Sensory characterization, acceptance, and stability studies on low calories fruit jelly candies

Abstract

The objective of this work was to characterize and evaluate the sensory acceptance and stability of jelly candies with flavor of orange (OJC) or raspberry (RJC), and alternative sweeteners (isomalt, maltitol syrup, and stevia). A qualitative sensory study showed that among potential buyers (70% of 200 participants), the main associations were related to taste, sensations/feelings, health, and appearance. A sensory panel (80 participants) performed the rating of liking, and the sensory intensity assays, which showed that both candies were rated within liking categories by more than 70% of consumers, and that the taste attributes were categorized at the right point. Color and gumminess were rated in the just point for RJC, while for OJC, these variables deviated from the expected. Regarding sensory stability, a penalty study advised that bitterness/sweetness ratio, and color attributes should be improved in order to extend the candies´ sensory shelf life. Additionally, a trained sensory panel evaluated the textural changes during storage of the jelly candies. The sensory studies carried out on the novel jelly candies showed substantial interest from consumers, therefore, they could be considered an alternative to replace traditional sweets, offering a nutritional contribution from fruits, without artificial preservatives and added free sugars.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05747-7.

Introduction

Non-communicable chronic diseases, such as obesity, cardiovascular diseases and diabetes, are the cause of death for millions of people globally. Most of these diseases could be prevented by controlling behavioral risk factors such as diet (Lima et al. 2019). In this sense, the interest in research on natural products in the development of frequently consumed food has increased. Fruits represent an excellent source to replace artificial dyes, while providing different bioactive compounds (fiber, polyphenols, etc.), which highlights them as interesting ingredients due to their nutritional and potentially functional properties (da Silva et al. 2016). The improvement on diet´s quality is being implemented through different food products, within which the confectionery industry centers its focus on the substitution or reduction of sugars, artificial colors and flavors (Cano-Lamadrid et al. 2020). In the context of sugar replacement, many alternatives are actually applied and studied. Stevia is a natural sweetener of high sweetening power, which is used in the development of a wide variety of foods such as juices, drinks, jams, and dairy products (Arumugam et al. 2020). In high concentrations stevia can impart a bitter aftertaste that limits its use, however, it has shown a synergistic effect with polyols, which reduces the required amount of this compound (Heikel et al. 2012). The most widely used polyols in foods are sorbitol, xylitol, maltitol and isomalt (Martínez-Cervera et al. 2014).

It is important to consider that the application of natural or reduced-calorie ingredients may modify the product´s quality, affecting the sensory, textural and shelf life characteristics (Quitral et al. 2019). Candies with a gelled structure are among the fastest growing product groups (Gok et al. 2020), and are consumed mainly for pleasure by large and diverse populations (Altınok et al. 2020), therefore, modifying their composition can result in a generalized effect. In this sense, Lekahena and Boboleha (2020) reported that the substitution of sucrose with sorbitol caused significant physicochemical (gel strength, water content, acidity) and sensory changes (appearance, texture, color, and taste) in seaweed jelly candies.

In the context of improving confectionery products quality, the incorporation of fruit ingredients is also an actual challenge. There are several reports of jelly candies containing fruit constituents. Among them, Cano-Lamadrid et al. (2020) explored the consumer insights about jellies containing pomegranate juice and apple purée, and obtained relevant information for the industry about color and texture characteristics, and useful evidence to understand consumer preferences. Nishiyama-Hortense et al. (2022) applied grape juice as a bio-ingredient and natural dye in the preparation of the jelly candies obtaining good grape odor and flavor, and also high levels of anthocyanins which provided a uniform purple color. Teixeira-Lemos et al. (2021) developed two types of gummy jellies with acceptable sensory attributes, one containing orange juice (sweetened with honey), and the other containing a purée of a mixture of berries. These authors pointed out the need of more studies to understand the jelly candies’ stability over time, and to establish a proper and safe shelf life.

Contemplating this, the aim of this work was to perform sensory studies to evaluate the potential acceptance of jelly candies containing fruit components and alternative sweeteners, as well as to analyze the sensory stability of these novel products.

Materials and methods

Materials

Propolis was provided by the Gualeguaychú Beekeeping Cooperative (Entre Ríos, Argentina). The ingredients used to develop the jelly candies were acquired in the local market and were food grade. All the reagents used in the different determinations were analytical grade.

Ingredients development

Ethanolic extract of propolis (EEP)

EEP was incorporated to the jelly candies in order to inhibit fungal growth along storage. Five grams of raw propolis were weighed and the resins were extracted with water:ethanol (30:70) in a total volume of 200 ml, according to the method proposed by Archaina et al. (2015).

Freeze dried yogurt

The plain yogurt was frozen at − 24 °C for 48 h and dehydrated in a Labconco lyophilizer (Freezone 1, USA), at − 50 °C, and 0.040 mbar pressure (Archaina et al. 2019). The resulting product was ground to obtain a powder.

Raspberry powder

Frozen raspberries were thawed for 30 min at 40 °C, then they were processed with a commercial slow juicer (Peabody from Hurom PE-HSJO2, China). The obtained pulp was processed three more times and the remaining residue (skin and seeds) was discarded. Maltodextrin DE 20 was added (25% w/w) to the raspberry pulp in order to obtain a physically stable powder, and to preserve both nutritional and sensory (aroma and flavor) properties (Archaina et al. 2018). The mixture was dried using a Mini Spray Dryer Büchi B290 laboratory scale device (Flawil, Switzerland) according to Archaina et al. (2018), with the following parameters: inlet and outlet air temperatures of 170 °C and 70 °C, respectively, flow rate of 8 ml/min, air pressure of 3.2 bar and nozzle diameter of 1.5 mm. The powder was collected in a PVDC bag that was sealed and stored at − 20 °C.

Preparation of jelly candies

Figure S1 shows the flow diagram of the process used for the preparation of jelly candies. Two jelly candies of different flavor were developed: orange (OJC) and raspberry (RJC). An internal sensory panel composed of 16 persons who evaluated 5 variables (Watts et al. 1992; Moskowitz et al. 2012) defined the final proportion of the ingredients.

The manufacturing process consisted of mixing the following components: isomalt (OJC: 12.07%; RJC: 12.53%), unflavored jelly (OJC: 10.84%; RJC: 8.62%), stevia (OJC: 1.41%; RJC: 0.99%), and citric acid (OJC: 1.04%; RJC: 0.89%). Then, EEP was added (7.5%), and the mixtures were heated in a water bath until the ethanol was evaporated. Following, the liquid components were added: orange juice (OJC: 11.32%), or reconstituted raspberry powder (RJC: powder: 5.21%, water: 19.15%). Stirring was applied until total dissolution of solids was achieved, and maltitol syrup was added (OJC: 51.70%; RJC: 40.44%). Finally, yogurt powder (OJC: 4.02%; RJC: 4.57%), ethylmaltol (both candies: 0.05%), and fruit essences (OJC: orange essence: 0.05%; RJC: raspberry essence: 0.05%) were added, and the mixture was homogenized.

The formulations were poured into silicone molds and stored at 25 °C for 5 h. After this time, the jelly candies were removed from the mold and packed in transparent bags with hermetic closures.

Water content

The indirect method of AOAC 969.35 (AOAC 1970) was used. The results were expressed as g percent of water/100 g of sample, as the mean ± standard deviation of 3 determinations.

Water activity (a_w)

It was measured using a Rotronic HygroLab C1 water activity meter (Bassersdorf, Switzerland). Results were reported as mean ± standard deviation of 4 measurements.

Qualitative sensory analysis

The Word Association Task was employed (Ares et al. 2008). A poll (Figure S2) was distributed by e-mail and social networks. Participants had to express their opinions, ideas and sensations about each product, together with the purchase intention. Once the poll was done, a word cloud was created for each jelly candy through the Word Art website, representing the words used to describe the jelly candies (Fig. 1). Then, the words were grouped into different categories, independently determined by three researchers, and the frequencies of mention within each category were calculated (Archaina et al. 2019).

Fig. 1.

Clouds of words obtained from the results of the qualitative sensory analysis for the OJC (A), and RJC (B) jelly candies

Sensory stability studies

The candies were packed in hermetically sealed transparent bags and stored at 25 °C protected from light for 90 days. Sampling was performed at three storage times (0, 45 and 90 days).

Sensory assays with a consumer’s panel

80 adults (18–65 old-years) from the Facultad de Bromatología, Universidad Nacional de Entre Ríos (FB-UNER) constituted the consumer´s panel.

Rating of liking assay

The samples were presented randomly, and were coded with 3-digit numbers. All participants had to indicate the degree of liking of the jelly candies. A 7-point hedonic scale that varied from "Like very much" to "Dislike very much" was employed (Anzaldúa-Morales 1994).

Sensory intensity assay

Through this test consumers expressed the perceived intensity of the following attributes: color, gumminess, acid, bitter and sweet tastes. A 5-point JAR (Just About Right) scale ranging from "Much less intense than I like" to "Much more intense than I like" was used (Bruzzone et al. 2012).

Analysis of penalties

This study was performed to determine the degree of influence on global acceptability exerted by each attribute valued at lower and higher intensities levels than the right point. For this, the JAR scale was recategorized, the lower intensity levels were represented with "1", those at the just point as "2", and those above it as "3". A “critical corner” was established, delimited by the penalty degree (value = 1) and 25% consumers. Therefore, all those attributes that fall within the critical corner, have a negative influence on the product´s acceptance (Ares et al. 2014).

Sensory assays with a trained panel

The sensory profiling method (ISO 13299:2003, 2010) was applied to study textural properties of the jelly candies. This method consisted of two phases (described in the Supplementary material), the first one comprising the evaluation, selection and training of the candidates who joined the panel: 23 persons (15 women and 8 men; 25–65 years old), all members of the FB-UNER. The evaluation and selection criteria were carried out according to the standard (ISO 8586, 2012). The second stage was the analysis of the jelly candies.

Statistical analysis

The results were statistically analyzed by analysis of variance (ANOVA) to determine significant differences between the samples. The analysis of the means was performed using the Fisher LSD procedure at p < 0.05 and multivariate (PCA), the statistical analyses were done using InfoStat v. 2018 for Windows.

Results and discussion

Qualitative sensory analysis

Figure 1 shows the clouds of words obtained from the results of the qualitative sensory test for the OJC (Fig. 1A) and RJC (Fig. 1B). A total of 200 people participated in the test and they provided the following number of words for each candy: OJC = 285, and RJC = 284. Participants showed positive and negative associations for the two jelly candies. The main mentions for OJC were related to the acid taste, while the sweet taste predominated in RJC, possibly this is due to the fact that the evaluators associated the fruit observed in the image with the characteristics that memory has registered for those fruits. Giménez et al. (2021) suggested that intentions towards food are formed by attitudes originated from information stored in long-term memory, and specific information about the product.

Table 1 shows the frequency of mention of words distributed in 3 main categories, differentiated by the intention to purchase: "Buyers", "Possible buyers" and "Non-buyers". Also, each category was divided into sub-categories. Among “Buyers” and “Possible buyers” the main associations were related to Taste, Sensations/Feelings, and appearance. In the case of OJC the “Health” subcategory also gained importance. For OJC and RJC in the “Non-buyers” category, the sub-categories that received more mentions were “Taste” and “Artificial”. Nishiyama-Hortense et al. (2022) performed a RATA technique for the characterization of a jelly candy containing grape juice, and found that the good acceptance of the candy was related to the hedonic terms tasty, pleasant, interesting, attractive and fun.

Table 1.

Frequency of mention of words within the categories and sub-categories identified from the results of the qualitative sensory analysis

Categories	Sub-categories	OJC (%)	RJC (%)
Buyers	Taste	32.1	51.7
	Sensations/Feelings	20.7	17.6
	Health	19.3	6.9
	Appearance	15.0	19.3
	Others	12.9	4.5
Possible buyers	Taste	29.2	36.4
	Sensations/Feelings	25.0	30.5
	Health	9.7	–
	Appearance	31.9	19.5
	Others	4.2	13.6
No buyers	Taste	36.9	62.2
	Sensations/Feelings	10.6	–
	Artificial	20.1	37.8
	Appearance	21.8	–
	Others	10.6	–

The purchase intention test showed that the RJC candy was the favorite. This was probably due to the striking color provided by the raspberry fruit. In this sense, the main liking drivers found by Cano-Lamadrid et al. (2020) on pomegranate based jelly candies were: high reddish color and high brightness. The percentage of consumers who would buy the jelly candies was: RJC = 73%, and OJC = 54%. The preconception of the flavor motivated by recollections of previous contact with the fruits, definitely influenced the choice of whether or not to buy the jelly candy. On the other hand, the negative interest rates were relatively low (12–19%).

Rating of liking assay

The rating of liking assay of the two fresh (t = 0) jelly candies (Fig. 2, solid black line) showed that both candies were mainly rated within the categories of liking, being the percentage of consumers that liked the candies 73.8%, and 81.3% for OJC (Fig. 2A), and RJC (Fig. 2B), respectively.

Fig. 2.

Rating of liking during storage at different times at 25 °C. OJC (A); RJC (B). Scale: 1) Dislike very much; 2) Dislike moderately; 3) Dislike slightly; 4) Neither like nor dislike; 5) Like slightly; 6) Like; 7) Like very much. The lines correspond to the days of storage: 0 days (solid black line), 45 days (dotted red line), and 90 days (dashed blue line) (color figure online)

Sensory intensity assay

Figure 3 shows the percentage of consumers that perceived different degrees of intensity of the studied attributes of the fresh OJC and RJC candies (Time = 0).

Fig. 3.

Sensory intensity of the attributes for the jelly candies during storage at different times. Color (A), Gumminess (B), Sweet Taste (C) Bitter Taste (D), Acid Taste (E). Bars with small black and white squares: Much more intense than I like; Black bars: More intense than I like; Gray bars: Just as I like; White bars: Less intense than I like; and Oblique lines bars: Much less intense than I like (color figure online)

The color intensity (Fig. 3A) of the RJC was categorized as “Just as I like” by most of the consumers, while in the OJC candies, it was categorized as "Less intense than I like" by a 51.3% of the consumers. Regarding gumminess (Fig. 3B), the RJC candies was mainly rated in the right point, while for OJC the gumminess intensity was categorized as “More intense than I like” by more than 45% of the consumers. Concerning taste attributes (sweet (Fig. 3C), bitter (Fig. 3D), and acid (Fig. 3E)), it was observed that their intensities were mainly at the "right point".

Sensory stability

Variation of the intensity of attributes and global acceptability

Concerning the sensory intensity assay, Fig. 3 also shows the variation in consumers’ perception of the intensity of the studied attributes during storage at different times at 25 °C. The color attribute presented important changes during storage (Fig. 3A), which in the case of OJC could be related to the increase in intensity resulting from the darkening caused by non-enzymatic browning. According to Paravisini and Peterson (2019), the Maillard reaction is the primary mechanism of orange juice chemical deterioration, causing an effect on brown color generation. On the other hand, the RJC reached more than 70% consumers perceiving the candies as “Less intense than I like”, this loss of color possibly occurred due to the deterioration of anthocyanins in the RJCs. Anthocyanin pigments are unstable and may degrade during processing and storage of food, causing an impact on the product´s color (Chen et al. 2020).

The gumminess (Fig. 3B), showed different behaviors in the candies during storage. In orange candies it was observed that during the first 45 days the category “More intense than I like” prevailed, while that after 90 days the intensity of the gumminess was “Just as I like”. Instead, in RJC it was observed that during storage the category “Just as I like” prevailed, however after 90 days there was a more homogeneous distribution between the categories.

The sweet and bitter tastes (Fig. 3C and D) behaved in the opposite way during storage, observing a decrease in sweetness and an increase in bitter taste. These valuations could be related, since the increase/decrease of one can induce a contrary perception in the other, as described by Stampanoni (1993). On the other hand, the acidity (Fig. 3E) decreased in both formulations along storage time.

Regarding the rating of liking along storage, Fig. 3 shows that the global acceptability for OJC was little affected during storage (Fig. 3A). In the first two storage times the liking categories showed levels higher than 65%, predominating mostly "Like" at 0 days and "Like slightly" at 45 days; while only a 10% of consumers selected the category “Dislike slightly”. On the other hand, after 90 days of storage the category "Neither like nor dislike" predominated, and 17% of consumers selected the category “Dislike slightly”. In the RJC candies, the rating of liking decreased to a lesser extent, with a score being over 65% in the categories of liking at the end of storage, while that the categories of disliking did not exceed 15% during all storage.

Figure 4 shows the penalty based on the percentage of consumers who established deviations from the ideal point for different attributes of the jelly candies along storage. In Fig. 4A it is observed that OJC did not present penalties in the initial time, but the variations in taste caused a negative effect on the acceptability, penalizing them after storage. The decrease in sweetness and acidity, together with the increase in bitter taste, could contribute to 18% decrease in acceptability, reaching 50%. In the case of RJC candies (Fig. 4B), despite that their acceptability reached 80% at t = 0; the low acidity, the low color, and the high bitter taste were penalized by the consumers during storage, causing 14% decrease in acceptability comparing to the initial time.

Fig. 4.

Penalty of different attributes based on the percentage of consumers who established an upper (+ / Black) or lower (−  / Blue) deviations from the ideal point. The shaded area corresponds to the critical penalty corner. OJC (A), and RJC (B). Storage times (days): ● (0); ▲ (45) and ■ (90). Coding: S = Sweet taste, G = Gumminess, A = Acid taste, C = Color, B = Bitter taste (color figure online)

Based on these results, in order to improve the acceptability, it would be necessary to mask the bitter taste, which mainly comes from propolis, possibly increasing the sweet and acid tastes, but not decreasing the EEP content, because a reduction in propolis concentration could cause a loss in its inhibitory capacity, affecting the candies stability. A similar penalty analysis was conducted by Cano-Lamadrid et al. (2020) on pomegranate based jelly candies. Their results showed that the attributes that needed to be improved (higher intensities) in the jellies were pomegranate flavor, sweetness, hardness, and solubility.

Variation of the texture profile

Texture profile was analyzed through a trained panel which selected several categories during training. The ranges in which the candies remained during storage (taking the values from the reference scale proposed by Hough et al. (1994) were: (1) Hardness, between dambo cheese and unsalted peanuts (7–9.5); (2) Adhesiveness to palate, between margarine and jam (1–3); (3) Cohesiveness, between Arcor chewy fruit candy and raisin (8–10); and Elasticity, between two different gelatin desserts (11–15).

Regarding the hardness attribute, it decreased 0.2 and 0.4 units, for OJC and RJC, respectively. The adhesiveness the behavior was inverse, increases of 0.7 and 0.5 units were observed for OJC and RJC, respectively. Cohesiveness increased in OJC candies (0.20 units) and decreased in RJC candies (1.0 unit). Finally, the elasticity presented decreases in both formulations, 0.3 and 0.2 units for OJC and RJC, respectively.

Multivariate analysis

Figure 5 shows the principal component analysis (PCA) carried out to appreciate the groupings of the samples during storage, in which 82% of the total variation between the samples was explained. Standardized values of the water content (OJC: 28% at 23%; RJC: 34% at 30%) and a_w (OJC: 0.766 to 0.763; RJC: 0.821 to 0.812), texture, and sensory variables were used, and were represented within 4 quadrants resulting from the CP1 (57%) and CP2 (25%). Standardized values of the physical characteristics (a_w and water content), texture, and sensory variables were used, and were represented within 4 quadrants resulting from the CP1 (57%) and CP2 (25%).

Fig. 5.

Variation of sensory attributes and physicochemical characteristics studied through principal component analysis. Samples OJC (black) and RJC (blue). Storage time (days): ■ (0), ▲ (45) and ● (90). Water content (W_C), a_w, Color (C), hardness (TH), cohesiveness (TC), elasticity (TE), adhesiveness (TA), acidity (Ac), sweetness (S), global acceptability (GA), gumminess (G), and bitterness (B) (color figure online)

CP1 predominated in the grouping at the different storage times. At first (right side) OJC and RJC were characterized by higher values of a_w, water content, gumminess, hardness, elasticity, acidity, sweetness and overall acceptability. As time passed, the samples moved towards the quadrants on the left side, with more incidence of bitter taste and higher adhesiveness, accompanied by a decrease in other texture characteristics. Regarding color, which was the only visual attribute studied, it influenced differently each type of candy, increasing during storage for OJC and decreasing for RJC.

The overall acceptance of jelly candies was directly related to the perception of sweetness, acidity and elasticity. It also depended to a lesser degree on gumminess and water content. According to Kopjar et al. (2016), the water content significantly influences the structural quality of the jelly candies matrix. On the other hand, the acceptance was inversely related with the rise in bitterness and adhesiveness that increased throughout storage.

Conclusions

In the development of fruit jelly candies, a satisfactory replacement of traditional sugars was achieved, by combining polyols as loading sweeteners and stevia as enhancing sweetener. A combination of sensory analysis techniques allowed to describe several taste and texture attributes, and to evaluate the evolution of those features along storage. Also, hedonic studies identified the consumers´ expectations, the acceptance of the developed candies, and the purchase intention.

According to the qualitative sensory study, this type of candies could be positioned favorably in the market, placed as healthier options than traditional sweets made mainly with sugars, sugar syrups, and artificial colorants and preservatives. Furthermore, these findings were reaffirmed by the high acceptability perceived by consumers during quantitative sensory analyzes. The global acceptance of the jelly candies was directly related to the perception of the sweet and acid tastes, and inversely related to the intensity of the bitter taste. In this sense, the penalty study showed that some attributes should be improved in order to extend the sensory shelf life of the candies. The drop in liking over time was mainly caused by the intensification of bitterness, and the changes in color. Additionally, this study showed that the textural characteristics depended on the water content of the samples. This information indicates the need to perform changes in the reformulation and/or the packaging and storage conditions in order to delay the deterioration of the sensory quality. However, changes in formulation should not include decreasing the EEP content, because a reduction in propolis concentration could cause a loss in its inhibitory capacity, affecting the candies stability.

Supplementary Information

Below is the link to the electronic supplementary material.

Abbreviations

a_w

Water activity

EEP

Ethanolic extract of propolis

OJC

Orange jelly candy

RJC

Raspberry jelly candy

Authors contributions

RR: Writing–Original Draft; Methodology; Validation; Formal analysis; Investigation. DA: Validation Writing–Review & Editing; Investigation. NS: Resources; Visualization; Writing–Review & Editing. CS: Funding acquisition; Project administration; Writing–Review & Editing; Conceptualization; Supervision.

Funding

This work was supported by the Agencia Nacional de Promoción Científica y Tecnológica of Argentina (PICT 2019/01978).

Data availability

Data and material will be available upon request.

Declarations

Conflict of interest

All the authors certify that they have NO affiliations with or involvement in any organization or entity with any financial interest, or non-financial interest in the subject matter or materials discussed in this manuscript.

Consent to participate

As corresponding author, hereby I declare that the coauthors have accepted to be represented by myself, and are jointly responsible with me for the contents of this work. Neither this manuscript nor any other with similar content have been previously published or considered for publication by another journal. I also agree to transfer the copyright to Journal of Food Science & Technology in case of being published.