Introduction

Quinoa (Chenopodium quinoa Willd), an ancient pseudo-cereal native to the Andean region of South America, has gained widespread recognition for its exceptional nutritional profile and adaptability. Unlike traditional grains, quinoa is gluten-free and a complete protein source, containing all essential amino acids, making it particularly valuable for individuals seeking plant-based nutrition (Hernández-Ledesma, 2019; Villacrés et al., 2022). Additionally, quinoa is a rich source of dietary fiber, unsaturated fatty acids, vitamins, and minerals such as iron, zinc, and magnesium, contributing to its classification as a functional food (Dakhili et al., 2019; Angeli et al., 2020). Quinoa’s resilience to extreme environmental conditions, including drought and frost, underscores its potential as a sustainable crop for food security in regions facing climatic challenges. This ability to thrive in nutrient-poor soils further elevates its importance as a climate-resilient food source (Hussain et al., 2021; Melini & Melini, 2021). These attributes, combined with its high nutrient density, have made quinoa a preferred choice in the development of functional foods aimed at improving public health outcomes (Carrizo et al., 2020; Romano et al., 2020). Quinoa’s functional value is due to its rich bioactive compounds, including flavonoids, saponins, and phenolic acids, as those have demonstrated strong antioxidant, anti-inflammatory and beneficial effects on cardiovascular system (Dakhili et al., 2019; Hernández-Ledesma, 2019). Furthermore, quinoa’s unique starch profile, characterized by low amylose content and high digestibility, enhances its versatility in food product formulations (Pellegrini et al., 2018; Li & Zhu, 2018). As a result, quinoa has become a cornerstone ingredient in the development of functional food products.

Functional foods, which provide health benefits beyond basic nutrition, are increasingly popular among health-conscious consumers (Li et al., 2025; Zhang et al., 2024). Quinoa’s incorporation into products such as fruit bars has gained particular attention for its ability to enhance protein content, amino acid balance, and fiber levels (Carrizo et al., 2020; Romano et al., 2020). Additionally, quinoa’s low glycemic index and satiating properties make it an ideal component for on-the-go pseudocereals snacks designed for energy management and overall health improvement (Hernández-Ledesma, 2019; Villacrés et al., 2022). Fruits are considered a great source of phytochemicals, vitamins, and minerals. Remarkably, nutrients are concentrated and dispersed in fruit bars. Since fruit bars contain a mixture of fruits, they have a richer nutritional content than a single fruit (Gorsi et al., 2024; Aziz et al., 2024; Wang et al., 2022). The bars serve as a healthier source of essential nutrients having different taste which is ready to consume (Padmashree et al., 2018). Lifestyle changes and dietary behaviors, increased understanding of healthy eating habits with sufficient nutrient needs, and busy routine activities have made food bars a great choice for high-energy intake sources (Barakat & Alfheeaid, 2023; Altuncevahir et al., 2024). Mango is consumed for its high content of vitamin C, carotenoids, and dietary fiber, which contribute to its antioxidant properties and unique flavor (Pathan & Siddiqui, 2022; Hussain et al., 2024a). Dates, on the other hand, are a natural source of sugars, potassium, and polyphenols, enhancing the energy density and overall antioxidant capacity of functional fruit bars (Agarwal et al., 2023; Pellegrini et al., 2018).

Dates and mangoes together create a balanced, nutrient-dense snack that caters to modern dietary preferences for convenience and health (Maldonado-Celis et al., 2019; Hossain, 2019). The increasing popularity of quinoa-based products reflects broader trends in the food industry toward plant-based, sustainable, and functional foods. The integration of mango and dates with quinoa in fruit bars further enriches their nutritional value (Hussain et al., 2021). Products combining dates, mangoes, and quinoa are gaining popularity across diverse food categories due to their nutritional and functional benefits. For example, mango-based fruit bars, made from whole mango (peel and pulp), provide substantial dietary fiber and phenolic compounds, enhancing their nutritional and functional value (Shouket et al., 2024). These bars also offer notable antioxidant capacity and potential physiological benefits, making them a natural and health-promoting snack option (Hernández-Maldonado et al., 2019). Quinoa-based gluten-free cakes, enriched with probiotics and protein, cater to dietary needs of health-conscious consumers while maintaining desirable sensory qualities (Amini et al., 2022). Additionally, date-enriched beverages, such as vitamin D-fortified milk, offer functional and appealing nutritional options for children (Jufri et al., 2023). Similarly, mango pulp addition in dairy beverage has also been made to get functional benefits (Siddique et al., 2024). Another innovative product line is fermented spoonable vegan products, made with quinoa flours blended with dates or other fruits, offering probiotic benefits and high nutritional value (Väkeväinen et al., 2020). Thus, fruit bars having quinoa, date, and mango in their recipe could offer valuable and diverse nutrient and bioactive compositions for health-conscious consumers; therefore, this work could prove beneficial for both consumers and food producers in order to have a new range of nutritional and functional food bars in the markets. This study focuses on the development, quality analysis, and nutritional evaluation of quinoa-based fruit bars enriched with mango and dates, aiming to create a product that offers exceptional health benefits while meeting sensory expectations. Additionally, it seeks to evaluate shelf life under varying storage conditions.

Materials and Methods

Procurement of raw material

This work was carried out during November 2023 to January 2024, at Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan. All plant materials utilized in this study are cultivated species; thus, no special permission was needed for their use. Nonetheless, their handling complied with all relevant national and international guidelines and standards. Quinoa (Chenopodium quinoa Willd.), a pseudocereal rich in high-quality protein, dietary fiber, and essential minerals, was obtained from the Agronomy Department of Muhammad Nawaz Shareef University of Agriculture, Multan, and used for the development of the functional product. Mango (Mangifera indica L.) was also procured from the local market, and pulp was prepared using a mixer (PS, 2944, Panasonic, Japan). Similarly, date (Phoenix dactylifera L.) was also obtained from the local market, and pulp was prepared manually. All chemicals required for the analysis were sourced from the local market in Multan. Each analysis was performed in triplicate to determine the mean values.

Proximate analysis

Prior to analysis, the quinoa sample was washed thoroughly with distilled water to remove the saponin layer responsible for bitterness. The cleaned quinoa was then dried at 105°C for 24 hours in a hot air oven (HAT, 110, Biobase, China) until constant weight was achieved and subsequently ground into powder using a crushing machine (Model CM-200, Panasonic, Japan). Proximate analysis of quinoa, mango, and date samples was conducted following AOAC protocols. Moisture content was determined using the oven-drying method in a hot air oven (HAT, 110, Eco Star, Pakistan) at 105°C for 24 hours (AOAC, 2000). Crude protein content was analyzed using Kjeldahl’s method with a Kjeldahl apparatus (Model KDN-08, locally available in Pakistan) (AOAC, 2000). Crude fat was measured through Soxhlet extraction using a Soxhlet apparatus (Model E-816, locally fabricated in Pakistan) (AOAC, 2000). Ash content was determined by incineration in a muffle furnace (MF-300, Pak Lab Industries, Pakistan) at 550°C (AOAC, 2000). Crude fiber content was analyzed using a fiber analyzer (Fiber Tech, Model FI-12, locally available in Pakistan) (AOAC, 2000).

Mineral analysis of raw materials

Calcium, sodium, and potassium content in quinoa, mango, and date samples were analyzed using a flame photometer (Model FP-410, Sherwood Scientific, UK). The analysis was conducted following standard protocols (AOAC, 2000).

Preparation of fruit bars

For development of food bars, the research work was performed in the Laboratory of the Department of Food Science and Technology at Muhammad Nawaz Shareef University of Agriculture, Multan. Fruit bars were prepared following the standard protocol described by Padmashree et al. (2018), with minor modifications. Dry ingredients were thoroughly mixed using a mixer (Model PS-2944, Panasonic, Japan), and fruit pulp was gradually incorporated. The mixture was then kneaded manually with clean, sanitized hands and shaped into bars using a rectangular mold. The detailed treatment plan is illustrated in Table 1.

Proximate analysis of fruit bars

Proximate analysis of fruit bars (quinoa date bar and quinoa mango bar) was conducted following AOAC protocols (AOAC, 2000). Moisture content was determined using the oven-drying method in a hot air oven (HAT, 110, EcoStar, Pakistan) at 105°C for 24 hours (AOAC, 2000). Crude protein content was analyzed by Kjeldahl’s method using a Kjeldahl apparatus (Model KDN-08, locally available in Pakistan) (AOAC, 2000). Crude fat content was measured via Soxhlet extraction using a Soxhlet apparatus (Model E-816, locally fabricated in Pakistan) (AOAC, 2000). Ash content was determined by incineration in a muffle furnace (MF-300, Pak Lab Industries, Pakistan) at 550°C (AOAC, 2000). Crude fiber content was analyzed using the standard method with a fiber analyzer (Fiber Tech, Model FI-12, locally available in Pakistan) (AOAC, 2000).

Chemical analysis

Mineral analysis of fruit bars

Calcium, sodium, and potassium content in bars made with quinoa, mango, and date samples was analyzed using a flame photometer (Model FP-410, Sherwood Scientific, UK). The analysis was conducted following standard protocols (AOAC, 2000).

Total sugars, reducing sugars and non-reducing of fruit bars

Total sugars, including reducing and non-reducing sugars, present in fruit bars were calculated according to standard protocols by the titration method using Fehling solution (AOAC, 2000).

Titratable acidity

Titratable acidity of fruit bars was determined by acid titration method according to the standard protocols using 0.1 N NaOH standard solution (AOAC, 2000).

Determination of pH

The pH of fruit bars was determined by using pH meter (Model PH-209B by Lutron) according to the standard protocols (AOAC, 2000).

Calorific value

Calorific value of fruit bars was determined according to standard protocol using factors of 3.75, 3.75, and 9.0 kcal/g for carbohydrate, protein, and lipid, respectively. All energy contents were summed to obtain the total calorific value of quinoa bars (Munir et al., 2018).

In-vitro starch digestibility

In vitro starch digestibility of fruit bars was determined according to the standard protocols adopted by Chau and Cheung (1997).

Water holding capacity

Water holding capacity of fruit bars was determined according to the standard protocol used by Mahnoor et al. (2024).

Physical analysis

Texture analysis

Texture of fruit bars was analyzed using a texture analyzer (TA.XT Plus, Stable Micro Systems, UK) according to the standard protocol used by Din et al. (2024), to determine hardness and fracturability.

Color determination

Color of fruit bars was analyzed according to the standard protocol adopted by Hussain et al. (2023), with some modifications, using a colorimeter (CFEZ0385, USA). Colorimeter readings (L*, a*, b*) were recorded and compared with standards to obtain actual results.

Brix content determination

Brix of fruit bars was analyzed using a hand refractometer (RHB-32ATC) with a 0–32 brix range, according to the standard protocol used by Siddique et al. (2024).

Microbiological analysis

Microbiological analysis of fruit bars, including total plate count and mold/yeast count, was carried out using the standard dilution method provided by Christen and Parker (2020), and validated through microbial inactivation assessments (Garre et al., 2019).

Sensory analysis

Sensory evaluation of fruit bars was performed at Department of Food Science and Technology, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan, with the help of teachers and students to assess the acceptability of fruit bars based on color, flavor, taste, texture, and overall acceptability using a 0–9 hedonic scale, as done by Arinzechukwu and Nkama (2019). Briefly, an untrained panel of 35 evaluators (volunteers from the department where trials were performed), comprising both genders and with an average age between 25 and 35 years, participated in the sensory evaluation. These participants were involved in the study from December 1, 2023, to January 30, 2024, when the final product was ready for assessment. The study did not include minors. Informed verbal consent was obtained from all participants and recorded for documentation.

Statistical analysis

The obtained data were evaluated to determine the acceptability and quality of fruit bars through statistical analysis using a two-factorial Completely Randomized Design (CRD) and Analysis of Variance (ANOVA) techniques, with a significance level of p ≤ 0.05(Aslam et al., 2023).

Results and Discussion

Proximate analysis of raw material

The results presented in Table 2 show that quinoa has the highest protein content, while mango has the lowest protein content. Table 2 presents the results, showing that quinoa also has the highest fiber content, while mango has the lowest fiber content. In terms of fat content, quinoa has the highest fat percentage, whereas both date and mango have the lowest fat contents. The moisture content is highest in mango, followed by date, with quinoa having the lowest moisture content. In terms of ash content, date has the highest ash content, while mango has the lowest ash content. Our findings are in accordance with recent studies that highlight quinoa’s superior nutritional composition compared to other plant and fruit sources. Quinoa’s high protein content and essential amino acid profile, as documented, underscore its potential as a complete protein source (Gómez et al., 2021). Additionally, the rich fiber content in quinoa is consistent with prior evaluations demonstrating its contribution to gut health and its classification as a high-fiber pseudocereal (Campos-Rodriguez et al., 2022). Furthermore, the elevated ash content in dates agrees with findings that study dates as a rich source of minerals, including calcium and magnesium (Odunayo et al., 2022). Similarly, the results of the chemical composition of mango pulp reported here are in line with the previous findings of Hussain et al. (2024a) and Hussain et al. (2024b), as the authors also reported a similar amount of ash, fiber, and protein in mango pulp. Thus, from this chemical composition of raw materials analyzed, it could be considered that quinoa, due to its diverse composition, could contribute these nutritional contents to the food products in which it is added.

Mineral analysis of raw material

The result presented in Table 3 shows that date has the highest sodium content, while mango has the lowest sodium content. The data given in Table 3 also indicates that date also has the highest potassium content, while mango has the lowest potassium content. In terms of calcium content, date has the highest value, while mango has the lowest calcium content. Our results align with previous studies that emphasize the superior mineral content in dates compared to other plant-based foods. Dates were identified as a rich source of potassium and calcium, critical for maintaining heart health and bone strength (Salomón-Torres et al., 2019). Similarly, quinoa’s relatively high potassium and calcium levels support its reputation as a nutrient-dense pseudocereal beneficial for various health conditions, as corroborated by other recent analyses (Rodríguez Gómez et al., 2021). Meanwhile, mango’s lower mineral content is consistent with its classification as a hydrating fruit rather than a concentrated mineral source (Shaikh et al., 2021). The mineral composition of the mango pulp reported here is also consistent with the findings of Hussain et al. (2024a) and Hussain et al. (2024b), who also reported a comparable level of calcium, potassium, and sodium in the pulp. Because of their varied mineral compositions, it is possible to infer from the chemical composition of the raw materials that all three of them could give these mineral contents to the snack bars to which they are added.

Proximate analysis of fruit bars

For proximate analysis of fruit bars, the results presented in Figures 1–5 show that moisture content had non-significant (p < 0.01) interactions during days but showed a significant (p < 0.01) effect for treatments. Moisture content ranged from 17.988% (Cd) to 14.258% (D3), with a maximum of 18.253% (Cd, day 15) and a minimum of 14.130% (D3, day 45). The data presented in Figure 2 reveal that ash content showed no significant (p < 0.01) interactions during days but showed significant (p < 0.01) effects for treatments. Ash content ranged from 4.6258% (D3) to 2.1650% (Cd), with a maximum of 4.6867% (D3, day 0) and a minimum of 2.0767% (Cd, day 45). The data given in Figure 3 show that crude fat content had significant (p < 0.01) interactions and treatment effects. Fat content ranged from 7.0883% (D3) to 0.9550% (M2), with a maximum of 7.1333% (D3, day 0) and a minimum of 0.9400% (M2, day 45). Similarly, Figure 4 presents results showing that crude protein content exhibited no significant (p < 0.01) interactions but demonstrated significant treatment effects on fruit bars. Protein content ranged from 14.437% (D3) to 8.893% (Cm), with a maximum of 14.514% (D3, day 0) and a minimum of 8.880% (Cm, day 15). The data presented in Figure 5 show that crude fiber content had significant (p < 0.01) interactions and treatment effects. Fiber content ranged from 6.8883% (D3) to 3.5500% (Cd), with a maximum of 6.9533% (D3, day 0) and a minimum of 2.0000% (Cm, day 45). The results presented in Figure 6 indicate that NFE content had significant (p < 0.01) interactions and treatment effects. The NFE content decreased for most treatments from day 0 to day 45, with a sharp increase observed in M1, M2, and M3 by day 45. Our findings on the proximate analysis of fruit bars revealed significant effects of treatments on moisture, protein, fat, fiber, ash, and NFE content, while interactions over days were generally non-significant. A similar chemical composition of energy bars developed from quinoa and other ingredients has also been reported by Kaur et al. (2018). These results align with findings demonstrating that the nutritional composition of fruit- and vegetable-based products varies significantly depending on the treatment methods and composition of raw materials (Kamau et al., 2020). The crude protein and ash content variations observed in our study are comparable to reports highlighting the impact of processing on protein and mineral retention in fruit-based products (Umar et al., 2021). Furthermore, the variations in fiber and carbohydrate levels are consistent with findings showing that blending ratios and processing techniques significantly influence these parameters in fruit-based products (Arinzechukwu & Nkama, 2019). The use of pseudocereals in the fruit bars has been found increasingly beneficial due to the high amount of ash, fiber, and protein contents in these crops (Sabeel et al., 2024).

Figure 1. Results of moisture content of fruit bars.

Figure 2. Results of ash content of fruit bars.

Figure 3. Results of fat content of fruit bars.

Figure 4. Results of protein content of fruit bars.

Figure 5. Results of fiber content of fruit bars.

Figure 6. Results of NFE content of fruit bars.

Chemical Analysis

Mineral analysis of fruit bars

Fruit bars having cereals and pseudocereals could be a good source of macro minerals (Kaur et al., 2018). For mineral analysis, the results presented in Figure 7 show that sodium content in fruit bars had non-significant (p < 0.01) interactions during days and treatments, with values ranging from 422.79 mg/100g (Cd) to 277.14 mg/100g (M1). The maximum value was 293.40 mg/100g (D3, day 0), and the minimum was 242.25 mg/100g (Cm, day 45). Further, the data presented in Figure 8 show that potassium content in fruit bars exhibited significant (p < 0.01) interactions during days and treatments, ranging from 625.90 mg/100g (D3) to 584.12 mg/100g (Cm). The highest value was 628.87 mg/100g (D3, day 0), and the lowest was 508.78 mg/100g (D2, day 45). Moreover, the data given in Figure 9 show that calcium content in fruit bars had non-significant (p < 0.01) interactions during days and treatments, with values ranging from 213.72 mg/100g (Cd) to 144.03 mg/100g (M1). The maximum value was 462.68 mg/100g (Cd, day 30), and the minimum was 127.50 mg/100g (Cm, day 45). Our findings were in accordance with studies showing that sodium levels in fruit-based products are minimally influenced by treatment variations but slightly affected by preparation methods (Pertiwi et al., 2022). Our analysis was very comparable with research demonstrating that potassium plays a crucial role in determining nutrient composition and quality, significantly influenced by treatments (Sahu et al., 2023). Additionally, our results were in line with findings highlighting that calcium content remains stable across treatments and contributes to the structural integrity of fruit-based products (Czech et al., 2020). Because pseudocereals contain a lot of minerals, their usage in fruit bars has been shown to be increasingly advantageous. Pseudocereals are high in vital minerals and have been validated for their ability to promote health, making them appropriate for people with mineral deficiencies (Sabeel et al., 2024).

Figure 7. Results of sodium content of fruit bars.

Figure 8. Results of potassium content of fruit bars.

Figure 9. Results of calcium content of fruit bars.

Total sugars, reducing sugars and non-reducing sugars

The sugar contents and variations in the total, reducing, and non-reducing sugars depend upon the ingredients and raw materials used in the development of food bars (Kaur et al., 2018). The result presented in Figure 10 shows that total sugars in fruit bars exhibited a highly significant (p < 0.01) interaction during days and treatments. The combined effect of treatment and days was non-significant (p < 0.05). Total sugars ranged from 62.150% (Cm) to 45.300% (D3). The maximum value was 62.700% (Cm, day 45), and the minimum was 44.900% (D3, day 0). These findings highlight significant differences based on treatments and storage duration. Data in Figure 11 depicts that reducing sugar contents ranged from 6.0% (Cd) to 16.0% (Cm) across treatments, with a significant increase noted in M1, M2, and M3 by day 45. Moreover, it can be examined from Figure 12 that non-reducing sugar content ranged from 40.0% (D3) to 46.0% (Cm), with day 45 depicting elevation for most treatments, particularly in M1, M2, and M3. The results of this study align with previous findings that total sugar content in fruit bars significantly varies depending on treatment methods and ingredient composition, with minimal interaction effects over storage time (Munir et al., 2018). These findings also correspond with evidence that sugar levels in fruit-based products are influenced by blending ratios and processing techniques, which contribute to the stability and nutritional value of the bars (Eyiz et al., 2020). Furthermore, the impact of sugar content on sensory properties and consumer acceptability reinforces the importance of optimizing sugar levels for producing high-quality fruit bars (Srivastava et al., 2019).

Figure 10. Results of total sugars of fruit bars.

Figure 11. Results of reducing sugars of fruit bars.

Figure 12. Results of non-reducing sugars of fruit bars.

Titratable acidity

The data given in Figure 13 show that titratable acidity in fruit bars had a non-significant (p < 0.01) interaction during days but exhibited a highly significant (p < 0.01) impact during treatments. The data given in Figure 13 indicate that titratable acidity ranged from 0.5750% (M3) to 0.3283% (Cd). The maximum value recorded was 0.5900% (M1, day 45), while the minimum was 0.3167% (Cd, day 45). These results highlight the significant effect of treatments on acidity levels in fruit bars. Our findings were in line with studies that reported the significant impact of treatments on titratable acidity in fruit-based products, demonstrating that treatments influence acidity levels while storage duration has a lesser effect (Yulistiani et al., 2022). The results were also comparable with research showing that the use of specific acidulants and processing methods significantly affect acidity and other chemical properties of fruit products (Tsegay, 2020). Additionally, our findings were consistent with studies emphasizing that variations in acidity contribute to the sensory attributes and overall quality of fruit-based bars (Gahane et al., 2024). This variation in the titratable acidity of the bar treatments could be attributed towards high acidity of mango pulp as compared to the date fruit, which might have contributed towards the rise in the acidity (Siddique et al., 2024).

Figure 13. Results of titratable acidity of fruit bars.

Determination of pH

The result explained in Figure 14 shows that the pH of fruit bars had a non-significant (p < 0.01) interaction during days but exhibited a highly significant (p < 0.01) impact during treatments. The data given in Figure 14 depict that pH values ranged from 5.9050 (Cd) to 4.2150 (M3). The maximum pH noted was 5.9200 (Cd, day 0), while the minimum was 4.2000 (M3, day 45). These findings suggest that treatments significantly affected the pH levels in fruit bars. Our results were in accordance with findings that treatments significantly influence pH levels in fruit-based products, while the impact of storage time remains minimal (Eyiz et al., 2020). Our analysis was very much comparable with studies highlighting that pH adjustments during processing can enhance the sensory and shelf-stability characteristics of fruit bars (Hanum et al., 2022). Additionally, our results were in line with research showing that pH stability is a crucial factor for maintaining the chemical integrity of fruit-based products during storage and handling (Gireesh et al., 2022). As mango and date have different pH values, which are also different from quinoa, the different variations of these ingredients are responsible for the variations in the pH of the bars.

Figure 14. Results of pH value of fruit bars.

Calorific value

The result presented in Figure 15 demonstrates that the calorific value of fruit bars showed a significant (p < 0.01) interaction across days and a highly significant (p < 0.01) effect across treatments. The data given in Figure 15 indicate that calorific values ranged between 316.41 kcal (D3) and 297.90 kcal (Cm). The mean values for treatments were between 315.57 kcal (D3) and 299.10 kcal (M1), while the mean values for days ranged from 303.29 kcal (day 0) to 305.34 kcal (day 45). The highest calorific value was 316.41 kcal (D3, day 45), and the lowest was 297.90 kcal (Cm, day 0). The bars having date as their ingredient have shown high calorific values, which are found to further increase as a result of higher levels of quinoa; these are possibly due to the high carbohydrates in these ingredients. Our findings were in accordance with studies showing that the calorific value of fruit bars is significantly influenced by treatments, with changes reflecting variations in the nutritional composition of the ingredients used (Munir et al., 2018). The results are comparable with research highlighting the importance of processing methods and ingredient composition in determining the calorific value of snack bars, which can significantly vary based on treatment combinations (Saletnik et al., 2021). Additionally, the data align with studies emphasizing that the calorific content of fruit bars is a critical factor for energy-dense snacks, ensuring product acceptance and consumer satisfaction (Eyiz et al., 2020).

Figure 15. Results of calorific value of fruit bars.

In-vitro starch digestibility

Figure 16 depicts that in-vitro starch digestibility of fruit bars had a non-significant (p < 0.01) interaction over the days but displayed a highly significant (p < 0.01) effect for treatments. The data presented in Figure 16 reveal that digestibility values varied between 455.76% (M3) and 336.86% (Cd). The mean values for days ranged from 399.14% (day 0) to 393.04% (day 45). The highest digestibility observed was 456.00% (M3, day 0), and the lowest was 321.64% (D1, day 45). The results were consistent with studies showing that treatment variations significantly influence in-vitro starch digestibility in fruit-based products due to structural modifications in the starch matrix (Zhang et al., 2019). These findings support evidence that heat and moisture-based processing techniques enhance enzymatic digestibility by altering starch crystallinity and molecular arrangement (Yan et al., 2020). Furthermore, the relationship between processing-induced changes in starch structure and improved digestibility aligns with prior research emphasizing the importance of functional modifications in optimizing the nutritional quality of fruit-based products (Zhou et al., 2020).

Figure 16. Results of in-vitro starch digestibility of fruit bars.

Water holding capacity

Figure 17 reveals that the water holding capacity of fruit bars was significantly (p < 0.01) influenced by treatments, while interactions across days remained non-significant (p < 0.01). Notably, the water holding capacity varied across treatments, with values ranging from 0.6873% for M3 to 0.5077% for Cd. Across days, the mean values slightly fluctuated between 0.6085% (day 0) and 0.6043% (day 45). The highest water holding capacity, 0.6890%, was observed in M3 on day 45, while the lowest, 0.5080%, occurred in Cd on day 15. Our findings were in line with research emphasizing that water holding capacity in fruit-based products is significantly influenced by treatments due to modifications in structural composition, while storage duration has minimal impact (Ozilgen, 2011). The results were comparable with studies that demonstrated the role of enzymatic and compositional changes in enhancing water retention properties, crucial for the textural and sensory quality of fruit bars (Canela-Xandri et al., 2018). Additionally, our analysis aligned with findings highlighting that coating and processing methods can optimize water activity and moisture retention in fruit-based snacks, contributing to prolonged shelf life and consumer acceptance (Eyiz et al., 2020). These higher water holding capacities of mango and quinoa-based bars could be attributed towards the high fiber contents in the mango and quinoa (Sabeel et al., 2024; Kaur et al., 2018).

Figure 17. Results of water holding capacity of fruit bars.

Physical analysis

Texture analysis

The data in Figure 18 illustrates a highly significant (p < 0.01) effect of treatments and days on the hardness of fruit bars, while the combined effect of treatment and days was non-significant (p < 0.05). Treatment values ranged from 627.50 (M3) to 241.30 (D₂), showing considerable variation. Day-based means were 462.64 (day 0) and 477.68 (day 45), indicating a slight increase over time. The maximum recorded hardness was 635.00 (M3, day 45), while the minimum was 233.77 (D₂, day 0). As presented in Figure 19, treatments had a highly significant (p < 0.01) effect on the fracturability of fruit bars, while interactions over days and the combined influence of treatments and days were non-significant (p < 0.05). Fracturability values varied from 72.790 (D₂) to 32.871 (M3) across treatments. The day-based means were nearly stable, with 52.542 recorded at day 0 and 52.419 at day 45. The highest value, 72.820, was observed in D₂ on day 0, while the lowest, 32.740, was recorded in M3 on day 45. The high hardness of mango bars having higher levels of quinoa might be due to the hard texture of these bars resulting from the high quinoa starch presence, while date bars, due to more water absorption, have shown low hardness values. The results confirm that treatments play a crucial role in determining the hardness and fracturability of fruit bars, as significant changes were observed across treatment variations (Eyiz et al., 2020). This study further supports findings that structural integrity, particularly hardness, can be improved through optimized processing techniques and ingredient modifications (Munir et al., 2018). Moreover, the observed variations in fracturability align with research showing that moisture content and protein interactions greatly influence textural stability and consumer acceptability (Ud Din et al., 2025; Kigozi et al., 2024). The variations of other ingredients like fat, fiber, and carbohydrates might also have contributed to the differences in hardness and fracturability of these bar treatments.

Figure 18. Results of hardness of fruit bars.

Figure 19. Results of fracturability of fruit bars.

Color determination

Figures 20, 21, and 22 respectively reveal that the treatments significantly (p < 0.01) influenced the ‘L’, ‘a’, and ‘b’ color values of fruit bars, while interactions across days were non-significant (p < 0.01). However, the combined effect of treatments and days was highly significant (p < 0.05). The ‘L’ value ranged from 48.450 (M1) to 28.000 (Cd), the ‘a’ value from 18.605 (D₁) to 4.732 (Cd), and the ‘b’ value from 12.500 (M2) to 7.570 (D₁). Across days, mean values for ‘L’, ‘a’, and ‘b’ decreased slightly, with ‘L’ reducing from 36.485 (day 0) to 16.246 (day 45), ‘a’ from 9.2100 (day 0) to 9.1575 (day 45), and ‘b’ from 9.6450 (day 0) to 9.4375 (day 45). The maximum values recorded were 48.480 (‘L’, M1, day 0), 18.630 (‘a’, D₁, day 0), and 12.800 (‘b’, M2, day 0), while the minimum values were 27.700 (‘L’, Cd, day 45), 4.710 (‘a’, Cd, day 45), and 7.520 (‘b’, D₁, day 45). The results are consistent with research showing that treatments significantly influence the L*, a*, and b* color values of fruit-based products, highlighting the importance of ingredient composition and processing techniques in enhancing visual appeal (Eyiz et al., 2020). These findings align with studies that demonstrate how color parameters are crucial for consumer acceptance, as they are directly linked to perceived quality and freshness (Manasa et al., 2020). Moreover, our results complement evidence suggesting that controlled treatments can stabilize color properties over time, ensuring consistency and prolonged shelf life in fruit products (Aghajanzadeh et al., 2023). The bars having low levels of quinoa and high levels of date and mango showed higher a* and b* values, while lower L* values, possibly due to the high pigments in mango and date compared to quinoa (Kaur et al., 2018; Hussain et al., 2024b).

Figure 20. Results of color (L*) value of fruit bars.

Figure 21. Results of color (a*) value of fruit bars.

Figure 22. Results of color (b*) value of fruit bars.

Brix content

Data in Figure 23 highlights that the Brix content of fruit bars was significantly (p < 0.01) affected by treatments and days, while their combined interaction was not statistically significant (p < 0.05). The Brix content varied across treatments, ranging from 71.975 (M3) to 47.350 (D3). Mean values across days showed minimal differences, with 62.654 on day 0 and 63.250 on day 45. The highest Brix content, 72.400, was observed in M3 on day 45, while the lowest, 47.100, was recorded in D3 on day 0. These results indicate that treatments had a pronounced effect on Brix content, with storage time contributing less variability. The findings are consistent with studies highlighting the significant influence of treatments on Brix content in fruit bars, emphasizing that ingredient composition and processing methods play a pivotal role in regulating sweetness levels (Eyiz et al., 2020). These results also align with research demonstrating that Brix levels are crucial for consumer acceptance, as they determine the perceived quality and flavor of fruit-based products (Aslam et al., 2023). Furthermore, our results support evidence that storage duration has a relatively minor effect on Brix content compared to the significant impact of treatments, which ensure consistency and enhance product stability (Arinzechukwu & Nkama, 2019). The similar sugar contents of quinoa and mango may be responsible for the small variations in the Brix of mango-quinoa bars, whereas the larger differences in sugar content between date and quinoa likely account for the significant variation in the Brix of date bars containing different levels of quinoa.

Figure 23. Results of brix content of fruit bars.

Microbiological analysis

The results presented in Figure 24 show that the total plate count and mold count of fruit bars were significantly (p < 0.01) affected by both treatments and storage days, with a highly significant (p < 0.05) combined effect. The total plate count ranged from 2.7897 CFU/g (M2) to 1.5750 CFU/g (Cd), while mold count ranged from 2.7975 CFU/g (M3) to 1.4975 CFU/g (Cd). The highest values recorded were 2.9600 CFU/g for total plate count (M2, day 45) and 2.0000 CFU/g for mold count (M3, day 45), whereas the lowest counts were 1.2300 CFU/g (Cd, day 0) and 1.2060 CFU/g (D1, day 0), respectively. Our findings are consistent with previous studies indicating that microbial loads, including total plate and mold counts, are significantly influenced by treatments and storage duration in fruit-based products, underscoring the importance of effective processing techniques for ensuring microbial safety (Arinzechukwu & Nkama, 2019). These results align with research demonstrating that appropriate treatments can significantly reduce microbial growth while maintaining sensory quality, thereby extending shelf life (Eyiz et al., 2020). Furthermore, the data highlight that combining suitable ingredient formulations with optimized storage conditions can minimize microbial contamination, enhancing the overall safety and quality of fruit-based snacks (Rasouli et al., 2019). The antimicrobial properties of quinoa may explain the lower total plate and mold counts observed in bars with higher quinoa content (Dev and Gupta, 2024). Additionally, bioactive compounds present in mango pulp likely contributed to the reduced microbial counts in these bars (Hussain et al., 2024a).

Figure 24. Results of total plate count and mold count of fruit bars.

Sensory analysis

The data presented in Figure 25 show that aroma, color, flavor, texture, and overall acceptability of fruit bars were significantly (p < 0.01) influenced by treatments, while interactions over days and the combined effect of treatments and days were non-significant (p < 0.05). Mean scores across treatments ranged from 6.5938 to 5.9688 for aroma, 7.1875 to 6.0938 for color, 7.1250 to 6.2674 for flavor, 6.9375 to 6.0035 for texture, and 7.1875 to 5.8750 for overall acceptability. The highest values observed on day 0 were 6.6250 (aroma, M2), 7.5000 (color, M2), 7.2500 (flavor, D2), 7.5000 (texture, D2), and 7.6250 (overall acceptability, D2). The lowest values, recorded on day 45, were 5.8750 (aroma, M1), 5.8750 (color, D3), 6.2500 (flavor, Cd), 5.6250 (texture, Cm), and 5.6250 (overall acceptability, Cd). These findings highlight clear variations in sensory attributes based on treatment formulations. Our results align with previous studies emphasizing the significant influence of treatments on sensory qualities such as aroma, color, flavor, texture, and overall acceptability—key factors for consumer satisfaction (Amalia et al., 2022). These observations are consistent with research demonstrating that optimized treatments can enhance sensory characteristics, including texture and flavor, leading to improved consumer acceptability (Tagud et al., 2024). Furthermore, our findings agree with studies showing that sensory stability can be maintained over storage time, ensuring long-term product quality (Verma & Bisen, 2020). The observed improvements in color and flavor support previous research highlighting the role of specific treatments in enhancing the visual appeal and taste of fruit bars (Devi et al., 2018). Lastly, these results corroborate evidence suggesting that consumer preferences for sensory attributes can be optimized through ingredient modifications and controlled processing techniques (Akesowan et al., 2020). Based on the findings, it can be concluded that fruit bars containing date and mango with 20% quinoa exhibited higher consumer acceptability compared to treatments with higher quinoa concentrations.

Figure 25. Sensory analysis of fruit bars.

Conclusion

The development of mango and date-based fruit bars enriched with quinoa demonstrates significant potential as a nutritious and energy-rich snack suitable for all age groups. Quinoa, recognized as a nutrient-dense pseudo-cereal, serves as an excellent source of protein and energy, while mango and dates contribute essential nutrients, particularly minerals, making their combination in fruit bars highly beneficial. This study successfully prepared fruit bars under hygienic conditions, incorporating varying quinoa flour concentrations (10%, 20%, and 30%) with mango and date pulps. Comprehensive physical, chemical, microbiological, and sensory analyses conducted over a 45-day storage period revealed that the fruit bars maintained favorable nutritional and sensory profiles throughout storage. Notably, bars containing 30% quinoa showed a significant increase in protein, fiber, ash, and mineral contents. Significant variations in pH, acidity, sugar content, and brix values were observed across treatments and storage days. Additionally, quinoa-enriched bars exhibited significantly lower total plate and mold counts, indicating improved microbial stability. Among all formulations, the date bar with 20% quinoa flour demonstrated the highest acceptability across all sensory parameters, balancing nutritional benefits with consumer appeal. This study lays a promising foundation for the development of functional, nutrient-dense snacks that meet modern dietary demands while promoting health benefits. Furthermore, it highlights the versatility and health-promoting potential of quinoa-enriched fruit bars as convenient, nutrient-rich snacks. These findings also underscore the importance of further research into the health impacts of functional fruit bars and their potential role in disease prevention and management.