio of the formulated cookies is presented in Table 3. A significant increase in the weight of the control cookies (5.65 g) was observed compared to the cookies formulated with 5 g, 10 g and 15 g of V. doniana leaf flour (WLC2) 5.02 g, (WLC3) 4.93 g and (WLC4)3.21 g respectively. The decrease in weight of the formulated cookies obtained in this study is in agreement with the findings of Mahmoud (2017) who also reported decrease in weight with increase in supplementation of Eucalyptus leaf powder in cookies. There was no significant difference (p > 0.05) between the diameter of the control cookies (WLC1) 3.85 cm, cookies with 5 g of V. doniana leaf flour (WLC2) 3.79 cm and cookies with 10 g of V. doniana leaf flour (WLC3) 3.55 cm. However, there was a decrease in the diameter of the cookies with 15 g of V. doniana leaf flour (WLC4) 3.32 cm and this is in harmony with the reports of Rabie et al. (2020). The height of the formulated cookies showed no significant difference (p > 0.05) between the control cookies (WLC1) 0.39 cm and the cookies with 5 g of V. doniana leaf flour WLC2 (3.79 cm), cookies with 10 g of V. doniana leaf flour (WLC3) 0.32 cm and the cookies with 15 g of V. doniana leaf flour (WLC4) 0.30 cm. There was a progressive decrease in the height, weight and diameter of the cookies with increase in the amount of V. doniana leaf flour incorporated. It was observed that there was also a progressive increase in spread ratio values with corresponding increase in the amount of V. doniana leaf flour added to the cookies and this is in line with the documentation of Singh et al. (2003) and Igbabul et al. (2018) who reported an increase in spread ratio of cookies with increase in non-wheat protein content. However, there was no significant difference (p > 0.05) in the spread ratio of the control cookies (WLC1) 10.47 cm, cookies with 5 g of V. doniana leaf flour (WLC2) 10.97 cm, cookies with 10 g of V. doniana leaf flour (WLC3) 11.28 cm and the cookies with 15 g of V. doniana leaf flour (WLC4) 11.60 cm.
Determinations | WLC1 | WLC2 | WLC3 | WLC4 |
Weight (g) | 5.65a±0.23 | 5.02b±0.13 | 4.93b±0.30 | 3.21c±0.05 |
Diameter (cm) | 3.85a±0.16 | 3.79a±0.16 | 3.55ab±0.15 | 3.32b±18 |
Height (cm) | 0.39a±0.02 | 0.38a±0.00 | 0.32b±0.00 | 0.30b±0.03 |
Spread ratio (cm) | 10.47b±0.80 | 10.95b±0.86 | 11.28a±0.93 | 11.69a±0.80 |
Means (±SEM) with different alphabetical superscripts in the same row are significantly different at p<0>
WLC1: cookies with 100 g of wheat flour and no leaf flour (control); WLC2: cookies with 95 g of wheat flour and 5 g leaf flour; WLC3: cookies with 90 g of wheat flour and 10 g leaf flour; WLC4: cookies with 85 g of wheat flour and 15 g leaf flour.
Table 3: Physical characteristics of wheat-Vitex doniana cookies
Antioxidant properties of mixture of dried and fermented Vitex doniana leaf flour and formulated cookies
The antioxidant properties of Vitex doniana leaf and formulated cookies in Figure 1 shows that the V. doniana leaf flour (CVD) had the highest free radical scavenging ability of 64.27% against DPPH followed by the cookies formulated with 15 g, 10 g and 5 g of V. doniana leaf flour (WLC4) 59.53%, (WLC3) 58.17% and (WLC2) 53.51% respectively. However, there was no significant difference (p > 0.05) between the antioxidant ability of the cookies formulated with 10 g and 15 g of V. doniana leaf flour. The least free radical scavenging ability of 34.24% was observed in the control cookies (WLC1). The increase in the antioxidant activity of the formulated cookies with corresponding increase in the amount ofV. doniana leaf flour observed in this study coincides with the findings of Mahmoud (2017), Ashoush and Mahdy (2019) and Rawung et al. (2021). The results obtained in this study demonstrates that the incorporation of V. doniana in our diet could be beneficial to health with respect to free radical scavenging.
WLC1: cookies with 100 g of wheat flour and no leaf flour (control); WLC2: cookies with 95 g of wheat flour and 5 g leaf flour; WLC3: cookies with 90 g of wheat flour and 10 g leaf flour; WLC4: cookies with 85 g of wheat flour and 15 g leaf flour; CVD: mixture of dried and fermented Vitex doniana laf flour.
Inhibitory activity of mixture of dried and fermented Vitex doniana leaf flour and formulated cookies on α-amylase enzyme
The effect of Vitex doniana leaf and the formulated cookies on α-amylase enzyme presented in Figure 2 shows that the V. doniana leaf flour (CVD) 75.06% had the highest inhibitory effect on α-amylase enzyme, this result is in line with the findings of Mohammed et al. (2016) and Ani et al. (2020) who both reported that the aqueous leaf extract of V. doniana was a strong inhibitor of α-amylase enzyme. With respect to the formulated cookies, there was a progressive increase in the inhibitory effect on α-amylase enzyme with increase in the amount of V. doniana leaf flour. It was also observed that the control cookies (WLC1) 12.15% had the least inhibitory effect on α-amylase enzyme. The cookies formulated with 15 g of V. doniana leaf flour (WLC4) had the highest inhibitory effect on α-amylase enzyme and this may present it as an agent that could perform a fundamental role in the management of type two diabetes mellitus.
WLC1: cookies with 100 g of wheat flour and no leaf flour (control); WLC2: cookies with 95 g of wheat flour and 5 g leaf flour; WLC3: cookies with 90 g of wheat flour and 10 g leaf flour; WLC4: cookies with 85 g of wheat flour and 15 g leaf flour; CVD: mixture of dried and fermented Vitex doniana leaf flour.
Inhibitory activity of mixture of dried and fermented Vitex doniana leaf flour and formulated cookies on α-glucosidase enzyme
The Vitex doniana leaf flour (CVD) exhibited the highest inhibitory effect of 82.58% on α-glucosidase enzyme followed by the cookies formulated with 15 g of V. doniana leaf flour (WLC4) 72.65%, the cookies with 10 g of V. doniana leaf flour (WLC3) 66.10%, the cookies formulated with 5 g of V. doniana leaf flour (WLC2) 46.88% and the control cookies (WLC1) 21.28% as shown in Figure 3. The high inhibitory effect of the V. doniana leaf flour (CVD)obtained in this study is in agreement with the findings of Mohammed et al. (2016) who reported that the aqueous leaf extract of V. doniana displayed a high inhibitory activity against α-glucosidase enzyme.
WLC1: cookies with 100 g of wheat flour and no leaf flour (control); WLC2: cookies with 95 g of wheat flour and 5 g leaf flour; WLC3: cookies with 90 g of wheat flour and 10 g leaf flour; WLC4: cookies with 85 g of wheat flour and 15 g leaf flour; CVD: mixture of dried and Vitex doniana leaf flour.
Glycemic index activity of processed Vitex doniana leaf flour and formulated cookies
Carbohydrates are usually grouped according to their glucose postprandial responses, which are commonly classified in terms of high (>70%), medium (56-69%) and low (<55> Therefore, cookies formulated with 15 g of V. doniana leaf flour may be the best option with respect to the management of diabetes mellitus
WLC1: cookies with 100 g of wheat flour and no leaf flour (control); WLC2: cookies with 95 g of wheat flour and 5 g leaf flour; WLC3: cookies with 90 g of wheat flour and 10 g of plant leaf flour; WLC4: cookies with 85 g of wheat flour and 15 g leaf flour; CVD: mixture of dried Vitex doniana leaf flour
The sensory attributes evaluated in the cookies made from Vitex doniana leaf flour include appearance (5.60-7.70), aroma (6.58-7.25), taste (6.23-6.95), texture (6.55-7.40), mouth feel (6.75-7.65) and overall acceptability (6.45-7.63) as presented in Table 4. It was observed that the panelist preferred the appearance of the control cookies (WLC1) 7.70 (like moderately) compared to the cookies formulated with 5 g, 10 g and 15 g of V doniana leaf flour ranging from 6.48 (like slightly) to 5.60 (Neither like or dislike). This could be attributed to the development of a darker colour as a result of the addition of V. doniana leaf flour which generated a difference from the regular yellowish cream colour. Appearance has been reported to be a fundamental sensory attribute which has the ability to influence consumer acceptability (Ifesan et al., 2009).
Attribute | WLC1 | WLC2 | WLC3 | WLC4 |
Appearance | 7.70a±0.97 | 6.48b±1.26 | 6.10bc±1.50 | 5.60c±1.92 |
Aroma | 7.25a±1.19 | 6.85ab±1.33 | 6.70ab±1.32 | 6.58b±1.41 |
Taste | 6.95a±1.40 | 6.60ab±1.37 | 6.33ab±1.31 | 6.23b±1.78 |
Texture | 7.40a±1.03 | 7.10ab±1.01 | 6.73b±1.52 | 6.55b±1.68 |
Mouth feel | 7.65a±0.95 | 7.25ab±1.10 | 6.98b±1.17 | 6.75b±1.50 |
Overall acceptability | 7.63a±0.90 | 6.98b±0.95 | 6.53b±1.34 | 6.45b±1.52 |
Mean | 7.43a | 6.88b | 6.56c | 6.36d |
Means (±SEM) with different alphabetical superscripts in the same row are significantly different at p<0>
WLC1: cookies with 100 g of wheat flour and no leaf flour (control); WLC2: cookies with 95 g of wheat flour and 5 g leaf flour; WLC3: cookies with 90 g of wheat flour and 10 g leaf flour; WLC4 - cookies with 85 g of wheat flour and 15 g leaf flour.
Table 4: Consumer acceptability of wheat-Vitex doniana cookies
There was no significant difference (p > 0.05) in the aroma of cookies which ranged from 6.70 to 7.25 and taste from 6.33 to 6.95 in samples WLC1, WLC2 and WLC3 however, all three samples were significantly different (p < 0>
The results obtained in this study shows that the supplementation of processed Vitex doniana leaf flour (dried and fermented in the ratio of 1:1) in the production of cookies demonstrated a positive influence on the nutritional and anti-diabetic properties of the cookies. The sample with 85 g of wheat flour and 15 g of leaf flour had a notable increase in ash, fat, fibre and protein content. It also had a high antioxidant activity and a high inhibitory potential against α-amylase and α-glucosidase enzymes. The glycemic index of the formulated cookies was in the medium to low range and the overall acceptability of the cookies was above average.
Contribution to knowledge
This research has been able to establish that dried and fermented Vitex doniana leaf flour may be employed in the production of functional cookies with anti-diabetic properties.
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