Development and Acceptability of Mature Coconut (Cocos nucifera) Water Naturally Fortified with Calamansi (Citrus microcarpa) Juice as a Functional Drink

Abstract

This study aimed to develop and evaluate the sensory acceptability and nutritional quality of mature coconut water (MCW) naturally fortified with calamansi juice as a functional drink, and to determine the most acceptable and cost-efficient formulation. A developmental research design using a single-factor formulation approach was employed. The study was conducted at the Surigao del Norte State University Food Innovation Center and Main Campus, Surigao City, Philippines, during the academic year 2025–2026. Three formulations of MCW were prepared with fresh calamansi juice at 0.1%, 0.3%, and 0.5% (v/v) — Formulations A, B, and C, respectively — while sugar and salt levels were held constant. Acidification and thermal processing were applied following the Hurdle Technology concept. A total of 120 respondents (100 general consumers and 20 food experts) evaluated the coded samples using a 5-point descriptive scale and a 9-point hedonic scale. Data were analysed using mean, standard deviation, and one-way analysis of variance (ANOVA) at the 0.05 level of significance. The most acceptable, cost-efficient formulation was submitted for nutritional analysis. All three formulations were described as having a light straw hue, a clear citrus aroma, a balanced coconut–calamansi flavour, and moderate sweetness. All sensory attributes were rated “Like Moderately,” except the composite appeal of Formulation A, which was rated “Like Very Much” (M = 7.56). ANOVA showed no significant differences in acceptability among the three formulations for any attribute (colour, P = 0.66; aroma, P = 0.06; flavour, P = 0.29; sweetness, P = 0.08; texture, P = 0.26; composite appeal, P = 0.11). Formulation A was selected for nutritional analysis on the basis of cost efficiency at comparable acceptability. By respondent profile, acceptability of Formulation A did not differ significantly by sex, nor by age for most attributes, but age showed significant differences for texture (F = 5.18, P = 0.02) and composite appeal (F = 4.07, P = 0.05), with older respondents giving higher ratings. Nutritional analysis of Formulation A (per 350 mL) showed 156 kcal, 0 g fat, 143 mg sodium, 37 g carbohydrates, 2 g protein, 5 mg vitamin C, 38 mg magnesium, and 514 mg potassium (26% of the recommended intake). MCW naturally fortified with calamansi juice is an acceptable, electrolyte-rich functional drink. Because the formulations were statistically comparable, Formulation A is recommended as the most cost-efficient option for further refinement, shelf-life testing, and possible commercialisation, supporting the valorisation of an underutilized coconut by-product.