Effect of Carrageenan and Glucomannan on Nipa Syrup Jellies and Their Potential for Development as Gelatin-Free Gummy Jellies

Abstract

Background and Objectives : Nipa syrup, a concentrated product derived from the sap of the nipa palm, contains a high total soluble solid content of 60-70 °Brix, making it often impractical for direct consumption. Therefore, development of new jelly products made of nipa syrup would enhance its practicality and convenience for consumption. The mixture of carrageenan (CG) and glucomannan (GM) as hydrocolloids has been shown to enhance the gel strength and improved water retention, thereby rendering them highly suitable for jelly and gummy jelly products. This study aims to evaluate the quality characteristics of nipa syrup and investigate chemical and physical properties, including sensory evaluation of nipa syrup jellies. Additionally, these plant-based hydrocolloids offer an alternative to gelatin-free gummy product. So, the potential of producing gelatin-free gummy jellies from nipa syrup was also studied to create a value-added product for today's consumers.

Methodology : Local nipa syrup was analyzed for pH, total acidity, total sugar, moisture content, total soluble solid, water activity (a_w), color values (L*, a* and b*), and  viscosity. Literature reviews and preliminary experiments were investigated to obtain nipa syrup-based jellies (data not reported). The resulting basic ingredients were composed of water, nipa syrup, sugar, brown sugar, citric acid and sodium citrate at 74.1%, 15.0%, 9.0%, 1.0%, 0.4% and 0.5%, respectively. CG and/or GM were added at 1% of the total mixture. The effect of CG:GM ratios (ranging from 10:0 to 0:10) on nipa syrup jellies was examined through chemical properties (pH value, acidity and moisture content), physical properties (color and texture) and sensory attributes. The texture profile analysis (TPA) was carried out using a texture analyzer, attached with a 10-Kg load cell. The textural properties of the jelly gel in parameters of hardness, springiness, gumminess and chewiness were calculated with the help of software provided along with the instrument. Assessment of sensory evaluations (appearance, color, odor, texture, taste and overall liking) by 30 panelists was performed employing a 9-hedonic scale ranging from 1 (dislike extremely) to 9 (like extremely). The optimal nipa syrup concentration (15-25%) was determined by analyzing chemical properties, color, and sensory attributes. The feasible production of gelatin-free gummy jellies was assessed by drying jelly gel at 60°C for 0-8 hrs. The dried gel was then analyzed of chemical properties and textural characteristics.

Main Results : The results showed that the pH value of nipa syrup was 5.21 with a_w of 0.80, and it consisted of 31.69% moisture, 1.26% total acidity, 28.09% reducing sugar and 78.27% total sugar with total soluble solid of 67.8 °Brix. The color values of nipa syrup were recorded as L* 56.41, a* 21.15, and b* 34.37, with a viscosity of 135.3 cPs. The ratio of CG to GM at 6:4 increased in hardness, springiness, gumminess and chewiness of nipa syrup jelly gel by using a texture analyzer. The sensory evaluations showed that the ratios of 6:4 and 8:2 were not significantly different (p ≥ 0.05) in overall liking, ranging from moderate to very much liked score assessed by sensory panelists. The jelly with 20.0% nipa syrup-based exhibited a pH of 4.06, 0.65% total acidity, 71.75% moisture content and color values of L*, a* and b* were 21.96, 2.62 and 3.97, respectively. In addition, the highest score of overall liking (7.73), ranging from moderate to very much liked was also obtained. Hot-air drying at 60°C for 6 hrs effectively reduced the moisture content in the gel, resulting in higher hardness, chewiness, and cohesiveness, while the pH and total acidity were stable. The drying gel demonstrated characteristics of gummy jelly with a chewy texture that was easy to bite and not excessively firm. This drying method demonstrates potential as a viable approach to produce gelatin-free gummy jellies from nipa syrup.

Conclusions : This research demonstrated that nipa syrup, derived from nipa palm sap, could be produced a nipa syrup-based jelly product with the two mixture of hydrocolloids, CG and GM. The value added nipa syrup jelly with CG and GM provided a stable structure and good textural properties. The gelatin-free gummy jelly was also possibly produced. The results showed that the local nipa syrup revealed a pH of 5.21, 31.69% moisture content, 28.09% reducing sugars, and 78.27% total sugars with a viscosity of 135.3 cPs. The jelly with CG:GM at a ratio of 6:4 provided a gel with desirable hardness, springiness, gumminess and chewiness, achieving the highest overall liking scores by panelists, ranging from moderate to high preference but not significantly different with a ratio of 8:2. The 20% nipa syrup in jelly  showed a pH of 4.06 and 71.75% moisture content with the highest overall liking scores. For the production of gummy jelly, hot air drying at 60°C for 6 hrs effectively reduced moisture content in gel and enhanced hardness, gumminess and chewiness, while the pH and acidity was maintained. These findings highlight the development of jelly and gelatin-free gummy jelly products to commercially add value to nipa syrup.