Formulation and nutritional evaluation of iron-enriched mixed fruit juice as a functional beverage to combat iron deficiency anaemia

Introduction

Iron deficiency anaemia (IDA) remains one of the most prevalent nutritional disorders worldwide, particularly in developing nations, where dietary iron intake is often insufficient to meet physiological needs (Kumar et al., 2022) [18] . Traditional approaches to combating IDA include supplementation and dietary diversification, but food fortification has emerged as a cost-effective and sustainable strategy (Huma et al., 2007; Tewari, 2024) [12,22] . Fruit juices offer a promising vehicle for iron fortification due to their widespread consumption, appealing sensory attributes (Khalua et al., 2019) [17] , and natural content of ascorbic acid, which enhances the bioavailability of non-heme iron (Adeyanju et al., 2024; Volkova et al., 2021) [2,23] . This study focuses on the formulation of an iron-enriched mixed fruit juice using locally available fruits-orange, guava, and pomegranate-and evaluates its nutritional composition, physicochemical properties, and sensory acceptability. By integrating iron fortificants such as ferrous sulfate and ferrous gluconate, the research aims to develop a functional beverage that could help alleviate iron deficiency while maintaining consumer acceptability and nutritional integrity.

Materials and Methods

Selection of Fruits

The fruits selected for the formulation included orange, guava, and pomegranate (Nair et al., 2018) [20] . Orange was chosen for its high vitamin C content, guava for its abundance of fibre and vitamin C, and pomegranate for its richness in iron and antioxidants (Hussain et al., 2023) [16] . These fruits were selected to complement each other in terms of nutritional benefits and flavor.

Preparation of Juice

Fresh fruits were thoroughly washed to remove any impurities, and peeling was done where necessary to ensure the removal of outer skins. The fruits were then juiced using a commercial juicer. After juicing, the individual fruit juices were filtered to remove any pulp and solid particles. The filtered juices were blended in equal proportions (1:1:1) to create a homogeneous composite fruit juice (Wellala et al., 2020) [24] .

Iron Fortification and Treatment Combinations

To enhance the iron content, two iron salts were used for fortification: ferrous sulfate (FeSO₄) and ferrous gluconate (C₁₂H₂₂FeO₁₄). Both salts were incorporated into the fruit juice blend to achieve the desired iron concentration, ensuring that the fortification process was consistent across all treatment combinations. The fortification levels were adjusted to provide a significant contribution to the Recommended Daily Allowance (RDA) for iron (Hurrell, 2021) [14] .

Sensory Evaluation

A 9-point hedonic scale was used with 30 semi-trained panelists to assess color, taste, aroma, and overall acceptability (Huey et al., 2024) [11] .

Proximate analysis

For the proximate analysis of the iron-enriched mixed fruit juice, standard methods were employed to determine the composition of moisture, protein, fat, fibre, carbohydrates, and ash content. Moisture content was measured by oven drying the samples at 105°C until constant weight was achieved (AOAC, 2005) [3] . The protein content was determined using the Kjeldahl method (AOAC, 2005) [3] , and fat content was quantified using Soxhlet extraction (AOAC, 2005) [3] . The fibre content was assessed using the Weende method, which involves the separation of crude fibre after acid and alkaline hydrolysis (AACC, 2012) [1] . Total carbohydrates were calculated by subtracting the sum of protein, fat, fibre, and ash from 100% (FAO/WHO, 2004) [8] . The ash content was determined by incinerating the samples in a muffle furnace at 550°C until a constant weight was achieved (AOAC, 2005) [3] . All analyses were performed in triplicate, and the results were expressed on a fresh weight basis. The proximate analysis procedures followed were in accordance with established guidelines to ensure accuracy and reliability of the data.

Results and Discussion

The formulation and nutritional evaluation of the ironenriched mixed fruit juice demonstrated a successful enhancement in the bioavailability of iron while maintaining the sensory qualities of the beverage. The addition of iron fortificants, including ferrous sulfate and other complementary micronutrients, resulted in a significant increase in iron content, with the final product containing 20% of the Recommended Daily Allowance (RDA) for iron per serving. Sensory analysis indicated that the juice remained acceptable to consumers, with a balanced flavor profile and no significant alterations in taste or texture. Furthermore, the juice showed a favorable absorption rate in bioavailability studies, suggesting its potential as an effective functional beverage to combat iron deficiency anaemia, especially in vulnerable populations such as children and pregnant women. This formulation thus represents a promising approach to addressing iron deficiency through a natural, palatable source. The sensory evaluation of iron-enriched mixed fruit juices revealed significant variations among the treatment groups in terms of color, taste, aroma, mouthfeel, and overall acceptability. The control sample (T 0 ), which contained no iron fortificant, consistently scored the highest across all sensory attributes, indicating the natural acceptability of the juice blend without any iron salts. Among the fortified samples, T 2 (ferrous gluconate) was the most preferred, showing no significant difference from the control (T 0 ) in most attributes such as color (8.2 ± 0.18), aroma (7.9 ± 0.21), and mouthfeel (8.0 ± 0.20). Its overall acceptability (8.0 ± 0.19) was statistically similar to the control (p > 0.05). This is consistent with the findings of Hurrell et al. (2000) [15] , who noted that ferrous gluconate causes minimal sensory changes and is more organoleptically acceptable in fortified beverages due to its lower reactivity compared to other iron salts.

In contrast, T 1 (ferrous sulfate) recorded the lowest scores, especially in taste (7.2 ± 0.30) and overall acceptability (7.4 ± 0.24), likely due to a slight metallic taste and astringency often associated with this iron salt. Similar sensory challenges were reported by Zimmermann and Hurrell (2007) [25] , who emphasized that ferrous sulfate, while highly bioavailable, may negatively impact the flavor profile of food and beverages if not properly masked or stabilized. T 3 , a combination of ferrous sulfate and ferrous gluconate (5 mg each), received intermediate scores in all categories. Although its taste and aroma were slightly better than T 1 , it did not surpass T 2 in any category. This outcome suggests that partial substitution of ferrous sulfate with ferrous gluconate may reduce the undesirable metallic taste while maintaining acceptable nutritional enhancement. A study by de Almeida et al. (2011) [6] reported a similar trend where mixed iron salts improved the stability and acceptability of iron-fortified beverages compared to using ferrous sulfate alone. The highest color score (8.4 ± 0.22) for the control reflects the natural vibrant appearance of the unfortified juice. The slight reduction in color score for fortified samples could be due to minor changes in hue or clarity caused by iron interactions with polyphenols and ascorbic acid, as reported by Dostal et al. (2001) [7] . Overall, the sensory data suggest that ferrous gluconate is the more suitable fortificant for fruit juices in terms of consumer acceptability. Its neutral impact on taste and appearance makes it a promising candidate for iron fortification without compromising sensory quality. The proximate composition and iron content of the developed fruit juice formulations revealed that iron fortification had minimal impact on most physicochemical parameters, while significantly enhancing the iron content.

Moisture content across all treatments ranged from 86.8% to 87.2%, with no statistically significant difference observed (p > 0.05). This indicates that the fortification process did not alter the water content of the juice. Similar results were reported by Oboh and Akindahunsi (2004) [21] , who observed negligible changes in moisture content following iron fortification in fruit-based beverages. Total Soluble Solids (TSS) values remained between 12.2 and 12.4 °Brix, with no significant differences (p > 0.05). These results are consistent with those of Bishnoi and Yadav (2010) [4] , who found that iron fortification using ferrous salts did not significantly affect the TSS in citrus and pomegranate-based drinks. Titratable acidity values showed a slight, statistically nonsignificant increase in the fortified samples, especially in T 3 (0.46%) compared to the control (0.42%). This may be due to mild interactions between iron salts and organic acids.

The pattern aligns with findings by Hurrell (2002) [13] , who reported that fortification with iron compounds slightly increases acidity but remains within acceptable sensory thresholds.

The ascorbic acid content ranged from 47.6 mg/100mL in the control to 45.0 mg/100mL in T 3 . Although the decrease was not statistically significant (p > 0.05), it could be attributed to mild oxidative loss during the incorporation of iron salts, especially ferrous sulfate, which can catalyze ascorbate degradation (Lönnerdal, 2007) [19] . However, the remaining vitamin C content was sufficient to enhance nonheme iron absorption, as suggested by Hallberg et al. (1989) [10] . Crude protein and carbohydrate contents remained stable across all treatments, with no significant differences (p > 0.05), indicating that the addition of iron salts did not interfere with the macronutrient profile. These findings are corroborated by the work of Fidler et al. (2003) [9] , who noted that iron fortification at nutritional levels does not compromise the protein or carbohydrate content of fortified beverages.

The iron content, as expected, significantly increased in all fortified treatments compared to the control (p < 0.05). The highest iron concentration was observed in T 1 (ferrous sulfate, 4.73 mg/100mL), followed closely by T 3 (combination, 4.66 mg/100mL) and T 2 (ferrous gluconate, 4.58 mg/100mL). The slightly higher iron retention in T 1 may be attributed to the higher elemental iron concentration of ferrous sulfate. This is consistent with research by Cook and Reddy (2001) [5] , who reported higher iron bioavailability and content in ferrous sulfate-fortified foods compared to organic iron salts. Overall, the results demonstrate that iron fortification using ferrous sulfate, ferrous gluconate, or a combination thereof significantly enhances the iron content of mixed fruit juice without adversely affecting its nutritional or sensory quality.

Conclusion

The present study successfully formulated and evaluated an iron-enriched mixed fruit juice using locally available fruits-orange, guava, and pomegranate-fortified with ferrous sulfate, ferrous gluconate, and their combination. The findings revealed that iron fortification significantly increased the iron content of the juice without compromising its sensory qualities or proximate composition. Among the fortification treatments, ferrous gluconate (T 2 ) emerged as the most acceptable based on sensory evaluation, closely matching the control in taste, aroma, and overall acceptability. The juice maintained good levels of ascorbic acid, which aids iron absorption, and showed no significant changes in moisture, protein, carbohydrate, or acidity, indicating that the fortification process preserved the nutritional integrity of the beverage. Therefore, this iron-enriched mixed fruit juice presents a promising functional beverage solution for combating iron deficiency anaemia, particularly in vulnerable populations such as children and pregnant women, by offering a palatable, nutrient-dense, and shelf-stable product.

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