Characterization of continuous Hibiscus sabdariffa fibre reinforced epoxy composites

The influence of fibre orientation on physical, mechanical and dynamic mechanical properties of Hibiscus sabdariffa fibre composites has been studied. The composites with longitudinal (0°), transverse (90°) and inclined (45°) fibre orientation were prepared using the hand layup technique. ASTM standards were used for characterization of continuous Hibiscus sabdariffa fibre composites. The composite with longitudinally placed fibres yields improved mechanical characteristics. The addition of longitudinal (0°) oriented continuous Hibiscus sabdariffa fibres to the epoxy enhances tensile strength by 460%, flexural strength by 160% and impact strength by 603% compared to neat epoxy. The longitudinal (0°) fibre oriented composite offers higher resistance to water absorption and thickness swelling compared to other types of composites. All continuous Hibiscus sabdariffa fibre epoxy composites possess an improved storage modulus than the neat epoxy resin. The glass transition temperature of continuous Hibiscus sabdariffa fibre composites is 8%–31% lower than that of neat epoxy. Scanning electron microscopy (SEM) images confirm the existence of voids in the matrix, fibre pullout and crack propagation near the fibre bundle, which indicates the stress transfer between fibre and matrix is non-uniform.

Comparison of flavonoid content and antioxidant activity in calyces of two roselle varieties (Hibiscus sabdariffa L.)

Free radicals can cause various degenerative diseases such as cancer and cardiovascular disease. Flavonoids have antioxidant abilities that inhibit damage from free radicals. The roselle antioxidant mechanism is associated with high flavonoid content. Red and purple roselles are two varieties of roselle (Hibiscus sabdariffa L.) cultivated in Indonesia. The aim of this research was to analyze the differences in flavonoid content and antioxidant activity in the calyces of two varieties of roselle (Hibiscus sabdariffa L.), red and purple. Total flavonoid analysis and antioxidant activity testing were done by spectrophotometry in the visible region. Total flavonoid content was analyzed by pretreatment with aluminium chloride and sodium acetate. Antioxidant activity was tested with 2,2-diphenyl-1-picrylhydrazyl. The total flavonoids for both red and purple roselle calyces ethanolic extract were 27.55 and 39.18 mg quercetin equivalent per gram. The half maximal inhibitory concentration values obtained for both red and purple roselle calyces ethanolic extract a were 51.59 and 42.17 μg/mL. The total flavonoid content and antioxidant activity of purple roselle calyces ethanolic extract was higher and stronger than red roselle calyces ethanolic extract.

Extraction and Solubility Modeling of Anthocyanins Rich Extract from Hibiscus sabdariffa L. using Supercritical Carbon Dioxide

This study aimed to evaluate the extraction yield, and anthocyanins content of Hibiscus sabdariffa L. calyces extract using different temperatures (T) at 50 - 70°C, pressure (P) at 8 - 12 MPa, and modifier ratio at 5 - 10%.

ENHANCE THE QUALITATIVE SENSORY CHARACTERISTICS AND ANTIMICROBIAL ACTIVITY OF BOVINE MILK BY USING (Hibiscus sabdariffa)

Bovine milk is one of the richest nutrients that contain minerals and vitamins that enhance immunity, especially in children, but because many children do not want to drink the raw milk, therefore this study aimed to enhance the sensory characteristics of raw milk by using hibiscus plant extract, which is characterized by red color and distinctive flavor as well as studying the effect of aqueous extract of Hibiscus sabdariffa on inhibiting the growth of microorganisms, by using three concentrations of the aqueous extract (0.5, 1.0 and 1.5%), where the statistical results showed a significant difference (P≤0.05) between the concentrations in color, texture and general acceptance, and the best results appeared when using a concentration of 1.0%, while the results showed an insignificant difference in flavor values with different concentrations of the extract added to milk, Because the hibiscus plant, it is considered an acidic plant, which affected the degree of acceptance of the product. As for the inhibition of the growth of microorganisms, the results showed that the growth of microorganisms was inhibited after keeping in refrigeration for 24 hours, where the growth of the total number of bacteria was inhibited to (6 × 10-7), while we note a decrease in colon bacteria to (2 ×10-6) either Fecal coliform bacteria, the result showed a decrease in numbers to (2×10-4), then was noticed a slight decrease in numbers continuously after incubation for 7 days in the refrigerator, where the results showed a decrease in the total number of bacteria (1×10-7) and coliform bacteria (1×10-6) while for fecal coliform was (1×10-4).

Efektivitas Seduhan Teh Rosella Kering Terhadap Peningkatan Kadar Hemoglobin Pada Ibu Hamil

Berdasarkan data hasil Riset Kesehatan Dasar (RISKESDAS) tahun 2018, prevalensi angka kejadian anemia pada kehamilan di Indonesia sebanyak 48,9%. Faktor penyebab anemia pada ibu hamil adalah karena kekurangan zat besi dalam tubuh. Salah satu upaya untuk meningkatkan penyerapan zat besi didalam tubuh yaitu dengan cara meningkatkan asupan vitamin C. Rosella (hibiscus sabdariffa) merupakan tanaman herbal dengan kandungan vitamin C yang tinggi 9 kali lipat dari jeruk citrus dan 10 kali lipat dari buah belimbing. Tujuan dari penelitian ini adalah mengetahui efektivitas seduhan teh rosella kering terhadap peningkatan kadar hemoglobin pada ibu hamil trimester II. Metode penelitian ini menggunakan Quasy Eksperiment dengan pendekatan non-equivalent control-group, Analisa data menggunakan analisis univariat, bivariat menggunakan uji t-test. Sampel dalam penelitian ini adalah ibu hamil trimester II dengan jumlah 20 responden dibagi menjadi 2 kelompok. Kelompok eksperimen diberikan seduhan teh rosella kering dengan dosis 115,2 mg/kgBB/hari sedangkan pada kelompok kontrol diberikan tablet Fe 1x1/hari. Setelah 14 hari, maka akan dilakukan pemeriksaan kadar hemoglobin kembali baik pada kelompok eksperimen maupun pada kelompok kontrol. Hasil uji t-test dengan taraf signifikansi α = 0,05 didapatkan ( p value = 0,045) pada kelompok eksperimen dan (p value = 0,046) pada kelompok kontrol dengan nilai rata-rata terjadi peningkatan kadar hemoglobin pada kelompok eksperimen sebanyak 1.070 gr/dl sedangkan rata-rata peningkatan kadar hemoglobin pada kelompok kontrol 0.900 gr/dl sehingga dapat disimpulkan adanya efektivitas seduhan teh rosella kering terhadap peningkatan kadar hemoglobin pada ibu hamil trimester II.