Quality Characteristics and Storage Stability of Guava Nectar Formulated with Natural Sweeteners.

Research background: Recently, extensive use of refined sugars and artificial sweeteners has led to negative health implications. Therefore, this study explores natural or unrefined sweeteners such as honey, date syrup and jaggery as potential alternatives due to their nutritional and therapeutic properties. Experimental approach: The study aims to optimize the amounts of honey, jaggery and date syrup to substitute the addition of sucrose for sweetness in guava nectar prepared using two processing treatments: hot filling and cold filling. The bioactive and rheological properties, mineral composition (in-vitro bioavailable iron) and storage stability of the nectar were further evaluated. During storage, the formation of 5-hydroxymethylfurfural (HMF), effects on antioxidant activity and non-enzymatic browning were monitored to assess changes in overall quality. Results and conclusions: The amount of sucrose substitution in guava nectar was optimized at mass fractions of 50, 25 and 30 % for honey, jaggery and date syrup, respectively, based on organoleptic properties. The optimized formulations showed a significant improvement in total phenolic content and radical scavenging activity. The guava nectar showed pseudo-plastic behaviour with a weak gel structure due to the dispersion of pulp particles, which contributed to its viscoelastic nature at low strain (<10 %). The substitution of sucrose with natural sweetener resulted in increased mineral content; however, the bioavailability of iron considerably decreased. During storage, degradation of ascorbic acid and colour, acceleration of non-enzymatic browning and development of 5-hydroxymethyl furfural were notably high by the end of the sixth month, but the formulations remained microbiologically stable. Novelty and scientific contribution: New products can be formulated using natural sweeteners instead of sucrose, which may offer higher nutritional and therapeutic value. However, in this study, the product could be improved by further research to reduce negative effects on quality characteristics during storage.