RAW DATA-Charity Mutheu
Description
This research investigates the use of Kappaphycus alvarezii seaweed gel as a natural stabilizer and nutritional fortifier for passion fruit juice, which is naturally prone to phase separation (syneresis) during storage. Research Hypothesis The study is built on the premise that the hydrocolloidal polysaccharides (specifically κ-carrageenan) in Kappaphycus alvarezii will form a three-dimensional network capable of immobilizing water, thereby reducing syneresis and increasing viscosity in the acidic environment of passion fruit juice. Furthermore, it was expected that the seaweed's natural mineral and phenolic richness would enhance the juice's functional and nutritional profile. Data Collection and Methodology To test these ideas, the research followed a structured experimental process: • Preparation: Seaweed gel was prepared by cleaning, hydrating, and blending sun-dried Kappaphycus alvarezii. Fresh passion fruit pulp was extracted and concentrated to 11 °Brix. • Formulation: Four juice formulations were created with varying seaweed gel concentrations: 0% (control), 5%, 10%, and 15% (w/w). • Testing: The samples underwent several analyses, including: 1. Physicochemical: Measuring pH, Total Soluble Solids (°Brix), and titratable acidity. 2. Bioactive & Nutritional: Assaying total phenolics, flavonoids, and antioxidant capacity (DPPH and FRAP), as well as mineral content (Na, K, Ca, Mg, Fe, Mn, Zn). 3. Sensory: A panel of 30 consumers evaluated attributes like appearance, aroma, and overall quality using a 9-point hedonic scale. 4. Stability: Measuring viscosity with a rotational viscometer and syneresis through centrifugation, viscosity, TTA and syneresis over a period of 21 days. What the Data Shows: Notable Findings The raw data shows raw results before running the results in Minitab software. The results demonstrated significant improvements in both the physical and nutritional quality of the juice: • Dramatic Stability Increase: Syneresis was reduced by approximately 75% (from 66.78% in the control to 16.53% at 15% supplementation). • Massive Viscosity Boost: Viscosity increased from 3,667 mPa·s to 458,333 mPa·s, changing the juice from a thin liquid to a thick, structured beverage. • Nutritional Fortification: The 15% formulation showed substantial mineral levels, including calcium (172.64 mg/100 g) and iron (40.05 mg/100 g). Antioxidant capacity also increased significantly. • Consumer Preference: Despite the technical superiority of the 15% formulation in terms of stability, the 5% formulation received the highest sensory scores, as it balanced improved stability with the best flavor and aroma profile.
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Steps to reproduce
To reproduce this research on stabilizing passion fruit juice with Kappaphycus alvarezii seaweed gel, follow these established protocols, methods, and instrument settings as detailed in the study: 1. Raw Material Preparation • Seaweed Gel Processing: Fresh Kappaphycus alvarezii was sun-dried (30–32 °C for three days), cleaned with distilled water (20 °C) to remove debris, and washed under running deionized water for 5 minutes to reduce residual salts. The seaweed was then hydrated in distilled water for 30 minutes before being blended into a smooth gel using a laboratory blender. • Juice Extraction: Pulp from fresh purple passion fruits (Passiflora edulis) was manually extracted, passed through a muslin cloth to remove seeds, and gently heated with continuous stirring until it reached a concentration of 11 °Brix. • Formulation & Pasteurization: Seaweed gel was incorporated into the juice at concentrations of 0%, 5%, 10%, and 15% (w/w). All mixtures were pasteurized at 85 °C for 15 minutes to eliminate microorganisms and inhibit enzymatic activity. 2. Analytical Methods and Instrumentation Parameter Method / Protocol Instrument Used pH Standard procedure [8] using 1:1 dilution (w/v) with distilled water. Hanna Instruments HI 2211 digital pH meter. Total Soluble Solids (TSS) Direct measurement of drops on a prism, expressed as °Brix. Atago PAL-1 hand-held refractometer. Viscosity Rotational method at 25 ± 1 °C using Spindle No. 3 at speeds of 6, 12, 30, and 60 rpm. NDJ-4 rotational viscometer. Syneresis Centrifugation of 30g samples at 2400 rpm at 5 °C for 10 minutes. Laboratory Centrifuge. Antioxidants & Phenolics Folin–Ciocalteu method for phenolics; Aluminum chloride method for flavonoids; DPPH and FRAP assays for antioxidant capacity. UV–Vis spectrophotometer (Shimadzu UV-1900i). 3. Reagents and Software • Key Reagents: Standard buffer solutions (pH 4.0 and 7.0) for calibration, 0.1 N NaOH and phenolphthalein for titratable acidity, Folin–Ciocalteu reagent, 80% methanol, aluminum chloride, sodium nitrite, DPPH in ethanol, and potassium ferricyanide. • Statistical Software: Data analysis, including one-way and two-way ANOVA and mean separation using Duncan’s Multiple Range and Tukey’s HSD tests (p ≤ 0.05), was performed using Minitab statistical software. 4. Workflow for Stability and Sensory Testing • Stability Study: Finished juice samples were stored in glass containers at 4 °C for 21 days, with physicochemical parameters measured at 7-day intervals. Sensory Evaluation: 30 semi-trained panelists evaluated samples using a 9-point hedonic scale for quality (appearance, aroma, flavor, overall) and a 5-point scale for purchase intent. Samples were assigned random three-digi
Institutions
- Dedan Kimathi University of Technology