Optimisation and Quality Evaluation of Guava-Pineapple Fruit Leather

Lee, Kimberly Hui Ee (2026) Optimisation and Quality Evaluation of Guava-Pineapple Fruit Leather. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Fruit leathers are recognised as nutritious, shelf-stable snacks. However, limited research has explored the optimisation of guava–pineapple proportions in mixed-fruit leather and its consumer acceptability, even though both fruits are abundant in nutrients and bioactive compounds. This study aims to investigate the optimal guava-pineapple formulation for fruit leather using a simplex lattice mixture design and to evaluate sensory acceptance of the optimised guava-pineapple leather in comparison with single guava and pineapple leathers. Five formulations with guava-pineapple ratios (1:0, 0.75:0.25, 0.5:0.5, 0.25:0.75, and 0:1) were prepared with the addition of brown sugar, guar gum, and citric acid, yielding samples with total soluble solids content (TSS) of 34.83-41.60 °Brix and pH of 2.95-3.34. The fruit leathers were analysed for colour (L*, a*, b*, ΔE, C*, and h°), texture, physicochemical properties (TSS, water activity, pH, titratable acidity), chemical properties (moisture content, total sugar content, total reducing sugar content, ascorbic acid content, total phenolic content, total flavonoid content), and antioxidant properties [2,2'-azino-bis(3-ethylbenzothiazoline-6- sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP)]. Results showed that the guava-pineapple ratio significantly (p < 0.05) affected the gumminess, chewiness, ascorbic acid content (AA), total phenolic content (TPC), total flavonoid content (TFC), ABTS, and FRAP of the leather. The optimal formulation of the guava-pineapple leather was identified as 0.9699:0.0301, with a composite desirability of 0.8998, which yielded high gumminess of 4660.97 ± 1.126 N, chewiness of 4347.67 ± 104.221 N, AA of 112.45 ± 14.98 mg/100 g dry solids, TPC of 140.36 ± 1.56 mg GAE/100 g dry solids, TFC of 154.32 ± 10.97 mg QE/100 g dry solids, ABTS of 311.27 ± 14.43 mg TE/100 g dry solids, FRAP of 326.35 ± 10.02 mg FESO4E/100 g dry solids. The optimised guava-pineapple leather was then compared with guava leather and pineapple leather through sensory evaluation using a nine-point hedonic scale (appearance, aroma, taste, texture, and overall acceptability) and preference ranking. The guava-pineapple leather achieved high scores in aroma of 7.367 ± 1.299, taste of 7.633 ± 1.245, texture of 7.700 ± 1.119, and overall acceptability of 7.933 ± 1.081. Preference test confirmed consumer preference for the guava-pineapple leather with 67% over guava and pineapple leathers. This study demonstrates that the guava-pineapple leather possesses favourable nutritional value and sensory properties, highlighting its potential as a value-added functional snack product.