Nutritional and functional characterization of date pulp-fortified cookies

Abstract

Date fruit (Phoenix dactylifera L.) is a sweet fruit with high antioxidant activity due to the presence of phenolic compounds such as flavonoids. Similarly, wheat flour is a rich source of dietary fiber, protein, vitamins, minerals, and different phytochemicals, providing many health benefits. Cookies were prepared from wheat flour and date paste (as a sugar substitute) in different proportions (0%, 10%, 20%, 30%, 40%, and 50%). Cookies were analyzed for proximate composition (moisture, crude protein, crude fiber, crude fat, mineral, and ash content), physical properties (diameter, texture, color, and spread ratio), antioxidant activity (DPPH), total flavonoid content (TFC) and total phenolic content (TPC). The mean results from all the experiments indicated that the addition of date pulp in cookies had a highly significant (p < 0.05) effect on moisture (8­16%), protein (14­15%), fiber (2­10%) and ash content (1­5%) of cookies. The TPC, TFC and DPPH values in CFD₅ were 325 mg GAE/100 g, 164.2 QE/100 g and 22 mg GAE/100 g, respectively. Likewise, the physical properties of cookies produced showed that the addition of date pulp in cookies had a highly significant effect on the thickness (0.4–0.7 cm), diameter (2.20–3.37 cm), bulk density (4–6.42 g) and spread ratio (4.04–4.8) of cookies. Furthermore, the sensory evaluation of date pulp-fortified cookies presented higher scores and overall acceptability than the control treatment. Overall, incorporating date palm pulp in cookies contributed to higher antioxidant potential and improved the physicochemical profile and aroma and texture properties; however, higher amounts of date palm pulp may have contributed to more color, affecting the sensory profile parameters.

Keywords:

• date pulp
• fortified cookies
• physicochemical characteristics
• antioxidant
• proximate composition

1. Introduction

In 2020, the global count of undernourished individuals reached a staggering 768 million, underscoring the critical issue of food insecurity and emphasizing the pressing requirement for inventive, nutritionally rich products sourced from underutilized and unutilized food resources. The remarkable reduction in certain malnutrition-related diseases has been demonstrated through dietary supplements enriched with high-value nutrients (AlYammahi et al., 2023).

Date fruit (Phoenix dactylifera L.) is a sweet edible fruit from the Arecaceae family. In 2020, the United Arab Emirates (UAE) ranked among the top ten countries in date production, with an impressive output of approximately 328,669 tons. These date fruits, abundant in the UAE, are known to have a high sugar content, comprising around 60% to 70% of their weight. The fruit’s easily assimilated simple reducing sugars make them readily digestible by human metabolism (AlYammahi et al., 2022; Tengberg et al., 2012). It is one of the most ancient fruit crops in the Arabian Peninsula, North Africa, and the Middle East. The date palm is an arid-adapted diploid, perennial and monocotyledonous plant (Sattar et al., 2017).

In recent years’ dates utilization for preparing various food products like honey, date bars, jams, fruits paste, cookies, squares, wafers, and date powder has increased daily to make it functional (Ahmed et al., 2012). They are rich sources of fiber and phytochemicals, including antioxidants, polyphenols, flavonoids, and carotenoids (Maqsood et al., 2020), all of which have been reported to have many health and medicinal benefits in recent studies (Boubekeur et al., 2022; Messaoudi et al., 2022; Sarvarian et al., 2022). Dates are also rich mineral sources such as magnesium, iron, potassium, calcium, and copper and minor sources of vitamin A (retinol) and B2 (Benmeziane-Derradji, 2019). Dates are nearly perfect diets, delivering a wide range of critical nutrients and potential health advantages (Al-Shahib & Marshall, 2003).

Wheat is one of the main ingredients in the formulation of cookies and is a crop that provides the primary energy requirement in the human diet. Gluten is the primary protein in wheat, making it the ideal flour for producing baked goods, bread, pasta, noodles, and a range of other cereal products (Shewry & Hey, 2015; Shewry et al., 2013). All age groups consume Bakery products globally because of their excellent flavour and easy digestibility (Awuchi, 2019). Diversified bakery products like muffins, bread, biscuits, pies, cookies, cakes, rolls, tortillas, and wafers etc. are available in the market and are made from grain flours such as wheat, maize, millet and others (Twinomuhwezi et al., 2020).

It is the most common dairy product among all bakery products and one of the most desirable snacks for people of all ages. It is also economical, available in different flavours, and cheap. Cookies are rich sources of carbohydrates and lipids but are low in dietary fibers, antioxidants, minerals and vitamins, making them unsuitable for excess consumption. The nutritional value of biscuits can be improved through supplementation and fortification using a wide variety of proteins, lipids, and mineral sources (Eyenga et al., 2020).

Cookies are the best quick snack products; they are tasty, cholesterol-free, easy to carry, and may contain many digestive and dietary properties (Hussain et al., 2020). The primary purpose of this research was to prepare functional date pulp-fortified cookies to explore their physicochemical, antioxidant potential, and sensory attributes.

2. Experimental study

Raw dates were procured from the Jhang Bazar market of Faisalabad. All chemicals used for the current study were purchased from Merck (USA). The research was performed at the National Institute of Food Science and Technology (NIFSAT) and Government College University Faisalabad (GCUF), Pakistan.

2.1. Formulation of date pulp

According to Peter Ikechukwu et al. (2020), date pulp paste was prepared. Firstly, dates were washed with clean running water to remove any adhering dirt and contaminants. Afterwards, the dates were de-seeded manually by cutting the date fruit. Date pulp and the pericarp portion were placed in a drying oven for 6 h at 70 ºC. After drying, the obtained date pulp in dried form was milled by a hand milling machine (Mechtech 357 R, Pakistan) and ground to fine homogenized powder through a mesh sieve (0.35 mm). Then, the obtained powder was stored in a food-grade bag at ambient temperature. Figure 1 shows the flow diagram of date powder production.

Figure 1. Date powder production.

2.2. Development of cookies fortified with date paste

Cookies were prepared according to the method of Peter-Ikechukwu et al. (2020), with slight modifications. Ingredients and recipes adapted for cookie preparation are discussed briefly here. All dry ingredients, including flour (1000 g), white sugar (300 g), salt (10 g), baking powder (10 g) and water (150 ml), were carefully weighed and mixed in a mixer, having a flat beater at 61 rpm for 3 min. Then margarine (400 g) and whole eggs (250 mL) were added to the mixed dry ingredients, and the dough was well kneaded for about 5 min. After kneading, the dough was spread on a clean and uniform table. The prepared dough was cut into six equal parts. One part was baked without any date powder addition and termed a control treatment (CFD₀). However, in other samples, date powder was added at 10%, 20%, 30%, 40% and 50%. The treatments were CFD₁, CFD₂, CFD₃, CFD₄ and CFD₅. After adding date pulp in different concentrations, each portion of the dough was again mixed for 3–4 min for equal distribution of added powder in the dough thoroughly and placed on plane sheets. The cookies were baked at 200 °C for 15 min in the oven, then cooled and stored at 25 °C.

2.3. Proximate analysis of cookies

The pH, moisture, protein, crude fat, crude fiber, nitrogen-free extract, ash contents, water-holding capacity and oil-holding capacity of cookies were determined by following the method of AOAC (2007). The procedure of Sakac et al. (2015) was followed to determine the mineral analysis of cookies. The atomic absorption spectrophotometer present at the High Tech laboratory of Government College University was used.

2.4. Antioxidant analysis of cookies

2.4.1. Total phenolic contents

TPC of cookies enriched with date pulp was determined by the method prescribed by Najjar et al. (2022); Messaoudi et al. (2022) with slight modifications. Sample extracts were defatted at room temperature, filtered through Whatman No. 1 filter paper, and dried at ambient temperature. The fat-free sample was extracted with methanol (80%) at 1:5 (w/v) for 3 h at ambient temperature. Afterwards, the mixture was filtered and concentrated to 3 ml for 1 g sample through a rotary evaporator. Solutions were refrigerated at 4°C till the completion of the test. About 125 μL of the sample was taken in a flask then 500 μL of distilled water was added. Then, 1.25 ml of 7% solution of Na₂CO₃ was added to it and the final volume of 3 ml with distilled water was given a stay time of 90 min for completion of the reaction.

$TPC=\frac{\mathrm{C}\mathrm{x}\mathrm{D}\mathrm{F}\mathrm{x}\mathrm{V}}{\mathrm{m}\mathrm{C}}$

Where,

C = Concentration of Gallic Acid (calculated with the standard curve)

DF = Dilution factor

V = Volume extract

m: weight of the sample treatment

2.4.2. Antioxidant activity

DPPH analysis of cookies was performed to measure the antioxidant activity in the sample by the method of Afify et al. (2012).

2.5. Physical analyses

A bomb calorimeter was used to determine the caloric value of the cookies. A color meter was used to determine color value by following the protocol of Susanti et al. (2021). Vernier calipers determined diameter and thickness according to the method described by Aljobair (2022). The Spread ratio was calculated by dividing the diameter by the thickness.

2.6. Sensory analysis

Sensory evaluation of cookies was conducted based on color, taste, texture, and overall acceptance by adopting the methods of Pamudi et al. (2021); Amagwula et al. (2022). Using a 9-point Hedonic scale, the sensory assessment of cookies was done by a 20-member panellist. Panellists were screened among students and staff members aged 25–40 years. The students and staff members selected for the sensory evaluation were postgraduate scholars and researchers at the Food Sciences department. The panellists were asked to sign the consent forms, and cookie treatments with random 3-digit coding were served randomly to the panellists. The panellists were asked to assign the score based on 9 scores for extremely liked and 0 for highly disliked.

2.7. Statistical analysis

All data collected in various experiments were subjected to analysis of variance (ANOVA) using statistics 10 Data analysis software for researchers. All experiments were conducted in triplicate, and the mean was taken. Values were represented as mean ± SD using a 5% significance level.

3. Results and discussion

3.1. Proximate composition of cookies fortified with date pulp

Moisture, protein, fat, fiber, ash contents, nitrogen-free extract, water and oil-holding activity results of control cookies fortified with different concentrations of date pulp cookies are shown in Table 1. Moisture content ranged from 10.37% to 16.5% and was significantly (p ˂ 0.05) higher than control cookies. Amin et al. (2019) and their study recommended that the moisture content range increases in cookies due to sugar levels which can bind water. The maximum amount of moisture was observed in CFD₅ (10.37%) because it contains more pulp than other samples. In comparison, a minimum amount of moisture was observed in CFD₀ (8.74%) because it is a control sample and no addition of date pulp in it. Mean values of crude fat and protein (Table 1) contents in various types of cookies enriched with date pulp indicated that there is no significant difference (p > 0.05) among these treatments (CFD₁ to CFD₅). It means that dates had minimal effect on cookies’ fat and protein content. These proximate results were also closely related to Amin et al. (2019). The mean value of fibers and ash in cookies was measured and represented in Table 1, which showed a significant (p˂0.05) increasing trend of CFD₁ to CFD₅. This confirms the earlier findings of Sengev and Oguche (2017). Therefore, dates are a rich source of minerals and fiber. Nitrogen-free extract (carbohydrate) showed a highly significant difference (p˂0.05) among these treatments as we go from CFD₁ to CFD₅; the value of NFE decreases. These findings are correlated with the results of Obiegbuna et al. (2013). Awuchi et al. (2020), evaluated the proximate and functional properties of flour blends and reported that the proximate and functional properties of food components, such as starch, protein, fiber, etc., can influence other parameters.

Table 1. Mean values for proximate analysis of cookies fortified with date pulp

Treatment	Moisture (%)	Fat (%)	Protein (%)	Fiber (%)	Ash (%)	NFE (%)	WHC (g/mL)	OHC
CFD₀	8.74 ±0.43^f	22.8 ±1.14 ^e	15.5 ± .77	1.98±0.09 ^f	1.2±0.06 ^f	49.82±2.49 ^a	1.22± 0.06 ^f	1.35 ± 0.06 ^f
CFD₁	10.37±0.51^e	21.74 ±1.08 ^f	15.94±.79	2.49±0.12 ^e	2.73±0.13 ^e	46.73±2.33 ^b	1.37± 0.06 ^e	1.37 ± 0.06 ^e
CFD₂	11.94±0.59 ^d	23.98 ±1.19 ^b	14.37±.71	3.85±0.19 ^d	3.85±0.19 ^d	42.01±2.10 ^c	1.43 ± 0.07 ^d	1.38 ± 0.06 ^d
CFD₃	12.38±0.61 ^c	22.89 ±1.14 ^d	15.34±.76	5.09±0.25 ^c	3.97±0.14 ^c	40.23±2.01 ^d	1.52± 0.07 ^c	1.42 ± 0.07 ^c
CFD₄	14.05±0.70 ^b	23.5±1.17^c	14.31±.71	7.50±0.375 ^b	4.13±0.20 ^b	36.61±1.83 ^e	1.67 ± 0.08 ^b	1.45 ± 0.07 ^b
CFD₅	16.5 ±0.82 ^a	24.45±1.22 ^a	14.25±.71	10.12±0.50 ^a	5.20±0.26 ^a	29.48±1.47 ^f	1.89± 0.09 ^a	1.50 ± 0.07 ^a

The capacity of the fortified cookies with date pulp powder to absorb water was calculated between 1.89 g/mL and 1.22 g/mL. The mean results of WHC of fortified cookies were significant (p < 0.05) increased. The reason is that the protein content of the date pulp causes an increase in water absorption during the mixing process. The maximum water absorption capacity was determined in CFD₅ (1.89 g/mL) due to the higher quantity of date pulp powder than other treatments. However, the oil-holding capacity for cookies CFD₀ to CFD₁ was 1.35–1.37 g/mL, respectively. There was no significant (P > 0.05) difference among CFD₀, CFD₁ and CFD₂ treatments and CFD₃, CFD4 and CFD₅, respectively. Oil holding capacity showed the better quality of cookies, softening the cookie texture and improving the mouthfeel with better aroma characteristics. Similar findings were also reported by Peter Ikechukwu et al. (2017).

means are values ± standard deviation of three replicates or (n = 3)

3.2. Physical analysis

Bulk density, weight, caloric value, diameter, spread ratio and thickness of the control and cookies with different percentage of date pulp powder is shown in Table 2. The average value of cookies showed a highly significant difference (p < 0.05) among these treatments. As we go from CFD₁ to CFD₅ bulk density of the product decreases. It means that dates pulp, when incorporated in cookies, will not increase their heaviness. This confirms the earlier findings by Obiegbuna et al. (2013).

Table 2. Mean values for physical analysis for cookies fortified with date pulp

Treatment	Bulk density (g)	Caloric value (Kcal)	Diameter (cm)	Thickness (cm)	Spread ratio	Weight (g)
CFD₀	6.42± 0.32^a	460±23.01^f	2.20 ± 0.11^f	0.45± 0.02^f	4.8± 0.24^a	2.25 ± 0.09^f
CFD₁	5.64 ± 0.28^b	472 ± 23.60^e	2.23 ± 0.12^e	0.49 ± 0.02^e	4.55 ± 0.22^b	2.37 ± 0.09^e
CFD₂	4.43 ± 0.22^c	478 ± 23.09^d	2.43 ± 0.12^d	0.55 ± 0.02^d	4.41 ± 0.22^c	2.55 ± 0.10^d
CFD₃	4.33 ± 0.21^d	483 ± 24.51^c	2.47 ± 0.12^cd	0.58 ± 0.05^c	4.25 ± 0.21^d	2.82 ± 0.11^c
CFD₄	3.57± 0.17^e	488± 15.10^b	2.57 ± 0.13^b	0.63± 0.03^b	4.07± 0.20^ef	2.86 ± 0.09^b
CFD₅	2.31± 0.11^f	499± 24.95^a	3.37 ± 0.16^a	0.71± 0.03^a	4.04± 0.20^f	3.09 ± 0.12^a

The average weight of cookies varied between 2.29 and 3.39 g, had a significant difference (p < 0.05). Dates, when incorporated into the product in different ratios will affect the weight of cookies. This confirms the earlier findings by Peter-Ikechukwu et al. (2020).

The caloric value of food is the total amount of energy a human body can generate during its metabolism, expressed in Kcal/100 g. The average amount of calories in different types of cookies CFD₁ to CFD₅ shows non-significant differences (p > 0.05) among these treatments. There was very little or no effect of dates on the calories of cookies with date pulp. These findings were correlated with the findings of Peter Ikechukwu et al. (2017), who reported that the caloric value of cookies is due to dextrose and sucrose contents in date pulp.

Thickness is an important physical property of cookies. Average diameter and thickness values in different types of cookies CFD₁ to CFD₅ were measured and represented a highly significant difference (p < 0.05) among these treatments. Dates had high moisture content; when added to the product, cookie volume was increased due to the high moisture content of date pulp. The thickness of cookies increases when the percentage of date pulp increases. These findings correlate with Peter Ikechukwu et al. (2017); Nadeem et al. (2017).

Average values of spread ratio in CFD₀ are high CFD₅ and had significant differences (p < 0.05) among these treatments. Dates have high moisture content; when added to the product it will affect the spread ratio of cookies. These findings correlate with Sengev and Oguche’s findings (2017).

The means are values ± standard deviation of three replicates or (n = 3)

3.3. Mineral analysis

All the cookies’ samples had significantly higher (p < 0.05) potassium, copper, iron and magnesium contents than the control. Dates are a rich source of minerals. Therefore, the mineral profile of the cookies fortified with date pulp was significantly increased. The highest average values of potassium, iron, copper and magnesium in CFD₅ were 59.9, 1.69, 4.1 and 7.05 mg/100 g, respectively. These findings are correlated with the findings of Anjum et al. (2012). These findings align with Amin et al. (2019), who reported that cookies fortified with 40% date powder exhibited 1.65 g/100 g mineral contents. The mineral contents of cookies fortified with date pulp are presented in Table 3.

Table 3. Mean values for mineral contents for cookies fortified with date pulp

Treatment	Potassium (mg/100g)	Iron (mg/100g)	Copper (mg/100g)	Magnesium (mg/100g)
CFD₀	50.5± 2.51^f	1.50 ±0.06^f	3.53±0.17^ef	5.07±0.25^f
CFD₁	51.25 ±2.50^e	1.52 ±0.06^e	3.54 ±0.17^e	5.15 ±0.26^e
CFD₂	53.05 ±2.65^d	1.56 ±0.06^d	3.69 ±0.18^d	6.05 ±0.30^d
CFD₃	55.43 ±2.77^c	1.62 ±0.06^c	3.88 ±0.19^c	6.59 ±0.32^c
CFD₄	58.21±2.91^b	1.65 ±0.06^b	3.99±0.19^b	6.88±0.34^b
CFD₅	59.99±1.99^a	1.69 ±0.06^a	4.12± 0.20^a	7.05±0.35^a

Means are values ± standard deviation of three replicates or (n = 3)

3.4. Antioxidant analysis of cookies fortified with date paste

TPC and DPPH inhibition average values of cookies fortified with date pulp are presented in Table 4. The mean values of TPC contents in cookies showed a significant difference (p < 0.05). With the addition of date pulp in cookies 10% to 50%, the production of free radical activity decreases. The maximum scavenging activity was observed in CFD₁; however, adding 10% date pulp showed the highest scavenging activity. This fact was confirmed by Abiola et al. (2017).

Table 4. Mean values for antioxidant activity of date pulp fortified cookies

Treatment	TPC (mg GAE/100g)	TFC (QE/100g)	DPPH (mg GAE/100 g)
CFD₀	435 ± 1.75^a	290± 1.5 2^a	60.52± 0.57^a
CFD₁	413 ± 1.65^b	264.51 ± 1.21^b	55.56 ±0.65^b
CFD₂	391 ± 1.55^c	241 ± 1.15^c	46.08 ± 0.45^c
CFD₃	369 ± 1.45^d	216.53 ± 1.08^d	38.93 ± 0.70^d
CFD₄	347 ± 1.35^e	192± 0.95^e	29.61± 0.55^e
CFD₅	325 ± 1.26^f	164.52± 0.85^f	22.0 ± 0.60^f

Similarly, the mean TFC value was 164.52 QE/100 g in CFD_5. A previously reported study by Rambabu et al. (2022) explained significant TFC values of date pulp using different extraction techniques. The antioxidant activity of cookies obtained from different concentrations of date pulp was measured by inhibition amount of DPPH by Afify et al. (2012). The mean results for the antioxidant activity of cookies showed significant results (p < 0.05) among all treatments. The mean values of DPPH in cookies ranged from 60.5 to 22 mg GAE/100 g. Therefore, dates are a rich source of phytochemicals; when added to the product they will affect the phytochemical profile of cookies. In previously cited research Rangaraj et al. (2021) present a successful approach to utilize date fruit waste material in formulating antioxidant-rich active edible films, offering a viable solution for food packaging purposes.

Means are values ± standard deviation of three replicates or (n = 3)

3.5. Sensory evaluation

The mean sensory scores of the cookies fortified with date pulp at different proportions are shown in Figure 2. This indicates significant (p < 0.05) results among all treatments. The results indicate that CFD₀, CFD₁ and CFD₂ get maximum score as compared CFD₃, CFD₄, and CFD₅. The addition of date pulp affects the product’s crispiness, color, taste, texture and overall acceptability. Olukorede Taiwo et al. (2017) and their study confirm these results. In this study, sorghum flour, wheat flour and date palm flour were used to develop cookies and they concluded that enriching wheat flour with sorghum and date palm flour improves its sensory properties. This is due to some coloring compounds in dates (2018).

Figure 2. Sensory evaluation of date pulp-fortified cookies.

4. Conclusion

The current study was planned to determine the physicochemical and antioxidant profile of cookies fortified with different percentages of date pulp. The fortification of date pulp in bakery products enhances the sensory properties and improves the physicochemical, antioxidant and mineral content. A positive increase in free radical scavenging activities and antioxidant potential was observed; the mineral profile of cookies was also improved with the addition of date pulp in cookies. This study proves that the date pulp fortification in bakery products enhances the product’s nutritional profile and is a source for the development of high-profile functional foods.

Acknowledgments

The authors extend their appreciation to the Deputyship for Research & Innovation, Ministry of Education in Saudi Arabia, for funding this research work through the project no. IFKSUOR3–267-3.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Even though adequate data has been given in the form of tables and figures, all authors declare that if more data is required, the data will be provided on a request basis.

Additional information

Funding

No funding was received for this study

Notes on contributors

Muhammad Afzaal

Muhammad Afzaal is an Assistant Professor at the Department of Food Science, Government College University Faisalabad, Pakistan. He also serves as an in-charge for the Food Safety and Biotechnology Laboratory. With over 10 years of teaching and research experience, He has participated in numerous national and international research projects and conducted training for food handlers to build their capacity in food industries through collaborative projects. He has over 100 national and international research publications with high-impact factors, as well as 15 book chapters. He has received the Research Productivity Award 2022 and the Outstanding Researcher Award for securing a position among the top 10 researchers. His research interests include Food Science and Technology, Food Safety, Food Bioprocessing and waste valorisation, Food Microbiology and Biotechnology, functional foods, Probiotics, and prebiotics. Dr. Afzaal is optimistic about finding innovative and effective practices to develop functional foods, processing quality, and safety, with the betterment of human health in mind.

Mohd Asif Shah

Mohd Asif Shah is working as an Associate Professor at the Department of Economics, Kebridahar University, Somali, 250, Ethiopia. Moreover, he has published more than one hundred seventy-five research papers (SCI/SCIE/ SCOPUS/ WOS Indexed) with 410 plus citations and has published hundred plus patents. He has attended more than thirty-five Research Methodology Workshops and Faculty Development Programs, sponsored by the Government of India. Other than this, Dr. Asif has an excellent grasp of the subject material and has been a popular instructor. He is an experienced professional evaluator with key strengths in project management, proposal writing, monitoring and evaluation, and team leadership accomplishments in coordination. He had experience in strategic planning and performance measurement, including indicator selection, target setting, reporting database management, and developing M&E and performance monitoring plans. In addition, I have a good knowledge of major evaluation methodologies like quantitative and qualitative methods, mixed methods, impact evaluation, data collection methods, analysis performance, and report generation skills.