ABSTRACT BONIEACIO, ELAIZA T. Department of Resource Engineering and Agricultural Mechanization, College of Engineering and Computer Studies, Pampanga State Agricultural University, PAC, Magalang. Pampanga. August, 2022. "Natural Product Development of Microwave-Dried Star Apple (Chrysophyllum cainito) Leaves" Adviser: Dr. Mari RowenaC. Tanquilut Drying is a commonly used method to improve the quality and prolong the shelf life of medicinal plants. In this study, the application of microwave drying on star apple (Chrysopyllum cainito) leaves was investigated for natural product development. The effects of microwave drying at 900W on the drying rate, moisture content, rehydration ratio, and physical properties were evaluated with respect to the treatments used such as drying time (150 and 300 seconds) and number of layers (2, 4, and 6). A six-week storage period was observed for microwaved-dried leaves. Stored samples with silica gel keeps the moisture of the samples, however, samples without silica gel were affected by temperature and relative humidity as variations on moisture content were recorded. Treatment T2L1 (300 seconds and 2 layers) was found to be the best among the microwave-dried treatments based on sensory evaluation and data analyzed using Randomized Complete Block Design (RCBD) 2-Factorial Experiment with ANOVA and multiple comparison of treatment means using the Least Significant Differences (LSD) Test. Treatment T2L1 also gave a drying rate of 0.46 g/m²-sec, a moisture content reduction of 52.05%, better rehydration at 90°C, and good storage characteristics. Oral administration of C. cainito leaves (ethanolic extract) in acute toxicity test exhibited no mortality rate and is found to be non-toxic to ICR mice. Results on the Phytochemical Screening - Qualitative Thin-Layer Chromatography (TLC) using different spray reagents of C. cainito leaves have been reported to possess constítuents like flavonoids, steroids, phenol, tannins, anthraquinones, anthrones, higher alcohol, and essential oils. However, alkaloids and coumarins were found absent. The microwave-dried C. cainito leaves has been found to preserve its nutritional value with most panelists preferred product on tea bags. It costs PhP 115.00 for a pack of ten (10) with two grams each.