Introduction

Candy products represent a major segment of the global confectionery industry and are widely consumed across different age groups due to their convenience, sensory appeal, and extended shelf life. These products are commonly classified into hard and soft candies based on their textural characteristics, which are primarily influenced by formulation composition and processing conditions [1]. Soft candies, including gummies and jellies, are characterised by their elastic and chewy texture, which is typically achieved through the incorporation of gelling agents such as pectin, gelatine, or starch derivatives [2]. The functional role of these gelling agents lies in their ability to form a three-dimensional network within the aqueous phase, resulting in a colloidal system with sufficient structural integrity while maintaining softness and flexibility [3]. In addition, glucose syrup and sugars play a critical role in controlling crystallisation, viscosity, and moisture retention, thereby influencing product stability and mouthfeel [4]. Despite their popularity, many commercially available soft candies rely heavily on refined sucrose, artificial colourants, and flavouring agents. This has led to increasing consumer interest in confectionery products formulated with natural ingredients and fruit-based components [5]. Recent studies have further highlighted the importance of fruit-based ingredients in the development of functional food products with improved physicochemical, sensory, and antioxidant properties, while also supporting sustainable utilisation of fruit resources and reducing post-harvest losses [6, 7].

The incorporation of fruit-based ingredients into confectionery formulations represents a strategic approach to developing value-added products using natural raw materials [8]. Mangifera pajang Kosterm., locally known as bambangan, is an indigenous wild mango species native to the lowland rainforests of Borneo, including Sabah and Sarawak in Malaysia, Brunei, and Kalimantan in Indonesia. The fruit is characterised by its fibrous yellow flesh, brown outer skin, strong distinctive aroma, and sweet-sour flavour [9, 10]. Previous studies have reported that M. pajang juice contains appreciable levels of carbohydrates, dietary fibre, and proteins, as well as bioactive compounds such as phenolics, carotenoids, and ascorbic acid. These constituents contribute to its antioxidant capacity and may help improve oxidative quality in food systems [9, 11]. Despite these favourable compositional and sensory characteristics, the utilisation of M. pajang juice in processed food products remains limited, and its application in soft candy formulations has not been reported.

The development of a fruit-based soft candy therefore represents a practical approach to expanding the confectionery application of this underutilised fruit while maintaining consumer acceptance through a familiar product format. Accordingly, this study aims to develop a soft candy formulated with M. pajang juice, optimise its formulation based on sensory evaluation, and evaluate its proximate, physical, and bioactive characteristics, including total phenolic content (TPC) and antioxidant activity. The findings are expected to demonstrate the feasibility of incorporating M. pajang into confectionery products in accordance with the Food Regulations 1985 for sugar confectionery, while supporting value-added utilisation of this fruit and its potential contribution to oxidative quality attributes in confectionery applications.

Materials and methods

Preparation and formulation of candy with M. pajang juice

The formulation of soft candy containing M. pajang juice was developed based on the method reported by Rochmawati and Ermawati [12], with appropriate modifications to suit the objectives of the present study. Four formulations (F1–F4) and a control formulation containing only pectin without sugar were designed by varying the concentrations of sugar and pectin to determine their effects on the sensory attributes, acceptance, and quality characteristics of the soft candy, while the other ingredients were kept constant. All ingredients were weighed and measured using an analytical balance (GR-200, A&D, Tokyo, Japan) according to the specified formulations presented in Table 1, with quantities expressed as percentages (%, w/w). Pectin and agar were dissolved in M. pajang juice and heated at 100°C for 10 min using a hotplate stirrer (Isotemp, Fisherbrand, Waltham, MA, USA) at 300 rpm, with continuous stirring until a homogeneous mixture was obtained. The mixture was then cooled to 40°C and stirred until thickened. Sugar, glycerine, sodium benzoate, and citric acid were then added sequentially and mixed until homogeneous. The resulting mixture was poured into silicone moulds with uniform square cavities and placed in a chiller at 4°C until fully set, as shown in Figure 1a. The solidified candies were subsequently removed from the moulds and air-dried to remove excess surface moisture, as shown in Figure 1b. The candies were then coated with icing sugar to prevent sticking and stored in airtight glass containers under dry conditions until further analysis. The same procedure was applied to all formulations.

Table 1. Formulations of soft candy prepared with Mangifera pajang juice (%, w/w).

Ingredient	Control	F1	F2	F3	F4
Fruit juice	87.00	87.00	87.00	87.00	87.00
Sugar	0.00	3.70	3.90	4.10	4.30
Pectin	4.90	1.20	1.00	0.80	0.60
Agar	1.70	1.70	1.70	1.70	1.70
Glycerine	6.00	6.00	6.00	6.00	6.00
Sodium benzoate	0.30	0.30	0.30	0.30	0.30
Citric acid	0.10	0.10	0.10	0.10	0.10

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Figure 1. Soft candy samples. (a) Samples during moulding and (b) after air-drying.

Results

Physical characteristics analysis of soft candy formulations containing M. pajang juice

Physical characteristics analysis was conducted on the control soft candy and the selected formulation, F2, with significant differences (p < 0.05) observed in colour attributes. Colour measurements showed clear differences between the two formulations, as summarised in Table 4 and visually illustrated in Figures 2a and 2b. The control sample exhibited significantly higher L* values, indicating a paler and more opaque appearance, whereas formulation F2 displayed lower L* values and appeared darker. In addition, formulation F2 showed significantly higher a* and b* values compared with the control. These results indicate that formulation F2 possessed a more intense and saturated colour profile than the control formulation.

Table 4. Colour attributes of control and F2 soft candy formulations prepared with Mangifera pajang juice.

Colour attributes	Control	F2
L* (lightness)	30.93 ± 0.20	26.42 ± 0.30*
a* (redness)	15.13 ± 0.35	18.67 ± 0.16*
b* (yellowness)	39.87 ± 0.76	43.57 ± 0.65*

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Values are expressed as mean ± standard deviation (n = 3). *: Indicates a statistically significant difference (p < 0.05) as determined using an independent-samples t-test.

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Figure 2. Visual colour comparison. Soft candy formulations (a) control and (b) F2.

Texture profile analysis further revealed significant differences (p < 0.05) in chewiness, cohesiveness, hardness, and springiness between formulations, as shown in Table 5. The control formulation exhibited higher chewiness, cohesiveness, hardness, and springiness than formulation F2, while formulation F2 showed lower values for all measured textural parameters. These results indicate that formulation F2 possessed a softer and less elastic texture compared with the control formulation.

Table 5. Texture attributes of control and F2 soft candy formulations prepared with Mangifera pajang juice.

Texture attributes	Control	F2
Chewiness (g)	1,434.461 ± 140.136	797.083 ± 199.625*
Cohesiveness	0.496 ± 0.014	0.372 ± 0.041*
Hardness (g)	4,438.645 ± 113.592	3,802.676 ± 22.572*
Springiness	0.652 ± 0.060	0.556 ± 0.082*

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Values are expressed as mean ± standard deviation (n = 3). *: Indicates a statistically significant difference (p < 0.05) as determined using an independent-samples t-test.

Discussion

The superior sensory performance of formulation F2 reflects the influence of formulation composition on consumer perception. Although all formulations contained the same proportion of M. pajang juice, differences in appearance were evident, likely due to variations in pectin and sugar concentrations that affected gel clarity and surface uniformity during heating and cooling [20, 21]. The lower appearance score observed for the control formulation may be attributed to its higher pectin content, which can produce a more opaque or hazy gel structure. In contrast, the clearer and more uniform appearance of F2 suggests that an appropriate balance between gelling agent and sweetener enhances visual appeal, which is an important determinant of initial consumer acceptance [22]. The lack of variation in aroma among formulations may be explained by thermal processing during candy preparation. Heat treatment can reduce volatile aromatic compounds naturally present in M. pajang juice, leading to lower aroma intensity in the final product [23]. Additionally, hydrocolloids may partially mask fruit aroma, resulting in only subtle sensory differences perceived by panellists [24].

Texture-related attributes showed clearer differentiation among formulations, with F2 receiving higher scores. This finding is consistent with the role of pectin and sugar in determining gel firmness, elasticity, and cohesiveness [25]. Excessive pectin can produce a harder and less desirable texture, whereas insufficient pectin combined with high sugar levels may yield a softer and less structured gel [26]. The balanced texture of F2 likely contributed to its favourable mouthfeel and overall sensory performance. Taste and mouthfeel appeared to be the attributes most strongly influencing overall acceptance. The higher scores for F2 suggest that the formulation achieved a desirable balance between the natural sourness of M. pajang juice and the sweetness imparted by added sugar. In contrast, the control formulation showed a more pronounced sour taste, which may have reduced acceptance, while formulations with higher sugar content may have been perceived as overly sweet by some panellists [27]. Overall, the consistently higher sensory scores for formulation F2 indicate that consumer preference was driven by a balanced combination of appearance, texture, mouthfeel, and taste rather than by a single dominant attribute. These findings support the selection of formulation F2 for subsequent proximate, physical, and bioactive analyses.

The higher moisture content observed in formulation F2 reflects the influence of formulation composition, particularly the presence of added sugar and the reduced pectin concentration. Sugar exhibits hygroscopic properties that enhance water retention, while lower pectin levels result in a weaker gel network that is less effective at binding water [28]. However, the moisture contents of both formulations were within commonly reported values for soft candies. According to Gunes et al. [29], moisture levels typically range from 10% to 20% for jelly or gummy products, 7% to 8% for harder candies, and 3% to 6% for aerated toffee-type products. The moisture levels observed in the present study were therefore consistent with those commonly reported for jelly-type confectionery products. Ash content followed a similar trend, with formulation F2 exhibiting a slightly higher value than the control. This increase may be attributed to the combined contribution of minerals naturally present in M. pajang juice and those introduced through added ingredients such as sugar, pectin, and agar. Although ash content provides an estimate of total mineral content, the values obtained in this study were within the range reported for confectionery products. For comparison, Sahlan et al. [30] reported ash contents ranging from 0.04% to 0.54% in honey hard candy, while Meilianti et al. [31] reported values of 0.27% to 0.56% in beetroot jelly candy. The higher moisture and ash values in formulation F2 relative to the control may reflect the use of fruit juice as a major formulation component, which can contribute both water and naturally occurring minerals to the final product. These findings suggest that formulation adjustment may be required to align the product more closely with conventional confectionery quality expectations.

Crude fat content was low in both formulations, reflecting the naturally low lipid content of M. pajang pulp. This observation is consistent with previous reports indicating that lipids in M. pajang are primarily concentrated in the seed kernel rather than the fruit flesh [32, 33]. Similarly, crude protein content showed only minor differences between samples, which may be attributed to dilution during juice preparation and the effects of thermal processing during candy production, which can reduce protein stability at elevated temperatures [34, 35]. In contrast, crude fibre content, as determined by the AOAC proximate method, differed markedly between formulations, with the control exhibiting a substantially higher value than formulation F2. This difference is directly related to the higher pectin content in the control formulation. As pectin contributes to the measured crude fibre fraction, increased pectin levels may elevate the recorded fibre content while also influencing gel strength and texture, which may explain the firmer structure observed in the control sample [36]. Carbohydrate content and energy value were higher in the control formulation than in formulation F2. This may be associated with the lower moisture content of the control, as carbohydrate content was calculated by difference and is therefore influenced by the proportions of moisture, ash, fat, protein, and fibre. In contrast, the higher moisture level in F2 may have reduced its apparent carbohydrate proportion. The higher calculated carbohydrate content of the control likely contributed to its greater energy value, as energy is commonly estimated using Atwater conversion factors for macronutrients [37]. Despite these differences, both formulations exhibited caloric values that were comparable to or lower than those commonly reported for soft candy products, which often exceed 300 kcal/100 g [30, 38]. This suggests the potential for the development of confectionery products with moderate energy density while still incorporating fruit-based ingredients. Overall, these findings demonstrate that formulation composition plays a critical role in determining nutritional characteristics and highlight the importance of balancing sugar and hydrocolloid levels to achieve acceptable quality, stability, and nutritional profiles.

Colour differences between the control and formulation F2 can be attributed to formulation composition and thermal processing. The darker appearance of formulation F2 is likely associated with the presence of added sugar, which promotes non-enzymatic browning reactions during heating [39]. In addition, the higher redness and yellowness values observed in formulation F2 are consistent with the natural pigmentation of M. pajang flesh, which is rich in yellow pigments such as carotenoids [10]. The combined effects of fruit-derived pigments and heat-induced browning contributed to a more vivid and intense colour, which may enhance visual appeal and positively influence consumer acceptance, as colour is a primary determinant of initial product perception [40]. Textural differences further reflected the influence of formulation composition on gel structure. The higher chewiness and hardness observed in the control formulation indicate a firmer structure requiring greater energy during mastication. This behaviour is consistent with the higher pectin content in the control formulation, as pectin promotes the formation of a dense and well-organised gel network capable of trapping water and increasing rigidity [36]. In contrast, formulation F2 exhibited lower chewiness and hardness, resulting in a softer texture that may be preferred by consumers who favour easy-to-chew confectionery products [41]. Higher cohesiveness and springiness in the control sample suggest stronger internal bonding and greater resistance to deformation, while the reduced pectin content in formulation F2 produced a less rigid gel structure with lower elastic recovery [36]. Despite this reduction, the softer texture of formulation F2 aligns with the sensory preference observed earlier. The agreement between instrumental texture data and the sensory findings supports the selection of formulation F2 as the most balanced formulation in terms of physical and consumer-acceptable properties.

The higher TPC and antioxidant activity observed in formulation F2 indicate improved retention of phenolic compounds compared with the control formulation. Although both formulations contained the same proportion of M. pajang juice, differences in formulation composition, particularly sugar and pectin levels, may have influenced phenolic stability during processing. Sugar can contribute to the protection of phenolic compounds by limiting oxidative degradation, while excessive pectin may entrap phenolics within a denser gel matrix, reducing their extractability [36]. Previous studies have reported that M. pajang flesh, peel, and kernel are rich sources of phenolic compounds with strong antioxidant activity [42], supporting the elevated values observed in formulation F2. In addition, phenolic compounds are susceptible to oxidation and polymerisation reactions during processing and storage, which can lead to the formation of darker, high-molecular-weight pigments and a reduction in measurable phenolic content [43–45]. The present findings therefore suggest that formulation optimisation influenced not only sensory and physical quality but also the retention of bioactive compounds. Preservation of phenolic compounds is closely associated with antioxidant potential in fruit-based food products. These findings highlight the importance of formulation optimisation in preserving phenolic integrity and maximising antioxidant potential in fruit-based confectionery products, while also suggesting a possible contribution to oxidative stability within the confectionery matrix, although oxidation was not measured directly in this study.

This study has several limitations. First, sensory evaluation was conducted using untrained panellists, which reflects general consumer acceptance but may provide less detailed sensory discrimination than a trained panel. Second, oxidative stability was inferred from TPC and radical scavenging assays rather than being measured directly in the product. Third, shelf life or storage stability was not evaluated, and therefore the retention of bioactive compounds and antioxidant activity over time remains unclear. Furthermore, colour characterisation was limited to direct L*, a*, and b* measurements, and derived parameters such as ΔE, hue angle, and chroma were not calculated. In addition, antioxidant activity was reported as percentage inhibition for DPPH and ABTS assays, and Trolox-equivalent calibration was not performed, which limits direct comparison with studies reporting standardised units such as µmol·TE/g.

This study identified the optimal formulation of soft candy developed using M. pajang juice. Among the tested formulations, F2, containing 3.90% sugar and 1.00% pectin, showed the highest overall acceptance and demonstrated a favourable balance of sweetness, texture, and mouthfeel. The selected formulation also exhibited acceptable nutritional and physical characteristics, with high TPC and strong antioxidant activity. These findings demonstrate the potential of M. pajang juice as a value-added ingredient in fruit-based confectionery products. Future studies should focus on broader consumer evaluation, direct assessment of oxidative stability, shelf life and storage stability, expanded colour characterisation, and antioxidant standardisation using Trolox-equivalent units.