Development of Hydrogel-Type Jam with Chia (Salvia hispanica L.) Mucilage, Blueberry (Vaccinium corymbosum), and Cushuro (Nostoc sphaericum) ^†

Abstract

In Peru, overweight and obesity affect 20–38% of adults, increasing the risk of NCDs (type 2 diabetes, heart diseases, and others) that emphasize the need for healthy foods. Chia (Salvia hispanica L.) seeds contain high amounts of polyunsaturated fatty acid essentials (omega-3) (17–23%), antioxidants, proteins, and minerals that prevent NCDs. Chia grows in the regions of Arequipa and Puno–Peru, with 4098 tn of production in 2023. Chia mucilage is a soluble fiber with a high water-holding capacity that possesses the techno-functional properties that would improve the properties of gelification and emulsification of foods: jams, ice cream, yogurt, and others. Peru holds the N°1 position in the ranking of blueberry (Vaccinium corymbosum) exporters. This berry contains antioxidants and flavonoids. Cushuro (Nostoc sphaericum) is a gelatinous spherical blue-green alga; it grows over 3000 masl on the Peruvian highland, and it contains good protein and polysaccharide contents. The work aimed to develop a hydrogel-type jam with chia mucilage (0.05–1.00%), blueberries (36–40%), and fresh cushuro (54–60%), compared with a control sample containing pectin and sugar. The characterization of the hydrogel-type jam was moisture (79.53 ± 1.51%), ash (0.20 ± 0.01%), protein (1.02 ± 0.28%), total carbohydrates (19.05 ± 1.76%), fat (0.21 ± 0.03%), antioxidants (318.56 ± 61.5 µm Trolox/g), and phenolic content (2.43 ± 0.93 mg GAE/g). Then, after 30 days of storage, the °Brix (9.9 ± 0.3), viscosity (3921.62 ± 1373.19), pH (3.18 ± 0.02), and water activity (0.82 ± 0.5) values of the hydrogel type-jam complied with the Peruvian applicable legislation (NTP 203.047) and health law (No. 30021). The hydrogel’s functional properties could help reduce the percentage of NCD, promoting the food industry with healthy products.

1. Introduction

In contemporary times, the increasing awareness of the importance of a balanced diet has heightened interest in functional foods, which not only fulfill basic nutritional requirements but also contribute to the enhancement of overall health and well-being. This trend has emerged as a response to the global prevalence of non-communicable diseases (NCDs), such as obesity, which is linked to the excessive intake of saturated fats, sugars, and sodium [1]. With the rising incidence of overweight, there is a growing demand for healthier food products, thus driving innovation in the development of functional foods. Chia (Salvia hispanica L.), grown in the Arequipa and Cusco regions, Peru, is known for itsrich nutritional profile in omega-3 fatty acids, dietary fiber, and protein [2]. Cushuro (Nostoc sphaericum) is a cyanobacterium that performs as a microalga that grows in the marine environments of the high Andean areas of Peru (>3000 masl). It has a high protein and iron content [3]. Blueberries (Vaccinium corymbosum) are grown in the Lima and Cajamarca regions, and they contain significant amounts of antioxidants, vitamins C and B, and phenolic compounds, which are vital for mitigating the risks of NCDs. The objective of this research was to develop and characterize a hydrogel-type jam with chia mucilage, antioxidants from blueberries, and fresh cushuro.

2. Materials and Methods

2.1. Raw Materials

Cushuro (Nostoc sphaericum) was harvested in the department of Ancash, province of Huaraz, district of Churup at the Churup lagoon. The chia (Salvia hispanica L.) and the blueberry (Vaccinium corymbosum) were obtained at the local market in Lima.

2.2. Extraction of Chia Mucilage

The extraction was performed according to the method described by Castañeda-Cachay et al. [4] with some modifications. The chia seeds were hydrated at 80 °C with agitation for 2 h in a stirring hotplate to extract the chia mucilage (CM). The mixture was dried in an infrared dryer (IRC D18, Inconfort, Seville, Spain) for 24 h at 50 °C at the Laboratorio de Alimentos Funcionales of the Universidad de Lima—Peru, ground with a mortar and pestle, and stored in aluminized bags at room temperature for further use.

2.3. Hydrogel Development

Four samples with different amounts of CM were developed and compared with the control sample (pectin and sugar) (

Table 1. Formulations for the development of hydrogel-type jam (HJ) with chia mucilage, blueberries and cushuro.

Samples	Cushuro (%)	Blueberry (%)	Sugar (%)	Pectin (%)	Sweetener (%)	Chia Mucilage (%)
Control	54.55	36.21	9.21	0.03	-	-
HJ 1	59.39	39.57	-	-	0.03	1.00
HJ 2	59.76	39.91	-	-	0.03	0.30
HJ 3	59.64	40.17	-	-	0.03	0.15
HJ 4	59.41	40.51	-	-	0.03	0.05

). The cushuro and blueberries were weighed and separated into halves. The first half was liquefied and mixed with the second half (4 °Brix), then the mixture was cooked for 60 min at 90 °C (8 °Brix), the CM was added and cooked at 90 °C until the hydrogel-type jam (HJ) was obtained (11 °Brix). It was packaged, cooled, and stored in refrigeration (15 °C) until further analysis. The formulations complied with the Peruvian Technical Norm (NTP 203.047).

2.4. Optimization of Chia Mucilage Concentration

Chia mucilage (CM) was extracted using different chia:water ratios: CM1 (1:40), CM2 (1:30), and CM3 (1:20), with agitation at 200 RPM and 80 °C for 2 h according to Castañeda-Cachay et al. [4] with some modifications.

2.5. Viscosity

The viscosity property was evaluated 24 h after the samples were prepared according to Jeong et al. [5] with some modifications, using the Rheometer (MCR 92 Viscosimeter Anton Paar, Graz, Austria) with plate-plate geometry (50 mm diameter and 1mm gap).

2.6. Hydrogel-Type Jam Characterization

2.6.1. Proximal Composition

The proximal composition was determined according to official methods [6] with some modifications. The moisture content was determined at 110 °C to constant weight. The total protein content was determined as % nitrogen × 6.25 factor using a Kjeldahl analyzer (UDK 139, VELP, Usmate Velate, Italy). The ash content was determined by incineration at 600 °C for 14 h in a muffle furnace. The fat content was determined with hexane for 4 h. The measurements for the proximal assay were performed in triplicate.

2.6.2. Total Phenolic Content (TPC)

The total phenolic content (TPC) was determined by the Folin–Ciocalteau method [6], adding to each sample 4.5 mL of Methanol, 2.5 mL solution of 0.2N Folin–Ciocalteu, and 2.0 mL of 20% Sodium Carbonate. The absorbance of the samples was obtained at 760 nm using a spectrophotometer (UV 1280 Vis Spectrophotometer Shimadzu, Kyoto, Japan). The results were expressed as µg of Gallic Acid Equivalent (GAE)/g HJ. The analyses were performed in triplicate and presented as mean values ± SD.

2.6.3. Antioxidant Activity

The antioxidant activity was determined by the DPPH method [6] with some modifications at 517 nm by spectrometry (UV 1280 Vis Spectrophotometer Shimadzu, Kyoto, Japan). The results were expressed as µg Trolox/g HJ. The analyses were performed in triplicate and presented as mean values.

2.7. Sensory Analysis

The sensory evaluation was performed with 30 panelists using a 9-point hedonic scale from 1 (I dislike it very much) to 9 (I like it very much) with a mean value of 5 (I neither like it nor dislike it) according to Casquibol et al. [6].

2.8. Statistical Analysis

The results were expressed as mean ± standard deviation. All the measurements were determined in duplicate or triplicate. An analysis of variance (ANOVA), which was used to analyze data, was acquired at a 95% significance level with the Minitab 19.0 Software (Minitab Inc., State College, Palo Alto, CA, USA).

3. Results and Discussion

3.1. Optimization of Chia Mucilage Concentration

Chia mucilage (CM3, 1:20) showed the highest chia mucilage concentration, with an efficiency of 92.17%. The mucilage obtained was isolated and dried, and the moisture content was 8.27% and corresponded to 9.6% of the seed weight. Similar results were reported with Linum usitatissimum mucilage by Castañeda-Cachay et al. [4], at temperatures of 85 to 90 °C, with seed:water ratio(1:20),with an efficiency of 9.73%.

Table 2. Viscosity and Sensory Analysis of the Hydrogel-type jam (HJ) with chia mucilage, blueberries and cushuro.

Samples	Chía (%)	Viscosity [mPa·s]	Color	Smell	Texture	Flavor	General Acceptability
Control	-	657.13 ± 11.95 c	8.50 ± 0.52 a	8.50 ± 0.52 a	8.7 ± 0.48 a	8.5 ± 0.52 a	7.5 ± 1.08 a
HJ 1	1.00	563,578.5 ± 1497.94 a	8.1 ± 0.31 ab	8.2 ± 0.42 a	4.9 ± 0.56 d	5.2 ± 0.42 c	5.7 ± 0.94 b
HJ 2	0.30	512,377.05 ± 1514.44 b	7.8 ± 0.63 b	8.1 ± 0.87 a	3.9 ± 0.56 e	5.1 ± 0.73 c	6.3 ± 1.15 ab
HJ 3	0.15	369.49 ± 6.12 c	8.4 ± 0.51 ab	8.4 ± 0.51 a	8.0 ± 0.66 b	8.0 ± 0.66 a	7.4 ± 0.96 a
HJ 4	0.05	392.99 ± 6.98 c	8.0 ± 0.47 ab	7.9 ± 0.56 a	6.2 ± 0.41 c	6.9 ± 0.56 b	4.1 ± 0.73 c

The results are expressed as mean ± SD (n = 10). a, b, c, d, e values in the same column with different letters differ significantly when p < 0.05.

shows the results of the viscosity and sensory analysis of hydrogel samples. Sample HJ 3 was selected for its sensory characteristics which are very similar to the control sample, with an acceptability of 7.4 ± 0.96.

The viscosity of samples HJ 1 (563,578 ± 1497 mPa·s) and HJ 2 (512,377 ± 1514 mPa·s) were higher than control sample (657 ± 11 mPa·s) at a 95% level of confidence, and samples HJ 3 (369 ± 6 mPa·s) and HJ 4 (392 ± 6 mPa·s) were lower than control sample. HJ 3 scored (8.4 ± 0.5) for color, placing it in the same statistical group as the control., The acceptability of sample HJ 3 were statistical higher than other samples and it was evaluated with better sensory characteristics and similar to control sample.

3.2. Characterization

According to

Table 3. Proximal composition, antioxidant activity and total polyphenol content (TPC) of hydrogel-type jam (HJ 3).

Samples	Moisture [%]	Ashes [%]	Protein [%]	Fat [%]	Total Carbohydrates [%]	Antioxidants [µm trolox/g]	TPC [mg GAE/g]
Control	76.17 ± 1.11 b	0.14 ± 0.02 b	0.82 ± 0.12 a	0.10 ± 0.02 b	22.78 ± 1.03 a	265.02 ± 46.32	2.28 ± 0.74
HJ 3	79.53 ± 1.51 a	0.20 ± 0.01 a	1.02 ± 0.28 a	0.21 ± 0.03 a	19.05 ± 1.76 b	318.56 ± 61.50	2.43 ± 0.93

The results are expressed as mean ± SD (n = 3). a, b values in the same column with different letters differ significantly when p < 0.05.

, moisture (79.53 ± 1.51%) content was higher than the control sample. The protein (1.02 ± 0.28%) content was significantly higher than the control sample (0.82 ± 0.12%), showing an increase of 19%, very similar to the reported by Nduko et al. [7]. Ashes (0.20 ± 0.01%) and fat (0.21 ± 0.03%) were higher than the control sample, with a low carbohydrate content (19.05 ± 1.76%) besides the contribution of chia [2] and cushuro [3] respectively.

The antioxidant activity of the sample HJ 3 (318.56 ± 61.50 µm Trolox/g HJ) was higher than the control sample (265.02 ± 46.32 µm Trolox/g Control) due to the high content of antioxidants present in the blueberries (6.1–36.6 µm Trolox/g) [8]. The total polyphenol (2.43 ± 0.93 mg GAE/g dm) content was statistically higher than the control sample (2.28 ± 0.74 mg GAE/g dm); according to Diaconeasa et al. [8]. Figure 1 shows the results of the storage of the formulation HJ 3 during 30 days. pH values ranged from 3.18 to 3.52 similar to the control sample (3.15 to 3.44) complying with the Peruvian Technical Norm [9] (NTP 203.047) (pH 3.0 to 3.8). However, the °Brix (7.6–9.9) in the HJ 3 sample was lower than the control sample (24.3–24.9), it is lower than the established by the NTP (65 °Brix) [10], due the fact that stevia was used as sweetener instead of sugar. Viscosity values (395.73–3921.62 UNIDADES) were higher than control sample (654.26–1979.64 UNIDADES), due to the properties of gelification and emulsification from chia mucilage (Atik et al.) [2]. The values of the water activity (0.80–0.82) was similar to the control sample (0.78–0.80) according the formulation developed.

The developed hydrogel (HJ 3) presented an intense purple color and a subtle sweet aroma characteristic of blueberries. For the sensory evaluation, 73% of the panelists rated its acceptability with a score above six (neither like nor dislike). The appearance, taste, texture, color, and aroma characteristics of the selected hydrogel sample (HJ 3) had average values of 6.47, 6.43, 7.00, 7.80, and 6.20, respectively, on the hedonic scale.

4. Conclusions

Chia mucilage contribuyed with consistency and viscosity to the hydrogel, similar to commercial jams. The gelatin-like hydrogel made with chia, stevia, cushuro, and blueberries presented high protein (1.02 ± 0.28%), low carbohydrate (19.05 ± 1.8%), high polyphenol(2.43 ± 0.93 mg GAE/g HJ) and antioxidants (318.56 ± 61.5 µm trolox/g HJ) content. HJ 3 is a healthy alternative because it contains lower caloric content due to its low °Brix and carbohydrate content, therefore can be an important complement to the family diet to promote healthy nutrition.