Ekstrak mengkudu (Morinda citrifolia) mempunyai kesan yang baik terhadap kesihatan. Namun begitu, pengambilannya masih terhad kerana rasa masam serta bau ekstrak mengkudu yang tidak digemari oleh pengguna. Penggunaan kaedah penyahasidan dan penambahan bahan perisa dilihat dapat mengurangkan rasa masam buah mengkudu tetapi kesan kepada ciri-ciri antioksidan masih tidak diketahui. Oleh itu, kajian ini dijalankan bertujuan untuk menentukan kesan penyahasidan dan penambahan 0, 4 dan 8% perisa lemon terhadap ciri antioksidan ekstrak mengkudu. Analisis yang dijalankan ke atas ekstrak mengkudu adalah penilaian nilai pH, ujian jumlah kandungan fenol (TPC), ujian penangkapan radikal bebas (DPPH) dan ujian kuasa penurunan ferik (FRAP). Hasil kajian mendapati bahawa nilai pH meningkat secara signifikan (p<0.05) setelah dinyahasid. Manakala, nilai TPC, DPPH dan FRAP ekstrak mengkudu pula menurun secara signifikan (p<0.05) setelah dinyahasid. Penambahan bahan perisa lemon ke dalam sampel ekstrak mengkudu ternyahasid, tidak memberikan perubahan signifikan pada nilai pH, TPC, DPPH dan FRAP. Secara keseluruhannya, rawatan penyahasidan membantu mengurangkan keasidan ekstrak mengkudu tetapi penambahan bahan perisa lemon tidak memberikan kesan signifikan kepada ciri antioksida ekstrak mengkudu.
Pepper (Piper nigrum L.) pericarp is an agriculture waste in the production of white pepper. It is underutilised agro-industrial waste which could be a promising natural source of cellulose. Hence, finding an optimum way to remove the non cellulose components without degrading the cellulose structure is essential. In this work, the effects of alkaline concentration (4, 5, and 6% NaOH) and number of soaking cycle (3 & 4 cycles) on the characteristics of cellulose from pepper pericarp were investigated. The obtained cellulose powder was characterized for its yield, α-cellulose content, particle size, zeta potential, morphology, whiteness index, crystallinity degree and thermal stability. The white powder cellulose after 4th cycle treatment with 4% NaOH appeared to have the highest yield (23.63%), α-cellulose (65.97%), crystallinity structure (51%) and better thermal stability at 334 °C. FTIR spectrum at band around 1732 cm-1 indicates a partial removal of non-cellulosic material at all alkalization condition due to the presence of remaining lignin and hemicellulose. These may contribute to formation of negative surface charge on all cellulose samples which may potentially enhance the functionality of the material as emulsifier. Based on two-way ANOVA test, concentration and cycle of alkaline treatment significantly (p<0.05) influenced the yield, particle size and zeta potential, meanwhile α-cellulose significantly influence by NaOH concentration only (p<0.05). The findings showed that manipulating the synthesis condition of cellulose powder influenced its properties which could be further used in various applications.
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