Pengaruh perbedaan waktu ekstraksi terhadap karakteristik kalsium Halimeda opuntia: The effect of different extraction time on the characteristics of calcium from Halimeda opuntia

Abstract

Halimeda opuntia adalah jenis alga hijau yang kaya akan kalsium karbonat. Metode ekstraksi kalsium dari H. opuntia terutama untuk durasi waktu ekstraksi masih belum optimal. Penelitian ini bertujuan untuk menentukan waktu ekstraksi terbaik kalsium dari H. opuntia melalui parameter kadar kalsium, warna, mikrostruktur, ukuran partikel, dan keberadaan gugus fungsi kimiawi. Metode yang digunakan dalam penelitian ini adalah Rancangan Acak Lengkap (RAL) satu faktor, yaitu waktu ekstraksi 1, 2 dan 3 jam. Ekstraksi yang digunakan, yaitu sol gel dalam larutan HCl 1 N pada suhu 90°C. Parameter yang dianalisis meliputi rendemen, kadar kalsium, air, abu, protein, warna, ukuran partikel, mikrostruktur (SEM), dan gugus fungsi kimiawi (FTIR). Hasil penelitian menunjukkan bahwa waktu ekstraksi berpengaruh nyata terhadap rendemen, kadar kalsium, abu, lightness (L*), redness/greenness (a*), yellowness/blueness (b*), ΔE, dan whiteness index (WI). Perlakuan terpilih pada waktu ekstraksi 1 jam dengan kadar kalsium tertinggi, yaitu 30,79±0,56%. Rendemen, kadar air, abu dan protein perlakuan terbaik, yaitu 24,11±0,57%, 3,36±0,56%, 81,76±0,36%, dan 0,90±0,10%. Nilai L*, a*, b*, ΔE, dan WI berturut-turut adalah 83,83±0,65; 0,34±0,05; 8,84±0,21; 13,01±0,48; dan 84,29±0,65%. Waktu ekstraksi yang lebih lama meningkatkan rendemen kalsium namun terjadi degradasi serta warna yang makin menguning. Analisis mikrostruktur perlakuan ekstraksi 1 jam menunjukkan permukaan menyerupai bola yang terlihat kasar dan tidak menggumpal dengan ukuran partikel seragam 3,25 nm. Hasil analisis gugus fungsi menunjukkan keberadaan kalsium karbonat dalam spektra FTIR H. opuntia teridentifikasi pada gelombang 1.407,1 cm-1 dan 872,2 cm-1. Waktu ekstraksi 1 jam dinilai optimal untuk mengekstrak kalsium dari H. opuntia.Halimeda opuntia is a type of green algae that is abundant in calcium carbonate. The extraction process for calcium from H. opuntia, particularly regarding the extraction duration, has not yet been fully optimized. This study aims to determine the optimal extraction time for calcium from H. opuntia by evaluating parameters such as calcium content, color, microstructure, particle size, and the presence of chemical functional groups. The method used in this study was a completely randomized design (CRD) with a single factor: extraction time with three treatments (1, 2, and 3 hours). The sol-gel method was used for extraction. The parameters were analyzed for yield, calcium content, moisture, ash, protein, color, particle size, microstructure (SEM), and chemical functional groups (FTIR). The results indicated that extraction time significantly affected yield, calcium content, ash content, lightness (L*), redness/greenness (a*), yellowness/blueness (b*), ΔE, and whiteness index (WI). The optimal extraction time was determined to be 1 hour, producing the highest calcium content of 30.79±0.56%. The best treatment also yielded values of 24.11±0.57% for yield, 3.36±0.56% for moisture, 81.76±0.36% for ash, and 0.90±0.10% for protein. The color parameters L*, a*, b*, ΔE, and WI were recorded as 83.83±0.65, 0.34±0.05, 8.84±0.21, 13.01±0.48, and 84.29±0.65, respectively. Prolonged extraction times increased the yield but caused a decline in calcium content and resulted in a more pronounced yellowish coloration. The sample that was extracted for one hour had a rough, spherical surface with particles that were not clumped together and were all the same size, 3.25 nm. FTIR analysis showed that calcium carbonate was present, with signature absorption peaks found at 1,407.1 cm⁻³ and 872.2 cm⁻³. We concluded that an extraction time of 1 hour is sufficient for efficient calcium extraction from H. opuntia